I am now part of the Pontiac club. All of my family is from MI and a lot of my family worked for Pontiac years ago so it was fitting to get a Pontiac of my own.
I found a 1967 Firebird that the owner was advertising as a 6 cylinder car. I found out that he was decoding the VIN with a Camaro decoder and it was originally a 400 / manual transmission optioned Firebird. It had no engine or transmission so I began my hunt for a 400 to go back in it. To keep the car "pump gas" friendly, I found a factory 9799914 RAIII 4 bolt buildable shortblock and "15" casting heads with a highrise, single plane aluminum intake paired with an M21 transmission. The intake has no castings or brand on it but it looks very nice and well-made. Included in the deal was a set of .030 Silvolite pistons. What would be a good choice for a cam? I would be looking for driveability for long trips but a good sound at idle and a good match with the rest of the build. I will be running power brakes so vacuum will be important but the manual transmission can handle some higher lift.
I also picked up a posi 10 bolt rear for a 70 Firebird. I will move the leaf mounts in slightly to match with the 67 leafs but I noticed that I have 2 "links" that come down from the rear pan to the rear end. They are currently resting on the top of the rear end so I assume that the rear end has already been changed since there is nowhere to mount these. Can somebody please share some information on these? They almost look like trailing arms that, I assume, mount on the rear end.
Thank you for reading and any support is appreciated.
I've always preferred the 068 factory grind for a 400. You could have the heads clearanced for 1.65 rockers for more lift.
1968 400 Coupe, verdoro green, black vinyl top 1968 400 Convertible, verdoro green, black top 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver)
A '70 Bird 10-bolt will still be an 8.2". If that's what you want, great. If you never plan to run sticky tires, an 8.2 will probably be just fine.
But if you want a stronger 8.5" 10-bolt, you'll need a '71-'81 F-body rear. The 8.5 out of an X-body will bolt right up, without moving the perches. But, an X-body posi rear might be hard to find.
The Summit 2801 is probably the cheapest decent cam for your set-up. It's a higher lift version of an 068.
Would not recommend a single plane intake on a street 400. Either a stock iron Q-jet, or a Performer would be better for a mild street 400, providing more low & mid range torque. One of these 2 dual planes, along with a well built & properly tuned Q-jet, will provide MUCH better street manners on a mild street 400.
Would not use cast pistons, ESPECIALLY the "8-eyebrow" type. The SP L2262F are the cheapest decent 400 pistons.
I would not use those #15 heads. I'd go with 6x-4 heads. You can shave a little off and get the compression above 8.5:1. Or, you can run low 8's CR & run a Voodoo 262 cam, if you want a bit more cylinder pressure.
I'd have one piece stainless valves installed, along with bronze guides, and a GOOD complete valve job, done by a good head guy, with experience doing performance Pontiac valve jobs. 1.66 exhaust valves are just fine for street use. SI sells the short 1.66 exhaust valves. Part #6001SG.
The links at the rear end are the factory traction bars that came on 67's to control the wheel hop. 67's had single leafs and needed the traction bars. In 68 they went with multi leaf springs and staggered the shocks so they didn't need the traction bars. Generally, manual transmissions got 2 bars. Other cars got one bar. If you don't use those traction bars, somebody will want them. They just unbolt from studs under the rear seat. Mine are long gone.
I have to agree with oldschool about the mis-match of parts that you've assembled. Not that it's all bad but a lot of us have done the same thing and ended up taking them back out and spending more money (and time) buying more appropriate parts that work better together. It really is about all the right parts working together than about an individual part.
Thank you guys for all of the insight. I am about to start the engine build. I am looking for a reliability and longevity for a lot of traveling with the car. I did some more research and found that the "15" heads that I have are actually 1970 455 heads. They have already been worked and upgraded with screw in studs so I would like to run them. I am still not sure if the block will bore to .030 over yet but if it will, my machinist claimed that the silvolite pistons will help bring the compression down around 9:1. Wouldn't this make it more streetable for modern fuel? Also, If I run this combo, would the 068 or Summit 2801 cam still be the best fit? I will ditch the single plane intake and get a Performer instead. Im planning on using an EFI kit as well. Thanks again!
"...my machinist claimed that the silvolite pistons will help bring the compression down around 9:1..."
Those "8-eyebrow" 400 cast rebuilder pistons are said to sit well down in the cyl, since they have to stock 1.7" pin height. That, along with all the sharp ridges of the valve reliefs, will most likely cause detonation.
Most well known Pontiac engine builders will not use those pistons. The base 400 Pontiac piston is the forged SP L2262F, in the bore size you need. These have only 4 valve reliefs, very similar to the factory pistons, but have a 1.714 pin height, which will raise the piston top, in the cyl, by .014. An Ebay store usually has the best price, usually less than $350--or less than $400, with molly rings.
Better, lighter, forged pistons are available for about $500.
The #15 heads are said to have 87cc chambers. @ 87cc, with flat top pistons, a .030 over 400 Pontiac will have about 9:1 compression. I entered these numbers into the Wallace CR calculator, & came up with 8.99:1 CR.
400 + .030, 87cc heads, 6.7cc valve reliefs, .039 x 4.3 head gaskets, .005 deck height CR = 8.99
The Summit 2801 would be a decent cam for this engine, and about the cheapest available. If you want slightly more cam, a Lunati #10510312 might work for you.
Those pistons are not going to sit .005 in the hole unless you get the black decked. The last set I had installed were more like .026 ITH. That's going to bring your compression down to low 8s I would guess. Great for a blower or turbo motor but will most likely not get out of its own way. Plus if by chance it ever does detonate they will probably break into several pieces. I'm not a fan of cast Pistons( can you tell?).
Great information! The calculator seems like a very useful tool if I understood all of the figures. I will go with the suggested Speed Pro/TRW pistons once the block is bored and I know the size needed. I am really wanting to get to an optimal balance for performance, reliability, and efficiency with this build. With the transmission being manual, would I benefit more from a higher lift cam like the 2802, XE268, or XE274 rather than the 2801? I have also been considering the roller cam option for longevity and performance. What are your thoughts on this and suggestions for specific cams if possible? The pricing difference seems to be relatively slight by the time you compare cam, lifters, springs, hardware, timing set, etc so I would like to hear thoughts on this if the "upgrade" is worth it. Valve spring suggestions would be appreciated for the flat tappet options mentioned as well. As I mentioned before, I will be running the Fitech EFI kit with the Edelbrock Performer intake. Thanks again for all of the support and insight.
At least the 2801 recommends a 9.5 to 1 compression ratio.
1968 400 Coupe, verdoro green, black vinyl top 1968 400 Convertible, verdoro green, black top 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver)
"...would I benefit more from a higher lift cam like the 2802, XE268, or XE274 rather than the 2801? I have also been considering the roller cam option for longevity and performance. What are your thoughts on this and suggestions for specific cams if possible? The pricing difference seems to be relatively slight by the time you compare cam, lifters, springs, hardware, timing set, etc so I would like to hear thoughts on this if the "upgrade" is worth it. Valve spring suggestions would be appreciated for the flat tappet options mentioned as well.
At 9:1 CR, I would not use an XE cam.
The 2802 is not a bad cam. It is sort of higher lift version of a Pontiac 744 cam, which was used in some manual trans Ram Air engines. I had one in a '69 RA3 GTO. But it had over 10:1 CR, manual brakes, & 3.90 gears. If I was gonna try the 2802 today, in a 400, I'd use Rhoads Super Lube lifters.
I think a cam with around 220 intake duration @ .050 lift is big enuff for a mild street 400, unless you just want a lot of lope & higher rpm power. The Crower 60242, 60916, & Lunati 10510312 would all probably make decent cams. And the Crower Cam Saver lifters might be a good choice. For 1.6 installed height valve springs, the Crower 68404-16 springs are popular, for the bigger HFT cams. For the smaller cams, some recommend the Comp Cams 988-16 springs.
A good, complete Hyd roller cam set-up will cost at least $1000 more than a cheap HFT set-up, depending on which roller rockers you choose. But, if you wanna go that way, there are small roller grinds that will probably work good with your combo. KRE has an HR224, & an HR 230 that might work.
Thank you. Ill probably throw an order together this weekend.
TRW pistons w/ moly rings, Summit 2802 cam, Rhoads lifters, Crower 68404-16 springs, ARP hardware, FelPro complete engine gasket kit, Edelbrock performer intake, and the FiTech EFI kit. Would this move my compression into the mid 9's as recommended?
Would a factory spec Melling oil pump be suggested or is it encouraged to use a HV/HP pump?
Ill also have to buy a transmission and rebuild the rear end. What would be ideal for the combo? I have the opportunity to snag a rebuilt M20 or M21 for a good price. And with either transmission, what gearing would be best to use to keep it responsive in town but friendly on the highway?
"...TRW pistons w/ moly rings, Summit 2802 cam, Rhoads lifters, Crower 68404-16 springs, ARP hardware, FelPro complete engine gasket kit, Edelbrock performer intake, and the FiTech EFI kit. Would this move my compression into the mid 9's as recommended?..."
The static compression ratio is calculated using the numbers required to use the Wallace CR calculator. The ACTUAL numbers of the engine, AS ASSEMBLED, will determine the static compression.
Now, if you don't think you have enuff compression, and want more, you can go with one of the "steep ramp" cams. The most popular are the CC XE series & the Lunati Voodoo series. These cams are said to increase cylinder pressure & power. Many say the XE cams make noise because of the way they slam the valves shut.
The Voodoo lobes close the valves more gently, eliminating the noise. These cams are recommended for the low compression engines. Once you get up to 9:1 & over, then using one of these cams MIGHT get you into the detonation range, with low octane gas. If you decide to try a Voodoo, a 262 might work. But don't use Rhoads lifters with it. The Crower Cam Saver lifters might give a little insurance, since they splash a little extra oil on the cam lobes.
Well, can't get the Jegs link to work. But they have the best price I've seen for these lifters. Summit will probably match or beat it, if you prefer to order from them.
If you're going with the 2802/Rhoads, it might be good insurance to go with the "Super Lube" version.
"...Would a factory spec Melling oil pump be suggested or is it encouraged to use a HV/HP pump?..."
The Melling M54DS is the most popular Pontiac pump. This is what I've always used. For 455's, I always shimmed the relief spring slightly, to increase pressure just a bit. But, for 400's, most recommend using the spring they come with. This is supposed to provide near 60psi.
"...Ill also have to buy a transmission and rebuild the rear end. What would be ideal for the combo? I have the opportunity to snag a rebuilt M20 or M21 for a good price. And with either transmission, what gearing would be best to use to keep it responsive in town but friendly on the highway?..."
The later model 400 4-speed Birds came with either 3.23 or 3.42 rear gears. Have to go with what you can live with, for your highway speed driving.
If you go with the 8.2 BOP rear, you can choose a 3.36 ratio.
OR, if your budget can stand it, you can buy a Super T-10 with a lower 2.88 or 3.42 1st gear ratio. That way you could get by with less rear gear, like say 3.08, with a 2.88 1st gear, or a 2 series rear gear, with the 3.42 1st gear. Some say the 3.42 1st gear sets are weak. But they should be OK, with street tires.
Auto Gear in Syracuse ny sells an all new Muncie with 2.99 1st gear. That way you can pair it with a 3.08 or 3.23 rear and be able to highway cruise at reasonable RPMs
Auto Gear in Syracuse ny sells an all new Muncie with 2.99 1st gear. That way you can pair it with a 3.08 or 3.23 rear and be able to highway cruise at reasonable RPMs
May be exactly the same trans, but Midwest Muncie lists one with an Auto Gear case & a 2.98 1st gear.
You said you wanted a good idle and be able to travel a lot on the highway. I wouldn't go overboard on the cam. Seems people forget they get higher horsepower with bigger cams at the high rpm limit of their engine. Unless you're racing you won't be spending a lot of time at 6,000 rpm You need a cam that will give you good low end torque, good idle and good street manners, from the way you described your intentions with the car, a mild camshaft would give you that. I wanted the same when I built mine so I got a rather mild [for my build] cam. I have all the torque I need for climbing long hills on the highway and still plenty of power when I need it. I'm quite sure I could get another 50 HP out of this engine with a simple cam swap but I would sacrifice some of the low end torque and the 50 HP would be above 5,500rpm. As far as a roller cam, I lean towards them. Not for extra power that can come with an aggressive grind but for insurance against a flat tappet cam losing a lobe or more during break in. There has been a lot of new builds losing the camshafts during or right after break in. Some people blame the camshaft manufacturers and some the lack of good oil. When the oil manufacturers cut down on the additives a rash of cam failures followed. Proper break in with break in oil should alleviate this but it still happens. The roller cost a lot more than a flat tappet but pulling the engine and making repairs after a cam failure costs more. If you do go for a flat tappet set up make sure you use a lot of assembly lube and strictly follow the proper break in procedures. I agree with Oldskool, the Melling standard Pontiac pump is my choice. While mine was on the dyno it stayed at 65psi all the way from off idle to 6000 rpm. My opinion anyway.
Sorry to continue carrying the thread further and further but I purchased a really nice set of 670 heads for a nice price today. I got a set that was rebuilt from a guy locally for $250. They were built by a reputable Pontiac machinist that I was planning on using for my block but the seller bought a built 455 with flat top pistons so he could not use these 670s. I really like the idea of using these since they would be numbers correct down to the date code for my new bird. Now that I have decided against the Silvolite pistons and have to purchase new pistons anyway, could I achieve my goals with a dished piston? I would love to use this head and keep the engine "pump" friendly to at least premium fuel. I found that the dished pistons are available at +17cc here:
I am open to additional expense for valves, thicker head gaskets, machining, or other hardware to use these heads for originality. Obviously I still plan on upgrading to the Crower springs to match the cam since stock springs were used for the 670's recent rebuild but should I look at a different cam grind that would decrease cylinder pressure and help reduce detonation? I have read and read but cannot seem to find anybody with personal experience and specifics on their build with the 670 heads.
As far as a roller cam, I lean towards them. Not for extra power that can come with an aggressive grind but for insurance against a flat tappet cam losing a lobe or more during break in. There has been a lot of new builds losing the camshafts during or right after break in. Some people blame the camshaft manufacturers and some the lack of good oil. When the oil manufacturers cut down on the additives a rash of cam failures followed. Proper break in with break in oil should alleviate this but it still happens. The roller cost a lot more than a flat tappet but pulling the engine and making repairs after a cam failure costs more. If you do go for a flat tappet set up make sure you use a lot of assembly lube and strictly follow the proper break in procedures. .
Dont know about that I would contribute most of the camshaft failures to user/installer error and improper break in and also internet mythology. I dont know about the oil myth either. Think about how many cars and trucks are still on the road that have flat tappet cams and just get whatever oil in them durring an oil change. Mine has 285,000 and no problems and i just use cheap oil with no additives. But one thing for sure is make sure you use real Made in USA parts.
Auto Gear in Syracuse ny sells an all new Muncie with 2.99 1st gear. That way you can pair it with a 3.08 or 3.23 rear and be able to highway cruise at reasonable RPMs
May be exactly the same trans, but Midwest Muncie lists one with an Auto Gear case & a 2.98 1st gear.
Yes. You can deal directly with Autogear and customize it how u want it. It doesn't have to be the rock crusher. My local Pontiac club took a trip there. It's a nice organization. My plan is to replace my Muncie with their 2.98 1st gear unit. Will pair nicely with my 3.23 rear.
I would probably go with a Tremec 5 speed if the difference gets to be that slight. I can get a rebuilt M20 locally for $500. I'm lucky because I have American Powetrain about an hour away so I can buy direct. They are the group that puts the Tremec kits together for specific applications.
"...Now that I have decided against the Silvolite pistons and have to purchase new pistons anyway, could I achieve my goals with a dished piston? I would love to use this head and keep the engine "pump" friendly to at least premium fuel. I found that the dished pistons are available at +17cc here:
Can buy custom dish pistons, with a big enuff dish to lower your CR for pump gas. But DON"T buy those "hypercast" pistons !!! You need forged pistons, NOT cast. There have been a lot of problems with those pistons. And the top ring gap must be bigger than the 2nd ring gap, by quite a bit. I would not consider those pistons for any build. If you wanna use those heads, you'll just have to bite the bullet an buy expensive forged custom pistons with the dish you need.
I'd shoot for 9:1 CR, but definitely no more than 9.25. Some say 9.5 is OK. But why take a chance on possible engine damage, for just a small amount of power.increase ? There is an Icon piston with a 15cc dish. But that's not near enuff to get the 670 heads down to 9.5 CR or less, unless the chambers are enlarged to around 90cc or so
"...I am open to additional expense for valves, thicker head gaskets, machining, or other hardware to use these heads..."
DON"T use thicker head gaskets !!! You need to keep your quench distance down to as close to .040 as possible. If you were to use, say the Butler .045 thick gaskets, and had a deck height of .010, that would make your quench distance .055. Some say that as the quench distance approaches .050 & beyond, detonation becomes more likely.
Fel-Pro 1016 gaskets are .039 thick. So, if you can get the deck height down to between zero & .005, the quench distance will be OK. When using stock length rods, there are 2 ways to reduce deck height. (1) Cut the block decks down by machine. (2) Order pistons with a larger pin height(compression distance) . Custom pistons can be ordered with a larger pin height(distance from the center of the pin, to the top of the flat part of piston).
The cheapest custom pistons I know of are the Auto Tec/Race Tec brand. They'll be $500 + shipped. Some of the other brands, such as Ross, can be on up into the $700-$800 range, with pins & shipping. Butler is probably the best place to order, if you decide on Ross pistons, since they can help you order exactly what you need. But, they are $700 + pins + shipping.
There are other Pontiac engine builders who can order the Auto Tec pistons, and help you build correctly using the 670 heads. I'm not positive, but I think Paul Knippen can order the pistons. And he probably can supply most all the other info & parts you need.
The chambers in the 670 heads can also be opened up to decrease compression & become more pump gas friendly. You can get all the 670 head info you need on the PY site. There are several well known Pontiac engine builders who post there. One of 'em has also started his own Facebook page. He works at a machine shop in AZ, and has a LOT of Pontiac engine building experience. He goes by the name gtofreek--real name Paul Carter. He can probably provide all the correct info you need.
Paul has done a lot of interesting stuff. I really enjoy his posts over there. He is very detailed and precise.
1968 400 Coupe, verdoro green, black vinyl top 1968 400 Convertible, verdoro green, black top 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver)
"...I still plan on upgrading to the Crower springs to match the cam since stock springs were used for the 670's recent rebuild but should I look at a different cam grind that would decrease cylinder pressure and help reduce detonation?..."
The valves in the 670 heads may be longer. The Crower 68404-16 springs are for a 1.6" installed height. If your installed height is 1.7" , some recommend the Comp Cams 995-16 springs. The final installed spring height must be known, in order to select the correct springs.
Of course, the installed height can be adjusted slightly, by either machining the spring seats deeper, to increase installed height, or adding spring shims, to decrease the installed height.
If your final static compression is 9.5 or more, I'd definitely go with a cam which has more adv duration, to bleed off some of the compression, at lower rpm. BUT, a better way to do it, is to build it with 9:1 CR instead of 9.5:1.
The Pontiac 744 grind had 301/313 adv duration, if I remember correctly. And the 041 had 308/320 adv. Most aftermarket cams with this much adv duration have a lot more duration @ .050 lift, than the Pontiac cams.
The Melling SPC-3 is supposed to be a 744 clone, and the SPC-8 is supposed to be an 041 clone. Don't know exactly how close the actual specs are to the original Pontiac cams.
Lunati has an interesting version of the 744 cam. It has the 301/313 adv dur, but has slightly less dur @ .050 lift, and has a hair more total lift, than the Pontiac 744.
CC & Crower show less adv dur for their 041 clones. But, some say that can be due to measuring the valve opening & closing events at a slightly higher lift. And, Crane doesn't list the adv dur of their 041 clone. So, I don't know how much variation there is between all these 041 clones. May not be enuff to make any noticeable difference. If this is the case, then the Melling is cheapest, from an Ebay seller.
I don't think it is internet mythology that new oil does not have the same additives the old oil had. I could be wrong. I also have vehicles with flat tappets and they get whatever oil is on sale, but those engines were broken in over 30 years ago using oil that had a lot of zinc. Most modern cars are built with roller cams. I don't know about camshaft myths either but I do know, personally, of five flat tappet rebuilds that have had cam failures, four of those used comp cams. Could be all four did not use proper procedures, but I doubt it. I also know, personally, of more than five flat tappet rebuilds that did not fail. None of those were broken in with over the counter run of the mill oil, but with high end, high zinc break-in oil. I don't think it is the manufacturer's making bad batches of cams, although it's possible, I think it's the oil. I'm not saying if you have a flat tappet engine it will fail, just saying flat tappet engines have more cam failures than rollers.
Better safe than sorry. Add zinc! And my advice (if anybody cares): Don't buy fancy diesel oil or racing oil. Buy good quality regular oil and add zinc. Diesel oil has too much detergent. Racing oil has too little detergent.
Hey NNorton, I still run 670s on my 400, (built years ago). It may not help you much because I went the opposite direction using TRWs replacement for stock flat top pistons (.030 over) and running 1 oz of octane booster per 1.5 gallons of regular fuel. I only drive the car about once a month so am willing to pay the price in fuel to enjoy the throttle response etc. of the way we ran them in the 70s! The cam as I recall has an adv lift of 458 and adv duration of 292. The lobe sep is 112 . A mild cam, has a nice medium lope, tons of low end and still wants to pull pushing 6K. I know you all will say I'm crazy running 10:75+ to 1 compression, but this little car is "funner" than ##it to drive! Don't we all love the power of a pontiac!
That is great info. I hear so much about the 670 heads and with their prices still as high as they are I figured they have to be put to use out there. What octane booster are you using and how long have you been running your build this way?
Torco Accelerator is one of the best out there. It really works, unlike most of the parts store boosters, which only increase the octane by a few points, rather than whole numbers.
You can Google up lots of booster info. Some say the best way is to buy some racing gas to mix in with your pump gas. I've done it both ways. The Torco additive is more convenient.
Getting back to ya NNorton and to Oldskool, In my first build with this same set of 670s I ran a 67 GTO 400 in my bird. It was .030 over with 12 to 1 TRW pistons with (10.5 cc dome). I just used '104' octane booster. The gas was much better then, but I can't remember the mix, I remember with 12 to 1s though, if the gas was even one point lower or higher the engine was very sensitive to it. Now, with only 10.75 or so to 1, I can get away with the stuff I buy at the local parts store. Although I mix it way more than the bottle says. (Im sure their quoting a ratio for an average car with a little spark knock). Timing is important! Once you get the advance set just where you want, mix your fuel the same each time you fuel. I carry a little measuring cup and funnel in the trunk. Just ad the juice for the gallons you pump. I will check the brand I've been using and post it tomorrow.
I am also seeing a big variance between the Butler and Wallace Racing compression calculators. I like the idea of running the 15cc Icon piston that you shared. However, the Wallace calculator shows 10.55:1 while the Butler calculator shows 9.65:1 with all of th same information. I also spoke directly with Sealed Power about their L2262F .030 over piston, and their "specialist" told me that I would be at 9.98:1 with the 72cc heads and this forged flat top piston. It seems like the Sealed Power specialist and the Butler calculator provided very similar information but the Wallace calculator is almost a full point higher. I entered 4.150 bore, 3.75 stroke, 72cc heads, 15cc dish, .041 gasket, and .000 deck height on both calculators. Am I missing something here?
NNorton, I used the same set of 670 heads on both engines. Both were 400s, Both were .030 over. (Both with 4 speeds). The only difference was one used a 10.5 cc dome and one used a flat top and a different cam. On the 12 to 1 engine I ran a cam with adv lift of 467 adv duration of 313. The 10.75 engines cam was adv 458/ 292. The first engine had less in the way of street manners, especially in traffic. The booster I've been using (because its available in my small town) is 'HP plus super concentrated formula'. It says use the 12 oz bottle for up to 24 gallons. That's only half an oz per galion! Like I said, I use 1 oz to 1.5 gallons. Again, timing is the most important thing. Get as much advance as you can without a ping, then keep the fuel ratio the same. Octane alone does not make HP. I also try to keep the ponchos under 180 degrees. Stay cool man! Cme469
"... the Wallace calculator shows 10.55:1 while the Butler calculator shows 9.65:1 with all of th same information. I entered 4.150 bore, 3.75 stroke, 72cc heads, 15cc dish, .041 gasket, and .000 deck height on both calculators. Am I missing something here?..."
I got 9.59 CR on the Wallace calculator. I added 4.3 to your figures, for the head gasket bore size. If you leave the head gasket bore size box blank, it does show 10.55 CR. i think that explains the big difference.
Thank you Oldskool. That is exactly what I was missing.
Cme469, I appreciate you sharing your personal experiences on this.
So it appears that the options, now that we would be at 10:1 or less, would be to run the 670 heads but choose the pistons and cam very wisely. I am very interested in the flat top option simply because of the lesser cost for the forged L2262F pistons but I do want the motor to be very driveable on the street. I also would make that cost back quickly if I could avoid octane booster by running one of the dished Icon pistons below on pump fuel. I would also want to have plenty of vacuum for the power brakes. I also noticed that the Icon pistons come in a wide variety of dish volume. However, the compression distance seems to be very different on some. They offer the IC938 with 10cc @ 1.300, the IC891 with 14cc @ 1.720, and the IC889 that was suggested earlier with 15cc @ 1.490, which are very different than the L2262F @ 1.714. I do see that the IC9946 is also a 10.80cc dish @ 1.714 like the L2262F if that would be a suggested option.
Also, what would you guys suggest as an "ideal" cam choice with the L2262F @ 6.7cc with mixed fuel or the 14/15cc dished Icon pistons on premium pump fuel?
I cannot thank you guys enough for helping me out with all of the info.
Those pistons with a lot different pin heights are for engines with different stroke lengths & sometimes rod length. A stock 400 had a 1.7 pin height. It is common for aftermarket forged pistons to have slightly more, like 1.714 or 1.720. This is still for a 3.75 stroke crank & stock length 6.625 rods. It is said that many Pontiac pistons came .020 or a little more down in the hole. So, a larger pin height will put the top of the piston closer to the deck, without machining any off the block.
Those IC9946 pistons are not dish pistons. They have 8 valve reliefs, That is so they can also be used with the earlier heads, which need the reliefs in a slightly different location. 389 heads fall into this category. These are not as nice a piston as the dish & 2-relief forged Icons.
"...what would you guys suggest as an "ideal" cam choice with the L2262F @ 6.7cc with mixed fuel or the 14/15cc dished Icon pistons on premium pump fuel? "
I don't know what would be the "ideal" cam. But, a decent compromise, to me, would be a Summit 2802, with Rhoads original Super Lube lifters(if you can stand the ticking sound they make).
No, I don't have any dyno results or drag strip tests to prove any of these cams. I'm just going by the cam specs. Around 220 duration @ .050 lift, with a 112-114 LSA, is a decent cam for mid range power, good vac, and a decent idle.
When a cam gets up to around 230 dur @ .050, it loses lower end torque, vac, and the idle is a bit more lumpy, in a 400. So, to me, that makes an 041 clone too nasty for most 400's. And it puts the Summit 2802, about in the middle of the pack. The Rhoads lifters will give the 2802 more low end torque, more vac, and a smoother idle. Therefore the combination should have a slightly wider power range than any of the other cams listed, using regular lifters. And, the Crower 60243 will have the most top end power.
Now that I have my compression ratio dialed down to roughly 9.5:1 with the 670 heads, I will be looking to complete the build and order the parts. I know I will have some additional hardware and expenses for the springs, valves, gaskets, crankshaft machining, camshaft dialing, balancing, etc. I will be using an M21 4 speed transmission with an 8.2 BOP posi rear end with 3.08 gears.
Build with 670 heads:
1970 9799914 Block bored .030 over and decked to .005 (MotorWorks Machine $425.00) 1967 670 72cc Heads (MotorWorks Machine $375.00) SS Valves (Manley 11355-8 & 11364-8?) (Summit $296.94) Comp Cams 995-16 (1.7") or Crower 68404-16 (1.6") Springs (Summit $111.97) Stock Rods (Owned) IC891 14cc Dished Pistons (Jegs $537.99) 2802 Camshaft (Summit $72.97) Rhoads Super Lube Lifters (Summit $264.97) Comp Cams 2112 Timing Set (Summit $46.97) Comp Cams RPM1451-16 Roller Rockers w/ Magnum Pushrods (Summit $262.97) Edelbrock Performer Intake Manifold (Summit $289.55) Stock Exhaust Manifolds (Owned) 650 Holley (Plan to Upgrade to EFI Kit Later) (Owned) ARP 190-3609 Head Bolt Kit (Summit $83.66) ARP 190-6001 Rod Bolt Kit (Summit $72.10) ARP 194-5401 Main Stud Kit (Summit $78.28) Sealed Power 205640M-300 Re-Ring Kit (Summit $276.99) Assembly (MotorWorks Machine 3hrs @ $80 p/hr = $240)
Parts - $2,395.36 Labor - $1,040.00
Total - $3,435.36
Does this seem to correct the "Mis-Match" of parts from the initial post? Also what would be the estimated HP/TQ from this build?
It also appears that going with the Edelbrock 61599 aluminum heads would be something that I will consider as well:
1970 9799914 Block bored .030 over and decked to .005 (MotorWorks Machine $425.00) Edelbrock 61599 Heads (Summit $2,546.42) Stock Rods (Owned) Federal Mogul Premium Rebuild Kit (Summit $689.95) 2802 Camshaft (Summit $72.97) Rhoads Super Lube Lifters (Summit $264.97) Comp Cams 2112 Timing Set (Summit $46.97) Comp Cams RPM1451-16 Roller Rockers w/ Magnum Pushrods (Summit $262.97) Edelbrock Performer Intake Manifold (Summit $289.55) Stock Exhaust Manifolds (Owned) 650cfm Holley Carburetor (Plan to Upgrade to EFI Kit Later) (Owned) ARP 190-3609 Head Bolt Kit (Summit $83.66) ARP 190-6001 Rod Bolt Kit (Summit $72.10) ARP 194-5401 Main Stud Kit (Summit $78.28) Assembly (MotorWorks Machine 3hrs @ $80 p/hr = $240)
I will be using an M21 4 speed transmission with an 8.2 BOP posi rear end with 3.08 gears.
Good luck with that set up in TN. Hope it is flat where you live. A M21 has 2.20 first gear. with a 3.08. that put your final drive ratio at 6.7. You are going to burn some clutches.
I will be using an M21 4 speed transmission with an 8.2 BOP posi rear end with 3.08 gears.
Good luck with that set up in TN. Hope it is flat where you live. A M21 has 2.20 first gear. with a 3.08. that put your final drive ratio at 6.7. You are going to burn some clutches.
X2
An Autogear m20 with 2.98 1st gear would be perfect
I will be using an M21 4 speed transmission with an 8.2 BOP posi rear end with 3.08 gears.
Good luck with that set up in TN. Hope it is flat where you live. A M21 has 2.20 first gear. with a 3.08. that put your final drive ratio at 6.7. You are going to burn some clutches.
X2
An Autogear m20 with 2.98 1st gear would be perfect
I would like one of those with my 3.36. It would smoke some tires in 1 and 2 gear.