Got a few questions about putting some power in my 400, figured I’d tap some experience here. What I’m lookin for is a car that can run a low 13 quarter mile and run on 93 pump gas as it will be driven 3 - 4 days a week. I don’t want to get into the bottom half as it has no need of rebuilding, just not enough power. After the engine is built well, a variable 75 – 150 shot nitrous will probably be in the picture.
Current setup is a 400 with 4X heads, stock intake and carb, generic headers, TH-350 w/ stock stall converter to I’d guess, 2.93 gears. Engine is from some 70 model Pontiac, casting # of 9799914 code YD.
My thoughts were to get a good set of heads ( open to suggestions as to head # and amount of head work ) ported and polished with a set of roller rockers, maybe some roller lifters to, edelbrock performer intake and 750 carb. Also an electric water pump and fan to save some HP.
Edelbrock performer plus cam, read a few things about losing low end power with a cam that has more than 230 at 50. I don’t want a real rough idle, or to loose power on the low end.
B&M shift kit for the TH-350, not to concerned about the trans, when it turns loose I’ll replace with a well built one, stall converter at the same time. Eaton 3.55 posi for the rear, will 3.55’s fit in the same housing as the 2.93? Headers with some hooker comps or super comps, the generics are good nuff for now.
I’m open to suggestions on everything, the only concrete parts are running pump gas and at least a pretty smooth idle. Hoping for about 400 HP all engine. If anything looks unrealistic, feel free to say. This is my first pontiac, so yall might have to spell out a few things. Thanks for your help.
Quenton should be good at answering this for you, he helped me w my set up...also John Wallace had some pointers.. I sent you a private message w some of the info...too long for here...
First of all, I am assuming that we are talking about a 3200 Lbs. Firebird.
IMHO, it sounds like you have everything you need already, and you should be well into the 13's without any help other than a cam, gears and headers. (The 3.55 gears you are looking for will not fit the 2.93 differential carrier, though any gears you choose will fit into the rear end housing. You will have to buy a series 3 differential carrier, which you already plan to do.)
However, I'd strongly recommend that if you're going to give it a shot of nitrous, you re-think your position of not doing something with the botom end. Pontiac's stock cast rods are good, but they should be heat-treated, re-sized and held together with ARP rod bolts to hold up under the amount of horsepower you want. (It's the rod bolts that are usually the culprit!)
You are right about the cam - more than 230 at 50 will rob torque from the low end, but you can get it back with either some cam advance and/or by staying with the stock cast manifold. Repeated testing has shown that the stock cast manifold with a CR prepped Q-Jet out-performs all others up to about 5,500 - 6,000 RPM. (I'll try to post the link.) Use Rhoads lifters and you'll have a silky-smooth idle, even with a cam like that. No need for a roller cam if you're not looking any lower than 13.
Heads and headers will make the difference. The 4X heads are good heads to start with. They don't take a whole lot of work to get them where you'll need them, unless they are the small-valve, press-in stud variety. (These would be marked -1H or -3H somewhere on a boss above the left two spark plug holes.) Also, the 4X heads have a smaller exhaust valve than the earlier 400 heads, and require a little more work to flow better. Banshee is the head flow expert. You really would do well to abide by his suggestions about what heads to use and what to have done to them. Of course, if you are going to pay for as much work as you're proposing, you may as well cut to the chase and buy a set of 87cc E-Heads. E-Heads will also let you run a full point higher compression ratio without detonation.
For the exhaust, you can spend a lot of money on Hookers, or a lot less money on Hedmans. The Hedmans will perform as well, and fit better. Get an "X" pipe in there, and a little more of that bottom end will come back.
Pump gas, a smooth idle and over 450 HP is easy with a 400, even without the shot. Getting that to the road efficiently is another matter.
Bjorn's right ... I should have sent this as a private message!
Cliff Ruggles (SP) is the guy to send a Q-Jet to. I haven't sent him one yet, so I can not comment from first-hand experience. However, he is very well respected and gets a lot of accolades on the "Performance Years" Boards.
If you put that kind of meat behind a 10-bolt with 3.55 gears, expect to lay out some cash for some axles. You might be better off with some 3.73 or 3.90 gears, but you'll have to forget about cruising at anything over 65 MPH.
I've got a 10-bolt 3.55 behind a 455, and I prefer to have really bad 60-foot times with scorching trap speeds by running relatively skinny tires rather than upgrade to a 12-bolt or buying expensive axles. Pontiac's 10-bolt is stronger than most other rear ends of about the same size, but it still has its limitations.
Make sure you're building the motor for the type of driving you'll do 99% of the time, and not for the other 1%.
I know what ya mean about axels, friend of mine snapped one on his new Mach 1 with stock tires. Ford covered it with the warrenty, but he forgot to mention it happened at a drag strip.
I wasn't planning to go to serious with the tires or the axels. If something breaks I'll replace it with the best I can, and try not to break it again.
Like Q said , its depending on how you want to drive 99% of the time.... in my case I like to drive longer distances at higher speeds , usually I cruise at 85-90 or more , and like the 'passing ability'...I`m very happy w my power band...kicks down at 60-65,and just goes!i`m at 90 from 65 in no time...and I like the 14 mpg at 70....90 mph = 3000 rpms for me,60 mph = 2000 rpms... thanks again Q, for the help!
Guess if I could find a 12 bolt from a camero, might be something to consider. My 86 Silverado has a 4.10 rear, I have no problem at all with it less I try to go over 80. Not to many places around here to go much faster than that anyway, and I really wouldn't want to get a ticket tryin to find the top end on I-35, the police just wouldn't understand. :rolleyes: 99% for me would be between 0 and 80, I know me so I would have it over 100 occasionly or at the strip, that would be the 1%. Thats why I figured the 3.55 would be a good comprimise.
Hey, why dont you just get a 69 428 with stock 390 hp under rated of course, more like 410 hp and run that. that way you could drive it most of the time trouble free and still run well into the low 12's and 13's. I have one in a 66 gto and it will pull high 11's in the quarter and it is a huge car! All i did was put in a nice roller cam set up ported heads a pair of slicks, and kept the rest stock. My car has a 4 sp though so that makes a huge difference. good luck, and if you run nitrous, rebuild the bottem end or it will blow. trust me, been there done that.
How fast you want to go depends on one thing...$$$.
As Quenton stated, should go with checking the rods first and resizing. Scat rods or equivalent for NOS applications. Must have tight clearances on rings as well. I highly suggest building up the lower end AKA "bulletproofing" the lower end. Honestly, I build all my motors with aftermarket rods. Not that stock rods are bad, just thatI prefer not to throw a rod, drop a valve into my $1200 stock looking, ported Pontiac heads.
I HIGHLY recommend to anyone building or having a motor built to not scrimp on the shortblock. Top end (heads, intake and carb not as crucial initially) But make sure a valve job, guide clearance check and springs are replaced or checked.
Then after the motor is assembled and you run it for a few months and get tired of it, have Cliff tweak the carb (less than $300) and have the distributor recurved ($1-150) After that, 60 minutes to remove heads and intake for a $4-600 street/strip port work and port matched to intake. I highly recommend investing in a set of Ferrea valves at this point.
This "pump gas" issue is difficult to work around as there is only a handful of good heads in the 9 to 9.7 CR range without milling the crap off the decks. A 72 CC large valve head (12,13,16,48,62,670) will yield a 10 to 1 ratio. 64's are 87 CC but very expensive and would only get you 8.7 to 1. 6X-4's are 91 CC but you have to mill the behesus out of them...to maybe 82 CC just to get a decently responding motor. Milling can get expensive as you have to mill 4 sides to match the intake after 40 thousandths.
I say get the 72 CC heads, have them ported, sharp edges removed from chamber (reduces detonation factor) tweak carb and distributor and it is unlikely (possible, but unlikely) that you will have any detonation at 10 to 1. If so, blend with 104-110 octane.
I set up a 428 with milled #48 RA III heads at 66 CC which is just at 11 to 1. I did what I posted above and I do not have issues with 94 octane. If racing, I blend 20 to 30% just to be safe.
Electric water pump is better left out for now. maybe a 10-15 hp gain. Lets get the basics done first.
Rear gear..3.55 to 3.73. Eaton POSI I swear by..rebuildable if needed and very nice for the $$$. Aftermarket axles, Moser makes them..$250 pair. Rear gear, Jegs or Summitt sell the complete rering kit for a nice price. You can fine 8.2 BOP units on Ebay for $299 new. $140 less that catalog.
Top end, RPM intake, cam, lifters and springs. Rhoads will be fine as well. Cliff with Q-Jet without question. You need to tell him everything about the car and setup.
Headers can be 1-3/4 to 1-7/8 prefer 4 tube Headmans.
I posted on another similar issue today..before rhetoric sets in, read that too...Once you get the fun going with true tried avenues, then experiment with other heads and such.
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
Cliff Ruggles, 128 Lansdowne Dr. Coraopolis, Pa. 15108. No funds needed up front, I prefer to clean/evaluate/leak test the castings, then I can add up what is needed and provide an accurate price........Cliff
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
Quick note on nitrous: if your ring end gap is too tight (need to have around .025"), the ring will butt because of the heat, lock up in the cylinder and pull your top ring lands off. Do you know for sure that your ring end gap is this big? It could be on a stock engine but then again...
