There are a lot of variables. The best ever all motors considered, some may say the RAV...
For the 400 back then (67-69) some may say the 670, 16 or the RA heads like the 97, 31, 96, 48 etc... there are just so many ways to go... it would depend on the motor, and what you expect from it.
For todays fuels, and usage, many would say the 6X4 is the hot ticket, but again, only if the rest of the motor is built with that head in mind, and it will not have the compression the older heads made..
So give us some more specifics, and some one like Quinton can answer you much better, than I can.
Any 2.11/1.77 head is great..6X and 5C are good baselines for starting. 1970 96's are good as well.
A very good alternative is the 67 670 head. Best intake flow and can be tweaked to RA specs by machining down the spring pad to accomodate stiffer springs 1.71" installed height..About 100# closed pressure, 210 open. I have done this with a set I have and used a 744 cam. The labor costs for machining the pads will run about $80.
Although the chamber size is 72cc which is too high for pump gas, my head recommendation will depend on your overall appliction and amount of use. You can use the 670 heads with a copper head gasket with a .063 thickness to reduce your overall compression.
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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.
First disclaimer: The following does not include Ram Air 2,4 or 5 heads, nor early 60's SD or 73 SD heads. We're talking "available" D-Port heads here.
Second disclaimer: These are my opinions!
The 5C is one of the best flowing heads in stock form. The 670 has the best flowing intakes, and if you have the combustion chambers opened up, you can get very streetable compression. Add a little valve unshrouding, exhaust bowl work and some port matching, and the 670 is a hard head to beat. (Of course, Tom is much more a porting expert than I, so he no doubt has additional hints.)
IMHO, the BEST heads in STOCK form - NO MODS - for today's pump gas would be:
326/350 Engine: 48 389/400 Engine: 64 428 Engine: 64 (with stock pistions, stock deck) 428 Engine: 96 (With flat top pistons and zero deck) 455 Engine: 96
My requirements are:
9.5:1 compression Big valves, and "Decent" flow. ("Decent" being a relative term for Pontiacs.)
Also know that for each of those heads listed above, there are alternatives, such as 12, 13, 16, 62 instead of 48; 7K3 instead of 96, 4X and 6X instead of 5C; etc. The 64 stands alone as the only high compression 455 head with large valves. There is also a 15 casting from 1970, which is essentially the same head with small valves. This head also appeared in 1968, but as a 400 small valve head.
For minor mods, like those listed above, the 670's would be great heads on any engine up to and including 428 CID, as long as the chambers are opened up accordingly. Most other heads (except for the 64's from 1970) would require milling to get the compression where it belongs.
For the same work, the best heads choices for a 455 would be 96, 5C and 4X, probably in that order
One place where Tom and I do not agree 100% is on head gasket thickness, and using it to alter compression ratio. I prefer cam timing changes.
I have not got that far with cylinder compression in relation to cam degree. HA! I like to not go to crazy with unshrouding, polishing and taking all the sharp edges out of a chamber unless/until the allocated budget is solidified.
Utilizing the increased head gasket thickness affords one the ability to initially use any 72-85 cc head without paying a guy like me $800 to unshroud, deburr, polish and radius to increase chamber volume.
I prefer, and this is my thinking...
Port the heads to 220-240 intake 180-200 exh (depending on app. and leave chambers alone. Either use a stock 6.7 cc piston and have the tops lathed to 14-16cc dish or go to custom Ross pistons. Hell, what is another $250 over forged TRW's? Ross is a better piece. I try not to mess with the chamber volume too much as I could use them on a 400-455 and with 30 hours of porting invested, I build my shortblocks based on the 4 sets of heads I have on hand and the chamber profiles of each. I have the 670's, 5C, 13's and RAII 96's I really like the 5C's that are in my black bird. I milled them to 80.5 CC and ported them to 260/220..and installed 1.77 exhaust. Aside from the heads, the motor is a basic .040 400, Torker II 850 Q-Jet, 3.55 gears and auto. Runs 12.60's on pump gas and a 245/534 110 Lunati installed 2 degrees retarded. The car initially ran 13.90's..With proper jetting, timing and other tweaking, I got the motor down to 12.60's with an additional 2 months and $400 The motor, all together cost me $3900.
There are alot of options and opinions and if you have unlimited funding, go spend the money on whatever you want. I say really think long and hard on what your overall goal is for the car and motor.
1. How long do you plan on keeping the car? 2. How much money do you have to spend? 3. How often will you drive car?
Based on those 3 questions, anyone can build you an engine. All you have to decide is what your overall goal is. You can get caught up real quick spending money on work or materials and have a piss poor running motor..IE Ross pistons, Crower rods, Meizere water pump, $1000 in chrome and aluminum pulleys, a junk, untuned carb and a set of 111 CC 6X heads with stock valves. Sure, You have $6000 in the block and it looks great, but I bet my Well tuned, stock motor with stock rods and pistons will run better. What I am relating is that you can spend 5 times the amount of money without really getting the HP to $$ ratio that one would expect to achieve.
If your desire is a weekend only or a car driven 100 miles a week..Compression ratio is not an issue if you have ability to mix fuel.
As Quenton said, 9.5 is a desirable ratio. I have gone upwards of 10.3 (figuratively) without detonation, but that is with cam duration increases and timing mods.
I once built a 428 with 670 heads milled to 65 CC. Basically copied Milt Schornacks Royal Bobcat 428 and had the distributor tuned and put her in the Bird. Sure, I had to run 106 octane, but through 3" exhaust and Flowmasters she ran 11.4's on 275 DOT tires. I don't drive it much..15 miles last year, but sure sounds like a B&%(h next to anything on the street. That motor/head combo ran me $6k and 2 years, but $3.29 gal. for 110 can get real old if you like to drive.
It is also about finding the right people to do your work, finding the right carb/cam/head flow/combination and looking at what other people have had success with.
Food for thought..12,13,16,48,62, 72 cc, screw in 2.11/1.77 all have virtually same flow numbers, stock form. All great heads to buy.
5C, 6X, also good 2.11/1.66 Chambers from 95-111 CC (need extensive milling on block/intake side for 400 application)
I mainly stay in the 67-70 era for heads and dabble in 5C's..Not to up on the 455 SD/HO 7K3's and any heads from 71-75..Gas crunch and questionable castings. The money was not there as in early 60's to 70 for R&D and competetion between the big 3. Thus the quality and performance seemed to take a nosedive.
Best to buy heads bare (no valves/rockers) as you would spend the $$$ here..this is where your HP is at. New guides, Ferreas, rockers, porting, some polishing.
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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.
Tom,the stock specs say that 68' 400 H.O. is 10:75/1 comp/ ratio with stock 16 heads is this runnable on today's gas w/o spark knock or is the rating not to exact?
Many an opinion on what was advertised by the factory and actual, and what others say. The advertised 10.75 was actually closer to 10.3-10.5..That is according to Pete McCarthy.
Theoretically that compression ratio is too high for 94 octane..A blend of 50% 104 and 94 may suffice with an untuned carb and distributor, but mixing is trial and error.
The best method to building a 72 cc headed engine is to have the advance curve and distributor reworked, as well as proper jetting and fuel flow at carb... working no less than perfect. I say this for one reason. I built a RA III headed 400 all stock and ran it on 93 octane..Had real bad spark knock on hard acceleration. I had Milt rebuild the distributor and change the advance. I reinstalled and the spark knock was gone up until 4800 rpm. A very big difference, still running 93 octane. (I would not recommend running it on 93 octane all the time under hard acceleration). Fuel was upgraded to 94-6 octane (6 to 1) and the engine ran extremely well with no spark knock through all shift points up to 5900. The morale, A properly tuned and maintained 10.5 CR motor will run great if you do not accelerate hard to the floor. You could build a 72 cc head 400 with a stock cam and carb and not get detonation. My 67 has 670's and YT 400..Absolutely no detonation on 93. No porting or unshrouding on heads.
To get back to the core of your question..
If you have the engine built right and tuned perfectly, YES, you can run 72 cc heads.
If you throw the engine together with an untuned distributor, improperly installed cam and untweaked carb..you are looking for trouble with using 93 octane.
Again, I have an opinion..here it is..
1. Cliff Ruggles..Best Q-Jet man in the nation. Tell him everything about the car from trans/weight/gear/displacement, and you will get the best rebuild back. 2. Milt Schornack rebuild /curve distributor. 3. J.T. Tinnian..Head and intake porting or better yet, Jeff and Mark Kauffman..street/strip port work and chamber work..Also intake port matching and cleaning. JT is getting old and slow..
The rest is trivial..trans/exhaust/weight..Yadda Yadda.
#1,2 and 3 will cost you from 15-1900..But I tell you what, you spend the money here, your Pontiac will freaking scream.
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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.
Tom, thanks for the info how do I get ahold of cliff ruggles?I'm going to have dan jensen out of portland recurve my dist. and do the engine building.But I do need my carb. reworked bad.Finding a good Q-jet man is hard to do.
i guess i should have been a bit more specific in my question about the heads....so i will try. i am looking to build a 400 motor. i have not got the motor yet but am only considering motors made in the late 60's, preferibly out of a bird. i am hoping to convert it into a ram air bird as my dominator intake was said to have already been ported to match. so with that in mind was there a series of heads out there that i should focus my search on, keeping in mind i am looking to stay at about the same years for a block and a motor?
YES! on Dan Jensen..I have not had anything done by him, but comes highly recommended from friends. Cliff is out of Pittsburg area, will get his E-mail and post it. Cliff IS the man.
To 68 Firebird 350's ?
Try to get a block in the 67-74 era. All blocks are the same dimensionally. The Pontiac head selection will depend on what your overall application would be. Tell me what you had in mind? Also, I would recommens buying a set from Mark/Jeff Kauffman already done and ported.
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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.
Tom,I am plan on having my motor built back to stock specs cam,carb I will have some head work done probably bored over not sure as to how far yet plus the lightweight pistons from Jim butler what I would like to know is at what point to I have to run race gas.You may be wondering why am I asking you this when dan can tell me well because I like to get different opinons because in most cases 2 diff. people won't give the same answer.Thank you for your time.Doug
Most engines over 9.5 to 1 will require fuel modifications. You can get away with a little more compression with properly jetted and tuned carb, as well as a well curved and properly functioning distributor. To be on the safe side, 9 to 1 is cool. A richer carb jetting, large cam (duration/lift) will allow more leeway with higher compressions. If you are going stock specs, 9-9.3 is cool. Again, there will be hundreds of opinions and combinations, so whatever suits your needs, go with it. Dan Jensen will not steer you wrong. Next time you see him, Tell him I still plan on him building my 428. He is friends with Jeff Dennison, one of the editors of Pontiac Enthusiast who bought a 428 from me last year, and he wanted to introduce me to him and have our engines built. Dan is not as well known like Butler, Nunzi or Keefer, but his quality control and workmanship is top notch and would not hesitate spending more for my Pontiac.
These days, the T/A's and Ram Air cars run like 10.20 to one on premium 93 octane. They can do so based on the computer controlling spark/fuel/air and the advent of aluminum cylinder heads.
Cliff Ruggles crperf@hotmail.com An excerpt follows with his address..
Tom, great, glad to hear the word "hobby". So many folks get all frantic about this stuff. I build custom carbs, they take time. I also test them and make sure they work correctly. This takes time. Even so a lot of folks get in a big rush for them, I work 7 days a week, at least 10 hrs per day, I get them done when I can. I don't let any carb leave here that I'm not happy with, this can also take extra time. Difficult to put this sort of work on a time line. As I mentioned I prepare them in the order recieved, when I do get to your carbs they will all be built at the same time, it will take about a week once I start on them. The address here is: 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
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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.
Firebird350: The intake was probably ported to match the intake port design of the Ram Air IV heads. This is done using the intake manifold gaskets as a template. The Ram Air IV intake manifold gaskets are available from many souces )(aftermarket).
To build a good 400 engine, the "available" heads look for the following casting numbers:
12, 13, 16, 48, 62 and 670.
These heads are all from 1968-1970 400 Engines, and in stock form will yield between 10:1 and 11:1 compression depending on the set up of the engine.
The Ram Air II and IV heads from the same era are casting numbers: 96 (68), 722 (69) and 614 (70). They run $1,500 to $2,000 per set.