Everybody seems to have different opinions when it come to cams. You didn't mention what the motor is going into. If it's an auto tranny car, the cheapest decent cam would be the Summit 2801. But if you use this cam, you'll have to use new springs, cause it has more lift than a stock cam. With stock springs, a duplicate of the 068 Pontiac cam is about the biggest thing you can get by with.

Now, if the car is a 4-speed sick, the Summit 2802 will work (with the appropriate springs). The biggest thing I would consider is a RA4 duplicate, such as the Melling SPC-8, and then only with Rhoads RL-9518 lifters to smooth out the low end a bit.

While the motor is out, it would be a good idea to have some taken off the heads to increase compression. If you take .050 off the surface, also have them take .050 off the intake port side so that the intake manifold will still line up correctly. I don't know what your budget is for this project, but one thing leads to another. While they're doing the heads, it's good insurance to buy new stainless steel valves to replace the almost 40 year old ones.

And if you do this, since you'll need new head gaskets, you can buy the .027 thick Cometics, with a 4.160 bore and increase the comp a bit more. All this extra comp will help to "add a bit more power".

Also be sure to use polylocks, and adjust the rockers to no more than 1/4 to 1/2 turn below 0 lash. Some roller tip rockers, like the PRW's will help prevent wear on the valve tips. Well, I won't take this any farther. But you can see how one thing leads to another, and can quickly blow your budget.

If you wanna price any of these items, from somewhere other than Summit, I'll help you find the best prices.

 

thank you Ponyakr the engine is going in my 1980 firebird currently i have a 71 pont 350 and i don't like it. I am hoping the 400 will wake up the car a bit. The 400 its going in with a th350 or th400 i have both i just got to decide, i know the th400 is better but if i go that route i have to change the driveshaft or at least the yoke. On the camshefts you were talking about the springs how do i go about and buy the right once could i get them on a camshaft kit??

 

Most of the high $ cams are available as a kit, with springs. But I'm not aware that any of these cams I mentioned are.

When I get time later tonite, I'll look up several choices and post that info for you.

Unless you run a loose converter ( say at least 2500 rpm stall ), the 2801 Summit is probably the biggest cam you'd be happy with. More later.

 

I prefer the XE series cams from Comp Cams but on a budget Summit cams are ok...

 

I've read that the XE series cams have much steeper ramps than older style cams. That means that they will open the valve faster and close it harder on the seat. This also means that a stronger spring will be required to keep the lifter in contact with the cam lobe. These 2 things combined will put more stress on the valves. So, if you go with this type cam, I'd consider it mandatory that you buy new stainless steel valves.

They are good insurance, even if you are going to use an older style cam with a bit higher lift, requiring stronger springs. Remember, if your valves are original, they are nearly 40 years old and have been thru many heating and cooling cycles. Many people get by with using them, but some don't. A friend of mine tried it and the head popped off one of the old valves and wiped out his motor.

 

Thanks alot guys. One more question sorry if its a dumb one. I was told that the engine i am getting is the w72 one which is the last of the 400 built and i guess it was a good performance one. The compression ratio on them its like 8.2:1.0 with what i could find, the summit cam 2801 requires a 9.0:1 or higher ratio i believe. Will this still work or do i have to shave off the heads a bit to raise the compression ratio. I am planning on doing that regardless I just dont know how much it is gonna raise

 

Yes, you can take enuff off the heads to get to at least 9:1 comp on a 400. Here's a 400 which Len Williams sells, with 6x heads, that he says has 9.25:1 comp.

http://lenwilliamsau...Long_Block.html

And here's just one site that shows some of the Cometic .027 thick head gaskets that will increase the comp a bit more.

http://www.spottsper...0head%20gaskets

I think they are available in a 4.160 bore size which will further raise comp. A .027 thick gasket with a 4.160 bore size will probably have to be special ordered. The cheapest place to buy Cometic gaskets may be to have Summit special order them for you, and have them drop shipped from Cometic. I'm not sure about that. You may be able to buy direct. I'll try to look into that further. But anyhow, a little over 9;1 comp will increase performance but still work with pump gas.

There is a site with a system for approximating your comp ratio with different combos. You just have to plug in your specs, such as chamber volume, bore size, stroke, piston valve relief or dish volume, distance from top of piston to deck, gasket crushed thickness and bore size of the gasket, etc. But you'll hve to know all these specs to use the site. For example: you or someone will have to check the head chamber volume. Cause you don't know for sure whether your heads have been milled before or not. Anyhow, I'll look up that site and post it here.

http://www.wallacera...om/cr_test2.php

 

Check out Wallace Racing's site, that will tell you which heads cc head chamber sizes and the compression ratios obtained.
It is sometimes a good idea to sit and think a while and get yourself a plan and budget together, thinking what you want to use the car for and how much power you can reasonably expect.
It is also reasonable to expect that changing the valves to stainless is one thing but so is machining knurled valve guides and hardening the valve seats if you go for the pre-73 cylinder heads so that they will run on unleaded gas.
Don is right about the steep bump sticks too...you will need to choose one which will give you the power you desire but temper your choice with driveability on the street.
For my money, I would go with the number 68 grind cams as they went into many of Pontiacs high performance motors, they have a slight lope and give a good smooth performance right through the power curves and good engine vacuum for your brakes, and you won't need to change converter stall either, which is sometimes thrown into the equation with some cam set-ups.
A new set of lifters are new stock lifters or Rhoads sets. I used the Rhoads sets, stock new springs, 68 grind cams and titanium lash caps. Pushrods length need not be changed nor would you necessarily need to fit slightly higher rocker arm ratios but they do perform better with the roller rockers because of the tip contact is kept flatter if the tips can roll across the top of the valves rather than the limited contact angles of the stock stamped rocker.

Jules

 

OK, here's some cam prices I found.

The best price I found for an 068 duplicate is a Melling SPC-7 from Auto Zone

http://www.ebay.com/itm/AUTOZONE-SPC-7-Camshaft-/251373486801?_trksid=p2054897.l4276

Of course the Summit 2801 is cheaper and has a bit more lift.

http://www.summitrac...-2801/overview/

http://www.summitracing.com/parts/sum-2802/overview/

http://www.ebay.com/itm/AUTOZONE-SPC-8-Camshaft-/251430113412?_trksid=p2054897.l4275

Summit always has the best price on Rhoads lifters.

http://www.summitrac...ew/make/pontiac

 

Now springs can be a bit tricky. I'll start with some that will work with the 068 cam. It has barely over .400 lift, so you can get by with fairly light springs. Somewhere between 90-100lbs is plenty of seat pressure. And somewhere around 250lbs or a bit less of open pressure will be plenty for this cam to turn 5000 rpm safely. It won't make power much past that.

http://www.fastengin...et-1967-79.html

For the XE268 cam, CC recommends 995-16 springs. They should work for the Summit 2801, 2802 and the Melling SPC-8 RA4 grind. I'll show these and others similar.

http://www.summitrac...6/applications/

http://www.ebay.com/...b5ec3#vi-ilComp

I personally like the specs on these Crower springs. They should drop right in, and give plenty of seat and open pressure with stock length valves on the 6x heads.

So, I have to recommend these Crower # 68404-16 springs.

http://www.summitrac...6/applications/

 

I think the Comp Cams XE 262 would be a great cam for that engine coupled with new stainless valves and some nice roller rockers.. I also agree with the cometic head gasket.. I would have the heads redone at a shop before slapping it in my car though. You can have them cut to gain a little more compression, which will bring up the Horsepower, and give you a little more rumble along with the cam..

 

Man you guys are awsome thanks alot for your time. I see now i have a few options so as soon as i get the engine this weekend i will see how much $$ i got left and ill start working on it. I will keep you guys posted for sure, you guys have been an awsome help

 

Call Butler Performance! Give them your car and engine specs and what you are trying to do with it and they will be more than helpful in picking out a cam.

 

I might have missed it but what heads are you running? I think that those 77 motors had 6X heads which are a decent flowing head but the larger chamber will hurt you in an attempt to raise compression.

You could always bolt on a set of older style heads like 12's, 13's, 16's, 670's, 48's, ect. The smaller combustion chambers on these heads would raise your CR and allow you to run a healthier cam.

 

Don't forget to think about what gear is in the back axle. I know a lot of those later 70's Firebirds came with some pretty tall highway gears in them. Going with a longer duration cam makes having a 3.23 or 3.42 gear more critical.

 

hey guys the the engine foes have the 6x heads, i found some 66 092 heads but they are from a 421 engine, they have 70cc chambers and 10.75 c.r. I am just worried that they might not fit anyone has any insides on this?? Joe i have the 3.23 in the back you think that will be an issues ??

 

That's WAY too much comp for pump gas ! And I've read that if you go with early heads you also have to get hardened valve seats installed to work with unleaded gas. I just don't see how you could come out any better or cheaper than going with the 6x or 5c heads, shave 'em and use the thin gaskets too raise your comp. Usable cores are available for $200-$300 most of the time. Less if you look around locally and don't have to pay freight. They came on most all 350's and 400's from around '74 thru '79. So that should make the 6x the most common head around.

 

The 3.23 gear should be fine, but I would stay away from the 1966 092 heads. In 1967 Pontiac made many changes to their heads which make it impractical to use pre-1967 heads on a 1967 or later engine. in 1967, Pontiac changed the valve spacing and valve angle, so most likely the fly cut reliefs on your pistons don't match, so you are asking for valve to piston clearance problems. Also, there are exhaust crossover changes to deal with, and pre-1967 heads do not have screw in rocker studs or pushrod guideplates. All this on top of a small combustion chamber that will make too much compression......so go with the 6X heads as a starting point.

 

I totally agree it's all about dynamic compression. If you have a cam with the intake valve closing late, then OK, you are only using about but the last half (95 degrees or so , i forget the exact amount) of the compression stroke to build cylinder pressure, so you can get away with a higher static compression, no argument here on that fact. If you know how to limit your total advance, so when that 041 cam starts packing the cylinder tight when you get up on cam you don't have too much timing at the higher rpm, you can tune for the combo, and everything will be OK. But without the high overlap cam to bleed off low rpm cylinder pressure, you can, as I'm sure you know, you can get into a very funky to tune combo. Not that you can't make it work, but without the 041 cam, you do need to keep an eye on static compression.

 

http://books.google.com/books?id=O--NmlNfSYwC&pg=PA73&lpg=PA73&dq=whats+the+most+compression+you+can+run+on+a+pontiac+motor+with+pump+gas&source=bl&ots=AHjusCfce2&sig=nhx1oFDXxRSrp4znVPRMFEE3RBQ&hl=en&sa=X&ei=eRQBU43ZJY37kQfBzYGQCA&ved=0CFUQ6AEwBA#v=onepage&q=whats%20the%20most%20compression%20you%20can%20run%20on%20a%20pontiac%20motor%20with%20pump%20gas&f=false

http://psp.aquacomp.net/topic.asp?TOPIC_ID=1803

http://forums.highperformancepontiac.com/70/9599907/drivetrain-restoration/maximum-safe-compression-ratio-for-premium-pump-ga/

http://transamcountry.com/community/index.php?topic=52770.15;wap2

You can go online and find LOTS of arguments, back and forth about max compression with pump gas. Many insist on certain cams so they can "get by" with more compression. And many will brag about how they have run 11:1 for years without any problems at all. Then there are many engine builders, and people in a position to know who recommend 9.5:1 as the max SAFE comp with today's pump gas. I don't personally know who's right and who's wrong. But as for me, I choose to err on the safe side. Especially with a 455, why push the limit just for a few measly HP. Just stay under 9.5:1, be safe, and enjoy 500 ft lbs of torque on pump gas. Or run over 10:1 with iron heads, but make sure you have EXACTLY the right cam and tune, and do so at your own risk, knowing that many engine building experts recommend 9.5:1 max. I have no problem with those who choose to run high compression. Hey, if that's your bag, "knock ya self out" !

 

Why not send those 092 heads over to the UK! .. Our unleaded is rated at 95 RON!
I guess we can run those higher octanes...I ran a pair of 670 heads on my 428 well enough and a pair of 96 heads on my 455, but the compression ratio there was a more realistic 9.5:1. I have heard of Pontiacs running as much as 10.5:1 ratios here in the UK. We still have to get the hardened valve seats treatment however....we expect that.
What is the best you can run on unleaded and how far advanced would you have to set your timing?

 

Back in the 90's I ran a 455(462) using #670 heads from a '67 GTO. I had an 041 cam at the time with other common Pontiac hi-po parts. I could only run about 25-27 degrees total timing because when that high static compression ratio crashed into the 041's ability to really turn the cylinder pressure on above 3500 RPM in a 455, I had the "worst of both worlds" from a detonation point of view that is. I had to really limit the total timing. Not that I care what my total timing number is....who cares. But I was dealing with a high static compression ratio plus a cam that was really hitting it's cylinder fill capability up in the upper RPM band and I really had to chop back my total timing to make the damn thing not ping above 3500 RPM. I welded up the slot in the distributor to make the timing stop early and that fixed the problem. But in the end I really had to come up with a funky tune on my mechanical timing and my vacuum advance to live on 93 octane. Of course, when I put Turbo Blue 114 octane in it, it didn't matter where I put the timing. Since then, I have put the #670 heads on the shelf along with a set #48 heads off a '69 GTO that I tried, and got a set of Edelbrock 87cc heads. What a difference, the whole motor seems more happy. Now I can still have agressive timing, and the friggin' thing will turn over when it's hot. I don't think you need to accept the whole "better stay away from high compression" story too much. I think to go a bit higher is OK because you can tune for that. But to go way over what you read on the internet, is going to get you out there in funk land on your tune. Not that you can't make it work, if you have great 100+ octane right down the street, hell yea. But if you don't, why go way high on static compression, just to have to tune that hard earned cylinder pressure out in the mid-range by out by backing off the timing? The amount of dynamic cylinder pressure that can be tolerated is a function of the fuel octane. You can get there many different ways, and ride the edge of ping really close with a good advance curve. At the end of the day, you can only generate so much usable cylinder pressure before detonation, how you want to get there is up to you, but it is a lot easier to change your ignition timing curve than change your static compression ratio( i.e cylinder heads).

 

Can someone tell me what the difference in these two cams would be and what might be better with a 69 400 with KRE heads? I am a little confused about some of the numbers, mostly with Lobe Separation and Intake Centerline as to what they mean and what is better to have. Thanks in advance!

Comp Cam HR
Intake Duration at 050 inch Lift:224
Exhaust Duration at 050 inch Lift:230

Advertised Duration:276 int./282 exh.

Valve Lift with Factory Rocker Arm Ratio:0.502 int./0.510 exh.

Lobe Separation (degrees):110

Intake Centerline: 106

Grind Number:XR276HR-10

Lunatic Voodoo Retro-Fit Hydraulic Roller Cam

Advertised Duration (Int/Exh): 270/278

Duration @ .050 (Int/Exh): 219/227

Gross Valve Lift (Int/Exh): .515/.530

LSA/ICL: 112/106

Valve Lash (Int/Exh): Hyd/Hyd

 

I'd say go with the smaller cam for a 400, the larger for a 455. The higher LSA of say 112 usually will provide more vacuum at idle, which can help with vacuum power brakes. I won't even attempt to get any farther into cam technology than that. There is certainly plenty of online details about cam technology you can read for many days.

 

Thanks Don, but how much vacuum am I really giving up going with 112 LSA vs 110 LSA? If I understood correctly some of the info I read, and I by no means understand all this stuff, but the greater the gap between the LSA and ICL (is that overlap?) means leass vacuum?

 

No, the LSA is what will affect vacuum. If you'll look at the specs for some racing cams, you'll find that some are 108 or less. This is supposed to increase top end hp, I'm told. If you'll look at some of the LSA'a for factory Pontiac cams, you'll find some of them to be 113 and even higher. They are meant for street operation, low end torque and enuff vac to work the brakes. When I have time I'll try to find a link that explains it all better.

 

I have the Comp Cams Hydraulic Roller XR276HR-10 cam in my 455 (462) with Edelbrock aluminum 87 cc heads. I'm getting a liitle over 15in. Hg of vacuum at idle @ 850 RPM. The timing at idle is 30 degrees using 15 degrees of vacuum advance hooked up. A 400 will be a bit less. This cam is alot like the factory 744 cam with a few degrees less lobe separation

 

Thanks Don and Joe, interesting info and has helped me learn a little bit, matter of fact, I just got a responce from Jeff Kaufman and he agreed with what Don stated, that the 110 LSA isnt very good for a 400 but 455 it is. With my setup he is also recommending a 112 LSA with a custom grind. Am waiting to see what he actually recommends as far as what the cutom grind would be. Thanks again for all the great info as usual!

 

When I decided to re-do the top half of the motor on my 68 Bird, I had several knowledgeable Pontiac guys recommend Crower cams.

Originally I built the motor to be a 68HO replica. It was a 400, .030 over with flat-top pistons, an 068 grind cam, #16 heads, cast iron intake, Hooker headers, and a warmed over Q-jet. At the time the car ran a 4 speed and a set of 3:23 gears. It was a real nice strong cruiser but after spending all that time and money on the motor, I felt that I wanted more HP and a little more rumble at idle.

I went out and scored a set of mildly ported #13 heads, I did a ton of research and eventually went with the Crower 60243 cam. While I was re-doing the top end over a buddy decided to go with a 9" rear for his 67 Camaro so I bought his 12 bolt 3:73 rear with a new Eaton posi unit.

Long story short the motor went back together with the ported #13's, the Crower cam, and an Edelbrock Performer RPM intake. All I can say is WOW what a difference! I haven't had the car dyno'd yet but estimates are in the 425HP range. All that power with a 4 speed and 3:73 gears makes this car a beast. I haven't really road tested it yet due to the horrible winter we've had but as soon as spring hits, I'm going to have it tuned properly on a dyno and drive the snot out of it.

If this car is a weekend cruiser, don't be afraid to go a little hotter with your motor because you will always want more power.

 

My 469 with RAIV cam 114 LSA and regular lifters was about 6in vacuum at idle LOL I run Rhoads lifters which bleed off at lower RPM too, which brought my vac up to about 14

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