Pontiac 400 rebuild question's

Hi , im have some questions...
My engine stock 1978 400 pontiac (yes 577 weak block )
I currently have smog engine with 6x 8 heads 7:8 compression
Th 350 BOP trans

I got 15 heads from 1968 10:5 comp pontiac 340hp
I gonna use stock intake and quadrajet carb and 3tube headers

My question's
Is k2801 summit cam good option ?
Does I need get new valve springs for this cam ? Or may choice k2802 with bigger lift ?
Does stock bottom with new piston rings gona last little bit of higher reving ?
What hp number can i expect from this combo ?
And my turbo 350 3 speed gonna last ? Is stock good working one .
This engine gonna end in 1974 firebird.

 

FWIW I personally like the cam that went by GM P/N 9779068, the old Tripower camshaft. The “041” camshaft used in the Ram Air IV was a little lumpy for automatics. I’m sure others here will have some better ideas.
Remember that Pontiac bottom ends don’t like high RPM’s. Pretty much 5500 with stock components like crank and rods.

 

I’m guessing you’re looking at the Hedman 3 tubes or something similar. It looks like a decent combination focusing on decent low end torque. Depends on the rest of the car and weight.

Nothing against Summit, but I’d be asking who grinds their cams. I prefer to get a cam from a cam company in know, USA, and use whatever lifters, springs, etc. they recommend. Last thing you want is to loose a cam on break in due to improperly made or mixed parts.

 

I'm a HUGE proponent of custom ground cams !
Look at the specs from several cam companys (comp...lunati...crane...summit...isky) and see for yourself what they all recommend and design (in your head/paper) what you like from each one
Then call Howard...Delta (I like them!) and talk to their phone rep. Get their input... tell them your thoughts...how the Pontiac will be driven (raced...street...street strip...cruised) and make your decision. + the price will prolly be LESS.
Worked for me and then you know exactly what specs you have in your cam !
6sally6

 

Yep, a lot of Pontiac cams are nothing more than Chevy copies.

At one time crane made a really good cam for Pontiacs, worked good with an auto and 2200 stall converter, even nicer with a 4-speed. Built several with this cam but they fazed it out in the early 90's.

So I went to having a couple cams built for me. Used chet Herbert on one but that ended up in a shouting match over the phone with Ole Chet himself before I got the right cam.

I went with .495 intake, .510 exhaust with 1.5 rockers. 235° dur @ .050 intake, 242° dur @.050 exhaust with 112° centerline.

Used these in two 455 motors. Ran 2200 stall converters. With one 3.55 rear and the other was like a 3.31 or close to it.

These came alive at about 2600 rpm. Pulled hard to about 5600.

These motors were what I called backyard motors, as in nothing exotic in them, I polished the rods, installed arp rod bolts and then had them resized. Heads were the good 6X that I port matched, blended the seats into the bowls, cleaned up ports a little and had a 3 angle valve job, had spring seats cut to fit springs. Just good Ole hot rodding 101.

Ended up with around 9.5 compression, never did get to take one to the track to see how fast they were. But 1 I built for a guy in a Trans am would eat his brothers 1970 ls6 450 horse, 454. The LS6 was built to factory specs and his brother would just shake his head, then comment that my motor was running pump gas and he was running race fuel. Ahhh the good Ole days !! Last I heard that motor was pushing almost 100,000 miles and never had a valve cover off of it...

...

 

Dad and I have built a lot engine over the years, http://www.pontiacpreservation***ociation.org/nominees/jim-hand.html
https://www.ebay.com/itm/157406601242
Here is what I would do, You have good heads already, all the 6x heads have the same port design, so just have the -8 heads milled down to 93 cc chambers, some where around .040" on both the deck surface and intake surface. The 6x head was the last head Pontiac designed, its well thought out design and flows decent cfm in stock form. It doesn't take a lot to get 225 cfm if you just remove some flashing and blend all the corners. Leave the smaller 1.66 exhaust valves, the bigger 1.77 won't help unless you open up the ports, if its not a race engine, you will never know the difference. The early heads with 2.11" intakes do not flow as well as the 6x if both are stock. And, the early engines are really over rated on compression, usually by 1/2 point. Use this chart, http://www.wallaceracing.com/cratio0001.htm
8.5 will be plenty of compression for a decent driver, heavy car, you don't want to be stuck with premium fuel with little gains.

For camshaft, the 2801 from Summit is good choice, its a slightly modified version of the Pontiac 9779068, '65-'72 HO four barrel cam used in the HO engines, sometimes called the RamAir 1 engine. I've used a lot of them with great results. For lifters, use Johnson Hylift or Crower Camsavers. Butler Performance sells a roller version of the 9779068 cam if you want to go that way. The flat tappet will need high zinc rated oil, Penn Grade is what we recommend, 10-30 and 30w break-in oil. The roller cam can use any high performance oil, you will need to change out the distributor gear for the bronze version. Roller cams have more harmonics than flat tappets and the distributor gear is a wear item that needs checked regularly.
Use Crower valve springs, see below for part numbers.

Set the distributor up for 34 degree total timing, all in by 2500 or so rpm, adjust up or down a few degrees as needed, 34 will pretty close. Use vacuum advance, limited to 10 degrees.

Three tube headers are slightly better than cast iron headers, but only slightly. Cast heads are a step up from log manifolds. Four tube 1 5/8" headers would a good choice if you need to purchase new ones. Use 2 1/4" pipe with a cross over or H pipe if you have the room.

You didn't say what gear ratio the car has, a low gear and big cam makes for a turd of a car. The 2801 will work with gears 3.08 or up. The factory cars with the 041 Ram Air III cam had to have 3.90 or 4.11 and no A/C ( 2802 Summit cam ).
The Turbo 350 will hold up fine, just don't shock it with a water burn out and have the tires grab hard on dry pavement, the input shafts can sheer off with enough torque and shock.

If the cylinders are good, new rings are OK, use a Moly rings, hone for a good crosshatch pattern. 5500 will be max rpm, 5000 would be the shift rpm. Your headers and exhaust will limit the top end performance.

Don't expect a race engine, it will make decent power and make for an enjoyable driving car. I've seen A '65 GTO with a 455, ported heads, q-jet, headers, and the 2801 cam run low 12 second @ 107mph quarter mile p***es, so the cam does work.

Lifters, Crower #66056X3-16 Camsaver lifters
Oil Pump Mellings M54D
Valve springs Crower #68404-16 High Performance springs that fit factory heads
Rear Main seal Best Gasket Company #6380X the only seal we recommend
Optional but really recommended, upgrade to 7/16" rocker studs with Poly-locks
https://butlerperformance.com/i-316...grade-conversion-kit1967-and-later-heads.html
Change out the oil pump, they are relatively cheap and good insurance, same with the timing gear set.

Send me a private me***age if you want to talk more or need information,
Joe Hand

 

Thanks all members for lot of information.

Joe I'm know 6x are one good flow heads but not in stock form ,i have already bought ported 15# heads from 1968 , im planed for diy rebuild , where a live, we have don't have machine shops that works on old us v8 engines ,
Higher compression isn't a problem. I live in Europe our gas is higher octane
My car is Pontiac Firebird from 1974
Previous owner put 454 chevy on it low gears and track bars , but this engine was blown they put high mileage 1978 400 pontiac on it , when i got it it have lot gas in oil , non working quadrajet ,,
new oil , cleaned quadrajet en car running good , but burning lot of oil on left bank side of engine .
I don't need a drag track killer
Only little bit more juice of smog era engine.
But pontiac are very torky , i blow drive shaft ujoint on first drive
I think 2801 is good choice for me .
I hear 3 tube headers are way to go because ground clearance and later maintenance .
I hope that bottom end is in good condition, new bearings and rings also is think new oil pump .
Pontiac parts are here difficult to find also expensive. Chevy parts are more common but i wil a Pontiac hart in it.

 

Sounds like a good plan. You can reuse a lot of parts if you take the time to inspect and clean. I was on a pretty tight budget back in the late '80s and '90s when dad I was racing every weekend, so putting together a used engine was something I know very well.

You will be happy with the 2801, its a good all around cam, pulls hard, and has a good idle. You will also like the three tube headers for the ease of installing them, four tube on a Pontiac is tough ! Be sure to clean the block really good after honing, a power washer down each lifter hole and oil p***age ( use the red pin point tip if you have access to one) works really good.

Good luck with the project, and let me know if you need any numbers or information.

Dad's book is back in print, I believe BOP Engineering is selling them if you want or need a copy of it.

Joe

 

Joe,
Thanks for the info on the Summit 2801/9779068.
I haven’t kept up on a lot of Pontiac parts. I forgot also about using the 1.65 rocker arms, that might also be a leg up on performance.

 

I doubt you would see much gain going to higher lift. The 2801 has more lift than the factor 068. The factory cams had .407" lift on both intake and exhaust, 2801 has .444 intake, .466" exhaust. You would jump to .488" and .512" with 1.65 rockers, that's a lot lift for this cam, be sure the heads have enough clearance. Add .060" for a safety margin on top of clearance for the seal. We always cut the guides for positive type oil seals on all 16 valves.
The factory Ram Air III ( 041 ) only had .470", this is the same cam they used in the early '60s in the NASCAR 421 engines.
FYI, the 744 camshaft in the Ram Air II had the same duration as the bigger 041, but only had .407" lift like the smaller 068 cam had. The lobes were simply cut off at .407" so they had flat spots where the lifters would bounce on at high speeds. It was very poorly designed cam!

 

Since Pontiacs are torque monsters vs high winderz like Chevy why not go with a tighter LSA ? (at least 110*LSA)
Just curious ..not look'in for a fuss......
6sally6