[Jay S]

Might be difficult to actually find a cam right now, may have to have to use a common generic grind like a 204/214 white box grind(summit 2800, jegs, melling, Elgin….) I have ran it in the 7s compression with ok results on various engines. Not my first choice anymore.

The smaller voodoo the 701 (256/262) is unavailable, no idea when it will be avaialable.

The crower 60240 doesn’t appear to be a available until November or December unless you can find someone that has one on the self. On a 110 ICL it’s intake closing is 65* abdc. I must have used a different centerline when I came up with 67* in the earlier post.

The Bullet I was thinking of (H00 int, H28 exh) is 260 intake to 270 exhuast [email protected] and [email protected], .440, .443” lift.. On a 110 LSA with a 106 ICL it’s actual intake closing is close to 59*, would be 56* if you just used a event calculator. Tim could tell you for sure. That is why I suggested it, it will build more compression than the other shelf cams I mentioned, and still be easy on valve terrain parts. Could even get by with pressed in rockers if you had too. The voodoos are ground a little different irc the 701 would have an actual intake closing of 62-63* and the 702 is close 65-66* on 108 ICL.

I think the 204 int / 214 exh (2800 summit) would have an intake closing of 63*. Rough number off the top of my head.

They are all in that range that would work for the 8ish compression.

Here is a Howard’s also, going to take a broad search to find something right now, even Howard’s is back ordered for more than a month if shipped direct. Might have a decent chance of finding it on someones shelf though.

[steve25]

How about just a copy of the factory 066 Cam.

[Jay S]

066 copy would be a melling spc-4. Looks like it is available. 066 pretty small, leaving a decent amount of performance untapped with it, the summit 2800 is a decent step over it in lift and duration. But going to have to use what can be found.

Looks like there are some small XE cams available at the big warehouses yet. Xe262 and the 268 both work good for very low compression, especially if your car has loud exhaust and your kind of deaf, valve terrain noise won’t be a issue then. . Suggest using a hylift Johnson lifters though, and not the hi energy that come with their cam kit. Better odds of getting a semi quiet combo. Performance wise that 268 can run pretty good yet even with 8.0 compression, even into the 7s.

["QUICK-SILVER"]

What transmission and rear gears this car have?

What intake/carburetor set up do you plan to run?

Exhaust system being used is also important.. Very important!

Exactly what RPM range do you call low end torque?

Clay

[Formulas]

The 2800 is an available camshaft having run one in a mid compression 350 it's no where near to big of a camshaft for any 400 as it's like a typical 60's/70's 4bbl camshaft in a 350

[Skip Fix]

The 2801 Summit works good in the low compression 400 in my 81. 93.5cc 6X-4 milled 0.050 but "ridge" in chamber smoothed so got it back to the starting 93cc.

[noalibi]

to answer the .010 question, that is merely a reference to clean up mild pitting in the cylinder walls. waiting on machine shop to give me an update on that. i also have a set of 350 4X-4H heads, are these any better for the 400? 1.96/1.66 -98cc. this is by no means a hotrod, more like a family jewel (66 GTO Convertible) that i would like to have a little more torque that will be running a holley sniper EFI. i've owned it for 35 years, and was bought new by my dad in 66 when he worked at a Pontiac dealership. i repeat, i don't need a hotrod, and will race no-one so please keep that in mind. i would love to have the original 389, but Dad "blew it up" in the early 70's when i was around 10 years old, as he raced "everybody" that would take him on. it was his daily driver. the biggest resistance i have to date is an LS Swap. i also have a 72 Blazer and a 72 Firebird that are running LSX's, i wanna keep this one true Pontiac.

[b-man]

Some food for thought, a low-compression 400 that had my friend questioning if it really was only a 400 when I took him for a ride:

https://forums.maxperformanceinc.com...1&postcount=22

Keep it simple. Running less than 9:1 compression doesn’t make it a dog.

[steve25]

Ok, I will ask of the OP for a third time I guess, where are you getting these needed .010” over pistons from?

B-Man, I am not saying that your 400 you referring to was not a strong motor, but you buddys Frame of reference might be coming from a sick or poorly tuned motor, and yes maybe of even more CID then your 400.

I have witnessed a built 74 455 ( non SD ) yanked from a guys 1978 GP and put right on a dyno.
The motor made a pitiful 270 hp .
The timing was found to be 39 degrees ( with iron heads ) and the jetting very lean and it was running hot even on the dyno, ( partial jammed T stat as we later found out ) how it did not blow up is a mysterious!

When the timing was reset to 34 and the jetting of the Q-jet got into the ball park the motor gained 40 hp!

[grivera]

My point is if OP has to get a different set of heads anyway may as well aim for something that will make 9:0- 9:5 compression. If OP already has the heads it skews things a little bit but I would argue he is still ahead to get the better heads.

[steve25]

Ok, so your going to go to a common ,030” overbore then, if you can make every effort to get pistons that use 1/16” compression rings, not 5/64”.

I would use those 4X - 4 heads if they are not cracked and convert them to screw in studs if need be.

[Skip Fix]

The 78 NHRA stockers can run 87cc chambers but still a low compression 400 and are deep n the 11s. My wimpy 180 HP stock 78 motor pushed my 3900lb TA to 130mph+ in the straights at Texas World Speedway. So they can be a decent street performer.
Heck if you are getting new pistons then get a mini dome to bump it to 9.5:1!

[steve25]

Your with me I guess Skip, still wondering what pistons will be used because like you said a custom one with a small dome will bring everything in line .

[77 TRASHCAN]

My point of view on using 6X-8 heads, as is.....My 77 TA (180HP) may have had a different cam from what Skip's came with, not sure, BUT it was a teenie weenie bumpstick. I've never gotten an exact idea of what my cam part number was, BUT several of the articles and mayber a Motor Manual, list the lift below .400". Likely they were going for max port velocity at driving RPM's. My TA ran well!!! Never drag raced it, to have an exact idea, but was fun to drive!!!
My thought being that a 066 (Sealed Power CS641) cam would be a considerable step up from the stock cam that was in my 400.

I'm Thinking the OP'er will not spring for $500-600.00 custom Pistons. Just looked some L2262F pistons, $429.00 for the set.

[grivera]

62 heads are not hard to find complete and ready to bolt on

[Jay S]

FWIW, I think the 180 HP engines that had the 6x-8s used a single pattern cam from the factory. [email protected]” on both the intake and exhaust. 107.5 LSA, 105 intake and 110 exhaust, .365” lift. Introduced in 77 and used in all the 6x-8 engines through the end of the production run. For certain, was engineered for brute low end torque to pull those highway gears, plus fuel economy. The 066 cam was pretty close to the original cam in my higher hp 77 400 with 6x-4s. But the higher hp engines had the cam retarded about 5 degrees from the factory for top end power for 20 hp difference between the 6x-8 engines and the 6x-4.

Lol, if Pontiac would have did a cam like a summit 2800 in the 6x-8 engine with full dual exh and 3.42s they would have had no trouble outrunning the 6x-4 w72 engines. 77s we’re really held back by their crappy single car though. I lost count of all the engines I have used that 204,214 cam grind in. Still have multiple engines with them, no Pontiacs. 300 Ford, 397 cid Windsor 351 stroker, 360 dodge, and a 440 dodge. Have the bigger 214/224 in a 455 yet. I loved my high school ride and the 214/224 in a little 318 mopar with headers, 8.5 compression,2200 stall and 3.23s. Ran Low to mid 15s, shifted at 5500 in a 3800 lb car. Even turbo charge on 318 and dropped the compression down into the 7s, it pulled the car fine when not on boost. It isn’t a big cam either. I agree with Skip, if my little low compression 318 can absorb that 2801 grind cam, 7s compression 400 won’t have any issue either. Just to be honest though, it really wasn’t a up grade e.t wise from the smaller 204/214 on any of the low compression engine I did and took to the track. Big enough cam it like headers.

Sounds to me for what the car is used for the 2800 cam and the 6x-8s would be just fine. I know of someone looking to sell their fresh 66 tripower 4 speed coded 389 though if you want to go back to stock looking coolness. . That era engine just has date codes and engine ID stamps, I don’t think it had vin stamping as for original cars, not until 67 anyway.

[Jay S]

I will add this for Steve C to read, cause it is kind of fun to use calculators, he knows enjoy playing with them. I brought up that v/p index sizing cams to intake closings, I will add one more dynamic too that. If you know your compression that your going to have, if your plotted the V/P index against the intake closing event on a graph there will be an area on the graph that is linear, then logarithmic (downward curve) and then will go back to linear again. Best results seem to be keeping the closing event in the logarithmic part of the graph, same way with compression for a given intake closing. If you get the compression to high for the intake closing and it is where the graph goes linear, you need a bigger cam, same deal on the bottom of the scale, if you have low compression and you plug the closing event in and the the V/P ends up down on the linear scale on the bottom side, the engine has to late of an intake closing for the static compression. I have played with intake closing and had v/p index from the 60s into the mid to upper 200s . The higher the compression is, that logarithic part of the curve trends up, or lower the SCR, it will move down. On a 400 with 8 ish compression I would guess the V/P logarithmic range will be 90 to about 140. 90 it turns into a pig, above 140 and the it start to hit a wall on the top side. That range is just off the top of my head guess, but if you don’t mind playing with calculators you can use that info and find the range that the DCR should end up and a starting place for your cam design, and work on the opening rates and E/I ratios from there. Most people just talk about DCR, but to really properly use it, the V/P index is actually pretty important. It is an indicator of the pressure waves that build the cylinder pressure. V/P index on the low compression late seventies 6x-8 was usually 120-140 depending on the altitude, kind of right at the top of where they could have good bottom end and still have good power, the Pontiac engineers did a lot of neat interesting stuff with cams.

[noalibi]

Originally Posted by Jay S

FWIW, I think the 180 HP engines that had the 6x-8s used a single pattern cam from the factory. [email protected]” on both the intake and exhaust. 107.5 LSA, 105 intake and 110 exhaust, .365” lift. Introduced in 77 and used in all the 6x-8 engines through the end of the production run. For certain, was engineered for brute low end torque to pull those highway gears, plus fuel economy. The 066 cam was pretty close to the original cam in my higher hp 77 400 with 6x-4s. But the higher hp engines had the cam retarded about 5 degrees from the factory for top end power for 20 hp difference between the 6x-8 engines and the 6x-4.

Lol, if Pontiac would have did a cam like a summit 2800 in the 6x-8 engine with full dual exh and 3.42s they would have had no trouble outrunning the 6x-4 w72 engines. 77s we’re really held back by their crappy single car though. I lost count of all the engines I have used that 204,214 cam grind in. Still have multiple engines with them, no Pontiacs. 300 Ford, 397 cid Windsor 351 stroker, 360 dodge, and a 440 dodge. Have the bigger 214/224 in a 455 yet. I loved my high school ride and the 214/224 in a little 318 mopar with headers, 8.5 compression,2200 stall and 3.23s. Ran Low to mid 15s, shifted at 5500 in a 3800 lb car. Even turbo charge on 318 and dropped the compression down into the 7s, it pulled the car fine when not on boost. It isn’t a big cam either. I agree with Skip, if my little low compression 318 can absorb that 2801 grind cam, 7s compression 400 won’t have any issue either. Just to be honest though, it really wasn’t a up grade e.t wise from the smaller 204/214 on any of the low compression engine I did and took to the track. Big enough cam it like headers.

Sounds to me for what the car is used for the 2800 cam and the 6x-8s would be just fine. I know of someone looking to sell their fresh 66 tripower 4 speed coded 389 though if you want to go back to stock looking coolness. . That era engine just has date codes and engine ID stamps, I don’t think it had vin stamping as for original cars, not until 67 anyway.

So would you recommend the summit 2800 cam with my setup? I have been juggling all suggestions.

[noalibi]

Originally Posted by "QUICK-SILVER"

What transmission and rear gears this car have?

What intake/carburetor set up do you plan to run?

Exhaust system being used is also important.. Very important!

Exactly what RPM range do you call low end torque?

Clay

-Running 3:42’s 400 trans
-Holley sniper EFI (planned)
-2-1/2” full exhaust w/ magnaflows
-power in the idle to 3000rpm range

[steve25]

With a 350, 389 or 400 motor If the compression ratio and can pick does not make for at least 160 psi then the motor will be a lame Dog !