.030 over 400 with L2262 and 16 heads....
 

Should I plan on getting these things dished, or will it run on premium fuel OK? Car will be street only. Cam is a lil comp cams 268H (218/218 @ .050). Pistons are forged flat top speed pros with 4 valve reliefs.

Also, with this mild build (will be using RA manifolds) would it even be worth the investment to get Ferrea SS valves?

Cam& #16's on a400/ Pontiac Gregg
 

The duration is way too short. Get either an Ultra-Dyne ( the best) cam with 280/288 gross duration, @.050 223/231, lift w/1.5's .463"/.485".
Comp:XE268H, 268/280 gross,224/230@ .050, lift w 1.5's .477"/ .480"
Both of these will run on pump gas, power brakes will work too !
The UD will make more power though, + 30 horse.

You can get the cams from me if you like.

Pontiac Gregg
1-303-776-0877
web site: http://www.pontiacengines.net

I agree the cam is too small for the car in your sig. I assume you will have 9.5-10 compression and non-ported heads and stock rods? A Crower or UD cam with intake duration in the 220-228 range and 112-115 LSA would be a good choice for a strong street application.

I would replace the valves and exhaust seats with quality parts. The valves are 35+ years old, seats may be pitted/recessed. As I recall, about $10-12 a valve should be a fair price for a street motor.

In answer to your question, yes, the pistons should be "dished". If chambers measure between 72 and 74 CCs, a 3" diameter, .080" deep dish will get the compression down to a manageable level.

The 268H is an antique. A similar (parametrically) cam with "modern design" would be the XE268H. We prefer the XE grinds in the lower compression engines, as nothing else has shown us the real performance they have.

Jim

Ditto on the dish, you'll be sorry if you don't. Also agree in regards to the cam, go bigger, as well as the XE grind (if you're going Comp).

Valves, yes, go SS, and the Ferreas are 'the' choice in my opinion. Do the heads right now and save yourself grief later.

I say leave the seats alone unless they're damaged. Clean-up/cut is fine.


.

Correct on the non-ported heads but I have tomahawk forged rods for this motor.

My thinking was that you wouldnt want a cam that pulled over 5200 RPM if you had stock rods. Since you'll have good rods, you can spin that sucker to 6 grand if you've got a halfway decent oiling system without hurting the motor.

I'd set the compression for 9.5 and run a crower cam. The idea is with unported heads, you'll have to make the power with compression and not with RPM (unported heads won't support making power over 5500). That calls for a cam with a wider LSA to spread the powerband out where you can use it with higher compression.

See, the only drawback with seriously dishing the pistons is stepping up HP later. You'd have to have your iron heads ported, or go aluminum. You'd want the compression you lost to dishing back if you went to aluminum heads. So point is, carefully consider present and future goals and RPM range of the engine.

The forged TRW's typically end up WAY below the deck at TDC, so you may want to look at correcting that situation along with making a better cam choice.

The type of transmission, converter stall speed, manual trans, gear ratio, etc must be considered along with the engine cid and static compression ratio when choosing camshafts. Since you are in the street section, I'd look at larger cams on wider LSA's.....Cliff

PS: one would have to "assume" the vehicle in the signature is getting the engine we are talking about here???"

Pistons/ Pontiac Gregg
 

You DO NOT need dished pistons ! The heads are open chambered.
I've done 100's of 400's with the same set up you have.
It's all in the ignition curve !! BTW run Auto lite # 85 plugs, gap @ .030.

Pontiac Gregg

You can't curve 'out' det on a street iron head 10.8 engine on 92 pump gas, not likely on a 10.3 engine, and it's a fine line on a 9.8 engine. Once you back it off so it doesn't ping, not only do you loose power, but you run into overheating issues, for one.

Good catch Cliff, yeah, someone should have mentioned the zero deck thing, especially on the the TRW/SpeedPros. They do end up in the hole, seen as much as .24 before!

What many don't realize is the fact that you don't loose hardly ANY HP going from say 10.75 to 9.25 SCR, like what, maybe 5% - 7%? I don't think even that much. If you pull off a 440HP 400, 5% is what, max, 25HP? You can make that up somewhere else, and it's certainly better to run a on-tune 9.25 engine than a 'crutched' 10.5 engine.

Real issue with running lower than say 9.5-9.25 is the cam selections. That's where people 'think' they loose power by dropping SCR.

I don't feel there's much of a drawback to dishing, even if later you choose a aluminum head. Just get the 72cc, could even run a thin gasket if you want more. Use a profile that builds pressure too if you want.

.

Wow, lots of great info to ponder. Thanks guys!

Sounds like I am in the market for a new cam, at the very least. I am not opposed to getting some Kemco additive as I doubt the car will get driven more than a couple thousand miles a year. (It will be my 2nd "toy" car.)

I should change my sig, because I have found out that my trans is actually a 1967 M-20 (was orig an M-21) and the pontiac 10-bolt was long gone. May run something like a 3:31 gear instead. (original equipment is listed.)

Hi Webfoot,

I'm going against consensus here but I know this combo should be fine as I have the exact same combo on Two motors.


I have the L2262 and #62 heads
Same CC and compression... and I have the Comp Cam 268H

I had two motors built exactly the same one with #62 & #13 heads also.

The combo has power galore, and absolutely NO issues with pinging of using 91 octane

I say go for it. I've had this motor now for ove 2 yrs and no issues.

Back then I asked the same question and my engine builder didn't bat an eye.

If there is no pinging go to the track,chassis dyno make a reading/run. Dump in half a tank of race gas and see if your times pick up. If they do yes you have detonation going on even if you can't hear it. When we dynoed my very open chamber RAIV 400 zero decked TRW piston motor no audible detonation standing next to the motor. Race gas picked up almost 10 hp.

Non ported heads #16s, TRWs, stock rods. Rev it to 6,200 rpm every time I drive it. Dyno'd it and the power never dropped even at 6200+ rpm. Pump gas.


http://www.youtube.com/watch?v=6dTfM...e=channel_page

"Dyno'd it and the power never dropped even at 6200+ rpm. Pump gas."--- But did you try race gas??? My power never dropped either on the RAIV, just made more. My pump gas 455 at 10.25 aluminum heads did NOT change power with race gas over pump gas.

I think my 78 virgin block is 0.012-0.015 down with it's TRWs

One other question, what is a good piston ring compressor? I like the idea of the non-adjustable ones such as summit sells, but the closest they have is 4.155, will this work or do I need another type?

I actually used race gas once at the track and it was the worst day I have had as far as times. I now just use piss water gas.

A friend with a lower compression SBC in his Canadian Pontiac Acadian had the same experience with race gas, Ran out of gas at the track and all they had was race gas, car ran alot slower than earlier runs with pump gas.

I use a set of ring compressors like the one in the link. It'll do most any size and works well. I build a lot of different stuff, so I need more than 1 size.

http://www.sjdiscounttools.com/kd850.html

Zero decking, balancing, setting bearing clearance, setting ring gaps and the other typical performance work to the long block will result in a very strong and reliable powerplant. I agree that 9.2-9.5 is a perfectly fine CR if you're not trying to press the ragged edge of horsepower on pump gas.

I've got Mr. Hand's good book and will take my time. Already checked ring gaps, they are .025 which I think is within tolerance. (?)

Bearings are clevite 77s.

If you watched the first video you might have yhought it was a race engine but its not, just a mild build with non ported heads, 16 heads and stock valves. Built the engine in 1991 and has seen many street miles. Heres another video with it idling and quick revs. I added a nitrous set up to it since mid 12s got boring, Now in the 11s.
Heres another quick video.

http://www.youtube.com/watch?v=Xuq-3...eature=channel

No problem running 14 degs advance and a total of 36 on pump gas and 16 heads. Dont say you cant run 16s on pump gas as most everyone I hang out with run 16s, 62s etc as we all have first gen birds and not one of us detonate. Im no super tuner but understand cars. I just dont have time supertuning to go faster with my combo but I bet if I spent a couple days changing things, 2more tenths are easily achievable. Too many different projects going on to worry about a couple more tenths.

Actually watched that video too, sounds real sweet.

What cam you running?

Its an old Crane Commader but edelbrock makes one that is called the torker plus I believe. Alot of companies followed close to the same profile so I would say that they knew what worked. I love the wide lobe separation for a nice broad torque band and high vacuum. 226-234 duration on 114 deg lobe separation and 466-488 lift if my memory is still good which I think it is. Make sure you elongate the pushrod holes!!!

I ran a 10.3 CR 400 (everything CC'd) with a RAIV cam and never had any issues with detonation and 36 degrees total timing. I had the motor apart and the bearings were fine with no signs of piston damage on the tops. I beat this motor hard.

Car sounds sweet! That's some incredible oil pressure 60 psi @ 600 rpm!

It was a cold motor. It drops to about 25 when hot. Still not bad for an 18 year old engine.The cool thing is that you could just hammer on it if you had to when cold and no hesitation and without any choke. It also starts up like this even after sitting for months. Who says Holleys dont make good street carbs? I just feel that the videos are good backin why this cam is so good in a mild 400.
Mid 12s on pump gas, mid 11s on nitrous, cool running, good cam for nitrous :3gears: good vacuum for power brakes, nice sound, quick rev'ing even with heavy TRW pistons. The heads had a quick gasket match and I elongated the pushrod holes.

Enough of my engine and cam choice we should go back to others cams and see why they prefer theirs. Videos would also be good for sound, rpms, and other data.

i had a undecked .030 400 with trw's and a set of 48's running an old crane ssh-310 nc. even with the wide lobes would ping on 93 under full load in 4th gear. 50/50 93 and cam II would pick .12! at the track.

What kind of 1/4 mile mph are you guys getting with your combos using the criteria mentioned in this thread. IE: 400's, 2262 pistons, small chamber, large valve UNPORTED heads, nothing really crazy for a camshaft... The reason I ask is that I run a similar combo in my 77 TA. 4 spd trans, 3.73 rear, RPM intake, Cliff's Q jet, comp hydraulic cam.... 222/228 @ .050 .465/.474 installed @106. Mine runs around 103-104 mph. Wondering if I have more power to be found with existing setup with some minor changes.
Chris

I run 48 heads with the .030 TRW 2262's. My 406 runs fine on 93 octane, 10% ethanol gas. I've used a Melling 068 cam, a 216/228 Crane and now a Comp 220/224 hyd roller. Never has pinged or detonated that I've heard or seen evidence of on any of them. I do like the hyd roller. Runs pretty well too. 13.26 @ 105.5 on a slow 2:12 60 FT.

12.56 seconds is my fastest with a 1.67 0-60 ft. 107.1 mph is my fastest mph with 16s and non ported , just a quicky gasket match. Funny though my 12.56 second was only a 105.6 mph.Automatic TH350 stock with some cheap shift kit, 3,000 hughes stall and 3:73s, Street Dominator open plenum manifold, 800 Holley DP.
3810 lbs, full tank of gas.