comp ratio with solid roller cam

[CGT]

If the engine is not together, I'd probably deck the block to 9.005....its always nice to have that squared up regardless of piston to head clearance, use the current pistons if he has them already with the .015 shim. Decking the block will give you better odds of that gasket not potentially causing you any issues anyway.

If the engine is together, or the other stuff is not in budget I would put the thinnest gasket on it you can find and run it. The cam doesn't scare me with that compression...of course it would run better with more, most stuff does. I've seen plenty of lower compression stuff run real good. What is the exhaust lobe?

[CamKing]

There has been many circle track classes that were limited to 9:1 or 9.5:!, and 355/358ci. In most of them, we would run a roller cam in the high 250's to low 260's. They would turn 7,600 to 8,200rpm. The only thing different with those cams, to yours is the LSA. Most of the race cams were on a 104 to 108 LSA, so that will hurt your bottom-end a bit. If you install the cam on a 104 Intake Centerline, that'll help.
What else would help, is a 4,000+ stall, and gear it ti turn 7,500+rpm. If you can't do those 2 things, get a smaller cam.

[F-BIRD'88]

Warning. If yiu cut the blockbthat muchbinstead of just replacibg the pistons thenvthere is acgood chance that now you won't have enough intake valve to piston clearance as the valve gets moved closer to the piston by cutting the block that much. Now you have to retard the cam from the nice advanced position. 102-104-.
(Or get a different cam $$$$)

I been there done this on this exact issue.
Put the low cost very good 1.56" summit T5 pistonns in the block as is.use the .015" gasket. Install your cam on 102 and go.
The cr is right 10.3:1 and the cam is in right.
You spent you money wisely getting correct 1.56" ch decent T5 hyper pistons .

If you cut the block with that 255° roller all bets are off.
Now the cam don't fit. VTP clearance issue.
Again, been there on this one..

You can buzz it plenty with these Summit T5 Hyper pistons
They are very good.
If this car will ever see nitrous you must make the top ring gap bigger as per KB HYPER piston instructions.

Useing the GMPP perf Head bolts set with the small socket size head makes it real easy to RETorque the heads after run in. Install those head gaskets clean and dry, no goop, no sealer. It will out live you.
Again cutting the block (on this one) will create more problems than it will solve.

[F-BIRD'88]

The summit 350 sbc piston you want is SUM-17350C-30
This is the 1.56" ch piston. $139 us.
Change the 30 suffix if you want another oversize. This is a .030" oversize 350 piston.


Avoid #SUM-17351C this piston is 1.54" ch..

If you order the Summit 350 Engine rebuild KIT
check the included piston specs . It now has the WRONG crap $79 1.54" CH piston in this kit.

So order the right 1.56" CH piston separate . SUM-17350C-30
Be sure you get this right when ordering.

[CGT]

Fbird, are you implying that decking the block will have a greater effect on vtp clearance than a thinner gasket or taller comp height?

With that cam and any of those cheap-ass pistons, if their is gonna be a vtp issue, it will be a radial issue not a depth issue.(Unless it is a super aggressive lobe) . I just got finished putting a 238 intake lobe in at 101° on those cheap pistons with .035 piston to head..similiar build . Over .150 clearance on intake. 1.94 valve though. I'm guessing he probably has a 2.08 valve.

A 255 lobe in at 101° would lose roughly .050 to .060ish vtp clearance on the intake from 238, roughly depending on lobe intensities and rocker ratios. A 255° lobe in at 106°....obviously less than that.

Bottom line, If their is going to be a vtp clearance issue, getting his piston to head clearance correct wont be the cause of it.

[gmrocket]

Who's intake lobe and what's the lobe grind #

[mag2555]

A lot will hing on the cranking compression!
I would not be surprised if at low rpm the motor can not over come the restriction of the Exh system and reversion from the Exh side makes the plugs a dry black color and tuning for a good livable idle a tuff deal!

[F-BIRD'88]

You can also source the correct Affordable priced HYPER T5 heat treat 1.56" CH 350 flat top piston there LOCALLY thru your local engine machine shop. It need not be a Hot Rod or Racing shop.. The UEM KB HYPER pistons work great.
If you know how to set up the engine tune the plugs DO NOT run black nor foul.

[CGT]

I would not be surprised if at low rpm the motor can not over come the restriction of the Exh system and reversion from the Exh side makes the plugs a dry black color and tuning for a good livable idle a tuff deal!

So compression will fix the reversion?

[F-BIRD'88]

In the end your friend will be very glad he spent a little more and got the correct pistons. with correct CR and CH.
Sell the 1.54" ch pistons... 10:1 to 10.5:1 real cr is where you want to be for street/strip 92 octane
When you do it right the cam (the cam you got) will work very well in on 102-104.
This is the exact engine /car for using a Street tunnel ram and 2x 600-650-750 edelbrock carbs.
This is also ideal for doing the 2x 4 carbs on a carb adapter on your good single 4bbl SBC intake.
The 2x Qjets in my Six Shooter set up will ROCK on this car.

[gmrocket]

In the end your friend will be very glad he spent a little more and got the correct pistons. with correct CR and CH.
Sell the 1.54" ch pistons... 10:1 to 10.5:1 real cr is where you want to be for street/strip 92 octane
When you do it right the cam (the cam you got) will work very well in on 102-104.
This is the exact engine /car for using a Street tunnel ram and 2x 600-650-750 edelbrock carbs.
This is also ideal for doing the 2x 4 carbs on a carb adapter on your good single 4bbl SBC intake.
The 2x Qjets in my Six Shooter set up will ROCK on this car.

Weeeeee, I was patiently waiting for the 2x4 tunnel ram or super duper horn dog 2x4 adapter on the single 4

Have you seen them 1950's intakes that have 6 x 2's? Or 8 x 2's??

I think the Munster mobile had that set up...sick!!

Forgot to add....i heard the BSFC's were killer

[travis]

I would seriously consider a much smaller cam, for several reasons (you did say street build although everybody’s interpretation of that is different)...or a set of light weight forged pistons. This combination of parts will easily rev way beyond what I would be comfortable with with heavy cast pistons. Sure, it will work for a while, but when they let go, there won’t be much left to salvage. If it is just a fairground cruiser, that’s one thing, but if you intend to actually drive it, that’s something else entirely.

What is the rest of the combo going to be? Weight, gears, converter, intended usage, etc.?

[Olds455]

Dang F-bird. Slow down. You spend the guys money faster than he does and assume everything is as easy as "1,2,3".

"Sell those pistons, buy these, sell that and that, do this, buy this, buy this, build this adapter or even use my invention that hasn't even actually been invented yet!"


Come on, man. Chill out. You want him to spend more in one paragraph than he's probably spent on the entire thing so far. Where is this mythical place where race parts sell instantly, also? We all need to know about that. Don't be greedy. I'm sure we've all got stuff we need to sell, since it's apparently just that easy. Seriously. Be realistic. Don't spend the guys money quicker than he can even post a response.

[F-BIRD'88]

I don't think those $79 rebuilder 1.54" ch cast pistons qualify as race parts.
Ya calling up your local machine shop and ordering a set of 350 sbc KB flat top claimer pistons is just not that hard guy.

[F-BIRD'88]

Weiand used to make this very 2 piece Dual 4bbl to single 4 bbl carb adapter(s). Old Weiand #7161 (dual)combined with Weiand #7160 (single) 4-71 blower adapters conbined. Not for holleys inline. Fits 2x4 AFB, AVS, avs2 and street demon 4bbl carbs inline., on a single 4 bbl intake manifold. The combined 2 as cast Weiand adapters together create a decent transition, with relative low profile. Mine, intended for max power will be a higher height for a even better 2x4 to 1x4 transition. Yet still shorter height than a tunnel ram.
The top of the 2xqjet Six Shooter adapter will be a bit different on top. And the transition is even better.