okay this is what i have:
a 350 4 bolt main 2 peice RMS casting number 10066036 heads are 993's 76cc chambers 1.94 intake 1.50 exhaust

i tore it down to the block and had several suprises

1 the wear on the flat tappet cam was mostly one the aft of the lobes like the cam was walking forward no lifter damage..no thrust plate or cam button should there have been something?

2 a cracked piston skirt i mean hair line crack just enough to get oil in it so i could see it better horizontally across the skirt about a half in. long

What i am looking to do is a rebuild while boosting my compression of a whooping 8.5 hope fully to around 9.5 i have picked out a the parts i am looking to use but am looking for input things like quench and clearnaces that i might have over looked so..
SUMMIT RACING

Clevite Main Bearings, P Series, 1/2 Groove, Standard Size, Tri Metal, Chevy, Small Block CLE-MS909P

Piston, Hypereutectic, Flat Top, 4.000 in. Bore, 5/64 in., 5/64 in., 3/16 in. Ring Grooves, Chevy, 350, 4 valve reliefs +5cc head volume STL-H345NP

Engine Re-Ring, Moly, 4.000 in. Bore, Standard Rod FEM-205658-00

Head Gasket, Rubber Coated Steel Shim, 4.100 in. Bore, .015 in. Compressed Thickness, Chevy, Small Block FPP-1094

that is it for now i am toying with the idea of converting this to a roller block so i havent choosen a cam yet.
the block cam with dished pistons with 4 valve reliefs will those pistons help compression or be a waste should i be looking for something in the -cc range?

is that head gasket to thin will it have any horrible side effects like a flame thrower held backwards?

or should i just find a set of smaller heads and port the snot out of them?

i mean i probably will never race this i am only building it to have built my own motor and to scare yodas

 

The wear on flat-tappet cam lobes is ALWAYS on the rear edge. The lifters aren't flt, and the cam lobe isn't either. The cam is taller on the rear of the lobe than the front, and the lifter is conxex with a radius of about 6'; the effect of the whole system is that the lifter rides entirely with its outside edge on the rear edge of the lobe, and that's part of what pulls the cam into the block.

No there's no retainer required, or any of the rest of that stupid factory roller crap.

Cracked piston skirt = excessive RPMs; only takes once.

Those pistons have a 1.54" compression height. Stock is 1.56". What that means, is that the piston is .020" FARTHER DOWN IN THE HOLE at TDC than stock; which is ALREADY .025", more or less. Meaning, at TDC, the piston face will miss reaching the top of the cyl, by about .045". Don't forget to take that extra unswept volume into account when "calculating" (guessing at using numbers) your compression ratio.

I don't like shim gaskets, since EVERY SINGLE MOTOR I've ever torn down that was built with them, WITHOUT EVEN ONE EXCEPTION, had at least one blown spot. Not necessarily "blown", as in blasted out and non-existent; but EVERY ONE had combustion leaks. I don't trust them, and MOST CERTAINLY NOT unless both the block and the heads are decked.

Throw the 993s in the trash. That's what I do with them. I've even paid people to come haul piles of that crap off of my property, back when I was doing enough motor work to accumulate lots of worthless cores that I was too lazy to haul to the scrap yard and sell myself. Those, and 882s, and 624s, and all the various 307 castings, and other such crap heads. Get a set of 416s or 601s, and spend your porting time on those instead.

If you decide to get the block decked, then get it zero-decked to the pistons, or just have them lop .040" off of it; and use .039" composition head gaskets.

 

Need to know how far the piston is into the hole to determine quench.
You'll need domed pistons to increase the CR with 76cc heads, or shave them down to 64cc. A retro-roller cam with lifters will be expensive.

 

thanks for the info i thought summit said those pistons had a 1.56 compression distance... so if i get rid of the 993s and get a set of 601s mainly because of the great porting thread on them would you still recommend having the block zero decked to the pistons? how much should i expect to spend on the decking?
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rgarcia i all ready have a set of roller lifters for it just need a thrust plate and cam....

 

They quote the stock compression height in their "specs". About all that does, is to differentiate that part # from the ones for 302, 327, or 383.

If you measure the part itself, I believe you'll find that it actually has a 1.54" CH.

Yes I would recommend having the block zero-decked. Basically, if you deck it, it costs the same whether you deck it to straighten it for the shim gaskets, or you zero-deck it. So, if you're going to spend the money ANYWAY, which one would you rather have? Spend the same, get more. Kind of like, Rule #0 Of Hot-Rodding.

Block decking is usually in the $175ish kind of range. Varies widely depending on competition and how hungry the machine shop is. DO NOT buy machine work based on the low bid.

 

sounds good i was just wondering on the price there seems to be only on machine shop around that has stayed in bussiness i would have to wait about a month for them to get to me...

now with the new pistons i need the crank rebalanced right? even if the pistons are the same weight as the old ones?

 

If the pistons are the same weight as the old ones, and the rods are the same ones, then you don't "have to" get it balanced.

On the other hand, it's always a good idea to have that checked.

They're going to charge you about the same for just checking the balance, as they would for actually doing the balance work. The money is in all the setup and handling and measuring. The act of grinding on stuff is quick and easy and therefore nearly free. What I REALLY hate though, is to take stuff somewhere, and since they've probably had bad experiences with other customers in the past who discovered that they paid AS MUCH to have their parts checked BUT THE SHOP DIDN'T DO ANYTHING TO THEM, and got PO'ed about getting charged for what they saw as "nothing", that they feel OBLIGATED to do SOMETHING to every piece just so people can look at them and know that "something" was done. I've seen some otherwise perfectly good parts get ruined that way. So if your shop says it doesn't need balancing, don't necessarily tell them to balance it anyway; even if it appears to you like you're paying for it.

Whatever you do, DO NOT, under ANY circumstances, let your flywheel and crank damper exist inside the shop at the same time as your rotating assembly!!! If you do, and you tell them to "balance" it, quite often they'll do themselves the favor of doing their balance work on those bolt-on parts. Which then means, you now have an UNBALANCED rotating assembly, with CUSTOM bolt-ons; and if at any time you have to change one of those external parts, you now have to take the motor apart, and have ANOTHER ONE "custom" balanced to match your unbalanced motor. Best way to make sure that doesn't happen, is to simply make it impossible, by never allowing those parts to be in the same place at the same time. Have the motor balanced to the STOCK specs, so that any part you now have or that you buy in the future, will bolt up and work right without having to be "custom" matched to the motor.