[1969chevyss]

Is that the same as dome with trough? im looking on summit now.

[cobalt327]

Another name for inverted dome is D-shaped dish. I do not know if a piston w/the specs I described is even made- I'm just saying what the ideal situation would be. You may end up having to use a round dish piston.

Depending on your skills and equipment, you could enlarge the chambers some to lessen the need for a dish or have this work done. But any hand work is going to be costly if done by a qualified shop.

[1969chevyss]

Ok I will search for the pistons and see will they meet my application. Also what are my options if I get the flat top piston with 5cc. Is the 10:3cr too high for street driven. Also an option is to use different heads, right.

[1969chevyss]

I just saw the comment about enlarging the chambers, yes this is something I could do. I will cross that bridge when I get to it.

[cobalt327]

When I plan on reworking the chambers, I will mark the heads left and right and keep them in that location. Then you simply place the heads on the engine w/a few bolts snugged down to hold them in place so you can flip the engine over. Reach down inside each bore to scribe a line that's the size of the bore. Keep the work you do to the chambers inside this line.

If the work is done w/some thought to unshrouding the valves, this can help the performance as well as helping the CR situation.

[1969chevyss]

I will keep this in mind but I will call around and see what the cost for something like that go.

[1969chevyss]

Here is the before of my engine block. Will post afterwards when i get it back from the machine shop.

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[1969chevyss]

Here is the information off the manufacturer website regarding the pistons. I think it is different than what the summit website states.

Mfg. Chevrolet
Eng. Family Small Block
Bore Dia. 4.030
Compression Distance 1.548
Weight (Grams) 545
Dome Volume -6.88
Head Shape Flat; 4 reliefs
Top Ring 5/64
2nd Ring 5/64
Oil Ring 3/16
Pin Style p or f
Bore Clearance See "Piston Fitting Information" on carton label

[sjkonyndyk]

I'm running a Vortec Block with a 383, 501 Lift cam and Dish piston. My CR is 9.35:1. happily runs on pump mid grade. I tightened my quench to .031. I know its close but with the dish there is zero contact.

If I were to do it again in a 350.

Shoot for 9.5:1 a Silvo Lite D-Dish piston, .038 Quench. Get the block decked to .010 In the hole. buy GM gaskets at .028 (about 19 a piece from the Chevy dealer). Run a 525 ish lift roller cam with a 108-109 LSA (good and rumbly and still decent vacuum) . (and get the Heads pocketed and polished) or buy a set of e-tec Vortecs. and sell your stocker Vortecs for 250-300 on C-list.

this should net you 350 -375 HP and really nice torque (if its on the street torque is king) Hence why i did a stroker)

with 9.5 and a really solid quench you never worry about detonation on a crappy tank of fuel or a screwup keeping your quench solid also boosts Volumetric efficiency (sp) Tech inspector helped my with all this. So did Cobalt the guys are sharp its been 10 Yrs since I touched a SBC and I cou;dn't be happier. Dave vizard has run SBC down to .028 Quench with minor kissing at 5K+ RPMS but its not necessary.

Couple things to watch out for. Use a CARTER universal fuel pump, about 85 from Fisher auto parts. (smaller than the Holleys, Mount it to the frame close to the tank with rubber behind it (its Loud)

SUPER IMPORTANT
Check your cam stud mine rubbed the Timing cover i had to tear it down, problem was the 1pc oil pan and the "Right Stuff" sealer I am removing the oil pan now to replace the oil pan gasket because it tore. The stud on the cam stuck out to far so CHeck Check Check.
Buy the cloyes Hipo roller Chain set 65.00 well worth it and run the cam back 1 setting. (can't remember which character to line it up with I can look at mine at work today) Also any tin TC will work just check the cam stud.

All told I have under 2K in the entire build.

[sjkonyndyk]

if your Fuel pump is half drilled ask the machinist what he would charge to finish it. mine said 125 Well worth it IMO the pump wiring and relay cost my 125 or more plus all the hassle.

[cobalt327]

Originally Posted by 1969chevyss

Here is the information off the manufacturer website regarding the pistons. I think it is different than what the summit website states.

Mfg. Chevrolet
Eng. Family Small Block
Bore Dia. 4.030
Compression Distance 1.548
Weight (Grams) 545
Dome Volume -6.88
Head Shape Flat; 4 reliefs
Top Ring 5/64
2nd Ring 5/64
Oil Ring 3/16
Pin Style p or f
Bore Clearance See "Piston Fitting Information" on carton label

These must be the twice-as-expensive pistons w/the single trough? The extra relief volume will bring the CR down a few tenths, about 10.1:1 w/the rest of the numbers as before.

The compression height should be 1.56" ideally, 1.54" is common to "rebuilder"-type pistons and these are 1.548". This will mean that you'll want to pay attention to head gasket thickness and deck height to keep the quench at or near 0.040".

What are the real specs on the less expensive pistons? I believe- given your goals- the cheaper pistons will do just as good, and the money you save can go to a torque plate hone job. Or did I say this already??

[1969chevyss]

Thanks for the reply, what is the part number on those pistons? I will ask the machine about how much they charge to drill a hole for the pump.

[1969chevyss]

Originally Posted by cobalt327

These must be the twice-as-expensive pistons w/the single trough? The extra relief volume will bring the CR down a few tenths, about 10.1:1 w/the rest of the numbers as before.

The compression height should be 1.56" ideally, 1.54" is common to "rebuilder"-type pistons and these are 1.548". This will mean that you'll want to pay attention to head gasket thickness and deck height to keep the quench at or near 0.040".

What are the real specs on the less expensive pistons? I believe- given your goals- the cheaper pistons will do just as good, and the money you save can go to a torque plate hone job. Or did I say this already??

These are the specs from the manufacturer website for the less expensive pistons part number H345ACP30.

[1969chevyss]

One website selling the same pistons have these specs.

H345ACP30 4.030" 64cc 9.47 cr

Dome Style: Flat Top 4VR
Rod Length:
5.700"
Compression Height:
1.548"
Dome Volume: -5cc
The more people I call and ask what the compression ration will be with 64cc I get a different asnwer each time.

[cobalt327]

Originally Posted by 1969chevyss

These are the specs from the manufacturer website for the less expensive pistons part number H345ACP30.

The more expensive pistons you first linked to (or that I did a search for, can't remember now which ones you linked) showed the expensive slugs to be either floating or pressed. The other cheaper pistons were shown as pressed only- that's why I assumed these latest ones you posted the specs on were the more expensive set, as they are shown as "p or f".

In any event, IMO you'll do better w/a compression height of 1.56".

The more people I call and ask what the compression ration will be with 64cc I get a different asnwer each time.

Don't worry about asking what the CR will be- what you REALLY need to know is the valve relief or dish volume. We or you can figure the CR from there- they have no idea what your deck height is or any other parameter unless you tell them then you're depending on their math to be correct. So ask for the exact piston volume, not the CR.