Piston ID

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Jan 28, 2006 | 09:18 PM

w1ctc

Thread Starter

Melting Slicks

Joined: Sep 2003

Posts: 3,050

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From: Orange Ct

Piston ID

I started to tear down motor in anticipation of putting on some better heads. The last time I did this was about 24 years ago and was surprised how little crud was in the valley. These heads are marked as 452 casting but they have 1.94/1.50 valves which means they were worked on (if all the info I could find was correct as they should have 1.72 intake valves). Can anyone identify these pistons? My next step is to measure the TDC position so I can decide what chamber size but I would like to know the dome CC’s to be accurate about it.
While I was doing this I dropped a socket and it went right down the exhaust pipe. Took me half an hour to fish it out. The fun never stops.

http://i1.tinypic.com/mskgi9.jpg

http://i1.tinypic.com/mskh6o.jpg

http://i1.tinypic.com/mskj6u.jpg

Jan 28, 2006 | 10:13 PM

BADBIRDCAGE

Race Director

Joined: Feb 2004

Posts: 11,039

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From: Del Boca Vista FL

Looks like your basic 11 to 1 piston for a small block. Has a flat topped raised section that actually helps fill the combustion chamber.

The 12 and a half to 1 pistons had a much taller dome that was not flat topped.

Rich

Jan 28, 2006 | 11:26 PM

Allcoupedup

Melting Slicks

Joined: Nov 2002

Posts: 2,460

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From: Wheaton IL

yup. I agree - looks like the TRW SHP forged piston. Look for a part # under that carbon. Should look like these.
http://65corvette.nonethewiser.net/p...ts/poptop2.JPG
http://65corvette.nonethewiser.net/m...4/3-2-0408.jpg

Do the pistons have a part # of L2166N? If so, they are the OE forged pistons. Don't assume you have 11:1 compression becuase you have these pistons. I have them too and mine is 10:1. You need to measure your piston crown/deck clearance and cylinder heard combustion chamber.

Brian

Jan 29, 2006 | 12:32 PM

w1ctc

Thread Starter

Melting Slicks

Joined: Sep 2003

Posts: 3,050

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From: Orange Ct

Thanks for the info guys. Those look like the same pistons Brian. I can't seem to find any dome cc specs on them. I'll measure the other stuff today and cc the heads I have so I know where I'm at now. I will shoot for 10/1 with the new heads. Its a 69 350 cu engine.

Jan 29, 2006 | 05:19 PM

dmentzer

Racer

Joined: Aug 2005

Posts: 355

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From: Ephrata PA

Are you sure it's a 350? All of the 11:1 TRW pistons I ever saw, including the LT1, looked like the pic below.

Jan 29, 2006 | 05:56 PM

Allcoupedup

Melting Slicks

Joined: Nov 2002

Posts: 2,460

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From: Wheaton IL

Guys, be careful when implying that piston choice yields a certain compression ratio. W1ctc probably threw out 11:1 becuase the old SHP engines were advertisied at 11:1. We all know that this is not the case. The pistons I displayed are the OE SHP pistons. Most catalogs suggest using these to achieve a 10.35:1 ratio and even this suggestion is dangerous.

We should all talk about piston dome volumes as an absolute unit of measurement for pistons. That being said I cannot remember the dome volume for the OE SHP pistons and I am too lazy to look it up in the archives right now.

Brian

Jan 29, 2006 | 07:57 PM

w1ctc

Thread Starter

Melting Slicks

Joined: Sep 2003

Posts: 3,050

Likes: 2

From: Orange Ct

Heres the bottom line on my 65 . The guy that sold it to me in 71 said he replaced the motor with a 69 350, had 11/1 pistons and a Sig Erison 268 duration cam. I just took all this as fact. In about 78 I replaced the heads since the old ones were shot with a set of 452 heads that were changed to 1.94/1.50 valves and have 64cc chambers (I measured today). The pistons are, in fact, 2166's and have a 5.3 cc dome displacement. Dementzer you made me think. even though the motor casting reads out as a 69 Chevelle 350, is it really? As it turns out, the stroke is 3.25 with 4 inch bore, a 327. Measured up the deck and all that and it comes out to 10.4/1 cr just as you said Brian. Now that I have that all cleared up, I can decide on what heads to buy. No, I won't ask the guy for my $2k back because the car dosen't have a 350. Never assume anything.

Jan 29, 2006 | 09:12 PM

dmentzer

Racer

Joined: Aug 2005

Posts: 355

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From: Ephrata PA

Hey, I wouldn't worry about not having a 350. The 327 is the correct size motor for your car, anyway. And, if it is a 69 block, then it should be a large journal crank. Much easier to find quality rods for it rather than the small journal.