Piston ID? [Archive] - Chevelle Tech

: Piston ID?


ak69
Oct 5th, 05, 3:18 AM
I just picked up another 454 short block. Going to put it on the stand tomorrow and pull the pan, see whats inside! Date coded 1973, Mortech site say casting numbers could be either 2 or four bolt mains. I do know the current bore is .030 over, has domed pistons in the bores and are stamped "7053P" on the piston tops............ring a bell as to brand with anyone? Curious.......................The price on this one was very good, FREEBEE :) It has been sitting in a dry garage for at least 12 years, oil still in the pan. Bores look to be in good shape, will be fun to see what the crank / rods and bearings look like. A friend has abandoned his hot rod dreams, and the engine has been reminding him for 12 years that he still aint building a car to go with it. At least now he can use the man door in the garage, engine has been sitting in front of it for 12 years!!!!!

sschevellefan
Oct 5th, 05, 3:25 AM
They are Speed Pro. I asked about the same piston number a while back and nobody could tell me anything about them. My neighbor has a motor with the same pistons, thats why I asked. Since it wasn`t my motor I did`nt continue looking for the answer. I hope you have better luck than I did.

ak69
Oct 5th, 05, 3:28 AM
Just knowing that they are speed pro is a good start. Thanks for the info!

ak69
Oct 5th, 05, 4:41 AM
Digging around in some books.............found this in my copy of "Max Performance CHEVY Rat Motors". Pistons listed as SP-7053P are forged, closed chamber type, dome at 30.6 CC's, P stands for pressed pins, and give 11.8 comp ratio with a 106 cc combustion chamber. Intersting stuff. My current 049 heads / chambers were milled to 112 cc's. 049's are open chamber heads and would allow the use of closed chamber pistons. Going from 9.5 comp to 11 comprression would open up alot more cam choices.............more interesting stuff! I have no info on weight of the SP's, could not be much more heavy than trw 2399's i am currently running. Roller cam and more compression..............here we go again! :)

ak69
Oct 5th, 05, 5:11 AM
A little more digging around...............looks like TRW2349 are the same pistons as SP-7053's. Got to love the internet, God Bless Al Gore for inventing it! Summit sells them new for 50 bucks a pop.

71454Chevelle
Oct 5th, 05, 7:38 AM
Craig,

Got some more info for you about the 7053P (or L-2349F) pistons from a copied page of an old Speed Pro catalog.

They are duplicates of factory 1970 11:1 comp ratio LS-6 engine. (forged and closed chambers). They have the weight listed (without pin) as 658 grams.

Dome sizes are as follows;

Standard bore= .265" height (30.6cc)
.030" overbore= .221" height (29.4cc)
.060" overbore= .210" height (27.9cc)

These are the pistons I run with a set of 049 ovals. Nice durable piston but a little heavy. :thumbsup:

Hope this helps.

ak69
Oct 5th, 05, 3:17 PM
Thanks Darren! Piston mystery solved. Forensic BBC detectives around the world would be impressed! Are your 049's chambers stock volume at 118/122 cc's?

The domes of the SP7053 in this block all look to be in good shape, very light carbon build up. They might be worth reusing. Going to pull the pan today and take a look at the crank and rods. :)

This short block also came with a T400 trans, it will make a nice core for a spare.

I even have the wife convinced that a "BIG TIME" racer like me needs extra engines and transmissions. What if I broke something in the second round of eliminations while trying to win a four dollar trophy? :)

71454Chevelle
Oct 5th, 05, 3:35 PM
Craig,

No, my 049's have been milled down abit to get the SCR up. Years ago when I had the motor rebuilt, I told the builder I wanted 9.5 cr. For some reason (I don't know why) the machine shop milled a few CC's off the dome of the pistons. :confused:

Didn't find out until just a couple of years ago when I was changing cams and freshening up the heads.

I took about .040" off the deck surface of the heads to get them down to 113cc. The dome on the pistons are about 22cc. This figures out to be right at 10.0 scr.