292 I-6 piston questions
 

i,am fixing to rebuild a 292 chevy engine and from what i understand the stock compression is 8.5 but if i use liquid propane gas pistons then the compression will be over 9.5 to 1. anybody got any info on this setup. i want as close to 10.1 compression as i can get. any help is appreciated.
bob

Re: 292 I-6 piston questions
 

to my understanding, the LPG pistons bump it about a point in compression. i don't have specifics, but alot of guys do it on www.inliners.org.

also, have you considered using a 194 head? the smaller combustion chamber ups the compression nicely, i'm told.

-Sam.

Re: 292 I-6 piston questions
 

not much info on that site. need some good tech on how to build a good stump puller engine. gonna check out the 194 head though.
thanks
bob

Re: 292 I-6 piston questions
 

Are you kidding??? Perhaps you didn't look long or do a search. There's ton's of info on L6's over there. Many have been in your boat and have posed the question.

194 heads are hard to find. Good luck.

Re: 292 I-6 piston questions
 

I've got a NOS GM camshaft still in the factory cardboard tube if you need one for your build.

Re: 292 I-6 piston questions
 

67 C30 Pm Sent.
Bob

Re: 292 I-6 piston questions
 

BCOWANWHEELS, although the 194 heads are getting rare there is also the option of milling your head to get to the CR you want.There are some sites with the combustion chamber specs and you will know your overbore.You need to know pistons and head gasket(it may help fine tune the CR).You should be able to get really close to your optimum CR this way.

Re: 292 I-6 piston questions
 

I have heard that some of these inlines came with dished top pistons,is this true?. If so, adding regular flat top pistons would help the CR.

Re: 292 I-6 piston questions
 

all of the straight 6's, to my knowledge, came with dished pistons. it'd be the reason for the low compression ratio.

-Sam.

Re: 292 I-6 piston questions
 

YEP ALL CAME WITH DISHED OUT PISTONS. only higher compression piston available is federal mogual #980p which is a 9-1 cast piston for lp gas engines. .150 deep dish . other than that only recourse is aftermarket forged pistons ( ouch ) $$$$$$$ so it looks like lp pistons for me..... now off to the machine shop with short block parts for cleanning and inspection to see if i,ve got a good rebuildable core.
bob

Re: 292 I-6 piston questions
 

FYI; 230's have flat top pistons...

Re: 292 I-6 piston questions
 

i,am lookin for 292 pistons not 230 parts.

Re: 292 I-6 piston questions
 

Bob,
What Brad said is correct. There is tons of info over at inliners.org. You have to do a search. Also, What samwise suggested about milling your head should help get you closer to the CR you want.
Yes, the inline pistons are dished as you stated, and the LPG pistons have less dish to them....bumps CR to 9:1. I have also read on inliners where some guys used 307 pistons(flat top).....if memory's working correctly.:crazy:(?) I believe with the 307s you have to do some machining on them though.Not sure.It would be worth the $$$ to get hold of a copy of Leo Santucci's Chevrolet Inline Six Power Manual.There's good info in there .

I believe in John 3:16 also.

Re: 292 I-6 piston questions
 

307 pistons work in a 250, and 283 pistons in a 230. unfortunately, the 292's pin placement is screwy, so a normal piston's deck hieght is out of whack on it. i think? idk. i just know that no other commerically made gm piston works in a 292. and it makes me sad. lol

-Sam.

Re: 292 I-6 piston questions
 

Aren't 307 & 283 pistons the same ???

Re: 292 I-6 piston questions
 

the pin height, so to speak, is different. i think.

thats why you can't use a 283 piston in a 250 - the piston doesn't end up in the cylinder right when on the conn. rod.

atleast, thats what i think i read.

-Sam.

Re: 292 I-6 piston questions
 

You're right, the pin location different on 283 and 307. The 307 has the 327 stroke (3.25") and the 283 has a 3.00" stroke. They both use a 5.700" rod, so the pin location is what changes. They are both 3.875" diameter.

Re: 292 I-6 piston questions
 

250's have flat pistons too. At least mine does