292 I-6 piston questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BCOWANWHEELS · 10-04-2007, 11:23 PM

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

samwise68 · 10-04-2007, 11:31 PM

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.

BCOWANWHEELS · 10-04-2007, 11:53 PM

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

Brad · 10-05-2007, 01:59 AM

Quote:

Originally Posted by BCOWANWHEELS

not much info on that site. need some good tech on how to build a good stump puller engine.

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.

67_C-30 · 10-05-2007, 05:49 AM

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

BCOWANWHEELS · 10-05-2007, 02:03 PM

67 C30 Pm Sent.
Bob

PanelDeland · 10-05-2007, 05:47 PM

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.

Blue71LWB · 10-05-2007, 05:53 PM

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.

samwise68 · 10-05-2007, 07:22 PM

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

-Sam.

BCOWANWHEELS · 10-05-2007, 10:05 PM

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

rwgregory · 10-06-2007, 01:49 AM

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

BCOWANWHEELS · 10-06-2007, 03:37 PM

i,am lookin for 292 pistons not 230 parts.

chvtrkman · 10-06-2007, 05:14 PM

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.

(?) 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.

samwise68 · 10-06-2007, 06:06 PM

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.

Spray-Bomb · 10-06-2007, 07:47 PM

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

samwise68 · 10-06-2007, 10:01 PM

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.

67_C-30 · 10-06-2007, 10:53 PM

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.

mvfd70 · 10-06-2007, 11:49 PM

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

10-04-2007, 11:23 PM	#1
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	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 __________________ I BELIEVE IN JOHN 3:16

10-04-2007, 11:53 PM	#3
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	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 __________________ I BELIEVE IN JOHN 3:16

10-05-2007, 05:49 AM	#5
67_C-30 I have a radical idea! Join Date: Jan 2005 Location: Sweet Home Alabama! Posts: 6,513	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. __________________ '67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club!

10-05-2007, 02:03 PM	#6
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	Re: 292 I-6 piston questions 67 C30 Pm Sent. Bob __________________ I BELIEVE IN JOHN 3:16

10-05-2007, 05:47 PM	#7
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	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. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

10-05-2007, 05:53 PM	#8
Blue71LWB Registered User Join Date: Nov 2006 Location: Alabama Posts: 120	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. __________________ Working on my first 1,000 post. I'm sure I'll get there before this project is over .

10-05-2007, 10:05 PM	#10
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	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 __________________ I BELIEVE IN JOHN 3:16 Last edited by BCOWANWHEELS; 10-05-2007 at 10:06 PM.

10-06-2007, 01:49 AM	#11
rwgregory Registered User Join Date: Apr 2005 Location: Chula Vista, California Posts: 495	Re: 292 I-6 piston questions FYI; 230's have flat top pistons... __________________ rwgregory 67 GMC 2500 ,2w/d wide box 305 V-6, 4-speed

10-06-2007, 03:37 PM	#12
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	Re: 292 I-6 piston questions i,am lookin for 292 pistons not 230 parts. __________________ I BELIEVE IN JOHN 3:16

10-06-2007, 05:14 PM	#13
chvtrkman Registered User Join Date: Sep 2007 Location: PA. Posts: 178	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.(?) 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. __________________ _____________________________________________ 69 C-20 292, 4 spd O/D, 4:56 rears. No a/c p/s p/b p/w......restoration project,"Operation:Stovebolt" 78 C-10 305 TH350 new (old) daily driver 02 Suburban Z71 a.k.a. the family truckster 99 Silverado 1500 Z71

10-06-2007, 07:47 PM	#15
Spray-Bomb Texas Big Wig Join Date: Jan 2007 Location: Mineola, Texas Posts: 5,620	Re: 292 I-6 piston questions Aren't 307 & 283 pistons the same ??? __________________ Just not low enough... ----------------------------- Sinister Killer

10-06-2007, 10:53 PM	#17
67_C-30 I have a radical idea! Join Date: Jan 2005 Location: Sweet Home Alabama! Posts: 6,513	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. __________________ '67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club!

10-06-2007, 11:49 PM	#18
mvfd70 Registered User Join Date: Jan 2007 Location: Opdyke, IL Posts: 775	Re: 292 I-6 piston questions 250's have flat pistons too. At least mine does __________________ 1978 Chevrolet Silverado 3/4 ton 400 small block. 2000 F-250 Powerstroke 2002 GMC Yukon Denali XL



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