L-82 Head/Cam Replacement-Disaster!
Racer
Joined: Feb 2010
Posts: 425
Likes: 2
You guys are the best! Ok here we go:
Back to the original intent: get as much power as possible from a the original L-82 block with the basic look of an L-82 and rotating mass with the exception of the heads and the cam.If I painted the heads blue, it would really look stock but I decided to go bare aluminum since most know the 882 heads are crap. Compression should be 10-10.2:1, pretty much the limit for pump gas and maximum timing. Can you go higher, probably, but for my application-perfect!
As far as decking the block, from more than one source and the engine builder himself: NOT necessary on a street engine rarely seeing over 5,000 RPM as long as the deck is straight-It is!A radical 350 pushing 6,500+ RPM requires a decking if not 100% absolutely straight.
Headers and 2.5 inch duals not being stock-give me a break!
As for the L-82 intake, multiple sources on this one again including the engine builder: a more radical roller cam turning 6,500+ RPM, yes, an aftermarket intake will make a difference. NOT on my combo-very little difference. The intake is 100% cleaned and allows the dual snorkel GM air cleaner assembly-NOT possible with any aftermarket intake. If when the engine is broken in thoroughly, carb tuned, and gets on the dyno, if the engine makes 400-425 Gross HP, intake stays as is. If not, intake porting could be in the future. If the L-82 intake costs 5-8 HP, who cares?
Something to think about: Karols 78 L-82 4 speed with 3.70 gears made 248 RWHP on the SAME dyno with under drive pulleys, Edelbrock Performer intake, 882 heads, Quadrajet, and an aftermarket flat tappet cam versus my 233 RWHP with L-82 intake, L-82 cam, 882 heads, poor compression on Cylinder 6 as well as broken rings on the other cylinders (much more to this story during the teardown), Holley 4175, etc. Think about that?-15 HP for a cam and intake versus an L-82 NOT running at 100%. The difference if it was apples to apples was probably <10 HP for the aftermarket cam and Edlebrock Performer-Again, give me a break!
We will see.
Back to the original intent: get as much power as possible from a the original L-82 block with the basic look of an L-82 and rotating mass with the exception of the heads and the cam.If I painted the heads blue, it would really look stock but I decided to go bare aluminum since most know the 882 heads are crap. Compression should be 10-10.2:1, pretty much the limit for pump gas and maximum timing. Can you go higher, probably, but for my application-perfect!
As far as decking the block, from more than one source and the engine builder himself: NOT necessary on a street engine rarely seeing over 5,000 RPM as long as the deck is straight-It is!A radical 350 pushing 6,500+ RPM requires a decking if not 100% absolutely straight.
Headers and 2.5 inch duals not being stock-give me a break!
As for the L-82 intake, multiple sources on this one again including the engine builder: a more radical roller cam turning 6,500+ RPM, yes, an aftermarket intake will make a difference. NOT on my combo-very little difference. The intake is 100% cleaned and allows the dual snorkel GM air cleaner assembly-NOT possible with any aftermarket intake. If when the engine is broken in thoroughly, carb tuned, and gets on the dyno, if the engine makes 400-425 Gross HP, intake stays as is. If not, intake porting could be in the future. If the L-82 intake costs 5-8 HP, who cares?
Something to think about: Karols 78 L-82 4 speed with 3.70 gears made 248 RWHP on the SAME dyno with under drive pulleys, Edelbrock Performer intake, 882 heads, Quadrajet, and an aftermarket flat tappet cam versus my 233 RWHP with L-82 intake, L-82 cam, 882 heads, poor compression on Cylinder 6 as well as broken rings on the other cylinders (much more to this story during the teardown), Holley 4175, etc. Think about that?-15 HP for a cam and intake versus an L-82 NOT running at 100%. The difference if it was apples to apples was probably <10 HP for the aftermarket cam and Edlebrock Performer-Again, give me a break!
We will see.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Will your engine run fine? No, it'll probably run great compared to what you had.
Your build is similar to mine. I did not deck the block, line bore it or even bore the cylinders.
Ball honed cylinders stock deck that varied .003" from one end to the other. My pistons vary from .023" to .026" down the hole.
I used D dish pistons and a 219@.050/219@.050 roller cam 270 seat duration.
I have 2500 miles on it so far. Have a 9.9:1 CR with .038" to .041" squish. Absolutely no detonation using 3 gallons 91 octane and the rest 85 octane fuel @ 4000 feet. I may be able to run straight 85 octane it's so ping resistant.
I run it hard, rev to 6000 rpm tires spin shifting into second on a TH-350 with 3.08 rear, scat crank and rods, performer intake, no problems so far and no pinging at any temp or power level.
I think yours will perform well too.
Your build is similar to mine. I did not deck the block, line bore it or even bore the cylinders.
Ball honed cylinders stock deck that varied .003" from one end to the other. My pistons vary from .023" to .026" down the hole.
I used D dish pistons and a 219@.050/219@.050 roller cam 270 seat duration.
I have 2500 miles on it so far. Have a 9.9:1 CR with .038" to .041" squish. Absolutely no detonation using 3 gallons 91 octane and the rest 85 octane fuel @ 4000 feet. I may be able to run straight 85 octane it's so ping resistant.
I run it hard, rev to 6000 rpm tires spin shifting into second on a TH-350 with 3.08 rear, scat crank and rods, performer intake, no problems so far and no pinging at any temp or power level.
I think yours will perform well too.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
Decking the block to zero increases octane tolerance, lowering the detonation threshold, and the 6 inch rod increases dwell time at TDC, further reducing detonation. I don't care what your builder told you, 0 deck is good for ALL engines, RPM range has nothing to do with it. Lower crevice volumes also reduce emissions and help with efficiency, as do higher compression ratios (to a point). LS engines have the piston UP out of the hole for a reason. They also have almost 6.125 long rods for a reason. You had to machine your block anyway, and recondition your rods, so IMO you could have made better choices, will your engine run fine ? Probably.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
Will your engine run fine? No, it'll probably run great compared to what you had.
Your build is similar to mine. I did not deck the block, line bore it or even bore the cylinders.
Ball honed cylinders stock deck that varied .003" from one end to the other. My pistons vary from .023" to .026" down the hole.
I used D dish pistons and a 219@.050/219@.050 roller cam 270 seat duration.
I have 2500 miles on it so far. Have a 9.9:1 CR with .038" to .041" squish. Absolutely no detonation using 3 gallons 91 octane and the rest 85 octane fuel @ 4000 feet. I may be able to run straight 85 octane it's so ping resistant.
I run it hard, rev to 6000 rpm tires spin shifting into second on a TH-350 with 3.08 rear, scat crank and rods, performer intake, no problems so far and no pinging at any temp or power level.
I think yours will perform well too.
Your build is similar to mine. I did not deck the block, line bore it or even bore the cylinders.
Ball honed cylinders stock deck that varied .003" from one end to the other. My pistons vary from .023" to .026" down the hole.
I used D dish pistons and a 219@.050/219@.050 roller cam 270 seat duration.
I have 2500 miles on it so far. Have a 9.9:1 CR with .038" to .041" squish. Absolutely no detonation using 3 gallons 91 octane and the rest 85 octane fuel @ 4000 feet. I may be able to run straight 85 octane it's so ping resistant.
I run it hard, rev to 6000 rpm tires spin shifting into second on a TH-350 with 3.08 rear, scat crank and rods, performer intake, no problems so far and no pinging at any temp or power level.
I think yours will perform well too.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
If you run stock everything with a stock compression height piston you will have the piston aprox. .025 in the hole. The stock piston has a compression height of 1.560. You can buy a Probe custom, 1.585 compression height, 4.030 bore low expansion forged flat top for about $500 for a set. This gets you a 0.00 deck height without decking the block. Combined with a .039 gasket you have excellent .039 quench, flat top, aluminum 65 cc heads, maximum detonation resistance and can save your block stamp. Figured this out building a factory correct BBC that I needed to save the numbers on and maximize power and streetability yet run modern pump fuel. By the time you figure you are already buying pistons, don't have to pay for decking, .039 felpro gaskets are cheap the net cost for the Probe custom pistons upgrade was negligible.
Le Mans Master
Joined: Aug 2008
Posts: 5,578
Likes: 61
From: Austin TX
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Correct. 4000 ft puts me around 9.0:1 effective CR. But I also am burning equivalent to 86 octane fuel. At sea level 91 would be more than adequate.
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Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
93 octane is available everywhere in New England around me. No issues if I need to run it. Mid grade is 89.
Original pistons were carboned, not detonation-poor combustion. Missing piston ring on #6. Broken piston rings on others.
Original pistons were carboned, not detonation-poor combustion. Missing piston ring on #6. Broken piston rings on others.
Racer
Joined: Feb 2010
Posts: 425
Likes: 2
Will your engine run fine? No, it'll probably run great compared to what you had.
Your build is similar to mine. I did not deck the block, line bore it or even bore the cylinders.
Ball honed cylinders stock deck that varied .003" from one end to the other. My pistons vary from .023" to .026" down the hole.
I used D dish pistons and a 219@.050/219@.050 roller cam 270 seat duration.
I have 2500 miles on it so far. Have a 9.9:1 CR with .038" to .041" squish. Absolutely no detonation using 3 gallons 91 octane and the rest 85 octane fuel @ 4000 feet. I may be able to run straight 85 octane it's so ping resistant.
I run it hard, rev to 6000 rpm tires spin shifting into second on a TH-350 with 3.08 rear, scat crank and rods, performer intake, no problems so far and no pinging at any temp or power level.
I think yours will perform well too.
Your build is similar to mine. I did not deck the block, line bore it or even bore the cylinders.
Ball honed cylinders stock deck that varied .003" from one end to the other. My pistons vary from .023" to .026" down the hole.
I used D dish pistons and a 219@.050/219@.050 roller cam 270 seat duration.
I have 2500 miles on it so far. Have a 9.9:1 CR with .038" to .041" squish. Absolutely no detonation using 3 gallons 91 octane and the rest 85 octane fuel @ 4000 feet. I may be able to run straight 85 octane it's so ping resistant.
I run it hard, rev to 6000 rpm tires spin shifting into second on a TH-350 with 3.08 rear, scat crank and rods, performer intake, no problems so far and no pinging at any temp or power level.
I think yours will perform well too.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Only one piston was .026 in the hole. The rest were between .0245 and .023 down the hole.
I used .024 for my calculations.
11.5 cc dish pistons.
61cc Dart SHP heads. I had them shaved from 67cc's.
.015" felpro shim head gasket.
270 duration cam on a 108 lsa, 4* advance ground in.
4.0" bore
3.48" stroke
5.7" rods
Comes out to 9.88:1 to be precise. Or 9.90:1 for the .0230 in the hole pistons of which there are two.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Think about how good a swimmer you could be swimming with alligators. I figure before his acting career as Tarzan Johnny Weismuller probably trained swimming with alligators, the reason he never lost a single swimming event he entered.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
Update!
Installed the "new" L-82 over the memorial day weekend (what a B**ch getting the engine connected to the Super T-10) and finally got her fired up yesterday. Lots of little things to do to get her running just right but I did seat the rings yesterday per the builders instructions after a 30 minute breakin procedure running Driven Oil Breakin oil and then changed to Driven Conventional oil for the road test. Holy smokes! The engine pulls like a freight train pretty down low. Need to get new ignition wires (old ones are too short and burned a wire), mechanical timing advance is sticking, reset the timing after I lube the weights, have the distributor recurved, replace the secondary metering plate with an adjustable metering block etc. Very impressed by the power and the engine is MUCH louder now with 10:1 compression. Zero detonation with the regular gas in the tank so far-plan to run at least 89 octane or 93. Is she as fast as my 10 Z06? No but pretty darn fast for a 78 C3-lifts the nose on hard acceleration! Stay tuned.
Installed the "new" L-82 over the memorial day weekend (what a B**ch getting the engine connected to the Super T-10) and finally got her fired up yesterday. Lots of little things to do to get her running just right but I did seat the rings yesterday per the builders instructions after a 30 minute breakin procedure running Driven Oil Breakin oil and then changed to Driven Conventional oil for the road test. Holy smokes! The engine pulls like a freight train pretty down low. Need to get new ignition wires (old ones are too short and burned a wire), mechanical timing advance is sticking, reset the timing after I lube the weights, have the distributor recurved, replace the secondary metering plate with an adjustable metering block etc. Very impressed by the power and the engine is MUCH louder now with 10:1 compression. Zero detonation with the regular gas in the tank so far-plan to run at least 89 octane or 93. Is she as fast as my 10 Z06? No but pretty darn fast for a 78 C3-lifts the nose on hard acceleration! Stay tuned.
Last edited by jb78L-82; Jun 3, 2014 at 06:12 PM.
Le Mans Master
Joined: Oct 2010
Posts: 6,938
Likes: 848
From: melbourne florida
2023 C3 of the Year Finalist - Modified
mine started good before, but with 10-1 compression it starts so quick its hard to even hear the starter.
good job, now go enjoy it. and you will!
good job, now go enjoy it. and you will!
Le Mans Master
Joined: Feb 2011
Posts: 5,943
Likes: 61
From: Southern NH
I've been waiting for an update on this one. glad it's running. I hope all the small things don't take too long to fine tune.
Do you plan on getting it back on the dyno to see how you've done?
Do you plan on getting it back on the dyno to see how you've done?
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Scott
Le Mans Master
Joined: Oct 2006
Posts: 6,842
Likes: 285
From: Palmdale CA
Update!
Installed the "new" L-82 over the memorial day weekend (what a B**ch getting the engine connected to the Super T-10) and finally got her fired up yesterday. Lots of little things to do to get her running just right but I did seat the rings yesterday per the builders instructions after a 30 minute breakin procedure running Driven Oil Breakin oil and then changed to Driven Conventional oil for the road test. Holy smokes! The engine pulls like a freight train pretty down low. Need to get new ignition wires (old ones are too short and burned a wire), mechanical timing advance is sticking, reset the timing after I lube the weights, have the distributor recurved, replace the secondary metering plate with an adjustable metering block etc. Very impressed by the power and the engine is MUCH louder now with 10:1 compression. Zero detonation with the regular gas in the tank so far-plan to run at least 89 octane or 93. Is she as fast as my 10 Z06? No but pretty darn fast for a 78 C3-lifts the nose on hard acceleration! Stay tuned.
Installed the "new" L-82 over the memorial day weekend (what a B**ch getting the engine connected to the Super T-10) and finally got her fired up yesterday. Lots of little things to do to get her running just right but I did seat the rings yesterday per the builders instructions after a 30 minute breakin procedure running Driven Oil Breakin oil and then changed to Driven Conventional oil for the road test. Holy smokes! The engine pulls like a freight train pretty down low. Need to get new ignition wires (old ones are too short and burned a wire), mechanical timing advance is sticking, reset the timing after I lube the weights, have the distributor recurved, replace the secondary metering plate with an adjustable metering block etc. Very impressed by the power and the engine is MUCH louder now with 10:1 compression. Zero detonation with the regular gas in the tank so far-plan to run at least 89 octane or 93. Is she as fast as my 10 Z06? No but pretty darn fast for a 78 C3-lifts the nose on hard acceleration! Stay tuned.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
yes I will get on the dyno probably next year after it is broken in better. Problem is that the builders dyno is a Mustang dyno NOT a dynojet that I used before so I will have to get it on 2 dynos.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Has anybody else noticed that the only people who seem to care about elevation and it's effect on an engine seem to be pilots? Must be from the experience of flying piston driven aircraft at high altitudes. Anyway, glad to hear your new engine is running well, keep us posted, ya hear?
Scott
Scott
good observation Scott.Jb78 good to hear you got it running. Get the little stuff sorted out and the fun starts.
