off the line performance question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

crm318 · 05-15-2008, 10:19 PM

i just reinstalled my engine with a new cam (.440/.440 212/212) and i took it to a long road to gouge on it. from a dead stop it could only chirp the tires. after that it would throw you in the seat like crazy. i took a turn and floored it and the truck when from side to side roasting until i let off (with an open rear). whats the deal?

jhow66 · 05-15-2008, 10:28 PM

3.07 gears.

**Yukon Jack** · 05-15-2008, 11:26 PM

How does that compare to how it drove before swapping cams?

piecesparts · 05-15-2008, 11:56 PM

Not enough info. tire size with those 3.07 gears (definitely to shallow of a gear ratio)

What is your timing set at and how soon does your advance come into play?

crm318 · 05-16-2008, 01:33 AM

it performed about the same. the tires are 275/60/15. i have it set at 12 degrees timing. this isnt a complaint really the truck performs exceptionally well. another issue is that the truck performs sigificantly better when i manually shift it (not just the shift, it pulls harder in between gears).

*Billla* · 05-16-2008, 01:45 AM

It's a pretty open question, but my immediate thought would be the need to invest in a torque converter...

HavinSomeFun · 05-16-2008, 02:21 AM

Quote:

Originally Posted by Billla

It's a pretty open question, but my immediate thought would be the need to invest in a torque converter...

I second that. I have a 2200 stall in mine and its not even close for what I need to move all that weight off the line.

piecesparts · 05-16-2008, 02:31 AM

Well, 3.07 gears with a 28" tall tire, is the worst part of the situation. The timing at 12 degrees is a fair setting, but you could work that one a little more and get more out of your engine combo. I would look at maybe timing your engine with a timing light that has an advance feature and see if you can get the engine to run with a "Total Advance" of around 35 degrees. Look at a set of 3.73 or 3.42 gears for a better bite. The torque converter would be important only if you are experiencing a phenomenom of the engine pulling the truck through the stop light when you are sitting at it waiting for it to change. The torque converter change would do a couple things here, First it would allow you to build more RPMs before the tranny pulled your motor down and Second it would allow you to sit at that stop without having to have a possible high idle for the camshaft and thus keep you from riding the brake. It would allow your tuning of the carb to stay out of the "transition circuit" and more into the idle circuit.

68GMCCustom · 05-16-2008, 03:25 AM

Quote:

Originally Posted by Billla

It's a pretty open question, but my immediate thought would be the need to invest in a torque converter...

and/or a lower set of gears and a posi.

05-15-2008, 10:19 PM	#1
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	off the line performance question i just reinstalled my engine with a new cam (.440/.440 212/212) and i took it to a long road to gouge on it. from a dead stop it could only chirp the tires. after that it would throw you in the seat like crazy. i took a turn and floored it and the truck when from side to side roasting until i let off (with an open rear). whats the deal? __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies

05-15-2008, 10:28 PM	#2
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Re: off the line performance question 3.07 gears. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

05-15-2008, 11:26 PM	#3
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,687	Re: off the line performance question How does that compare to how it drove before swapping cams? __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

05-15-2008, 11:56 PM	#4
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: off the line performance question Not enough info. tire size with those 3.07 gears (definitely to shallow of a gear ratio) What is your timing set at and how soon does your advance come into play?

05-16-2008, 01:33 AM	#5
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	Re: off the line performance question it performed about the same. the tires are 275/60/15. i have it set at 12 degrees timing. this isnt a complaint really the truck performs exceptionally well. another issue is that the truck performs sigificantly better when i manually shift it (not just the shift, it pulls harder in between gears). __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies Last edited by crm318; 05-16-2008 at 01:37 AM.

05-16-2008, 01:45 AM	#6
Billla Account Suspended Join Date: Sep 2005 Location: Monroe, WA Posts: 3,814	Re: off the line performance question It's a pretty open question, but my immediate thought would be the need to invest in a torque converter...

05-16-2008, 02:31 AM	#8
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: off the line performance question Well, 3.07 gears with a 28" tall tire, is the worst part of the situation. The timing at 12 degrees is a fair setting, but you could work that one a little more and get more out of your engine combo. I would look at maybe timing your engine with a timing light that has an advance feature and see if you can get the engine to run with a "Total Advance" of around 35 degrees. Look at a set of 3.73 or 3.42 gears for a better bite. The torque converter would be important only if you are experiencing a phenomenom of the engine pulling the truck through the stop light when you are sitting at it waiting for it to change. The torque converter change would do a couple things here, First it would allow you to build more RPMs before the tranny pulled your motor down and Second it would allow you to sit at that stop without having to have a possible high idle for the camshaft and thus keep you from riding the brake. It would allow your tuning of the carb to stay out of the "transition circuit" and more into the idle circuit.



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