96+ Vortec 5.7 in my 71 Cheyenne - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Tim240Z · 02-24-2005, 03:47 AM

For various reasons (which I won't bother going in to), I need to convert my truck to squeeze as much fuel mileage out my truck as possible.
I am currently running a rebuilt (by me) 350 with vortec heads and L98 Vette cam grind and RPM performer intake and 750DP, and TH350.
I've considered just putting in a OD tranny, but after much soul searching, I've decided to transplant with a 5.7 Vortec out of a 96+ chevy truck or sub.
I've searched through pages and pages here and found a little info, but nothing really substantial.
I have no problem with the conversion, it should be as close to bolt on as can be (done an LT1/T56 in my 240Z , as well as many other conversions).

What I am looking for is info on any particular issues with engines that I should look for....reliability issues (I saw something about intake gaskets), any idiocincracies with the engine/tranny that I should be on the lookout for.

Thanks,
Tim

Leinie · 02-24-2005, 04:26 AM

If your replacement engine had orange antifreeze in it- replace all the gaskets that contacted that crap.

How much MPG increase do you expect to get ?

Tim240Z · 02-24-2005, 04:34 AM

Right now I get about 10 with a tailwind....hoping for 15-18 on the freeway.

incoma · 02-24-2005, 04:58 AM

I've head of 20+ with a newer model fuel injected engine (LS1 style) and a 4L60E transmission properly tuned.

bigbluthng · 02-24-2005, 01:17 AM

96-98 chevy/gmc trucks and 96-99 full size vans have the vortec engine. i have heard to get the 062 casting heads rather than the 906 castings because the 906s don't flow as well on the exhaust side. i know a guy that does cylinder head porting and said it's boloney.check out recyler.com for local deals. most of the intake gasket failures are related to overheating.
you probably already know a properly tuned q jet will perform like fuel injection; smooth and reliable with great economy. if you really plan on keeping the 350 trans, consider swapping out the gears in your rear to some numerically lower.

02-24-2005, 03:47 AM	#1
Tim240Z Senior Member Join Date: Jan 2005 Location: LAX area, So Cal Posts: 499	96+ Vortec 5.7 in my 71 Cheyenne For various reasons (which I won't bother going in to), I need to convert my truck to squeeze as much fuel mileage out my truck as possible. I am currently running a rebuilt (by me) 350 with vortec heads and L98 Vette cam grind and RPM performer intake and 750DP, and TH350. I've considered just putting in a OD tranny, but after much soul searching, I've decided to transplant with a 5.7 Vortec out of a 96+ chevy truck or sub. I've searched through pages and pages here and found a little info, but nothing really substantial. I have no problem with the conversion, it should be as close to bolt on as can be (done an LT1/T56 in my 240Z , as well as many other conversions). What I am looking for is info on any particular issues with engines that I should look for....reliability issues (I saw something about intake gaskets), any idiocincracies with the engine/tranny that I should be on the lookout for. Thanks, Tim __________________ 1972 Suburban C20 454/TH700R4, eaton-corporate 4.10 (looking for 3.7) Sold: 71 Cheyenne 20 Installed a 99 5.7L L31/4L60E from Suburban 1500 (2005)

02-24-2005, 04:34 AM	#3
Tim240Z Senior Member Join Date: Jan 2005 Location: LAX area, So Cal Posts: 499	Right now I get about 10 with a tailwind....hoping for 15-18 on the freeway. __________________ 1972 Suburban C20 454/TH700R4, eaton-corporate 4.10 (looking for 3.7) Sold: 71 Cheyenne 20 Installed a 99 5.7L L31/4L60E from Suburban 1500 (2005)

02-24-2005, 01:17 AM	#5
bigbluthng Registered User Join Date: Aug 2003 Location: canyon country, ca, USA Posts: 336	96-98 chevy/gmc trucks and 96-99 full size vans have the vortec engine. i have heard to get the 062 casting heads rather than the 906 castings because the 906s don't flow as well on the exhaust side. i know a guy that does cylinder head porting and said it's boloney.check out recyler.com for local deals. most of the intake gasket failures are related to overheating. you probably already know a properly tuned q jet will perform like fuel injection; smooth and reliable with great economy. if you really plan on keeping the 350 trans, consider swapping out the gears in your rear to some numerically lower. __________________

02-24-2005, 04:26 AM	#2
Leinie Registered User Join Date: Feb 2001 Location: USA Posts: 2,613	If your replacement engine had orange antifreeze in it- replace all the gaskets that contacted that crap. How much MPG increase do you expect to get ?

02-24-2005, 04:58 AM	#4
incoma Registered User Join Date: Mar 2004 Location: Lexington, KY Posts: 865	I've head of 20+ with a newer model fuel injected engine (LS1 style) and a 4L60E transmission properly tuned.



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