Project Need More POWA - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bilfman · 03-21-2013, 11:35 PM

Well I guess thats why auto companies have R&D and engineers.

So the ongoing love affair of truck and wrench continues. I initially had a TH400/NP203 with 4.56 gears. So when I rebuilt the diffies I went with 3.73's and lockers. Worked well.

Then by chance I found the Holy Grail combo of a 1991 4L80E/NP205, I figure that has to be installed. Build thread here http://67-72chevytrucks.com/vboard/s...d.php?t=537481

Problem was I was then a little lacking in power when pulling my beast of a boat in 4th. 1850rpm at 60. Since the diffies were brand new I didn't want to go through re gearing again. It was also quite close enough that I thought a little more hp would fix er up good.

So I decided some upgraded 781 heads. Port matched and some porting with larger exhaust valves, monster torque grind cam and some roller rockers would put the beast where I want to be.

Feels good now, just waiting for the snow to melt to try the boat behind it now.

First pic is the more restrictive peanut heads, second is the 781's, good comparison shot.

lowridergmc · 03-22-2013, 12:11 AM

Waiting for the snow to melt...so about July then hey
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bilfman · 03-22-2013, 01:28 AM

If we are lucky!
Posted via Mobile Device

03-21-2013, 11:35 PM	#1
bilfman Registered User Join Date: Dec 2011 Location: Regina, SK, Canada Posts: 622	Project Need More POWA Well I guess thats why auto companies have R&D and engineers. So the ongoing love affair of truck and wrench continues. I initially had a TH400/NP203 with 4.56 gears. So when I rebuilt the diffies I went with 3.73's and lockers. Worked well. Then by chance I found the Holy Grail combo of a 1991 4L80E/NP205, I figure that has to be installed. Build thread here http://67-72chevytrucks.com/vboard/s...d.php?t=537481 Problem was I was then a little lacking in power when pulling my beast of a boat in 4th. 1850rpm at 60. Since the diffies were brand new I didn't want to go through re gearing again. It was also quite close enough that I thought a little more hp would fix er up good. So I decided some upgraded 781 heads. Port matched and some porting with larger exhaust valves, monster torque grind cam and some roller rockers would put the beast where I want to be. Feels good now, just waiting for the snow to melt to try the boat behind it now. First pic is the more restrictive peanut heads, second is the 781's, good comparison shot. Attached Images __________________ 1979 Chevy Dually Crew 4X4 454, D60 Tru-trac, D70 Detroit Locker, 3.73, 4L80E/NP205 1971 GMC 3/4 Ton 4X4

03-22-2013, 12:11 AM	#2
lowridergmc Registered User Join Date: Dec 2012 Location: saskachewan Posts: 150	Re: Project Need More POWA Waiting for the snow to melt...so about July then hey Posted via Mobile Device

03-22-2013, 01:28 AM	#3
bilfman Registered User Join Date: Dec 2011 Location: Regina, SK, Canada Posts: 622	Re: Project Need More POWA If we are lucky! Posted via Mobile Device __________________ 1979 Chevy Dually Crew 4X4 454, D60 Tru-trac, D70 Detroit Locker, 3.73, 4L80E/NP205 1971 GMC 3/4 Ton 4X4



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