Big Block C1500

[85GMCSierra]

New to the forum! I have an 1985 GMC Sierra Classic. I’ve had this truck since I was in high school and the truck has been in my family since it was new.
The truck has a mild built small block, th400, and 3.73s now. I’d like to build a 530+hp 468 big block and rebuild a spare th400 and put that in the truck
What advice do y’all have for making this swap?
As far as headers, serpentine set up, leaving 1/2 ton small block coil springs, cooling system? Things that can be overlooked in the beginning.
I do plan on adding cal tracs and running 325/50r15 drag radials. Mostly street driven with occasional track time

You must be registered for see images attach

 

[fast 99]

Have you watched Engine Masters? They recently aired a dyno run of a 407 small block. Had aftermarket heads and lower end but it produced 550+ HP with a relatively mild cam and compression. Know it won't have torque of a big block produces but might be a cheaper easier change. Just tossing it out there.

 

[Catbox]

Welcome from Oregon!

If I were just starting to look for an engine to build into my new street machine engine.
I would source a 1996 to 2000 7.4 Vortec 454 to build from.
They already have roller cams and that just skips some of the worry when you first start them up.

Rollers don't need the break in and they are perfect for the oil that is in use today.

When I build my next engine for my truck that is what will be going into it.
I found mine in the local Pick N Pull on half price day, it was around $150 for the whole long block.
Plus the $85 for the matching 4L80 transmission that came from the same truck.

You must be registered for see images attach

If you put a new manifold, a carb, and a ZZ502 camshaft into the engine with no other mods internally, they put out an internet claimed horsepower of around 450 hp.
That is with stock heads and internals.
They sound so good...

Youtube has been a place to get much information on what people have done with the L-29 designated engines for me.

 

[85GMCSierra]

Thanks guys!
I have a good block and 781 heads already. The ports have been lightly ported and polished. Stock valves.
It was an engine my uncle built back in the day for his 81 dually.
My plan for the engine build is
.060” over
Around 10-10.25:1 cr
2.19/1.88 with a good valve job on the heads
A smaller Straub solid roller. 244/255 @.050 .627/.597” w 1.7 rocker
RPM air gap With an 850 Holley

 

[bucket]

When I swapped my C10 with a basic 454, I left the stock engine mounts in place, reused the stock size radiator (new replacement) and didn't change the coil springs either. I had been using dual electric fans from a Buick Rendezvous and left that setup in place too. I used to drive it in stop-go traffic a lot in the summer and I never had any problems with it running hot.

 

[fast 99]

Those later big blocks don't seem to be in demand. Our local PP had 3 at one time. None were sold they were scrapped. Seems kind of sad to me I always liked BB. I don't want to go to the expense with my trucks both have new engines. They would just end up another thing on the floor that's in the way. Have also seen a couple 8.1's but guess they are a totally different animal, also scrapped.

 

[squaredeal91]

I've always wanted an 8.1 for fun

 

[Catbox]

And for headers....
I have found that a set from a 1968 to 1972 big block Nova fit just fine.
I have a manual transmission, I cannot see an automatic being any more of a hassle.

A buddy had a set that he was not going to use anymore and gave them to me.
They had been previously beat on by the previous owner and that didn't need to be done for the truck.

You must be registered for see images attach

They slipped right in on both sides, I only hammered on them a bit around the Z-bar linkage for the clutch.

You must be registered for see images attach

You must be registered for see images attach

Under the truck is where the beauty happens.
You cannot see them at all just glancing under the truck.

You must be registered for see images attach

You have to put your head on the ground to see the collectors...

You must be registered for see images attach

Never mind the flex pipe that is in there, that is a temporary stop-gap while I procrastinate buying the new transmission crossmember that will let me fit the dual 3 inch piping under there.

 

[Shorty81]

Welcome from Ohio. I have a 76 454 block, .060 over with Skip White 496 rotating assembly. 781 heads. Holley 750. 10.6-1 compression. Very happy torque monster!

 

[bucket]

And for headers....
I have found that a set from a 1968 to 1972 big block Nova fit just fine.
I have a manual transmission, I cannot see an automatic being any more of a hassle.

A buddy had a set that he was not going to use anymore and gave them to me.
They had been previously beat on by the previous owner and that didn't need to be done for the truck.

You must be registered for see images attach

They slipped right in on both sides, I only hammered on them a bit around the Z-bar linkage for the clutch.

You must be registered for see images attach

You must be registered for see images attach

Under the truck is where the beauty happens.
You cannot see them at all just glancing under the truck.

You must be registered for see images attach

You have to put your head on the ground to see the collectors...

You must be registered for see images attach

Never mind the flex pipe that is in there, that is a temporary stop-gap while I procrastinate buying the new transmission crossmember that will let me fit the dual 3 inch piping under there.

My findings are the same. My C10 has Hedman brand, those I just had to tweak the shifter pivot linkage for clearance and I modified my stock single exhaust crossmember so both 3" pipes could run above it. I have an unknown, 80-90's vintage set of Nova headers on my '78 and they fit perfectly with my original dual exhaust crossmember.

 

[85GMCSierra]

Welcome from Ohio. I have a 76 454 block, .060 over with Skip White 496 rotating assembly. 781 heads. Holley 750. 10.6-1 compression. Very happy torque monster!

How was the quality of the skip white rotating assembly?
I’m thinking about going with the std stroke +.060” over kit from them

 

[85GMCSierra]

Thanks guys! I was wondering what car headers would fit! Like how the nova headers are tucked up under the truck.

 

[Ricko1966]

Good luck to you. Good Info!!! From everyone.

 

[Soundmound]

Welcome from Oregon!

If I were just starting to look for an engine to build into my new street machine engine.
I would source a 1996 to 2000 7.4 Vortec 454 to build from.
They already have roller cams and that just skips some of the worry when you first start them up.

Rollers don't need the break in and they are perfect for the oil that is in use today.

When I build my next engine for my truck that is what will be going into it.
I found mine in the local Pick N Pull on half price day, it was around $150 for the whole long block.
Plus the $85 for the matching 4L80 transmission that came from the same truck.

You must be registered for see images attach

If you put a new manifold, a carb, and a ZZ502 camshaft into the engine with no other mods internally, they put out an internet claimed horsepower of around 450 hp.
That is with stock heads and internals.
They sound so good...

Youtube has been a place to get much information on what people have done with the L-29 designated engines for me.

Excellent info! Will be handy when the time comes to toy with that '97 454 Burb I picked up.

 

[Shorty81]

How was the quality of the skip white rotating assembly?
I’m thinking about going with the std stroke +.060” over kit from them

very happy. Been in the truck about 7 years now