Big block swap C1500

[Sean Buick 76]

What year big block are you swapping in?

 

[L31MaxExpress]

I have my doubts that the 91-93 454SS use the higher pressure pump and injectors, but no proof on hand. If you look 'em up on Rock (C1500, or any model, w/454) those years use the same pump as the small block.

Richard

I can say 100% without a shadow of a doubt the 1992 454 SS I worked on years ago had the high pressure system and the high pressure 46# injectors. That one got a set of tall deck 427 heads that had some work done to them, a roller cam upgrade and a carbureted manifold with a TBI adapter. To feed it had to go to the high pressure 61# marine injectors that flow ~104 lb/hr @ 30 psi.

 

[L31MaxExpress]

what is really weird is that that same post says that the low psi system uses #80 injectors and the high psi system #90 injectors it is hard to wrap my head around how a slight change to the fuel system can gain 25hp 20ftlbs

It was a swap to dual cats and a different exhaust system that added the power. The HT502 TBI swap kit came from GM with the high pressure regulator and the dual cat exhaust setup.

 

[L31MaxExpress]

Why hell no on the MC, I've seen it done and its a massive improvement in braking power. The major difference is the piston is larger and one fitting is different for which an adapter exists.

Also calling 8.5 axels garbage is bs from my research. I've read about plenty of stock axel 8.5 rears running 600+hp, much higher even, with just a posi, welded tubes, and a girdle diff cover.

You seem to be making a lot of assumptions without direct knowledge of how a big block compares to a small block.

HELL NO on the master cylinder because it actually takes away from braking power in a panic stop. People confuse pedal travel and feel with actual hydraulic pressure multiplication. If you keep the same booster, the larger NBS master cylinders pistons build less pressure with the same pedal pressure applied. I tried one once years ago and it was downright dangerous. I ended up having to stand on the brake pedal with 2 feet in an actual panic stop kind of shut down at 75 mph. Hydroboost it and use the matching hydroboost master cylinder. That will actually truly help braking power. Use the larger Police Tahoe or 3500 SRW calipers that match the 1.34" bore of the hydroboost master. I actually went to a smaller bore wheel cylinder which drastically reduced the tendency for the rear to lockup in a hard stop and provides more rear bias in normal stopping. The same displacement of fluid in the master cylinder moves the wheel cylinders and thus shoes against the rear drums more quickly with a smaller bore vs larger bore on the wheel cylinders while reducing the maximum force applied on the shoes which in my case was locking rear tires at 75 mph and kicking in the ABS increasing stopping distance. Reducing that rear lockup and ABS action made for a much smoother, quicker, consistent stop from speed.

Later on I have swapped mine to a 2012 van hydroboost and master when they needed to be replaced because a newer van disc brake rear end is on the list to swap. I had to install a drum brake residual valve in the rear brake line to keep air out of the wheel cylinders with the NBS van master. The residual valve is an integral part of the OE master as well and not present on a NBS master. I also do not have the low drag calipers and thus have no need for a master cylinder that has the larger 3rd piston needed for the quick takeup calipers. The newer van hydroboost unit has a larger piston set in it that matches the larger piston master cylinder, thus providing the same level of hydraulic pressure. I ended up using 01-02 3500 vans rotors that where thicker and allowed me to use even larger 3500 dually front calipers and pads. The larger van front rotors and 3500 dually calipers can be bolted on a 2wd 2500 or 3500 8-lug truck and rotors have much more thermal mass which allows them to operate cooler.

 

[L31MaxExpress]

Well i guess i will add it to my future mods list. If the 8.5 doesn't instantly explode i guess ill see how long it lasts. Any advice on my other questions?

The 8.5 blew up in my Express van not towing behind a 350 making ~300 hp at the time. I got a 9.5" with 3.73 gears and a G80 from a 6-lug 2500 van. Knocked the studs out, welded up the holes in the flange. Took the axle to a competent machine shop with a box of new studs and had them re-drilled 5 on 5 and they pressed new studs in it. The backing plate, wheel cylinders, shoes, were all the same, slide the 5 on 5 rear drums on it and went. You need the U-bolt plates from the 9.5 if you need to source one in the future.

 

[97c1500ext]

What year big block are you swapping in?

Haven't got a motor yet but im looking for a 96 to 2000 vortec 454.

 

[97c1500ext]

The 8.5 blew up in my Express van not towing behind a 350 making ~300 hp at the time. I got a 9.5" with 3.73 gears and a G80 from a 6-lug 2500 van. Knocked the studs out, welded up the holes in the flange. Took the axle to a competent machine shop with a box of new studs and had them re-drilled 5 on 5 and they pressed new studs in it. The backing plate, wheel cylinders, shoes, were all the same, slide the 5 on 5 rear drums on it and went. You need the U-bolt plates from the 9.5 if you need to source one in the future.

I really am not trying to argue about this but i just really dont understand and struggle to find a straight answer like many other questions. Plenty of racers do 8.5 swaps over an 8.2, is it really as pathetic as people say? Is there a difference between the 8.5 in these trucks and the 8.5 in camaros or other chevys? I understand they are narrower but i cant find anything that says much else. My main case which i should have made clear from the start is i already have a newly rebuilt 8.5 with a trutrac in the truck. Its not a stock G80 grenade. I also intend on adding TA Girdle and potentially having the tubes welded.

 

[97c1500ext]

Pretty much seemed to have a chip on your shoulder with the original LS swap comment from the get go. I was all set to answer helpfully until I read that. I dont like small blocks, and replaced them with a big block in about everything I drove for a long time.

Take it as you wish. I dont want my thread clogged with people dumping on the old school and telling me to put an LS in as I've seen in many other threads. The point is not to make the truck make as much power in the most effective way possible. LSs are fine and good but the point is to put a big block in the truck because big block, thats it. Its not a DD, its not a tow truck, its not even a race truck, i just like Big Blocks and it feels more original in the largely LSswap the world culture these days. I have an 02 1500HD which might be my LS project some day but thats not today.

 

[Sean Buick 76]

Yes the 8.5 is pretty crappy and not worth investing money into in my opinion. The only reason to build up a 8.5 is if you can’t get a 14 bolt to swap in.

 

[Erik the Awful]

Is there a difference between the 8.5 in these trucks and the 8.5 in camaros or other chevys?

Your truck weighs a thousand pounds more.