Big block swap C1500

[L31MaxExpress]

The ABS in my 97 Express works perfectly. It worked perfectly in 2 Tahoes and a Suburban that my brother and I have owned over the last 10-15 years as well. Anybody claiming that needs to learn how to correctly diagnose and repair their brake system because it is 99.5% of the time not the ABS system causing the issue.

 

[L31MaxExpress]

'94-95 TBI 7.4's definitely use a different (higher pressure) pump and injectors than earlier 7.4's. Those are the only 2 years - 94-95. Earlier TBI 7.4's use the same pump as a small block TBI.

However, OP appears to be working on a '97. He hasn't told us, but I'm assuming it based on his member name. For Vortec 5.7 and 7.4, those use the same pump.

Richard

Same 190 lph pump on the Vortecs from the 4.3L to the 8100. GM supplied a 96-97 EP381 pump with the 502 hp Ramjet 502. My 97 van is still on the bucket pump version of the same pump and has not been an issue feeding a 500 hp 383 on E70 pump fuel. It is a ~12 year old Delphi replacement with a Racetronix hotwire.

 

[99xcss4]

'94-95 TBI 7.4's definitely use a different (higher pressure) pump and injectors than earlier 7.4's. Those are the only 2 years - 94-95. Earlier TBI 7.4's use the same pump as a small block TBI.

However, OP appears to be working on a '97. He hasn't told us, but I'm assuming it based on his member name. For Vortec 5.7 and 7.4, those use the same pump.

Richard

this is from a post I found a few years ago it is from gm full size please correct if this info is not accurate

TBI L19 454 230 hp @ 3600 385 lb/ft torque @ 1600 rpm 3/4 and 1 ton as well as 1990 454SS (9-13 psi low pressure fuel system)

TBI 454 255hp @ 4000rpm 405 lb/ft torque @ 2400 rpm
454SS(91-93) and 94-95 3/4 and 1 ton trucks at 28-32 psi (high pressure system)

The Vortec 454 uses 8 24 lb/hr fuel injectors that are sequentially fired

 

[someotherguy]

this is from a post I found a few years ago it is from gm full size please correct if this info is not accurate

TBI L19 454 230 hp @ 3600 385 lb/ft torque @ 1600 rpm 3/4 and 1 ton as well as 1990 454SS (9-13 psi low pressure fuel system)

TBI 454 255hp @ 4000rpm 405 lb/ft torque @ 2400 rpm
454SS(91-93) and 94-95 3/4 and 1 ton trucks at 28-32 psi (high pressure system)

The Vortec 454 uses 8 24 lb/hr fuel injectors that are sequentially fired

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

 

[99xcss4]

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

 

[97c1500ext]

Probably the same pump.


I'd expect both hoses and the radiator are different, with the radiator being bigger.


Hoses may/may not be different. Pump may be different, but I bet the pressure/volume is the same.


I suspect the booster will be fine.


HELL, NO.


HELL, NO.

The problem with brakes on GMT400s is less a matter of ABS, and mostly due to the horse-shiit rear drums on most 1500s.

LEAVE the master cylinder and ABS, get rid of the 254mm leading/trailing shoe drum brakes...along with the garbage 8.5" axle. A 9.5" six-lug axle in the right gear ratio, from a C2500 would bolt right up, but needs the six lug wheels, or you'd have to install 5-lug axle shafts.


Get a good distributor. The stock Vortec distributor is plastic, and the distributor cap has a common problem with the insulation breaking-down between the center button and the #3 conductor.

Likely need stiffer front springs, and a proper alignment...which means rebuilding the front suspension/steering systems.

I'm thinking that the motor mount cushions are the same, but the brackets bolted to the engine may be different. Make sure the engine you buy has the motor mount brackets attached.

The Genuine GM service manual set is your friend. Download the service manual set for your vehicle--and perhaps the donor vehicle--from the links in the Sticky thread section of the Engine forum.

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.

 

[97c1500ext]

'94-95 TBI 7.4's definitely use a different (higher pressure) pump and injectors than earlier 7.4's. Those are the only 2 years - 94-95. Earlier TBI 7.4's use the same pump as a small block TBI.

However, OP appears to be working on a '97. He hasn't told us, but I'm assuming it based on his member name. For Vortec 5.7 and 7.4, those use the same pump.

Richard

Yes, a 97. My goal is a 7.4 Vortec. I presently have a 5.0 vortec so im not sure if that keeps up with the 5.7 or 7.4 pump.

 

[89RCLB]

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.

 

[Erik the Awful]

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.

Don't mistake brake pedal feel for actual braking power. A larger piston will give you a firmer pedal, but less hydraulic pressure to the brake system for a given pedal pressure. There have been members reporting going back to the GM400 after having to make an emergency stop with the GMT800 master cylinder and finding they couldn't stand on the pedal hard enough to stop effectively. The GMT800 piston is too large, unless you also swap the front calipers and rear brakes as well.

There is also a mismatch possible. Most (all?) of the GM400 half-ton brake systems are quick-take-up, and you can't mix and match their parts with "normal" brakes. GM ditched the quick-take-up brakes for the GMT800s.

If you want a brake upgrade, the brakes on the 9.5" axle are better. You'll want a 9.5" with the big block anyways. Then make sure they're adjusted well and the brake system is thoroughly bled.

 

[someotherguy]

Research more.

Richard