Anyone ever mess with a 5.7 GM diesel ?

[455Grandville]

Got my 80 Bonneville diesel running well, rebuilt the heads, installed ARP head studs, etc.
Stock its 105 hp, Im wanting more power:
I have a 5.7 diesel exhaust pickup Y pipe Im using for dual exhaust, but I was thinking of turning up the pump 15 % , I know other diesels can handle this, but unsure if the 5.7 will ?

[Mr. P-Body]

Do you have the Lucas or the Roosamaster pump? An '80 model SHOULD be the Lucas. The Lucas is MUCH better and more dependable.

I wouldn't turn the wick up too high on this one, though. The crank/rods/block combo isn't the strongest one I've ever seen... A small turbo might be the ticket.

[RAIV55]

Do you have the Lucas or the Roosamaster pump? An '80 model SHOULD be the Lucas. The Lucas is MUCH better and more dependable.

I wouldn't turn the wick up too high on this one, though. The crank/rods/block combo isn't the strongest one I've ever seen... A small turbo might be the ticket.

Another vote to go easy on that one. Crank and block failures were common with those. Cams (pre-rollers) and heads/ head gaskets also were weak spots too. By '82 GM cured most of the issues but then they couldn't give 'em away.

[455Grandville]

Do you have the Lucas or the Roosamaster pump? An '80 model SHOULD be the Lucas. The Lucas is MUCH better and more dependable.

I wouldn't turn the wick up too high on this one, though. The crank/rods/block combo isn't the strongest one I've ever seen... A small turbo might be the ticket.

Lucas; however its a 1984 replacement block, I think in 81 they started drilling and tapping the main bolts deeper and this solved the caps moving (and breaking cranks)
Every 5.7 crank Ive seen was cast :eek: .
Somewhere along the lines they went to larger headbolts also.

Another vote to go easy on that one. Crank and block failures were common with those. Cams (pre-rollers) and heads/ head gaskets also were weak spots too. By '82 GM cured most of the issues but then they couldn't give 'em away.

I think I better NOT turn it up, I was considering 10% which is usually 10 % more power. Ive heard the later ones were decent motors, but youre correct by 82 people wouldnt touch 'em and gas prices were back to normal.

[goatman-68]

Do you have the Lucas or the Roosamaster pump? An '80 model SHOULD be the Lucas. The Lucas is MUCH better and more dependable.


I have been rebuilding diesel injection pumps for over 25 years and have never seen a (Lucas) pump on a 5.7 GM diesel. The early 5.7 had a Stanadyne DB pump, then in 1980 I think they went to a DB-2 pump, still a Stanadyne.

Anyhow, I agree with the others not to crank it up much, maybe give the screw an 1/8th turn in.

I used to have a 84 Cutlass Sierra with a 4.3L diesel and when I rebuilt the pump i cranked the fuel as high as it would go (bottomed the leaf spring) and it was a real chimney. The only thing it was good for was tailgater's. If someone was on my butt, instead of locking up the brakes, I would just put it in nuetral and mat the pedal. The air would turn pitch black and the tailgater would drop back 50 feet or so......:D

[455Grandville]

I have been rebuilding diesel injection pumps for over 25 years and have never seen a (Lucas) pump on a 5.7 GM diesel. The early 5.7 had a Stanadyne DB pump, then in 1980 I think they went to a DB-2 pump, still a Stanadyne.

Anyhow, I agree with the others not to crank it up much, maybe give the screw an 1/8th turn in.

I used to have a 84 Cutlass Sierra with a 4.3L diesel and when I rebuilt the pump i cranked the fuel as high as it would go (bottomed the leaf spring) and it was a real chimney. The only thing it was good for was tailgater's. If someone was on my butt, instead of locking up the brakes, I would just put it in nuetral and mat the pedal. The air would turn pitch black and the tailgater would drop back 50 feet or so......:D

Lately Ive been pulling 28 + mpg, so I think I'll leave it alone. I dont feel like pulling the damn thing again.
As for the 4.3 they had 6 bolt heads around each cylinder and I know diesel guys that swear by it.

[Mr. P-Body]

I attended classes while employed at a GM dealer in 1981. They went over the distinct differences between the Lucas and "old" Roosamaster pumps. The Roosamasters were famous for going "full rich" wthout warning, leaving clouds of diesel smoke everywhere they went, and not able to get out of their own way. The dealership sold Caddies, Pontiacs, Buicks and GMC. Never heard of a Stanadyne pump in a 5.7. Maybe different geographic areas got different equipment. I was in Southern Idaho (Nampa) at that time.

Jim

[goatman-68]

Mr. P-Body -- Stanadyne and Roosamaster are one in the same. The name changed sometime in the late 70's or early 80's. As far as the Lucas pump, I still question that and will check into it, not that it is a big deal...............:biggerGri

[RAIV55]

I used to work in a dealership and done my share of warranty work on those things. Still remember those days. Head gaskets on a diesel paid the same as a 350 chevy in the same vehicle.

All I recall seeing on the 5.7's was Roosamaster and later Stanadyne pumps. Still have the bent wrench and timing tool laying in the tool box.