Hey guys just wanted to shoot a few questions out, I picked up a 91 caprice ex cop car today, it's got the 5.7 9c1 in it, wanting to convert it to carb for A demo derby motor and wasn't sure of a couple things

The motor has the block off plate for the mechanical fuel pump, so all I should need is the rod and mechanical fuel pump right? If so, how do you put the push rod in? I assume the cam would have the lobe for it already

What intake would be the best to run, and is there a certain bolt pattern I need? I know the vortecs need special intakes because of the angle of the head holes

Also, since my motor should be a roller, is there a certain distributor gear I need, bronze steel etc?

Besides that all I should need is a hei distributor, a fuel pump, intake and carb, or am I missing somthing?

Thanks in advance guys

Once you remove the block off plate the pushrod just slides in and then falls back out again
Need some grease on the end of it to hold it in place while you bolt the pump up

If you are going to run a mech fuel pump you have to remove the elec pump from the tank and rework the tank pickup.
Most doing carb swaps just install a bypass fuel regulator to drop the pressure down to suit the carb , no need to drop the tank.

Any '87+ carb intake will bolt up but you can save $$ by using any older SBC carb intake and just elongating the 4 center holes to suit the different bolt angle used on the late cast iron heads
Many aftermarket intakes come with those holes slotted to suit either early or late style heads

the engine rpo is not 9c1, thats the police package. some of the police cars had lt1 but not all. check the rpo list for lt1, l99, lo5, lo3.

if lt1 there is a conversion manifold to install a carb. not sure how the trans will like it but maybe if all you need is first and reverse that will be fine.

http://www.summitracing.com/parts/na...2592/overview/

'91 is TBI. LT1 didn't come out until '92, and then only in Vettes. LT1's didn't have a mechanical fuel pump boss.

Having a block-off plate only means the block has been machined for a mechanical fuel pump. It does not mean the cam has the lobe for it.

so should be a lo5 if 91 5.7? it seems to me way easier to just leave it alone if it runs. maybe take the pcm and or wire harnesses and get them away from the fenders and mount it somewhere safe on some rubber isolating bushings

I was thinking along the same lines. But, for a demolition derby car, the constant slams will probably kill the in-tank pump. Perhaps an isolated in-line pump and keep the TBI.

Thanks for the quick replays guys, sorry I haven't been back on, got slammed with it at work


I'll be running a metal boat tank in the back seat of the car, so I won't have to worry about the original tank, I checked my motor today and I do have the hole machined in the block, but I'm still not sure if I need a bronze tipped fuel pump rod, I've heard a steel one can chew up the cam since it's a roller?

Also upon further inspection my motor is a lo5, so I guess I'll start searching for a edelbrock performer, also still not sure on the hei dist, would I need a special gear on the bottom or will any dist out of a carbed chevy work?

Thanks guys

if its a lo5 all you need is a hei from the 70's with vacuum can.

You don't "need" a bronze-tipped fuel pump rod. But, it wouldn't hurt.

Before you get too far, you'd better verify your cam has a fuel pump lobe. Not all LO5 cams did.

Well guys I picked up some goodys last weekend, a accel hei distributor, edelbrock 1406 carb and a performer intake for 140 bucks, not to bad if I say so myself

Also been throwing around the idea of putting a small rv type cam in it for the added pushing power, and since I'll have the intake off anyway, would anyone have any good recommendations on a cam? Preferably one with the mechanical fuel pump lobe and with a stock stall converter?

Thanks again guys

It's a roller cam. Anything you put in will have to be roller, or you're also going to need to change the lifters and pushrods.

I have an '87 LB9 cam laying around. Pretty sure it has a fuel pump lobe (I can check later this evening). Should be better than the LO5 cam.

if its the same as the lo5 in the trucks, it will be like you want it for a derby now. the tbi trucks have their power right off idle. you arent going to be revving it with a auto and stock converter.