How to Convert a Chevrolet or GMC Pickup from a Four- or Six-Cylinder to a V8

Let's have fun! These conversion instructions work for a Chevrolet S10 or a GMC S15 pickup. It is an inexpensive and easy project, and provides excellent performance.

Find a candidate for the conversion, unless you already have one. These trucks are plentiful and it is not difficult to find one with a nice body and interior. You can get one with a blown motor or high mileage a very reasonable price.

Purchase the conversion kit. It includes motor mounts and special headers. These can be purchased at any speed shop and they are not expensive. The motor mounts are actually plates that offset the original mounts. The steering column interferes with regular headers, so the headers in the conversion kit are made so the column goes through them.

Purchase a flexible transmission fill tube, as there is not enough room for the standard fill tube. All in all there is plenty of room to work on the engine when installed.

Find an engine and transmission. Small block Chevy engines are a dime a dozen - and so are Turbo 350 transmissions. You can also use a 700R4, Turbo 400, 200-4R or a torque flight if so desired. The engine and transmission will fit in easily and on the original crossmember with no modification. Even the driveshaft fits a 350 with no modification.

Purchase a floor shifter. Any type will do. You will also need a three- or four-core radiator. Just measure the one presently in the truck and give the dealer these specs.

Make sure when you purchase your engine you get all the accessories you can (such as the power steering, alternator, air compressor, etc). What you can't get at the same time as the engine, you can scrounge. Used parts are the way to go to keep it inexpensive.

That is all you need and this can be done by a C-class mechanic. It's a very simple conversion.

The results are a truck that runs like a scalded dog, primarily because of the light weight.

I have been into racing for the last 40 years. This is how I built mine and some of specs as well as resuts.

Results: 7.20s in the eighth mile, big cam sound with smooth idle, 16 mpg city and 22 to 23 mpg highway, 385 hp.

Specs:

Ø 1986 GMC extended cab

Ø 350 4 bolt 30 over

Ø Steel crank

Ø Clevite bearings

Ø Chevy pink rods - much stronger but cheap. I like good but cheap on everything here for the most part. Some things of course, you do not have not much choice in expense.

Ø Speed Pro, 9.5 to 1 pistons, floating

Ø Childs and Albert Totalseal top ring and speed pro second and third oil rings

Ø Double timing chain

Ø Crane cam with 465 lift and split centerline of 108,110 and 292 duration. The reason for this split center is so that you can have a little bigger lift without killing the idle and also some decent valves for gas mileage. Remember, don't open them farther just longer with the duration on the street.

Ø Crank scraper and a windage tray. You want better control of your oil and its return to the pan as well as less resistance and drag on the motor. Do not forget to paint the inside of the lifter galley to smooth out the return of the oil to the pan. Do not get any paint in the lifter holes.

Ø Edelbrock performer heads with closed chamber 53 cc

Ø Victor Jr air gap intake manifold

650 Holley Carburetor - vacuum secondary with a package of springs to adjust secondary opening. Use the next heaviest spring to keep the secondaries from opening to fast. On the carb, I found that the best mixture all around was a size 81 jet for the primaries and a size 92 jet for the secondaries.

Ø MSD multiple spark distribution - very important for gas mileage and power.

Ø Standard points-type distributor. Points, when used with the MSD, act only as a switch and last a long time.

Ø Mallory super coil

Ø Standard distributor mechanical advance curve kit. Use the lightest springs so that you have 32 degrees advance off idle.

Ø 700R4 transmission with a TCC switch for lockup. The switch is for a non-computer controlled transmission.

Ø 3.50 ring and pinion

Ø Scorpion roller rockers

Finally, the last thing that makes measurable difference is to set the exhaust up right. I used dual exhaust with single chamber Flowmasters on 3-inch pipe. Use a yellow grease pencil to draw a line from the header back down the exhaust. Drive the truck hard for a couple miles - you will see the grease pencil melted in one spot. This is where you put the crossover pipe. This counteracts the internal fluctuations of the valves opening and closing and facilitates the flow of gas.

And there you have it. Have fun and see you at the strip or car show.