Chevy Performance Tech Q&A - July 2014

Kevin McClelland May 9, 2014 0 Comment(s)
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Budget S-10

Q I am currently working on my '82 S-10 shortbed pickup. The engine I currently have between my framerails is an old 350 block out of an '89 Camaro IROC. The bottom end is completely stock. I'm working with a limited budget. The top end consists of a set of double-hump heads with 2.02 valves, double springs, screw-in 7/16-inch screw-in studs COMP Cams 1.6-ratio roller rockers, a COMP Cams hydraulic flat-tappet nitrous cam that specs out at 0.487/0.501-inch max lift, 274/292 advertised duration, and with 113 degrees of lobe separation. For the intake I'm running an Edelbrock Performer with a 750 Holley double-pumper carb, and a 150-shot nitrous plate on it. The trans is a TH350 with a mild shift kit and a 3,000-stall converter. The ignition system is nothing special, as it sports an old-school HEI distributor and top-mount coil. I'm curious to know an estimated horsepower number for this setup. I am told it should be around 385 naturally aspirated, but I'm a bit skeptical. The truck is about as light as I can get it while retaining mostly stock body panels and suspension. I'm hoping this engine on spray is enough to power my S-10 into the mid-11s this season. The rear will remain stock for now, with just a mini-spool to get me through this season until I can put a better one together. Is this doable, or am I still dreaming?

S-10 Racer
Via email

A Whoever gave you the 385 hp estimate was pretty darn close. We'd peg it in the 350-360 hp range. The Performer intake is probably one of the first upgrades you should look at. Any of the Performer RPM intake line will give you at least an extra 10 hp in your application, and we like it better for the nitrous application, as the plenum of the manifold is larger and you should have better distribution with the RPM.

Getting into the 11s is going to be all about traction. The trans/converter is there to support what you're trying to do. You didn't mention gearing, but you did say you're going to install a mini-spool. This will give you both tires to work with, but unless they have some grip, it's all going to be for naught. Next, the stock 7.5-inch rearend with 26-spline axles is going to give up under nitrous hits. Make sure that if you get the truck to stick, wait until at least the 60-foot clocks before engaging the nitrous. Hitting the diff with all that torque on the launch will certainly spell disaster for the stock diff. Keep your eye out for an 8.5-inch S-10 rearend, which is a direct bolt-in to your truck from the 4.3L H.O. L35-powered S-10s and most of the late-model 4x4 S-10s. They are getting really hard to find, as we've been on the hunt for another swap.

Good luck with your truck, and have a blast. Working with what you have and seeing how quick you can run is a ton of fun. Doing it on a budget can be very rewarding.

Chevy Vortec L31 Motor

Q I have access to a '98 Vortec 350 L31 small-block out of a Chevy Tahoe. I'm wondering if this is a good base engine to start with. I'm basically going to leave the bottom end stock, but will be adding a cam, intake, headers, and such. Should I stick with the stock Vortec heads or go with an aftermarket setup? Money is pretty tight right now but the engine is free, and I do have most of the parts mentioned above sitting at home. I had planned to put the engine into a '67 Chevy C10 pickup. Thanks.

Jaime Castellanos
Pacifica, CA

A The Vortec small-block is a perfect building block to create a really nice street cruiser. The stock iron Vortecs are the last iteration of the iron LT1 cylinder heads. First, GM designed the aluminum LT1s, which debuted on the '92 Corvettes on the Gen II small-block. Then, a year later, the iron headed LT1 was released in the F-cars. The iron LT1 heads flowed better and performed better than their aluminum counterparts. Finally, in '96, the Vortec small-block came along. Everything GM learned in the previous two versions of cylinder heads was incorporated into the iron Vortecs. These heads are the best production small-block head ever produced. They will give you outstanding performance for the money.

Adding a dual-plane performance intake manifold, a mild hydraulic roller, headers, and free-flowing dual exhaust will produce well over 400 hp, and as much as 430 lb-ft of torque to pull around your '67. The only thing you will need to do is upgrade the valvespring package to accept the lift range of your performance camshaft selection. We really prefer the GM Hot Cam package (PN 12480002) to throw into these engines. It will give you over 410 hp and the 430 lb-ft quoted above. This cam specs out at 218/228 degrees duration at 0.050-inch tappet lift, 0.525/0.525-inch max lift with the 1.6 roller rockers, and is ground on 112 centers. This package gives you outstanding idle vacuum and a mild performance idle. It comes with camshaft, LT4 valvesprings, retainers, spring seats, keepers, and 1.6 roller rockers. Again, you will need to do a little machine work to install this spring package, but it's well worth the upgrade.

Hopefully we've convinced you to use this core engine to build your budget swap. There are many money saving ideas out there if you have the right components. You've got them right in your garage.



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