Performance Tech Questions - Performance Q & A

Kevin McClelland Aug 1, 2009 0 Comment(s)

A: There is a very short answer to your question. You will want to use the pump that matches your accessory drive system. The '82 Camaro front dress utilizes the long-style water pump. GM switched from short to long water pumps back in 1969 on small-block engines. The only vehicles that stuck with the short pump were Corvettes and pickup trucks.

The only other hiccup you may see is when you run serpentine beltdrive accessory drive systems. All the factory serpentine systems on small-block engines used a reverse-rotation water pump. If you were unlucky enough to install the wrong pump on a reverse-rotation system, you would have major heating issues. Stick with the pump that the General designed the system around, and you won't have a problem. Enjoy your 383!

Fuel-Sipping Small-Block
Q: I am looking to replace the 350 engine in my street rod. I drive the car on long trips and would like to build an engine that will give me better gas mileage. I want to build a one-piece rear main 265 small-block to put in a 3,000-pound street rod with a TH700-R4 and 3.42:1 rear gears. I have an excellent source for good engine cores. I recently purchased a 3.00-inch-stroke crank, 5.94-inch-long rods, and flat-top pistons out of a '94 L99 LT1-type engine. I also have a nice 305ci one-piece rear main block (the same bore as the 265ci engine). The heads I'm planning to use are casting number 471513 with 1.74/1.50-inch valves. I have opened up the combustion chambers around the valves to end up with 55cc chambers, which should give me about 8.8:1 compression with thin head gaskets.

I also have several stock roller camshafts to choose from: 350 ramjet, L99, stock 305 Vortec, stock 350 Vortec. I'm leaning toward the RamJet cam with the 109 LSA. Is there an aftermarket roller cam that will work well? I have an Edelbrock Performer intake or an Edlebrock SP2P economy intake, with which I plan on using a 600-cfm 1406 Edelbrock carb. Would a Q-jet or 500-cfm Edelbrock work better? I will use 11/2-inch Block Hugger headers and will not need to spin the engine over 4,500 rpm.

Another thought I had was to build a 302ci using a 350 one-piece rear main block. Will I lose much mileage over the 265 engine? I don't remember anyone building a 302 for low-end torque and mileage. Thanks for your help.
Jim Martin
Hutchinson, KS

A: No, we can't think of anyone building a high-torque 302. Many people have built up engines by swapping out parts from all the engines that Chevy built over the years. Let's take a look at a few specifics.

First, the stock bore on a 305 is 3.736 inches, while on the 265 it is 3.750 inches. You can take your good core 305 block and have it overbored for the 265 pistons. This will give you a fresh cylinder wall for the new rings to seat against.

The rest of your plan is quite solid. The cylinder heads you've chosen are from a quite rare 267 small-block built only for the '79 model year. This was GM's test at making a very clean smog engine for the lightweight Monzas. The engine was weak in every respect! It had a very small 3.500-inch bore with the standard 305/350 stroke of 3.48 inches. Choking the engine down with such a small bore was its downfall. If you are going to use these heads, we suggest having the ports massaged in the bowl area and the short side. This won't increase the port size by much but will pick up the flow by 10 percent. This will help efficiency in every way from mileage to making power.

From the camshafts you listed, we'd go with the RamJet camshaft also. The cam is relatively short at 196/206 duration at 0.050 inch tappet lift, 0.431/0.451 inch max lift with 1.5 ratio rockers, ground on 109 centers, with the intake installed at 104 degrees. The tight centers with the advanced intake lobe will build good cylinder pressure, with your little engine giving it some snap.


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