I am a small engine specialist in Canada and understand the basics of engine repair and operation but must concede not completely knowledgeable on the power output of a Ford 302. I am working on a 1988 302 Ford small-block with a C4 trans in my 1948 Ford F1 panel truck. The engine had a grumpy two barrel so I purchased a 4 bbl kit and did a swap. The engine perked up a lot but due to its old age it eventually went flat on me.
I pulled it and had it professionally rebuilt with better heads, a mild cam, and short tube headers.
I was about to reinstall the 4 bbl but have an idea of a quad setup like a pair of 500 or maybe 600 cfm carbs .I don’t want to drown the engine in fuel but I do want to punch it up just a little more. What idle rpm and ignition timing should I look at? Also what horsepower might I get in return? Thanks for all the good advice.
B.B.
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It sounds like you have a decent yet mild little small block Ford.
And it also sounds like you’d like the dual four barrel system more for appearances than for performance. You didn’t get into specifics with the heads or the camshaft but I will assume that you possibly went with a set of the later model, iron GT40 heads that came on the later fuel injected small block Fords.
The Case Against a Dual 4-Barrel Setup
The GT40s are pretty good for production items and will help with a little more power. Without more information it’s hard to give you an accurate answer in terms of power but I don’t think that two four-barrel carburetors will help all that much with power, and here’s why.
Even the better GT40 small block Ford heads still are limited not by the intake side but rather on the exhaust side. The flow numbers are not the best, which means the exhaust side of your engine will be the restriction. This is merely an estimate but about the rpm point where a dual four-barrel intake manifold and carb package would begin to offer some power advantages, that restrictive exhaust side will limit the power potential. Not only that, but a mild cam will also limit the rpm potential to again not much more than 5,800 to 6,000 rpm.
Add to this the expense of a new 2×4 manifold and a pair of carburetors and you might find this option has quickly surpassed your budget.
A Better Carburetor Option
You didn’t mention what four-barrel carburetor you are currently using. What I think would be a far more streetable package that will work very well right out of the box would be an Edelbrock Performer or a Performer RPM dual plane, single four-barrel intake along with a 650 cfm carburetor.
A comprehensive parts list is found at the end of this article.
Edelbrock introduced their AVS2 four-barrel a few years ago and I have done quite a bit of testing with this carburetor. What makes it a great street fuel mixer are the primary side annular discharge boosters. These boosters create a crisp off-idle throttle response that you will notice the very first time you open the throttle as you pull away from a dead stop.
I think a 650 cfm AVS2 carburetor would be a great idea for your panel truck regardless of the intake manifold you choose. You didn’t mention which four barrel manifold you are using but if it is an OE manifold, the Performer version I think would be both affordable and can offer a torque increase over a stock manifold.
We’ve listed several intake and carburetor ideas in the Parts List below but my recommendation would be the Performer intake with the AVS2 650 cfm carb. Plus this package will be less than half the cost of a 2×4 manifold arrangement.
Timing Advice
As for timing, I would set the initial timing at 12 to 14 degrees Before Top Dead Center (BTDC) as a good starting point. With the vacuum advance unplugged, rev the engine and check full mechanical advance. The easiest way to measure this is with a dial-back timing light. Or you can buy an MSD timing tape and install the correct tape on your balancer and read the timing with a straight non-dial-back light. You should shoot for 36 degrees of total advance.
Idle speed is more of a personal issue but with 800 to 850 rpm will work well. Once you set it with the trans in Park, make sure the engine will idle properly with the transmission in gear. Also carefully lean out the idle mixture screws to produce the highest idle manifold vacuum then reset the idle speed to the rpm you desire.
As for power, I really can’t estimate without more information but remember this is only a 302ci engine, so realistically this little Ford would probably make around 275 to 280 hp but without knowing compression, cam timing, and other information, it’s very difficult to give you an accurate number.
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