I love hopping up my stovebolt motors and I have been doing it since I was a teenager, so for some 47 years. The stovebolt motor is as susceptible to performance improvements just like any other motor. More compression, more flow, more cam, more carb, more power. But, its relative. Getting 10 percent more power out of a 400 cubic inch motor is not the same as getting 10 percent more power out of a 235 chevy. The gains are relative to the motor.
Dual carbs are for those who want a little more power and like to tinker because dual carbs require a little tinkering.
So a lot of the aftermarket intakes for the early 235 and 216 motors were set up for small base carter carbs. Why? Because the motors came with those carbs. If you were going to install a dual intake on one of those motors, you only had to buy the intake and one carb.
The later motors, for example 56-63, came with Rochester B and BC carbs so the aftermarket intakes for those motors were set up for the wider base of the later Rochester so again, you only had to buy the intake and one carb to do the swap.
The problem, those carbs were in fact really too big to work well in a dual or triple set up. In fact, to get them to run right, you have to do a lot of work to the various circuits. But the other issue, those carbs have problems inherent in the design, like the pesky freezing power piston, that is in addition to any issues with the dual carb set up
The Carter YFs are good carbs, but the W-1s are better I think because they have a mechanical power system that can be adjusted, where the YFs have a vacuum/mechanical system that cannot be easily adjusted and thus in a dual set up, YFs will run rich, just like the Rochesters.
One solution is to use a pair of Holly Weber 5200 progressive two bbl that came on the Ford Pinto. I like the versions for the 1974 Pinto. They run pretty good right out of the box. Small primaries, larger secondaries. Almost perfect.
So you are thinking, why not just a single 5200 on a stock manifold with an adapter? Does not really run all that well, a single 5200 is just a little two small.
So, if you want to do a few things to improve your motor, have the block surfaced nice and flat. Have the head surfaced nice and flat. Bore the block to the next available oversize so you have nice straight well machined bores. If you want a cam that breathes just a little better and you are using mechanical lifter, get a cam for a 261 chevy truck. Can't find one, send your cam to Schneider Racing Cams in San Diego and have it reground. Cantrell, the owner, likely has even better grinds that get you a little more power (remember its relative) then the 261 cam. Otherwise, have your cam reground to stock specifications.
Want to do some other things? If you are reusing a stock distributor, have it properly rebuilt. You would be surprised at how much better the motor will start and run when its working as it should rather than as a 60 year old distributor that has never been serviced. Have the rocker arm assembly properly rebuilt (Rocker Arms Unlimited in California. They are the only game in town). Not cheap, but the motor will run way better and way quieter with the valves properly adjusted and the rocker arms staying where they should be when operating. They can also re-machine your lifters so you have a nice fresh machined lifter face for your nice fresh reground cam.
Last edited by Dragsix; 11/21/2024 1:59 PM.
