The Stovebolt Site Forums The Shop Area Engine Shop Beefing up my 235

I'm a newbie looking for advise. I need some help in decided how to "beef" up my 235cu-inch. I'm considering the following:
Fenton headers with 2 single barrels carb's.
OR with 2-double barrel carb's
OR 2-4 barrel carb's OR 1-4 barrel carb. I want better gas mileage and a bit more power. I'm in the process of changing out the rear end ratio from a 3.90 to 3.38 and maybe a 4-speed saginaw. I want a carb set-up that's reliable and where I'm not constantly "tinkering" around with the adjustments. Tall order? My truck is a 55 2-series. Please visit my pics site. Any and all input would be greatly appreciated. :p

www.picturetrail.com/cjb40

in my opinion the best set up for performance and mileage and reliability would be a single 4 bbl set up. They usually use a holly 390 cfm carb. I lost about a mpg when I put one of these on my 270. If it is set up properly you could get better mileage, but don't plan on it. You will have to find some source of heat for the manifold as it will no longer be attached to the exhaust. It may be eazier to hook the accelerater up with cable. I bent some rod and used a scavenged bell crank from the junkyard. It worked ok after I got it adjusted.

There is an old saying, "speed costs money--how fast do you want to go". There is only one way to get both more power and increased economy and that is turbocharging, very pricey. No other type of supercharging will do this and no multi carb setup will do it either. A shallower rear will really help.

Would this source of heat come from the radiator thru a pipe heated with water? I don't quite follow...

I just want to be able to go down the hwy at 60 to 65 but be able to have the needed pwr to acceclerate lane changing when needed. I'm not a speed freak. That phase went away years ago.

pissa40 From what I can gather you need a set up like mine. I have a 235 with an 848 head for better compression, Fenton hedders with dual exhaust, twin Holley/Webber 2 brl. carbs. The carbs have a small primary for econemy and the secondarys are set up on a progressive linkage. I then installed a 3 speed overdrive transmission from the mid 60's with a 3.90 rear end which gives me a 2.73 final drive in OD. I receientlly drove to Denver from Arlington Texas and averaged 18 mph overall. You can get those carbs for 65 bucks each from Tom Langdon out right. A lot cheaper than a 4 brl carb and better fuel mileage.
Tom

i have a 54 with the 235 and fentons and offy with two carbs and a nova rearend and 2.73 gears and a s/10 5 speed. i have the power i want but can't check the mileage speedo not hooked up. but when i did check it with a 1.1 ratio i only got 9.5 in town and 12.5 on the road but the carbs needed adjustment. ron btw i have 235/75/15 tires.

All of the most highly respected and world reknowned Chevy 6 engine builders like Frank McGurk and California Bill were ignorant if additional carburetion will not increase your fuel economy. The problem is that with additional fuel mix capability it will be difficult if not impossible to avoid using the extra horses. Drive exactly like you drive your under-carbureted machine today and you will see economy improvements. Cob it and you will be visiting the gas station attendant more often.

My '50 has a '59 261 with a mild cam, Fenton headers, McGurk intake with 2 Holley/Webers, 4.11 gears and a Tremec 5 spd. We drive it all over and drag race it on weekends (1/8 mi). The truck will go an honest 100mph and get 20 mpg cruising at 65mph. It is very driveable and great fun. There are pic's of it in the Gallery under Ron and Kim Plender.

The common links to vastly improved speed, mileage, or overall performance for these sixes is the T-5, or an O.D. tranny and radial tires. I have a Gear Vendors O.D. and radials with a mostly stock(except fentons & dual exhaust) 235. 3:90 gears. 3:08 equiv. in 4th over. It is the ultimate combo. I have 7 forward gears and can get 20 mpg at 65 with low rpms. The O.D. and the tires did way more for me than a carb change ever could. (unless your old carb isn't working correctly). But for fun, I'm doing it anyway. In fact, I'm doing what Arpee did and building a cadillac 261 stroker. Only with a Edelbrock intake and dual 1 bbl Rochesters.

The original intake manifold is connected to the exhaust manifold to provide some heat to keep the gas as a vapor. When a gas mixture moves through the intake, it cools down a little and has a tendency to pool up on the bottom of the intake. This in turn will cause a hesitation when you step on the accelerater. That is why you need heat to the intake manifold.

Getting heat to your intake is typically done with exhaust or water. It depends on what intake you are running.

You mentioned you were going to be running Fentons. The Fentons have a plug in them that can be removed for use with exhaust heat on the original manifold. Several of the venders sell a kit for this purpose.

Getting back to my original reccomendation... a 4bbl intake... These are usually designed to bolt up with the stock exhaust. They get heat the same way the factory intake gets heat. Using the after market adapter plate for the fentons to the stock intake should work on the 4bbl intake.

Some 4bbl intakes come set up for water heat, some have no provisions for heat at all.