The Stovebolt Site Forums The Shop Area Engine Shop Want more power - but i like my 235

there are a lot of posts on here that give a lot of information, but running a search on 235 power - well retuns nearly every post... lol

So here goes - I dont want a V8 - but I need a little more power before installing aftermarket AC. I am in Texas it is freaking hot.

So I have fenton dual exhaust, stock cam, and a 15 year old rebuild(only 3000 miles or so. I have hte stock 3.90 gears, but this being a 4x4 - 33 inch tall tires(nearly the same size as was installed in 1958). Pulling out into traffic can get interesting. So I am looking for some more low end grunt. I have the SM420 4 speed ultra low transmission 1st is 7.5:1, so I am always starting in 2nd. I have a single rochester on it now, and a spare on the shelf for when the dual intake arrives.

So basically am I missing any tricks of the trade in getting the most out of this engine? I really need to be able to pull out a bit faster.

Any and all suggestions will be most welcome - well all of those who don't say to drop in a V8..

Thanks

I would think that if you use first gear to get the truck rolling then catch 2nd you could accelerate much quicker. More gear or smaller tires would also help.

Get ready for a major loss of low-end torque when you go to the dual-carb setup. The only real advantge to going to twice as much carburetion as you need is a little more top-end horsepower and RPM, assuming you ever get the truck off the starting line.

Two things help takeoff, low gears and/or lots of compression. It's possible to mill the cylinder head, but not without a lot of other machining involved. Swapping to a 700R4 automatic will help the gear ratio situation, since it's got as very low-ratio first gear, and the torque converter effectively doubles engine torque at breakaway, just before the wheels start to turn. That will give you a better holeshot with the tall tires, and if you go to a converter with a higher stall speed, the ability to wind the engine up a little tighter on takeoff will help, also. If you insist on sticking with the standard transmission, you'll need to find a lower-geared rear end like a 4.56, and that will drop your top-end speed somewhat. Lower-profile tires are the obvious, and least expensive solution to your takeoff problems.
Jerry

This is a 4X4 from 1958 - fairly rare - so I dont really want to change any of the primary components liek the I6 or the SM420.

The tires work well for running down the road - 60mph = 2300 rpm.
The tires are also very dang close to waht was installed in 1957/58.

My objective is to increase the HP of the engine by a little to make up for what the AC unit will drain.

What about cams? differnt headers/intake differnet carb setups?

Jerry thanks for the infomration on the loss of torque - that is the last thing I want to do.

THis truck has a stock cam and I am willign to change it.

Did not want a v8 because in 1957 V8's were only available in the GMC trucks - not the Chevy trucks.

As far as an axle swap the front axle is basically a custom axle from 1958, so unless ring and pinions are being made for the stock 57 10 bolt axles in 4.56:1 that woudl not be an option either.

I may just steal the electric AC compressor from a prius and use that - then no engine HP loss as the altenator is already draggin on the crank.

I can understand why you want to keep it original, and that's a good idea. How about this- - - -find a 261 engine, and do some go-fast mods on it, and keep the 235 in long-term storage to go back to original if you ever decide to do that. The 261 is almost a bolt-in swap, no permanent modifications, and it responds well to upgrades like overbore, stroke increases, camshaft changes, increased compression, and even multiple carbs- - - -IF you do your homework on venturi size. Most people go too far with carburetion and end up with something that's only good for wide-open running. A relatively short-duration, high-lift camshaft makes good low-end torque, but you'll end up with piston-to-valve clearance problems unless you do some creative machining. The "848" part number cylinder head for a late-model 235 works well on a 261, giving a compression increase. That's particularly true if you increase the bore and/or stroke. Do your modifying on a replacement engine, and you can keep the original one on reserve for a retro-fit later if you want to.
Jerry

Thanks Jerry

As I read more on this site - more possibilites are opening up.

One of the rules of thumb we live by on the dirt track is "There's no replacement for displacement!" The 261 engine can be bored and stroked to about 300 cubic inches, with a corresponding increase in horsepower and torque. It's not cheap, and you'll need to find a machinist who knows his stuff to offset-grind the crankshaft but the 261 engine has a great deal of potential. When I was pit crewing a team of "hobby class" racers at the Nashville Fairgrounds track back in the early 1960's, the only real competition our two 46 Ford coupes with flathead V-8 engines had was a 51 Chevy coupe with a "Canadian Pontiac" 261 in it. All of us were doing the NASCAR thing and cheating out the wazoo, so there's no telling what internal mods the 261 had. It had LOTS of torque off the turns, so I always thought somebody had put a stroker crank in it!
Jerry

Check out the dual Offy intake w/ carbs and accessories in the Parts for Sale Forum in the Swap Meet. A good deal if it's still there.