The Stovebolt Site Forums The Shop Area Engine Shop 2 -1 barrels or 1-4barrel

ready to send the crank and head to the machine shop. how much should i bore the block and how much should i shave off the head? i am thinking of going a little mild and boreing .030 and shaving .030 off the head. of course recessing the valve the same. what degree cam grind should i go and what intake manifold set up should i go with?1 barrels or a 4 barrel?

please send me any info. i am not trying to go nascar speed thanks

forgotto mention i have a 57 235 going into a 53 1/2 ton thanks

Depends on whether you want an "original" look or a more modern one. Back in the old days, the double one barrel Offy manifold was all the rage. The more "modern" guys use the Holly 4 barrel. The dual singles is a little harder to work with because you have to balance the flow and get the choke working right, but they didn't have four barrels to put on those trucks back then.

You can buy a four barrel and manifold from Stovebolt Engine Company that works really well with the 235s.

As far as boring and shaving goes, I assume you know what you're doing, but you can find a lot of helpful information at inliners.org.

Truck won't pick-up coming off the banking with a four-B

There are a bunch of good manifolds no need to be an Offy lemming!!

535window: I'd rather have the 4barrel. Used for a long in L6 and liked a lot, it was a holley 390cfm and a clifford, but the engine was a 250.
Don't know if there is the same advantage on the 235, but the 250/292 clifford manifold is soo much better than the offy, that I'd give them a call before buying one from any other brand.

535 win. , I have a Cliford water heated intake w/ a 4 brl. Edlbrock , ''AFB'' ,on a 235. I would highly recemend this, it worked great at first and always does. Very easy to adjust, ritchen or lean by changing metering rods, verey easey. Although mine needed abselutley no changes.

Or you could go the sleeper route, like I'm doing. I'm using both factory intake and exhaust. Exhaust is getting split into two behind the intake heater. This is a bit of work but when done will look very close to stock. The intake is getting modified to accept a 350 cfm two barrel carb. With a few mods to the oil bath air filter (sneak a K&N in there) it keeps stock appearance. Add a warm cam and you have the mechanical equivalent of what you are doing, except like they did it back in the day. I'm beginning to find Fentons and Offy's a wee bit tired. Just like small blocks - yuck!

I figure this is the best of all worlds - performance from the mods, easy on the pocket book, keeps stock appearance, no multiple carbs to balance, and no huge 4 barrel looking real out of place strapped to the side of the engine.

cheers,

Ryan

I like the idea of using 2 or 3 carbs on a inline 6 because it keeps the intake manifold runners short and evens out the mixture between all the cylinders. Short runners make for better throttle response and easier cold starts. I am thinking of going either triple rochesters (downdraft) or triple mikunis or webers (sidedraft) with a custom manifold. You can find matched sets of used mikunis on ebay for pretty cheap (from motorcycles and snomobiles). For tuning purposes I will plumb in oxygen sensors in a tubular header exhaust manifold.

The only advantage that a single 4 bbl has over multiple one bbls is tuning- the multiple carbs have to be well matched.

Hi, I'll put in my two cents! With the rebuidable 292 that I picked up recently, came some spare parts. This motor is a good reason why you should always use plenty of lube when assembling a motor. They didn't, and now it's a possible rebuilder for me. From what I hear, it ran less than 1/2 an hour before it quit. Anyway, the guy threw in the home made three carb set up and some headers with zero miles on them. It looks like a very good weld job and I like the fact that it's homemade, so it's going back on the 292 when it comes back from the machine shop. Aluminum has it's place, but if you can, use home made or non mass produced stuff to give your truck that nostalgic look!

I read on this bullitin board about difficulties with the Holley 390 cfm 4-barrel on a 235. I went the Edelbrock route with a 500 cfm w/auto choke on top of a Clifford intake and couldn't be happier. Always starts and runs smoothly. Used 40" glasspacks with 2" split exhaust. The exhaust guy said it sounded like a Jag! Best sounding 6 he ever heard.

Would you 'rivers of knowledge' tell us how the performance improved and what kind of economy you lost, or what kind of MPG you are getting now with the 4 barrel conversions? I have though a lot about this and also the electronic ignition conversions. I have done those to all my motorcyles with at least an improvement in never having to tune them up again.

Anyone remember those early pontiac firebirds (68-69) with the overhead cam 250s? Wonder how well they'd work? I had a 68 camaro and I thought about making a poor man's jag out of it by hot rodding the 6. Back in the 70's everyone thought I was nuts, but my brother had a couple of E-types and they were neat cars. Plus I sear that car handled way better than its V-8 cousins, although, when you read about the engine weights you think - hmm, must have been in my head.

The 4 barrel is superior. I ran several combinations of 2 and 3 Rochesters and it was endless tweaking, swapping jets, leaky float bowls, linkage a major pain etc, etc. When they ran well, MPG sucked. Edelbrock on a heated Clifford intake ran perfect out of the box and MPG went from 13 to 19 MPG.

Anybody ever made an equal runner length intake for the 235/261? like mass produced, or one off? Eventually Id like to make one for a single 4 barrel, kinda like they have for the mopar /6.

What do you guys thinK?

On the moderately tuned 261 in my 37pu, I tried a whole bunch of carb and manifold combos in the last 6 years.Started with 2 Rochesters on a heated Offy manifold, 2 Pinto Holleys on the same manifold . I then bought a Clifford heated 4bbl maniflod. First tried a 500 4bbl Edelbrock,a 500 Carter AFB, a Holley 600 4bbl ,and now a Rochester 4gc off a 64 283.Spent enough time to tune all the carbs and actually there is little power difference between them that you can feel.The first set up with the Rochester B's ran very well on the home made water heated Offy manifold.Used #57 main jets,drilled out the air bleed on the venturi cluster .002 more, and reduced the size of the power valve orfice to .025 from the stock .032.The engine had smooth seamless power, no flatspots and about 18mpg with 3.36 gears.However on hard acceleration in first gear, gas would slosh up the accelerator pump shaft cavity and spill on the manifold.Not really a fire danger, but it stunk, yuk.Perhaps a set of Carters or a pair of glass bowl Holleys would work well while keeping the old time look if that waht you like.On my engine ,the 500 Edelbrock always had a momentary bog as the secondaries opened. No amount of jetting changes or air valve fiddling solved the bog.The 600 Holley was too large but produced good power and no bog as the vacuum secondaries started to open .On some engines,Holley 4bbls, like the 390 or my 600 need a lot of air bleed changes to get proper mixture during part throttle cruising. On all carbs, changing main jet sizes generally won't cure part throttle driveability problems. You must get into the air bleeds to make a meaningful difference.Remember the Clifford 4bbl intake has a large plenum under the carb. the plenum acts like a holding cell for air fuel mixture, so the carb may act bigger than it is.As with most modifications, the engine tuners preference plays a large part in deciding what is good or bad.An engine that bogs just slightly as the pedal is floored then picks suddenly, may feel faster than a smooth transition.Of course the smooth one has faster acceleration.Sometimes a carb that works great on one engine ,won't perform well on another engine that is similar.The current old Rochester 4bbl suits me fine but is really no better than the 2 old Rochester B's for power and fuel mileage.

I was running the Holley 390 on a clifford, fentons, HEI and a clifford 260 cam in my '54 235. The only thing that I didn't like was the cam.

As been said before, the 235 is not a true performance engine. The engine design does not lend itself to high RPM or over 200 HP. Thus, carb swapping doesn't make much difference because of the head design and airflow charateristics. (siamesed ports, shrouded valves, low CR, etc...)

If you like the vintage look, and like tuning strange fuel delivery problems, use a multi-carb setup. Else, use a Holley or Edel carb in the 390 to 500 CFM range on a clifford intake, and spend your time fixing something else on the truck.

BTW, the clifford cam is a good performance cam, but not for a heavy car with 3.55 gears. It doesn't really "come on" until about 2200 RPM. I'm going with a M4F this time and see what happens.

chip