I have an offy dual carb intake, and two Rochester B's (the ones that came on the 216) and the linkage and plumbing etc. My question is will this work well on my 235? I'm using the stock cast exhaust manifold (single outlet) will they just bolt together and heat up or do I need a heat plate? Will I really see enough gains by making the switch to make it worthwhile (or is it just the cool factor, because I have to admit dual carbs look cool). Any more advice before I dive into the switch?
The 6's really seem to respond well to headers / split manifolds and dual exhaust. I think the 235 needs help in the exhaust dept as well as the carbs. Dave
Dive right in! Inline 6 popers respond very well to even the smallest bit of tweeking. Plus, there cool as hell. Good luck with it. Michelle
The heat riser box may have a different bolt pattern between a 216 and a 235.If the intake is for a 216 then it may not bolt up to your 235 exhaust manifold heat riser.If it's for a 235 with the 216 Bs no problem.You should be able to see the difference if there is one.I'm sure it could be adapted.You should also think about a split exhaust manifold.
I have a split manifold that was given to me but it's obvious the guy just cut a single outlet in two and welded caps on either end, I don't think the heat plate would bolt up. Is there another way to do it?
People have egged out the bolt holes in order to bolt a 216 intake to a 235 exhaust manifold (or vice versa); I think that the two bolt holes closest to the cylinder head are the ones that differ between the two engines, and the outer holes are the same. However, a 216 intake has a flat gasket surface where it mates to the exhaust manifold, and a 235 intake has an angled surface. If you were running some sort of aftermarket headers, it wouldn't matter. If you're going to use a homemade split manifold anyway, just find another manifold that jives with your dual intake and split it or have it split. By the way, the tests that Frank McGurk ran on stovebolt sixes years ago proved that two carburetors give the biggest boost of any single modification, and even an otherwise stock engine can handle them.
Get an exhaust manifold now and work out a heat riser using that rather than having to do it all over again later .A lot of suppliers carry exhaust manifolds for those puppies and they are fairly cheap . Speedway has Fentons and Stovebolt in Arizona specializes in those motors .
How about a 2v? I'm putting together a 54 235 right now, and plan to split the ex manifold, and run a modified HEI from an S10. I've got a nice 2v carb sitting here that I'm thinking of using on my stock manifold using an adapter (if I can find one, or make one). Has anyone run that setup and how'd it work out? Just wondering if the adapter would be too restrictive. Anyone know who sells the adapter, or any advice on this setup? Didn't mean to highjack.
Check my 261 link in my signature. I made Torque and HP graphs to all the dyno numbers of the McGurk article. It shows how much difference dual intake and headers make over stock manifolds. It's the easiest, cheapest and most effective way to increase power on a 235/261. An early 235 with stock intake/exhaust manifolds and cam has peak torque around 2000 rpm. You need to improve breathing, if you want to go on the freeways at higher rpm. Late car 235s already had stock cams with more duration and lift and heads with higher compression from the factory. Just adding carbs and headers on those engines give huge gains over early stock 235s.
I know that P.A.W., Performance Automotive Warehouse offered a 2V to single carb adapter for around $12.00. I think the last catalog I bought is from 2002. I thought about using one myself on my 261. I would also like to hear from anyone that has used this combo in either single or double form. Thanks, BlackCherry
This weekend at shades of the past I saw a '53 that had a dual offy intake, two adapter and two carter 2 barrel carbs. I don't know if the engine can take that much gas... but it obviously ran well enough to make it to the show.
Yeah, that sounds like a lot of fuel for that motor. I think a single 2v should work fine, but I'm still wondering about the efficiency of the adapter. I know dual singles have more cool factor, but I am just after a low buck performance gain if possible.
I have a 216 in my '48 right now, but I want to rebuild a block I picked up a while back. My question is, I got the block for free but I don't know if its a 235 or a 261. How can one tell the difference? The driver side has a triangle pattern of bolt holes about the size of my palm, and it seems the water pump has the same narrow slit my 216 has; so I could conceivably reuse my water pump. Any respondents?
Try the casting numbers promt on the left of the screen,it will help ID your block http://www.inliners.org/
A stock 6 like a Chevy 235 is a low rpm slug with maybe 110 real HP.Adding more carburation,a better exhaust and a mild 3/4 cam gives maybe 160 HP with very little loss of low speed torque.These modifications really make the engine more free reving and much better throttle respnose.And usually the fuel mileage is better than stock from my experience. A 2 bbl on a stock intake is better without those tappered adapters that mess up air flow.I took a stock 235 intake,enlarged the carb opening with hole saws and then a grinder to roughly match a Holley 2300 350 cfm 2 barrel.I ground into the heat riser area but welded it up with a MIG welder that worked fine on the cast iron intake.Then I made a plate for the carb to bolt to from inch thick Phenolic,the brown laminate resin carb spacers are made from.Drilled and tapped holes in the intake to bolt down my spacer and for carb studs.Did some finish work to match it up to the carb which was mounted with float bowl facing foward.Took some backyard engineering to work out the linkage. Bolted in on an other wise stock 261 Chevy,huge improvement in performance and response and better fuel mileage that the stock Rochester one barrel.The stock jetting was fine,#53 Jets I believe.
I just dropped a 58 235 in my 53 chevy. It's 30 over and has a pretty hot cam. I threw on a Fenton dual exhaust and a 2 carb intake with 2 1 barrel Rochesters. When I went on my first drive on saturday and was very impressed with the power that the little 6 made. I had no problem lighting up the tires. That is something I didn't think I would be able to do with a inline 6 in a 3600 lb car. Letting a 6 breathe does a world of good. Most people don't take the time to have the engine ballanced. I did and I am very pleased with the performance. Here is a pic and a video. It's not really pretty right now but it will be soon.
The cam would decrease low end torque or the dual carbs would decrease low end torque, because that's actually the problem that I'm having with the engine right now. I swapped from a 4.11:1 to a 3.55:1 and while I can do 90 in the car now it's pretty sluggish starting off from red lights and REALLY sluggish going up my hill of a driveway.
yeah, inlines have a very impressive torq band, the stock 6,s were more like a tractor engine, and anything you did would improve em up. So with just a few mods and taller gears you have a very different car. Isky reportedly got a jump start in the cam business by grinding cams for chevy 6,s before the V8 came on the scene. and an old timer car guy that i knew told me about his first new car it was a 58 Chevy 6. I asked 'why the 6?' He said 'for a sleeper'. He he said he raced V8,s , and regularly beat many. He had some tricks Like bigger carb, taller gear, an small cam I think. the 6,s came out late in the game like out on the lakes, but if you look at some of their times they did good. they were beating lots of Ford flatty,s. And the forge steel GMC,s annihilated records but by then the Hemi,s appeared and it all changed. So if you just keep it simple with the basic 3 c,s [carb, compression, and cam] it will stay up with traffic just fine.
Cool site! Thanks for the info. I wonder which side of the block the casting numbers are? That motor is laying on its side with the p***engerside facing down.
So I have a fresh rebuilt Chevy 235 that is 40 over. It looks like it was never broken in. All the hone marks look like it was just done. A few questions...I also would like to add the split six exhaust and a dual single carb intake set up. If I wanted to kick up the cam a bit what would work best? And how would it be ordered? I never messed with hopping up engines before. Also I am going to go with the 3 speed manual trans. Should I put solid lifters in it? I have a set of solid and hyd lifters. Thanks in advance. P.S. I traded a pair of 54 Cadillac hubcaps even up for this motor.
GoManGo I have 2 words to answer all your questions: Call Patrick ****s (520-836-1117 - you can thank me later)
The cast numbers will be on the p***enger side.Someone that knows the codes can tell you what shift on which day the engine was built.The cast # will get you the year.
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