Inliners International Forums General Discussion Engines 235-261 max lift?

What would be the maximum valve lift for a stock Chevy 235 or 261 without modifications such as head or block milling? I have the choice to get a new, inexpensive cam but want the one with the most lift (both have the same duration)Thanx

The overall lift isn't so important as the lift during overlap when both valves ae open at piston TDC.The 235/261 intake valve can hit the piston if clearance aren't checked carefully.A cam like the stock Corvette cam (261 cam too)or The Howard's M4F, have around .405-.428 lift, and will generally cause no problem on a zero deck height block if the head isn't shaved much.

I guess I would like to know what you are trying to use this engine for??

Coil bind would be another concern.

Gearhead, I'm going to use this engine to eat flatheads. It's a 58 261 that's going in a fenderless 32 Chevy 5W. I'm guessing about 2500 lbs, 4spd, 4.11 gears.
If I understand it correctly, I could actually have one cam with less lift hit the piston then one with more lift depending on when that lift occurs? I have a cam with .470" lift but that seems like a lot to me. I was wondering about getting another with .430" lift. I kind of want to get some blueprinting done before I tear into this engine.

There is an article in the Jan/Feb issue of the 12 Port News about stroking a 261 into a 292 and there is some info on head modifications and cam specs. Its by Robert Duggan. Your going to need to do some serious head work to get it to actually need a cam with the specs your talking about.

Yes, after messing with my 261 a bit I figure that the best way to make it perform is to modify it so it can rev higher, then worry about the cam. The rods and pistons limit that right now on my engine.
I think the order of mods on a 261 should be:
1. Intake and exhaust (these are quite restrictive even on a stocker)
2. Increase compression
3. Forged rods and pistons, and a good balance job to let it rev higher
4. head flow work
5. Moderate but not wild cam
6. Extreme stuff like 12 port head


[This message has been edited by 4onthefloor (edited 07-16-2003).]

A few years back, Leo Santucci sent an article to the 12 Port News entitled "Beating a Dead Horse". Leo didn't actually write the article, but rather it was a letter from an unidentified racer, who was relating how he had built a 261 for drag racing and went to some pretty extreme measures to get the head to breathe and the engine to stay together. I don't recall all of the details, but it was probably one of the funniest articles ever printed in the newsletter - although it wasn't meant to be humorous. The guy was running lots of displacement, a series of big cams, lightened crank, using different rods, piston height, etc. and had spent several seasons trying a variety of head tricks with lots of compression and lift. He finally gave up after reaching the conclusion that he could either make good HP, or have an engine that didn't blow up or otherwise fail after a couple of racing weekends - but not both. Please don't think I am trying to burst your bubble, but the fact is that you can only go so far with a 235/261 before you reach the limits of reliability and usability on the street. With the limited breathing of the stock head, high RPMs don't result in a lot of HP for the investment, but will certainly reduce the life of the motor.

Of course if your budget allows, a 12-port head would be the answer to a lot of these problems.

261s have had some success in circle track racing, where torque and gearing are the key factors,
but most 6-cyl round track racers these days (mostly nostalgia events) have gone to the 250 for it's higher RPM capability.

Even back in the day when there was a lot of L6's racing against flatheads, most drag racers chose the GMC engine for its sheer strength and torque. The GMC has its RPM limitations too, but breathes a whole lot better. So if you were starting with a clean sheet of paper, a GMC 270 or 302 would have a bunch more potential.