Stock cam vs 260

[Velosopher]

I love all the technical expertise of many of the members here. I am just about to put my 140 heads and carbs etc on my 110 engine. Engine will be dropped. Can anyone tell me the approximate HP gain from putting in a 260 cam vs. my current stock cam. I say 260 cause I don't want to lose low end. Most of my driving will NOT be on the highway. Is it worth the extra effort and expense? If it is a very noticeable difference I will make the change. Thank you.

[miniman82]

My preference is against stock cams, though I ended up with an Isky version of one in my engine. A 260 isn't a wild enough cam to lose bottom end, I bet you'll like it. The extra top end punch makes it worthwhile.

[martyscarr]

I would expect a horsepower LOSS if you go from a 110 cam to the Isky 260.

The stock cam for 110 engines is the 3839891 cam; specs for both cams are as follows:
3839891 - duration at .050 is 218, lift is .409
Isky 260 - duration at .050 is 208, lift is .417

The Isky 260 will give you good low end torque, but the -891 is a better cam for the 140. In fact, the -891 cam was used in the 140 manual trans engines, as well as in the 64 turbo engine.

The Isky 270 would give you a bit more than the -891 cam, it still has good low end and better top end than the -891 cam. It will respond even better with head work, but it is still a very mild cam.

Your car is has a manual transmission, doesn't it?

Marty Scarr

[atwistedgrip]

270

[Velosopher]

Yes, it has the factory 4 spd. 270 seems the consensus right now. How does the 270 idle? I actually don't like the way a 280 idles, especially with the stock exhaust i will be running. Sure wish I could drop the coin on angled exhaust and headers. Maybe in a couple years. How much time should I expect a cam replacement to take on my first attempt? Thanks for the replies.

[flat6_musik]

Personally, I'd say 270 b/c you've got the stick and it's fun to "row it" and keep it up on the power band. To me, that's what a sports car is all about! But geez....R&Ring a cam is almost bordering on a full engine rebuild, because you're splitting the case.....yeeeshhh! But I'd do it just to hear it idle with that sweet lopey sound!.....and I tend to like to bite off more than I can chew!

[Velosopher]

Yeah, not sold on the idea of splitting case right now. If I do that then I will want to get a new crank and on and on.
I will update as I get further down the road on this.

[UNSAFE]

Heck with the Isky cam - get an Otto 20 and be happy !

[4carbcorvair]

I went with the OTTO 20. Lost a smidge of low-end. Plenty of mid/top end. Have had it up to about 5800 rpm and it still wanted to climb. I get right around 22mpg with my 140. :) It idles fine.

[Velosopher]

Otto 20 eh? I will look into it. I didn't hear from anybody about how long I should expect the cam replacement to take?
After the heads and cylinders are already off. Thanks.

[flat6_musik]

I'm sure you could at least kill a weekend doing it, and actually it more depends on if you've "dived in" to a corvair engine before, if you know a few of the shortcuts and if your engine is a crudball that you're going to wanna clean up before re-assembly.

I think Phil knows quite a few shortcuts, as he's done a lot of "banzai" engine repairs on his car.

[UNSAFE]

I didn't hear from anybody about how long I should expect the cam replacement to take?

Changing a Corvair cam is a PITA compared to something like a small block Chevy V8. The crankcase halves must be seperated. This is best done on a workbench. Just about everything must be removed to get to the cam. It's a good time to check the crank and bearings and see if a rebuild is in order.
You might want to consider a Fail-safe cam gear. You must use new lifters and follow a cam break-in procedure. If you haven't done it before I'd plan on two weekends to allow for cleaning parts or any other obstacles.