is my cam to big for the heads i have

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2 fast z28

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ok just wondering I have a comp cams xe268h cam in my 340 small block with early j heads with the bigger valves just wondering if the heads are being my limiter on making more power it does have 10:1 pistons in it also I feel like the car should pull harder on the top end just wondering thanks
 
It's not to big. Airflow is limited and a limiter in power production.
 
Too big...not at all,my buddy runs that cam in a 318 if your springs can handle i'd go bigger,but thats just me..:D
 
2 fast z28 said:
ok just wondering I have a comp cams xe268h cam in my 340 small block with early j heads with the bigger valves just wondering if the heads are being my limiter on making more power it does have 10:1 pistons in it also I feel like the car should pull harder on the top end just wondering thanks
Click to expand...

It should run pretty good.

I run a HE268 in my 'teen, and it pulls pretty good to 6200 or so before it starts fading.

Maybe it needs to be tuned better.
 
did you degree the cam?
what is your rear gear?
are you running a stock converter, 4 speed?
 
ok see I not sure if the cam was degreed it was supposed to be but my cam card says nothing of what it was installed at I'm running 410 in the rear with a 727 with a 3400 stall converter maybe I'm expecting more out of the motor
 
rumble fish when u say air flow is the limiter are you talking in the heads there is also a offenhauser tunnel ram on it to with two 450s and I had a wide band in the exhaust and wide open its at 12.3 ish
 
The heads are always the limiting factor. But the camshaft is not too big. Too popular, too chosen and too run of the mill and too over rated, yes, but not too big.
 
I have one in a 9.5 360 with 2.02 j heads. With an RPM intake and exhaust manifolds it screams good for what it is. But that is with 3.73's and a 2500 converter. Sometimes a cam swap becomes more than the sum of its parts in your head, resulting in slight disappointment.
 
I also have a 69 340 with Stock 2.02 heads and the XE268H cam. I also have the Eddy Air Gap, 750 Eddy Carb, 1 5/8 inch headers, 4 speed and 3.55 gears. It pulls like a train. Maybe I just got lucky with the parts combo.
 
Yes the head which flow on a good iron head as cast & stock Vaal da is only in the 200-210 range. Give or take a few cfm. The added info would have also been nice to know. Still missing some though not needed at this point.
 
2 fast z28 said:
ok see I not sure if the cam was degreed it was supposed to be but my cam card says nothing of what it was installed at I'm running 410 in the rear with a 727 with a 3400 stall converter maybe I'm expecting more out of the motor
Click to expand...

That cam is bottom end/mid-range in a 340. I think with your gears and converter you could use more cam, as bottom end and mid-range get used up pretty quick with your current setup. I ran a 268 duration/.490 (older grind, not 268XE) in a 318 with 2500 stall and 3.91 gears and I thought it ran great, and that was in a smaller engine with less gear and stall. Either cam up, or lower your gear ratio to something like 3.55's and stall to 2500. just my .02 worth.
 
I think it will have plenty of power that will last well beyond 5500. You'll be fine.

I have taken a STOCK 318 with a 4 barrel and headers to 6K plus and it was still pullin. Those cams were typically in the 190s for duration @ .050".

I think some of yall miss the point that a cam with a duration of 220 @ .050 might be "mild" but it's THIRTY FRIKKIN DEGREES BIGGER than a stock cam. That's a huge jump.

The stock 340 cam was in the 220 @ .050 neighborhood and those would pull to seven grand. Long as you use the right valve springs, nothing's gonna lay down up high, power won't fall off, it will be fine. You keep goin up in duration and I can guarantee one thing......you will LOSE some bottom end torque and I don't think you want that.

Cams are like carburetors. Err on the small side and you will always be happier.
 
I'm running headman 1 5/8 headers into 2 1/2 inch exhaust with a h pipe with flowmaster 10s should flow pretty good I'm wondering if I should go to a bit larger cam do to the gears and stall converter just my thought
 
fine tune what u have. cams are related to rpm. do a cranking compression test. try more ignition advance
 
Take it to a "timed acceleration trial" and find out what it's actually making. Then tune/change from there. It should run fine but I've seen plenty of "10:1" engines that weren't, and the right camshaft put in wrong, and guys that shouldn't be trying to tune carbs, that it doesn't matter. Many of these cars are not performing up to the sum of their parts. So find out how it performs (MPH vs. weight) and go from there.
 
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