Compcams

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Crazyswedish

Crazyswedish

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Joined
Mar 26, 2017
Messages
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Location
Sweden
What camshaft give me better performance ?
Comcams : 20-249-4 or
20-229-4
Can modified heads to go .600lift
NOT a roller camshaft.


Engine spec :
750 holley flow 800cfm.
Victor junior.
Ported edelbrock rpm heads 2.02 valve..flow 275cfm. Think about valves 2.055 in 1.60 out and max out the port work.
1.5 roller tip rockers
Kb pistons 10.9cr.
1.3/4 headers.
Mufflers 3.5 straight true with short pipes..not street legal.
 
Automatic or 4-speed?
Both will only work with enough rear-end gearing (4.11 ish).
 
Better performance from any particular cam depends on what you are using the car for. Is this engine/car for drag racing or just driving on the street?
Your heads are specified for .575" lift from the factory. The retainers need to be changed or the tops of the valve guides need to be milled down, and the valve stem seals may need to be changed.
 
nm9stheham said:
Better performance from any particular cam depends on what you are using the car for. Is this engine/car for drag racing or just driving on the street?
Your heads are specified for .575" lift from the factory. The retainers need to be changed or the tops of the valve guides need to be milled down, and the valve stem seals may need to be changed.
Click to expand...

This is my outlaw street race car, only.
So a little of dragrace.
4500stall.
I want to go faster when a new car is ready to race against me.
I have a new xe295hl but i Wonder if there some different in power to go solid or hydraulic cam.
I can "mod" my heads to go for more lift, not more than .600lift. My valve to pistons i think will be the safe to go max .600 lift..
After the max ported heads, 2.0255 valves, and then hope for 300cfm, can the heads support more power with this cams or should i go for a bigger cam.
Worked down the weigh 100kg (swedish) on my car.
 
OK, understood on your goals. That information helps a lot. If you are an outlaw in Sweden, does that mean you are a Viking? (Just a joke...)

For your street racing, do you often get into 3rd gear?

4500 RPM stall? Wow, I hope your engine revs up very high; it needs to so you have an adequate ratio of minimum to maximum usable RPM's. But that high stall speed makes sense to me with a cam duration around 300 degrees, and the CR is not all that high for 295 to 300 degrees of duration, so you are certainly going to have to rev the engine a lot.

Neither cam that you list has over .564" lift so I am wondering why you are thinking about .600" lift? Are you looking at 1.6 ratio rockers? Anytime you go with a higher lift to duration ratio, it tends to make minimum to maximum torque band broader. But your RPM band is going to be narrow when you are racing, because of your torque converter stall speed.

So the only advantage I can see now for higher lift is just more peak power with the increased head flow. It is probably going to have less torque at low RPM cruising speeds; the dynamic CR is going to be very low with cams above 300 degrees duration with your static CR. (I compute 7.6:1 with the solid lifter cam that you listed.) That loss of lower RPM torque may not be important to you.

THIS may be case where a narrower LSA and a custom cam may help. I think others are better equipped to comment; it has been 35 years since I bought a 300 duration cam!
 
nm9stheham said:
OK, understood on your goals. That information helps a lot. If you are an outlaw in Sweden, does that mean you are a Viking? (Just a joke...)

For your street racing, do you often get into 3rd gear?

4500 RPM stall? Wow, I hope your engine revs up very high; it needs to so you have an adequate ratio of minimum to maximum usable RPM's. But that high stall speed makes sense to me with a cam duration around 300 degrees, and the CR is not all that high for 295 to 300 degrees of duration, so you are certainly going to have to rev the engine a lot.

Neither cam that you list has over .564" lift so I am wondering why you are thinking about .600" lift? Are you looking at 1.6 ratio rockers? Anytime you go with a higher lift to duration ratio, it tends to make minimum to maximum torque band broader. But your RPM band is going to be narrow when you are racing, because of your torque converter stall speed.

So the only advantage I can see now for higher lift is just more peak power with the increased head flow. It is probably going to have less torque at low RPM cruising speeds; the dynamic CR is going to be very low with cams above 300 degrees duration with your static CR. (I compute 7.6:1 with the solid lifter cam that you listed.) That loss of lower RPM torque may not be important to you.

THIS may be case where a narrower LSA and a custom cam may help. I think others are better equipped to comment; it has been 35 years since I bought a 300 duration cam!
Click to expand...

Rew to 6500rpm now, after that the engine want rew more.
3gears 402m but not in 201m "strip" (last year i saw the cops, 5 times and one of these i "strip" them out with my mc..Just "clean" *** on that bike ;)
No cops here were i live..they have enough in the "big" town.
I sent a mejl to compcams 3 weeks ago, all the info like this..no answer.
The compcams look like the biggest on the net.

7.6cr..scary.
 
Yes, more static CR would often be used for this big of a cam, so that the final DCR will not be too low. But, at least you are set up to rev the engine high to help overcome that low DCR. I rallied an Opel 1.9L that had a big cam in it and I am sure the dynamic CR was in the low 6 range. But it was ran OK above 3800 RPM or so.
 
Don't let the size of the web presence dictate where you buy from.

The problem with most Mopar cams is they are mass produced with Chevy specs and are not ground for the Mopars .904 lifter diameter. Get all your engine specs together then get in touch with Hughes Engines, Bullet cams, Howards cams or Mike Jones at Jones Cams... they will grind a cam for the Mopar lifter that will blow away any off the shelf cam.

I'd also think about longer valves if you hope to get to .600 lift...
 
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