I'm looking for recommendations on whether or not I should swap the heads/cam on my 402 with another pair I have. Will I pick up performance or loose it by changing the configuration?

Current configuration:
402 +.030
063 heads (stock oval port 100.9 cc with 2.06/1.72 valves)
Dual plane with 750 holley
XE274 cam
9.7 compression (trw forged pistons)
4 speed
3.73 gears

I'm thinking of swapping the heads to 840 rect port castings with 2.19/1.88 valves. This would decrease compression to 9.2 due to 106.9 cc chamber. I'd go with a factory dual plane intake with my 750 holley

The other change I thought about is I have a CC Magnum muscle solid cam. I thought about seeing if I have clearance to install it a 4* advance. I'm concerned about the lift with it.

So am I better off leaving it alone?

What's wrong with your present set-up? What's the present performance like, track times, etc.? It seems to me that you have a good combo just the way it is.

Originally posted by rpol78:
The other change I thought about is I have a CC Magnum muscle solid cam. I thought about seeing if I have clearance to install it a 4* advance. I'm concerned about the lift with it..the lift has nothing to do w/piston to valve clearance..its the duration...call Comps Tech Line..what are the specs?..I vote to leave it alone..if you want the resto look,put the squareport intake on your 063's

I agree with the above. Those 063 heads sound fine for your application. They are great heads. If you would like more performance out of them take them off have the ports cleaned up, a 3 angle valve job, and 2.19/1.88 valves with some unshrouding cause of the small chambers. This might enlarge the chambers just a shade, but the added flow will for sure help your combo. The rectangular port heads would be to much air for your combo, well, not to much air, but not enough port velocity to promote solid bottom and mid range torque.

Daniel

I am the number one big port fan but not on a street 402. You have just about as good a head as you can get for your combo.

The car runs ok. Like most of us I just want a little more umph. I also have most of the parts to put together an 11:1 numbers matching L78 motor for the car, but I'd be back to the rect port heads.

Using a dual plane vs. a single plane wouldn't I pick up some of the port velocity (aka some of the lower end torque)? Would bumping the compression get me closer to being able to handle the rect ports or a 408 CI is it just too small of an engine?

The CC magnum muscle specs are:
.575 intake
.604 exhaust
IVO 30* IVC 70*
EVO 73* EVC 33*

It looks like everyone is saying leave it alone.

Have you tuned it, timing, carb, etc.? In 2004 there are definitely better ways to go than rect. ports on a lil' 402. If you want more torque down low then maybe you need a smaller cam.

I've played with the tuning on it. I put an adjustable vacuum advance on it, tried different mech advance springs, tried different jets, changed timing, etc. Don't get me wrong, it pulls pretty good up to about 6K. Primarily I was looking to try to squeeze a little more out of it. I don't actually drag race it since it's in a convertible. I mostly play around on the streets. I had a '60 vette with a 327 that seemed to run about the same, but it's a lot lighter car. The vette weighed in at about 2800 lbs. verses this is in a camaro which probably has 500 to 700 more lbs.

What is that cam? solid? hydraulic? roller? What is the duration at .050 and advertised?

..and I'll tell you..don't ever trust your "seat of the pants"..very misleading..

Remember your car is heavy and with only 402 cubic inches it will only be so fast unless you make it unstreetable. Find a 454 and build it. You won't believe the difference in torque(seat of the pants feel)

I have almost your same combo except I am running a 700R4. The 063 heads are almost perfect for your 402. Mine has been punched out .040" to a 410. I am also running 1 step bigger cam, the XE284. On the engine stand dyno this comco ran a best of 508 Hp and 565 TQ (I believe these numbers are correct it has been a year since I looked at them. I would think all you need is to have a little head work done. As stated before have a little clean up work done and add the bigger 2.190" intake valves. The only thing I would suggest is to leave the 1.720" exhaust valves as they are. When you go to the 1.880" exhaust valves with a long duration cam the bigger valve tend to cause shrouding problems and actually decrease flow number at hight (4800) rpm's.
I enjoy my combo, but be warned if you go to a cam much bigger streetability may become an issue. My car is just on the ragged edge of what I consider streetable. If you need to know anything else about my setup let me know.

Regards,