Cam and valve train questions, 383

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Plik

Plik

Ragin Cajun
Joined
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FABO I need your advise. I'm trying to select a cam and valve train for my engine build. First off, let me tell you what I've got so far.

-'72 duster
-'64 383 block
-.060 over bore
- 3.38" stroke
- Dome pistons (~10.2:1 CR)
- Eddy RPM Heads
- Eddy RPM Intake
- 750 carb
- Isky adjustable rockers (non roller)
- 6500rpm rev limit
- A833 close ratio
- 3.55 gears/~27" tire

Questions:

1.) Cam? I'm looking at the comp cam - XE285HL (.545/.545 lift , 241/247 duration) It shows up as a good match on comp's cam selector program and I've read some good reviews on it in Mopar magazine. Car will be a weekend road/strip warrior with some highway/street crusing. Will this cam be too aggressive? What does FABO think?

2.) What valve spring do i use? Comp recommends their dual valve spring arrangement (924-16)noted as requiring guide modification to fit special valve seals (505-16). Is this modification required for just stock cast heads? Will these springs clear the seals on the eddy heads? Or can i just run the eddy springs (so said .006" max lift)? I plan of swapping out the locks and retainers regardless.

3.) Lifters? I'd like to run the Pro Mag lifters (867-16) but Comp recommends (824-16) for '68 and earlier 383s. The only difference i can tell is in seat height, but does this really make a difference when using aftermarket push rods? I assume this is due to the early b/rb rod design?

Any help you could give me would be greatly appreciated.

Thanks,
Plik!
 
As I understand it the "earlier" lifters are for the pushrods with the smaller ends. You're running adjustable rockers, so you need the pushrods and lifters recommended for them. With that much lift you will need to check valve to piston clearance and probably machine the pistons. I don't think that cam will be very street friendly, but it will be better with the four speed than it would be with an auto.
 
What's the intended purpose of the car? Is it gonna be a street car? If so, that's a pretty big cam.
 
The car will be a weekend street car with occasional trips to the track. What cam would you recommend for my setup?
 
The 474 MP cam would be a good choice.
 
There are a couple of caveats in building a 383 vs anything else. First is the deck height which is always substantially higher than the catalog/blueprint spec. Usually around .060+ taller. So you have to have the block blueprinted to get the pistons at the right deck height of 9.98". If you do that and they do come up proud of the deck, the next thing you want to do is make sure the spark plug clears. Those pistons assume straight plugs and the RPMs are angled. Assuming that's done and the plugs clear... I would go down a few notches to the Magnum 270H or the XE274H. With the pistons at zero deck, the Felpro Performance head gaskets, and the RPMs you still will only manage about 10:1. Really you want a point more than that. If it were me, I'd have the block decked to get to 9.975" which leaves the piston .005" higher than the block. This will also require milling the end rails to get the valley pan to fit properly. Then I'd have the heads milled .030 to get the chamber size down to 81ccs. This also means the intake manifold sealing surface needs to get milled to have the intake fit properly. That will give you a solid 10.5:1 with dynamic ratios around 8.5:1 which is perfect for pump unleaded. It also gives a quench distance of .035" which is plenty for that piston. Building 383s is always more of a pain and more $$.
 
Have you or anyone else ever considered running a roller cam?

I think the next cam I go with will be a roller. Therefore I don't have to worry about which oil to use with the cam as I do now with the flat tappet cam. I realize the cost but in the long run wouldn't it pay for it's self eventually? Having to buy a zinc additive sucks!! I would like to catch up with the times and run a roller. Just saying.......... roller cams have some nice lifts don't they?
 
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