Comp cam, xr274hr-10 or xr268hr-10

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scrappydoo

scrappydoo

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Hi,
I have a good running 5.9 magnum out of a dodge ram on its way downunder and I would like opinions on the cams in the title.
Car is 1967 Dodge Dart GT conv.

stock 904 converter, dougs headers, m1 dual plane manifold, 600cfm holley or quadrajet, compression bumped up to 9.5:1. And ports cleaned up and matched to manifold.
Diff is tall, 2.7?:1. I'm not sure exactly what ratio it has but it is tall.

I would like it to have a slight lopey idle, but nothing too severe and I still want good mileage.
Thanks.
 
I would run the 268 if you are wanting to use the stock converter. It will have a slight lope to it but not bad.

The 274 will have a little more lope and may need some more stall in the converter.
 
268 with a stock converter and tall gears like you have. The 274 might sound cooler but it'll be a dog off the line with tall gears and a stock converter.
 
I think I have found the ideal camshaft.
Comp cams 264hr-12. Has the long snout for driving the fuel pump.
Specs
Only thing is comp cams don't have a spring to go with it.
Does anyone have some recomendations to suit the magnum heads?
Thanks.
 
scrappydoo said:
I think I have found the ideal camshaft.
Comp cams 264hr-12. Has the long snout for driving the fuel pump.
Specs
Only thing is comp cams don't have a spring to go with it.
Does anyone have some recomendations to suit the magnum heads?
Thanks.
Click to expand...

Looks like a good cam for you but the only thing is the lift. Make sure you measure your heads and see if their capable of that much lift. Any time you get over .500 lift your walking on glass.

Look through their beehive valve springs and see what they have listed. I was looking through them last eve. for a different engine so I know they have quite a few different sets. I'm sure they have them for a magnum engine. Sometimes you just have to match them up by size. Magnum heads use a 1.64" installed height spring so look for springs that use that installed height or close.

BTW: Are you sure that one has the long snout? I don't see anywhere on the page where it says it does.
 
Yeah, they have 2 different versions of the same cam one with long snout part no. 20-614-9 and the 20-614-9 short snout.
I posted the link to the short snout one as it has the specs for the magnum rockers.
.512 lift as opposed to .480"
I'll be pulling the heads to mill them down a little and also clean up the ports, so I'll measure the heights I can run on the stock setup, I have read that .500" is max on stock magnum heads.
I really would like to know what seat pressure rollers like to have and I'll find some springs to suit.
Thanks.
 
Those springs and retainers should work fine but man are them buggers expensive!! I bet you could do a search on Summit and find some for half that price. Just a thought.

BTW: JMO I'd replace the keepers too as your taking a big risk using used keepers and they cost nearly nothing. I've seen the results of keeper failure. Not pretty.
 
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