It's time for me to do a cam swap, and I was leaning to the Comp XS274S solid flat tappet until I began reading about the annoying break-in procedures and greater chance of killing a lobe...all that and they make less power than a roller setup. I'm a "solid" type of guy, and really like the idea of the XR274R solid roller. I'm 24 and this is not my daily driver...I don't want to completely mismatch a cam with what I have, but I do like to make a 327 scream up high and have a solid middle.

XR274R
INT EXH
ADV: 274 280
0.050: 236 240
Lift: 0.564 0.570
LCA: 110
ICL: 106

My Combo
I have a +0.030 327 stock deck, stock pistons
200cc Aluminum Pro Toplines (too big I know, for an engine build that never happened)
64cc chambers
1.52 Pro Magnum Rockers
9.25 comp w/ 0.028 gaskets (close estimate)
Weiand Dual Plane manifold
Edelbrock 600cfm carb
Tremec TKO 5 speed
3.73 rear end
No power brakes

I know my existing combo could use some improvement...but what do you guys think of the XR274R cam? Thanks!! Power estimates?

The XR274R in my Comp catalog has 0.377" and 0.381" lobe lift. In order to get the 0.639" valve lift you'd have to use a 1.7:1 rocker arm ratio. With a standard 1.5:1 ratio the lift will be a more reasonable .564"/.570".

It should run pretty well in a 327.

The XR274R in my Comp catalog has 0.377" and 0.381" lobe lift. In order to get the 0.639" valve lift you'd have to use a 1.7:1 rocker arm ratio. With a standard 1.5:1 ratio the lift will be a more reasonable .564"/.570".

It should run pretty well in a 327.

Whoops, that was the BBC version! Makes much more sense now...

Thanks!

You should be all right with that cam, since you are running the Pro-Topline heads. If they were stock Double Humps or something, they probably wouldn't breath well enough for that cam.

I'm thinking that your cr is too low for that big cam, I may be wrong.:noway:

I'm thinking that your cr is too low for that big cam, I may be wrong.:noway:
I agree with you.
You can run this cam and see benefits, it's a roller (more power!) and will rev high, but don't change your intake to a single plane whatever you do, I bet you would have a hell of a time taking off from lights and idle quality would diminish. that is what is happening to me.

I think it will work just fine with 3.73 gears and a 3.27 1st gear. My 327 with a 240°/240° solid roller had no trouble at all driving right away from a stoplight, made peak torque at about 4500 rpm and was well over 300#ft to the rear wheels at about 3000 rpm.

FWIW, Jan 08 Super Chevy ran an article where they put the smallest THumpr roller in a 327 with 9.9:1 and ported 1.94's and made 399 lb-ft and 416 HP. It had less intake duration and less lift than the XR274R.

I think it will work just fine with 3.73 gears and a 3.27 1st gear. My 327 with a 240°/240° solid roller had no trouble at all driving right away from a stoplight, made peak torque at about 4500 rpm and was well over 300#ft to the rear wheels at about 3000 rpm.

Oh man, I found that 2 barrel vs 4 barrel (on that 327) thread you wrote 3 years ago, and those numbers you posted are impressive! I know my combo will be shy of what your 327 put down, but it just shows what the often overlooked 327's can do. With a solid roller, it's almost too easy!

FWIW, Jan 08 Super Chevy ran an article where they put the smallest THumpr roller in a 327 with 9.9:1 and ported 1.94's and made 399 lb-ft and 416 HP. It had less intake duration and less lift than the XR274R.

Thanks for the tip! I am going to scour the site for that article.

Oh man, I found that 2 barrel vs 4 barrel (on that 327) thread you wrote 3 years ago, and those numbers you posted are impressive! I know my combo will be shy of what your 327 put down, but it just shows what the often overlooked 327's can do. With a solid roller, it's almost too easy!



Thanks for the tip! I am going to scour the site for that article.

If you can't get it, let me know, I'll fax you a copy.

Melrose, I couldn't find it...it would be great if you could fax it! You have PM