View Full Version : Hyd Roller Comparison - Comp XR270HR vs Howards 280/292


DesmoEd
03-25-2011, 10:48:16 AM
I decided to do a cam swap while the 355 was out of my '73. Its a street cruiser with vacuum p/b and Vintage Air a/c

'71 2 bolt decked block bored .030

Scat rotating assembly balanced w/ARP hardware
.049 quench
7qt pan w/windage tray and crank scraper
Hyper flattops static CR 10.1-1
Edel Perf RPM heads 64cc/185 cc setup for hyd roller
Comp 1.6 roller rockers
Holley 300-36 Hi rise alum intake
Holley HP 650 DP
Hedman 1 3/4 headers
MSD billet w/6AL

6 months ago the car was built with TH350, 3;73, and Comp XR270HR hyd roller cam


COMP

270 / 276 adv duration
218 / 224 @ .050
110 LSA
.528 / .535 w/1.6 rockers)

The new 4 speed setup will be M-20, 3;42, and Howards 280/292 hyd roller. I am also running a 30# billet flywheel and 11in Centerfore clutch

Howards

280 / 292 adv duration
224 / 230 @ .050
112 LSA
.535 / .542 w/1.6 rockers


The Howards looks a little slower and easier on the valvetrain. The 112LSA should help with the idle and with running p/b and a/c..............at least thats what I hope:o

Any comments?

I was thinking this should be good for 390hp/420tq

Notalent
03-25-2011, 10:53:37 AM
Stay away from a 110lSA if you want vacumm.

DesmoEd
03-25-2011, 03:35:29 PM
Stay away from a 110lSA if you want vacumm.



I am switching from Comp 110LSA to Howards 112LSA

tallman1970
03-25-2011, 04:02:43 PM
You will be fine.I wouldn't go any bigger with p/s and a/c even with a 4speed.Nice clutch setup.

DesmoEd
03-26-2011, 10:21:26 AM
You will be fine.I wouldn't go any bigger with p/s and a/c even with a 4speed.Nice clutch setup.




thanks, anyone else?

anyone have a program to run the cam number differences?

quick79z
03-26-2011, 12:12:02 PM
both cams are mild so vacuum will be good, that howards stuff is GOOD! so is comp though, id go with the bigger of the two obviously cause they are not huge cams, for all around performance good millage and vacuum the howards cam should be great, if you wanna pick up some aceleration go to 108 lobe centers but it will get choppy, i think you will make more power than you think! i love my comp cam [with crower lifters] lol

DesmoEd
03-26-2011, 02:00:27 PM
both cams are mild so vacuum will be good, that howards stuff is GOOD! so is comp though, id go with the bigger of the two obviously cause they are not huge cams, for all around performance good millage and vacuum the howards cam should be great, if you wanna pick up some aceleration go to 108 lobe centers but it will get choppy, i think you will make more power than you think! i love my comp cam [with crower lifters] lol



The XR270HR made 14" vacuum at idle - its 218/224@.050. Good off idle cam with tons of midrange

The XR276HR in my '69 vette makes 13" vacuum at idle - its 224/230@.050

In a 350/355 230@.050 looks to be a good number for making hp and still having enough vacuum for accessories.

I expect a small hp gain out of the Howards but mostly to move max hp/tq up higher and make it more 4 speed/high rpm eager:cool:


I am hoping the 112LSa provides a nice idle for a/c

I'd be happy at 390/420 :cool: