Comp Cam question

[thatguy]

Anybody ever run this cam? Thinking of trying it in the Miller. B impellor
Similar to the 284 extreme Hyd. flat I have now.
Comp.# 11-456-8
Here is the link
http://store.summitracing.com/partdetail.asp?part=CCA%2D11%2D456%2D8&view=1&N=700+150+
Tommy

[caribbean20]

in my 502. Spinning a mag/bronze A/B cut, in a new tight pump, around 5,300 rpms. I have the Dart Pro 1 aluminum heads. Had the boat out first time this weekend, ran best ever. Motor is a little rough on the idle, I just keep it over 1,000 rpms and no problem around the dock.
Anything else I can tell you?

[thatguy]

in my 502. Spinning a mag/bronze A/B cut, in a new tight pump, around 5,300 rpms. I have the Dart Pro 1 aluminum heads. Had the boat out first time this weekend, ran best ever. Motor is a little rough on the idle, I just keep it over 1,000 rpms and no problem around the dock.
Anything else I can tell you?
That sounds good. Mine is just a .040 over 454, Brodix 280 cc Alum. Rect. heads.
Think I'll give it a shot. Do you run the comp lifters with it?
Tommy

[MACHINEHEAD]

The first thing that struck me was why bother. Just looked up the specs on both cams . Your existing cam is 284adv/240@.050/153@.200/.574lift intake
290/246/154/.585ex. The hyd. roller is298/242/153/.566int and 304/248/159/
.566ex. Numbers are one thing but lobe area is something else. Im sure the roller has more lobe area but not by very much. 5% maybe. If the hyd.flat is going away, replace it with something you are going to feel. The xr300hr would be a step up. This cam is under.580 lift so a spring change may not be needed. I would recomend the comp hyd. roller lifters. I would like to see 140 on the seat and 380-420 open preasure. Some shims may get you there. Check coil bind. Pushrods might also be too long. Your combo will make about 630hp at 5500 with headers and the xm300hr.

[MACHINEHEAD]

Sorry I was in 496 land. About 575HP

[thatguy]

Thanks,
When I first built the engine the Hyd. cam went away on fire up. I put a new one in and dumped and flushed, But the engine needs to come apart. I like how it runs with the stick that is in it. But just figured that since it will be apart I might as well go roller. It has maybe 6 hours actual running time and I know the bottom is going away from the iron in the oil. I have a couple sets of new roller springs, just need the lifters, stick and pushrods.
Don't want to get too wild with it (no flycuting or such), just want to go with a roller replacement. (Wish I would have done it the first time!)
Your numbers are very close, turns 5200-5300 RPM now.
Thanks again, Tommy

[MACHINEHEAD]

If you are looking for a replacment hyd. roller you picked the perfect one. I am concerned about the flat going flat. Your springs may have been to stiff, too much seat preasure, too much open preasure. What I am saying is that you may not need to change them. 130 - 140 lbs on the seat can almost guarantee a hyd. flat tappet failure but would be just right for your current rpm range with the roller. Just check them first. Looked at some notes and looks like PR lenth is 7.8 int. and 8.7 ex. Just to get you close !

[thatguy]

If you are looking for a replacment hyd. roller you picked the perfect one. I am concerned about the flat going flat. Your springs may have been to stiff, too much seat preasure, too much open preasure. What I am saying is that you may not need to change them. 130 - 140 lbs on the seat can almost guarantee a hyd. flat tappet failure but would be just right for your current rpm range with the roller. Just check them first. Looked at some notes and looks like PR lenth is 7.8 int. and 8.7 ex. Just to get you close !
Thanks!
I will have a pretty good thrash ahead of me to get it done on my days off, but hey, thats the fun part right?
Tommy

[MACHINEHEAD]

Sure