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scotty
New member
Username: scotty
Post Number: 3
Registered: 11-2003
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 9, 2004 - 11:13 pm: |       |
I've been flogging a ZZ4 Partial block, Hot Cam, with Edelbrock Performer RPM heads for a few years now. PLENTY powerful, but I'm trying to squeeze a few more RPMs out of it. I see that the Comp Cams Hyd. Roller cams show power right thru 6800 RPMs, I'm dead at 6300. Is it their lifters? More spring pressure? Or cam profile? (ramps)(which I doubt)
........ Or, am I confusing valve float/pump up with simply "running out of cam"?
........ Any Thoughts? Thanks. |
gregt
Advanced Member
Username: gregt
Post Number: 167
Registered: 8-2003
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 9, 2004 - 11:30 pm: | |
I'm running the ZZ4 also with the HOT cam and I've been discussing potentail upgrades with a Comp Cams tech. By and large, the best upgrade right now would be the beehive springs #26918. The only problem I forsee may be those heads. I'm not familiar with the spring pocket on those and am not sure about the O.D. of the springs. Are you using the GM springs for the ZZ4? According to Comp Cams, their beehive springs will run 7000 RPM or more, depending on the cam. I am seriously considering the XR276HR cam on my ZZ4 with 1.6 rockers which will bring the lift to .510/.544 and I am garranteed no valve float to 7000 RPM. There's no way I'm going to run there, but it is piece of mind knowing that I'll have some headroom. According to Comp, they've done extensive testing on a ZZ4/HOT cam/750 Holley setup and have gained 18HP just changing out the springs. They tell me the XR276HR is good for another 24, for a total of 42HP. And thats using 1.5 rockers. He tells me I should pick up a few more with the 1.6s. The other piece of YOUR equation, though, is in the heads. I dont know how differently they flow than the ZZ4 heads. I dont think you're running out of cam. I think you're floating. |
scott
Senior Member
Username: scott
Post Number: 216
Registered: 4-2001
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 10, 2004 - 11:43 am: | |
scotty, the HOT cam won't rev past 6300 without some kind of rev kit. The ramp profile is going to float the valves around 6000, whether you have stiffer springs or not. You can add a rev kit, like the AFR Hydra Rev, or go with a different camshaft. If you want much higher RPM, you might want to consider a mechanical roller camshaft. The HOT cam makes it's peak horsepower around 5800 RPM anyway, so revving it further is kind of a waste of time. |
scotty
New member
Username: scotty
Post Number: 4
Registered: 11-2003
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 12, 2004 - 9:02 am: | |
Thanks guys, that's a TON of information! Acutally I have the Hydra Rev kit.
.... So if I were to use a more aggressive cam, would there be an advantage to using the better Comp Cam lifters over my stock GM ones? I have considered a mechanical roller, my cam is pretty noisey anyway!
.... My reason for needing a few more RPMs is that (S-10 in the 1/4 mile) I'm limited to a 26" tire and 3.91 gears. My 8-3/4" Mopar rear has nothing available between 3.91 and 3.55. So at about 112 mph, and for the last 100 feet of the 1/4 mile, I'm looking to open the door and push with my foot...
(Message edited by Scotty on December 12, 2004) |
68chevy
New member
Username: 68chevy
Post Number: 10
Registered: 10-2004
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 21, 2004 - 4:52 am: | |
Here's the part numbers for the beehive spring conversion: CCA-26918-16 (springs), CCA 4705-16 (spring cups - they fit over the stock .570 guide in the zz3/4 head and do not require machining the head), CCA-787-16 (retainers for non-LS1 11/32" valves while using beehive springs), CCA-648-16 (valve locks - machined, not stamped) You will have to use the GM valve stem seals #460483, which are more expensive than the smaller aftermarket Viton rubber seals, but they work great - they are about 3-4$ each) I just orderd the parts - I'll post again and let you know what shims I had to use under the spring cups if any. I also ordered the comp cams pro-magnum roller lifters # CCA-875-16. I'll let you know how they sound and feel. I think the above article on the benefits of the beehive spring is the key. Be confident in comp cams quality - valve train is all they do and they are very good at it.
(Message edited by 68chevy on December 21, 2004) |
68chevy
Junior Member
Username: 68chevy
Post Number: 11
Registered: 10-2004
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 5, 2005 - 3:20 am: | |
I just assembled my heads. The rough installed height with the new springs was 1.79. I did not re-measure installed height after the springs were installed since the 130# of seat pressure was sure to push the retainer to the installed height of 1.8". All the comp cams parts fit perfectly. The quality of the springs and parts in my prior post was amazing. Their new springs are cutting edge - they have not been sitting on a shelf for years. |
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