Big Block Valvetrain Experts -Step inside...
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,872
Likes: 3,548
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Big Block Valvetrain Experts -Step inside...
I have a ZZ502 that was purchased from a fellow CF member. His shop supposedly knew what they were doing when they-
-milled the heads to raise static compression to around 10 to 1
-changed the cam, valve springs, pushrods and roller rockers
However- they retained the stock Hyd Roller lifters.
From my understanding the stock Hyd Roller lifters can’t handle anything more than about a .555 lift. Realizing that was a problem I purchased some Crane Hyd Rollers (13532) and took out the factory hold down & spider.
Now –I’m looking at the valve springs- Beehive 26120-which from the specs can’t handle anything over .600 lift.
Cam is a 242 (int) and 248 (exh) at 50 and lobe lift is .617 and .622 w/ Comp’s Magnum Rockers 1.7 ratio.
I can’t check for coil bind w/ a gauge-since it’s a Beehive. Spring height is 1.880 and coil bind is 1.230. So needing .60 BEFORE coil bind- It looks as though these springs won’t work?
I’ve looked at Comp’s Catalog and they do show that a couple Cams w/ lift as high as .612 and recommends the Beehives 26120.
Should I pull the Beehives?
Richard
-milled the heads to raise static compression to around 10 to 1
-changed the cam, valve springs, pushrods and roller rockers
However- they retained the stock Hyd Roller lifters.
From my understanding the stock Hyd Roller lifters can’t handle anything more than about a .555 lift. Realizing that was a problem I purchased some Crane Hyd Rollers (13532) and took out the factory hold down & spider.
Now –I’m looking at the valve springs- Beehive 26120-which from the specs can’t handle anything over .600 lift.
Cam is a 242 (int) and 248 (exh) at 50 and lobe lift is .617 and .622 w/ Comp’s Magnum Rockers 1.7 ratio.
I can’t check for coil bind w/ a gauge-since it’s a Beehive. Spring height is 1.880 and coil bind is 1.230. So needing .60 BEFORE coil bind- It looks as though these springs won’t work?
I’ve looked at Comp’s Catalog and they do show that a couple Cams w/ lift as high as .612 and recommends the Beehives 26120.
Should I pull the Beehives?
Richard
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Beehive 26120 right from the CC spring pages is meant for up to .650 lift using 1.900 installed height @ 144#'s of seat pressure.
Just verify the 1.900 installed height and you should be good with just over .600 lift.
just scroll down to 26120
http://www.compcams.com/technical/Ca...07/296-306.pdf
Just verify the 1.900 installed height and you should be good with just over .600 lift.
just scroll down to 26120
http://www.compcams.com/technical/Ca...07/296-306.pdf
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,872
Likes: 3,548
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
I have Comps "Master Reference Guide" and they say .590 lift in one place and .600 in another. Made me want to dig deeper...
Looking at the chart, it does show .650 - 1.900 to 1.250 height
But after reading this-
http://www.compcams.com/Technical/FA...lveSprings.asp
Installed Height - Coil Bind - .060” = Maximum Recommended Valve Lift
1.900 minus 1.230 minus .060 = .610
So-I'm close BUT I'd rather err on the side of caution when one spring is keeping the valve from the piston.
Think I should still run with them?
Thanks -
Richard
Looking at the chart, it does show .650 - 1.900 to 1.250 height
But after reading this-
http://www.compcams.com/Technical/FA...lveSprings.asp
Installed Height - Coil Bind - .060” = Maximum Recommended Valve Lift
1.900 minus 1.230 minus .060 = .610
So-I'm close BUT I'd rather err on the side of caution when one spring is keeping the valve from the piston.
Think I should still run with them?
Thanks -
Richard
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
It is not listed, but you might be able to do a 1.920 or 1.930 installed height. You would have to check the seat pressure to not go below 130 - 135#'s for a mild H-roller like you have.
It is a common thing to shim up and down or to use + .050 retainers to raise and lower seat pressures. Like my springs were made for .750 max lift and they had 225#'s of seat pressure. I only rev to 7500 rpm so I can get away with under 200 pound seat. so I used + .050 retainers to set the seat pressure at 195# and it gave me a max lift of .800
It is a common thing to shim up and down or to use + .050 retainers to raise and lower seat pressures. Like my springs were made for .750 max lift and they had 225#'s of seat pressure. I only rev to 7500 rpm so I can get away with under 200 pound seat. so I used + .050 retainers to set the seat pressure at 195# and it gave me a max lift of .800
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,872
Likes: 3,548
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
I was thinking that would be an option. I'm going to get my Machine Shop buddy to check out the heights.
Thanks-
Nice car you have by the way- the track video was great.
Richard
Thanks-
Nice car you have by the way- the track video was great.
Richard
