Absolute-Speed Heads users - Q's on your valvetrain
04-25-2006 | 05:42 AM
#1
Absolute-Speed Heads users - Q's on your valvetrain On his AS heads, Jay commonly used +.070" longer REV valves, especially with the REV Dual-Springs, Comp 987 or 977s. If you're a user of Absolute Speed heads, can you answer as many of the following questions as you can....?
- What valves are installed on yours (stock length or +.070")?
- What springs are you using?
- What rockers are you using (stock or other) ?
- Did you verify your rocker-wipe on the valve, and did you shim your rocker?
- What Pushrod length is being used? (state how much your heads are milled and/or if thinner head-gasket, and BC of cam)
- Did you verify the PR length for proper preload?
- What preload are you using?
TIA !
- What valves are installed on yours (stock length or +.070")?
- What springs are you using?
- What rockers are you using (stock or other) ?
- Did you verify your rocker-wipe on the valve, and did you shim your rocker?
- What Pushrod length is being used? (state how much your heads are milled and/or if thinner head-gasket, and BC of cam)
- Did you verify the PR length for proper preload?
- What preload are you using?
TIA !
04-25-2006 | 07:42 AM
#2
* I think I do have the longer valves
* Comp 977s
* Yella Terras
* not shimmed and are right on
* 7.35 pushrods. Heads are milled to get a 58cc chamber with 5.3s (I think .030). Felpro head gaskets
* Yes, comp pushrod checker
* .010 with Comp "R"s. Works perfect to 7k.
Im about to sell mine for anyone reading this thread
* Comp 977s
* Yella Terras
* not shimmed and are right on
* 7.35 pushrods. Heads are milled to get a 58cc chamber with 5.3s (I think .030). Felpro head gaskets
* Yes, comp pushrod checker
* .010 with Comp "R"s. Works perfect to 7k.
Im about to sell mine for anyone reading this thread
04-25-2006 | 06:40 PM
#5
- What valves are installed on yours (stock length or +.070")?
Longer valves, I did measure but don't remember exactly how much longer they were but .070 sounds like the right ballpark. We also measured where the valves sit in the 5.3 head relative to the 5.7 and it sat lower. Overall on my heads I measured a .050 difference
- What springs are you using?
Patriot Gold Duals
- What rockers are you using (stock or other) ?
Stock with Harland Sharp Bearing Mod
- Did you verify your rocker-wipe on the valve, and did you shim your rocker?
No. No.
- What Pushrod length is being used? (state how much your heads are milled and/or if thinner head-gasket, and BC of cam)
7.375 Aftermarket cam base circle (.0485), .013 thinner gasket, .003 mill cleanup
- Did you verify the PR length for proper preload?
No because math says it should be pretty close to stock and I'm still using stock lifters.
- What preload are you using?
Roughly stock, within tolerance.
Here's a thread I made when configuring my setup regarding PR length, it may be helpful for you. https://ls1tech.com/forums/generation-iii-internal-engine/442905-check-my-math.html
I probably should've verified my setup with a PR checker and verified preload but I spent 2 weeks doing and checking the math. Considering that most people use 7.4's or 7.35's (.050 variance) without problems I figured my math was well within tolerance. Also measure some of your stock pushrods to get and idea of their actual length. There seems to be a disparity on the actual length of stockers but at least this way you know how much your actual setup is changing. Good luck.
Longer valves, I did measure but don't remember exactly how much longer they were but .070 sounds like the right ballpark. We also measured where the valves sit in the 5.3 head relative to the 5.7 and it sat lower. Overall on my heads I measured a .050 difference
- What springs are you using?
Patriot Gold Duals
- What rockers are you using (stock or other) ?
Stock with Harland Sharp Bearing Mod
- Did you verify your rocker-wipe on the valve, and did you shim your rocker?
No. No.
- What Pushrod length is being used? (state how much your heads are milled and/or if thinner head-gasket, and BC of cam)
7.375 Aftermarket cam base circle (.0485), .013 thinner gasket, .003 mill cleanup
- Did you verify the PR length for proper preload?
No because math says it should be pretty close to stock and I'm still using stock lifters.
- What preload are you using?
Roughly stock, within tolerance.
Here's a thread I made when configuring my setup regarding PR length, it may be helpful for you. https://ls1tech.com/forums/generation-iii-internal-engine/442905-check-my-math.html
I probably should've verified my setup with a PR checker and verified preload but I spent 2 weeks doing and checking the math. Considering that most people use 7.4's or 7.35's (.050 variance) without problems I figured my math was well within tolerance. Also measure some of your stock pushrods to get and idea of their actual length. There seems to be a disparity on the actual length of stockers but at least this way you know how much your actual setup is changing. Good luck.
04-25-2006 | 08:11 PM
#6
My90Iroc -
Looks like you did pretty good on your calcs; the only thing you neglected/forgot was the effect of the 1.7 ratio rocker on the .050" valve height. The .050" valve height only equates to a .029" effect at the pushrod.
Your measurements of the valve height was exactly what I was looking for - been calculating my #s for the last 3-4 weeks, each time I revisit them I come up with better precision and/or a shift in the nominal due to something such as this.
Looks like you did pretty good on your calcs; the only thing you neglected/forgot was the effect of the 1.7 ratio rocker on the .050" valve height. The .050" valve height only equates to a .029" effect at the pushrod.
Your measurements of the valve height was exactly what I was looking for - been calculating my #s for the last 3-4 weeks, each time I revisit them I come up with better precision and/or a shift in the nominal due to something such as this.