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Launching!
Joined: May 2012
Posts: 232
Likes: 0
From: Mayfield, KY
I have the same LE cam in my z28. Lloyd recommended me Lunati dual valve springs for the cam so that's what I'm running with 1.6rr's. Still haven't fired the engine yet but hopefully will this week once I get new pushrods in. Do you happen to have any videos of the car idling with that cam? I can't find anyone running it
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
You could also do 2 .060" and 1 .030".....
1.9" installed height seems high. If that is accurate I could see you having the issues you are having. That would put you at about 87lbs on the seat vs 144lbs on the seat at 1.750".
If you shoot for a 1.750" (2-0.060" shims) installed height, your seat pressure should be 143.6lbs (65% increase) and your open pressure should be 358lbs (versus your current 302lbs). And you'll have 0.072" clearance from coil bind.
1.9" installed height seems high. If that is accurate I could see you having the issues you are having. That would put you at about 87lbs on the seat vs 144lbs on the seat at 1.750".
If you shoot for a 1.750" (2-0.060" shims) installed height, your seat pressure should be 143.6lbs (65% increase) and your open pressure should be 358lbs (versus your current 302lbs). And you'll have 0.072" clearance from coil bind.
TECH Fanatic
Joined: Jun 2007
Posts: 1,255
Likes: 11
From: centerville, ohio
Well I am updating this thread again. I'm pretty sure I found my high rpm power loss problem. Lloyd Elliot recomended to me an installed height of 1.740-1.760". I just measured my installed height at 1.900". Lloyd mentioned that even at 1.800" you can get valve float. I'm VERY happy I found out what the problem is! I should have measured the installed height originally but I just never did. No idea why.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
I have the same LE cam in my z28. Lloyd recommended me Lunati dual valve springs for the cam so that's what I'm running with 1.6rr's. Still haven't fired the engine yet but hopefully will this week once I get new pushrods in. Do you happen to have any videos of the car idling with that cam? I can't find anyone running it
TECH Addict
Joined: Dec 2010
Posts: 2,610
Likes: 4
From: Maricopa, AZ
Not sure, I haven't used shims before. I'd put them where they'd fit best. And I meant 2-.060" and 1-.030" shim from the measured 1.9".
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
How did you measure the installed height ? I don't think a 1.9 can be achieved without longer valves and cut spring pockets, recheck that. The 26918 spring setup at 1.740 won't handle .580 lift. Marginal maybe. Although the newer redesigned springs are rated for .625 lift.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
I held the valve up with air and then took the spring retainer and locks off. Put the micrometer in then put the retainer back on and the locks back in and opened up the micrometer until it took up all the slack.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
I just looked up the tool I bought and it states for most 4 and 6 cylinder engines. (Did not see that when I ordered it) But it looks exactly the same as the "Fits most V8 engines" model. The only difference being how far it actually opens up. The one I have is 1.4" to 1.8" and the "V8" one is 1.6" to 2.1" I can't imagine that makes all the difference.....
http://www.proformparts.com/product-...ategory_id/170
http://www.proformparts.com/product-...ategory_id/170
I have seen that some are beehive specific. I wonder if that is an issue... Why would they make them different though? Then a normal valve spring height micrometer won't work properly... makes for more confusion if you ask me.....
http://www.proformparts.com/product-...ategory_id/170
http://www.proformparts.com/product-...ategory_id/170
I have seen that some are beehive specific. I wonder if that is an issue... Why would they make them different though? Then a normal valve spring height micrometer won't work properly... makes for more confusion if you ask me.....
Last edited by v8vette84; Sep 7, 2014 at 07:40 PM.
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1.74-1.76 is still within the 1.4-1.8 checker you have, you don't need the v8 one. You'd only need the v8 one if your install height requirement was over 1.8. It sounds like the issue you were having like hrc said was too large install height causing too little pressure causing valve float at high rpms. If at 1.74 you have too much lift and will bind your 918s are not going to work, but you need to check coil bind on the 918s at your lift with your rocker ratio. I still would suggest a dual springs that's not so close to being maxed out, but if you can shim the 918s to 1.75 height and you find that you still won't bind, it should be fine. Just start shimming. Don't buy another tool.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
Ok will do, thanks! TO check for coil bind all I have to do it turn it over and see if the spring hits itself or the valve guide? Or is there another way I have to do it? How much clearance do I need between the coils to compensate for when they heat up?
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
I have the same LE cam in my z28. Lloyd recommended me Lunati dual valve springs for the cam so that's what I'm running with 1.6rr's. Still haven't fired the engine yet but hopefully will this week once I get new pushrods in. Do you happen to have any videos of the car idling with that cam? I can't find anyone running it
Here are 2 videos I took of the exhaust. In the daylight is without cats, the night time video is with cats. Not the greatest quality but you can kinda hear the idle.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
Does this matter? I just realized I never installed the suggested locators. There are locators on there now but I have no idea id they are correct or not. Does it matter at this point?
These are the suggested locators from Comp.
http://www.summitracing.com/parts/cca-4705-16
Here are the locators I have been using...
Picture of the head without the locator.
With locator.
P.S. yes I know the valve seal is missing, I took it off to get the locator off.
These are the suggested locators from Comp.
http://www.summitracing.com/parts/cca-4705-16
Here are the locators I have been using...
Picture of the head without the locator.
With locator.
P.S. yes I know the valve seal is missing, I took it off to get the locator off.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
I'm sure sure if it really matters which ones but I was just going to shim it.... I mean I already know how far off I am. If I get different locators that do the same thing then I'll just get a different height and have to buy different shims. At least that's what I think anyways.
TECH Fanatic
Joined: Jun 2007
Posts: 1,255
Likes: 11
From: centerville, ohio
I saw that when I went back through the post. You said you bought the heads used and installed the 918's yourself. What springs were on the heads before, and what retainer combo and spring cup did you use for the 918 install ?
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY