 Performance Isky Cam, establishing valve lash setting |
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| Joseph Mills |
 Aug 25 2004, 01:26 PM
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#1
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on a Sonoma diet now...  Group: Members Posts: 1,482 Joined: 29-December 02 From: Oklahoma City, OK Member No.: 39  |
Why do "performance" cams with greater lift/duration specify greater valve lash? Is it a performance gain, or durability, longevity gain?
I just recently received the cam specs for my engine from the PO. It shows valve clearance should be set at: .013N .015X This just seems really loose! Is this for very high rpm? The engine is a 75 2.0 with 44IDF's, Euro P/C's, Mallory dizzy & CD, and has Iskendarian cam, lifters, pushrods & springs. I just recently had some headwork done and replaced the valves. Should I use the above specs instead of .006/.008? (IMG:style_emoticons/default/confused24.gif) |
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Replies(1 - 8)
| SLITS |
Aug 25 2004, 02:03 PM
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#2
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"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None  |
1. Since you are producing more heat, the expansion of components is greater.
2. Since the opening and closing ramps, lift, etc are more severe, the lash is opened up. 3. Yes, it is normal - On our full-race cams we were setting 0.018 +/- 0.002 |
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| Joseph Mills |
Aug 25 2004, 02:17 PM
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#3
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on a Sonoma diet now... Group: Members Posts: 1,482 Joined: 29-December 02 From: Oklahoma City, OK Member No.: 39 |
So I presume the valves will be VERY noisy when cold, but subside somewhat once they become warm?
Should I plan on adjusting the valves more frequently than 3k? (IMG:style_emoticons/default/rolleyes.gif) Any other considerations? |
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| SLITS |
Aug 25 2004, 03:38 PM
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#4
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"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None |
They are gonna make more noise. Adjustment intervals will be trial and error - you might start by checking them at 1000 mile intervals and see how they hold adjustment.
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| Joseph Mills |
Aug 25 2004, 04:22 PM
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#5
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on a Sonoma diet now... Group: Members Posts: 1,482 Joined: 29-December 02 From: Oklahoma City, OK Member No.: 39 |
Thanks Ron.
I'm doing them now. |
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| Jake Raby |
Aug 25 2004, 07:52 PM
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#6
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
That lash is way too much!
What material are your pushrods made of?? Are they steel or aluminum? If they are stock, or aluminum set those valves to .006 on the intake and exhaust when cold. If they are steel set them to ZERO LASH when cold!! Isky must be high giving settings like that! Thats insane! As the engine heats up steel pushrods stay the same length and the engine grows around them creating lash- more than enough lash. BTW, valves should only need to be set every 6K miles, not every 3K. Only hot running engines need the valves set that often |
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| seanery |
Aug 25 2004, 07:58 PM
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#7
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waiting to rebuild whitey! Group: Retired Admin Posts: 15,852 Joined: 7-January 03 From: Indy Member No.: 100 Region Association: None |
I thought you were fishing!
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| Jake Raby |
Aug 25 2004, 08:10 PM
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#8
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
I'm leaving in the mornin'......
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| Joseph Mills |
Aug 25 2004, 09:01 PM
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#9
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on a Sonoma diet now... Group: Members Posts: 1,482 Joined: 29-December 02 From: Oklahoma City, OK Member No.: 39 |
QUOTE(Jake Raby @ Aug 25 2004, 07:52 PM) That lash is way too much! What material are your pushrods made of?? Are they steel or aluminum? If they are steel set them to ZERO LASH when cold!! Isky must be high giving settings like that! Thats insane! Thanks for your viewpoint Jake. They "looked" like steel when they were out (very smooth bright chrome looking ends - but very light. I should have put a magnet on them. The cam, lifters, pushrods & springs are Isky. It seems like a radical setting to me - I set them and they are REALLY loud, even when the engine warmed up. Just for clarification, I will get the catalogue that gives those specs, scan it and post it here. Maybe something can be learned from this. Any other opinions? |
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