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Old 11-18-2006, 04:05 PM
metalman
 
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pushrod length?

Hi Lads, I have a rattle in my top end of my 351 Cleveland that I am sure is due to incorrect push-rod length. I was hoping someone more experianced than myself could help me confim or correct me on this. I have put in a new cam and lifters and after a 100 miles or so i have a rattle. The push-rod length I have is 8.425' I have non adjustable yella terra roller rockers and a hydraulic camshaft with specs of 224\234 dur@50 thou with 0.536int. 0.562exh. lift. it has new lifters and was run in correctly. I originally thought that it was from to shorter push-rod, but from what i have been reading, they seem to long. Any input would be greatly appreciated.

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Old 11-18-2006, 11:43 PM
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Are those rockers adjustable? How did you set lifter preload?

What brand cam is that? I will be building a 351C with Aussie 302C 2V heads and I like the specs on that cam. What is the LSA?


Steve
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Old 11-20-2006, 03:16 AM
metalman
 
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it is a cam dynamics cam. they are non-adjustable roller-rockers. I too have 302 heads on a 351.
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Old 11-20-2006, 06:46 AM
aka Duke of URL
 
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Quote:
Originally Posted by metalamn

I have a rattle in my top end of my 351 Cleveland that I am sure is due to incorrect push-rod length. I have put in a new cam and lifters and after a 100 miles or so i have a rattle.

I have non adjustable roller rockers it has new lifters and was run in correctly. I originally thought that it was from to shorter push-rod, but from what i have been reading, they seem to long.
Usually, lifter clatter is from too short of a rod (or low oil pressure/delivery). If it was too long, it may not allow the valve to fully seat (lifters will pump up) and lead to rough idle.

The only way to ascertain correct rod length on the non-ajustable setup is by collapsing the lifter (special service tool) (MOROSO offers one for aluminum rollers) and measuring air gap between the rocker arm and valve stem tip. You then insert the correct length rod (s) to arrive at proper pre-load. You must also verify correct valvetrain geometry at this point.
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Old 11-20-2006, 12:35 PM
metalman
 
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Thank you for that, Any chance you could tell me what the air gap shoud be?
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Old 11-20-2006, 11:34 PM
aka Duke of URL
 
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Quote:
Originally Posted by metalamn

Any chance you could tell me what the air gap shoud be?
OEM specs are;

ALLOWABLE 0.100"- 0.200"

DESIRED 0.100"- 0.150"

COMPETITION CAMS has excellent tech material(s) (online) regarding finding correct pushrod length and proper geometry.
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Old 11-21-2006, 12:30 AM
metalman
 
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Thank you very much for your help, I will get a hold of the lifter collapsing tool and measure the gap and go from there.
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