[vsengdara]

Hi,
Is there any possible way to determine pushrod length without a checking tool? Is it possible to determine the pushrod length based on specific modifications? My engine is a 1969 351W with the following modifications:
1. Edelbrock 60229 Performer RPM Heads 60cc Chamber, 170cc Intake Runner,
http://www.summitracing.com/parts/EDL-60229/

2. Comp Cams k35-414-3 Magnum Hydraulic Cam and Lifter Kit
Cam, Lifters, Valvetrain, Hydraulic Flat Tappet, Advertised Duration 270/270, Lift .500/.500
http://www.summitracing.com/search/?keyword=Comp Cams k35-414-3&dds=1

3. Proform rocker arms, 3/8 in. Stud Mount, Full Roller, Aluminum, 1.6 Ratio
http://www.summitracing.com/parts/PRO-66911/

Using the stock pushrods (measuring 8.14 in) caused a set back in my 1969 rebuild. With less than 5 km on the new rebuilt engine, the cam got damaged and one of the pushrods got bent. I also noticed that the guide plates were eating at the stock pushrods. I know one reason why the guide plates are eating at the pushrods is because the stock pushrods aren't hardened steel. But, I think more importantly is that the pushrods are the wrong length.
Do you guys think the stock pushrods are too short or too long?

Are there any members here with the same modificatins that can help me determine pushrod length?

I know getting the pushrod measuring tool is the sure way to go. Unfortunately, getting the tool will set me back another 3-4 weeks since I am in Laos.

Any help would be appreciated. Thanks.
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[1969XR7Vert]

Sure there is, do you have a tap and die set? If yes, take a stock pushrod and cut one end off, leaving some of that end and taking maybe 1/2" out. Then, tap the inside of the two tube pieces for whatever size threaded rod is slightly bigger than the tube ID. Add a piece of threaded rod and a couple of locknuts you have your own, homemade adjustable pushrod.

Hope this helps.

Regards,

Bob

 

[Bad69cat]

Unless you have a machine shop that would let you borrow one - Bob's suggestion is a good homemade way to go. Unfortunately you have found the blunders of not working that crucial step. The reason your guideplates look to be eating into the PR's is that they are flexing due to incorrect length most likely. I think once you get it right you will be in good shape. Good luck

 

[letsroll]

Before you get too attached to those proform rocker arms read this thread especially the comparison of the rockers ....
http://www.mercurycougar.net/forums/showthread.php?55260-roller-rocker-valve-geometry-PITA!

 

[vsengdara]

Thanks Bob... will go to the machine shop tomorrow.

 

[vsengdara]

69Cat,
Would the grinding and flexing of the PR suggest that they are too long?
Thanks.

 

[vsengdara]

letsroll,
thanks for the heads up. i'm wondering... you mention that the ideal PR length was 8.15... would that suggest that the PR length almost has no change from the stock PR. My mechanic measured something like 8.149 for the stock pushrods. or i may be wrong.

 

[Bad69cat]

No - letsroll is pointing out how much difference there is in the thickenes/quality of the rockers! Which did make a difference in the overall geometry. You should take that into consideration....