Breaking rocker arm studs

JohnnyD

New Member
Aug 6, 2022
9
Im in the process today using the comp rod checker and using everyone input on what to check. im confident my next post will be i found the problem using everyone advice. thanks .
 

need-for-speed

Veteran Member
Feb 7, 2003
1,278
Conroe, TX
Did you install new push rods? Sounds like rocker arm geometry problem. They made push rod checkers that look like a plastic rocker arm that you slide on over the stud then check push rod length.
I know how the adjustable length test pushrods work. How do these work ?

pr length chkr.JPG
 

67johnny

Veteran Member
Apr 14, 2016
430
vancouver
Im in the process today using the comp rod checker and using everyone input on what to check. im confident my next post will be i found the problem using everyone advice. thanks .
Just another thought... was asking about the cam specs thinking a high lift cam (over .480) may get into a bind issue requiring the need for a Louis Tool > https://www.summitracing.com/parts/pro-66485
A 1.6 rocker can cause enough of a lift increase to require the use of this tool.
Cam specs ???
 

Cardinal

Veteran Member
Lifetime Gold Member
Jun 22, 2003
8,359
Endicott, NY
I have many questions!

1. Did you degree the cam in?
2. Did you zero the harmonic balancer zero to the zero of the timing tab with the #1 piston at TDC?
3. Did you install a timing tape around the harmonic balancer so that you could them adjust the valves without the engine running at 0 (#1), 90 (#8), 180 (#4), 270 (#3), 0 (#6), 90 (#5), 180 (#7), 270 (#2)?
4. Did you verify valve to piston clearance?
5. Are the rocker arms binding on the rocker arm studs which is caused by the incorrect length of the pushrods?
6. Did you check valve spring coil bind? Ther has to be at least .060" of clearance between any of the coils in a valve spring.
7. How did you set the lifters? Did you do 1/2 turn of preload on all lifters? I highly advise buying one of my Adjust-A-Covers to adjust the valve preload while running the engine. https://nastyz28.com/threads/new-standard-height-adjust-a-covers.318463/#post-3912548

UPDATE 08/10/2022: I just sold one of the standard height Adjust-A-Covers and had the person use PayPal to pay for it! PayPal charged me $11 for one $60 transaction! I therefore will no longer use PayPal! Instead, send me a Postal Money Order or a bank money order.
 
Last edited:

JohnnyD

New Member
Aug 6, 2022
9
intake valve lift 0.414 exhaust 0.428 and im using 1.5 rocker arms
exhaust duration at 050 inch 196 intake 191
 

67johnny

Veteran Member
Apr 14, 2016
430
vancouver
Cardinal has a few good idea's to investigate for sure.
Did see one last year where the new flat top pistons were installed upside down and the valve relief eyebrows were of course in the wrong place! Not a good outcome.
10 degrees after TDC is typically the point where intake valve clearance is smallest and 10 BTDC on the exhaust.
Good info on that here> https://blog.diamondracing.net/checking-piston-to-valve-clearance-the-right-way
Am sure you would have very little issue with a stock cam like yours.
That said... EOIC method with half a turn has always worked for me .
 

JohnnyD

New Member
Aug 6, 2022
9
result of my push rod checker. valve on the left has the checker set at 7.122 and this is what the gm part number # 10241740 as 5/16 7.122 inch long. the valve on right has the push rod that i got from chevrolet performance parts that describes as being 7.122 also but the actual measurment is 7.195 rods measured with digital caliper. the lash was set with top dead center compression stroke on #1 cylinder which is the one in picture and since my lifters were pumped up i made a half turn after zero lash. would you agree the pic on the left is ideal and the one on right is to long. spring coil bind is ruled out i have more than. 060 clearance
 

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ob355

Member
Mar 4, 2022
95
the left looks too long, the mark is more to the bottom of the valve stem. The right i cant even tell by the picture. Did you check them with the full valve spring installed?
 

need-for-speed

Veteran Member
Feb 7, 2003
1,278
Conroe, TX
the left looks too long, the mark is more to the bottom of the valve stem. The right i cant even tell by the picture. Did you check them with the full valve spring installed?
The left looks well centered to me. It maybe just a half an RCH to the bottom. Agree on the right one.
 




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