SBJD valve train problems May 30, 2010 02:18AM
I have a SBJD in a hot farm class, 640, 2.75 x 3.0 slotted charger, 3000 rpm, P pump,water no cooler. runs pretty good but have broken rocker arm assembly hold down bolts (billet hold downs ) several times, one time idling in the yard ( 7/16 x 2" grade 8 ) . This winter we drilled and tapped the holes to 1/2" used 1/2 x 3 1/2 hard set screws and thought we had it solved. Thursday night our association tech guys checked cubes by filled number 6 cylinder with fuel/oil mix. We sucked out the fluid and cranked it over a few times before reinstalling the injector. When I started it up the next day, it started quicker than usual and immediately started to miss. Drove it outside and it got worse. Pulled the valve cover and hold down studs 2, 3, and 4 were broken off and also broke the thread casting on number 5. 6 seemed ok. Would hydraulic lock on number 6 haved caused all that damage? We got it going that day and it ran fine at the pull that night. Any ideas? One more thing the three times it broke last year was always number 6. TIA
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Re: SBJD valve train problems May 30, 2010 02:34AM
whats your email might be able to point you in a good direction
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Re: SBJD valve train problems May 30, 2010 06:14AM
Is the rocker arm assembly the same every time. You have not changed shafts or anything?
Sounds like the shaft could be bent, or you need the extra hold downs?
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Re: SBJD valve train problems May 30, 2010 06:50AM
After the first time when the rocker arm shaft broke we went to a tool steel shaft and over head oiling. I don't think that the shaft is bent. It's amazing what that shaft has withstood.

gemocc@gmail.com
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Re: SBJD valve train problems May 30, 2010 07:15AM
Allen set srew bolts hard and brittle. Try using 12pt hardened bolts from Mcmaster-carr, there like a grade 12. Also check for coil bind on your valve springs. Make sure you have clearance between the coils when valves are completely open. Also are you sure the valves are not hitting the pistons because of cam lift? Hope this helps.
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Re: SBJD valve train problems May 30, 2010 07:51AM
your problem is very common. Put hold downs on the ends that are held down by the end head bolts. Kinda like a little L shaped bracket. Goes under the head bolt and around the shaft.
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Re: SBJD valve train problems May 30, 2010 07:52AM
Also, dont use the aluminum hold downs. You have to use the steel ones. Cut the bars off them to make them look just like the aluminum ones.
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Re: SBJD valve train problems May 30, 2010 08:55AM
We had that same problem with our Deere. The brackets on the end to hold down the shaft did eliminate the problem. This year we have a new rocker shaft hold down system from Brad Grey(Grey Billet Products-found in builder's links) It is absolutely awesome. I would give Brad a call and get his hold down system. The assembly holds down the shaft at every possible point and also will keep the rocker arms in perfect alignment, even when installing the rockers and shaft. It is a great product. Although you may need the tall plastic valve cover, I am not sure it fits under the stock valve cover. BTW the plastic cover is better anyway because it utilizes a o-ring instead of that stupid cork gasket. Good Luck!
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Re: SBJD valve train problems May 30, 2010 12:37PM
Yes Brads roller rocker setup is RIGHT ON!! and the only way to go! Thumbs Up
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Re: SBJD valve train problems January 02, 2021 09:47AM
Do you have a picture of that L shape braket ?
Thanks
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