runnin a rather big crane SOLID camshaft.....constantly running valves. They will not stay adjusted, loosen up after a few runs on motor. Am I missing something here. I do have roller tip rockers with polylocks but they just wont stay in adjustment. Any suggestions ? ? The studs are not pulling out changed them to screw in with noiling through pushrods. 389 pontiac 63 heads. thanks in advance for your input...Mr Haney
I had this problem on a racing SBC one time. I'm going to assume that you're getting the poly locks good and tight, so the elementary stuff is out of the way. In my case, I was running a radical cam and a set of Harland Sharp rockers. When mine kept coming out of adjustment, the people at Harland Sharp told me that the studs themselves might be flexing and allowing the locks to loosen. I installed a stud girdle, and the problem went away.
take a look at the ends of your rocker arm studs , if they are not perfectly flat and square the center set screw doesn't get the proper grip on them. i use to machine them flat on the sbc's i raced with and it seamed to make a difference
thanks for the input. my factory pontiac heaqds seem to have a stud girdle kinda cast into heads from factory, pretty cool inovation from pontiac. The studs from what i remember were machined flat. Will check out that venue closer. Never heard of locktight method but phone call to crane dont hurt. Must add that keeping the rpm's down under 6K is a bit of a challenge .....gotta work on that.....got stock 63 rods......ran out of money. thanks......Mr Haney
Hello, Are you tightening both the lock and nut together for the last 1/8-1/4 turn? On most engines I have worked on this is the only way I have been able to keep them from loosening up. I have been informed that there is no way just using the small lock will hold on some engines. This will suck on a solid cam. Another tip I got was to set your hot lash on one cylinder and re-measure when the engine is cold. Now you can set the rest cold. Hope it helps
NO....is my answer to your question. I was simply bringing adjustment up to spec, then locking the allen head set screw down. Hey, that makes sense to me, never thought . I like the cold adjust method you mentioned but is that kosher ? ? My studs were faced off at machine shop so they dead flat [ earlier suggestion ] thanks for the tips....well understood Mr Haney
Try locking both together for an 1/8th turn, see if that helps. If it is a different cylinder all the time it should fix it. If its the same or only a couple make sure you don't have a lobe going away. Yes the cold lash bit also works, I stay away from using a number because different setups change differently. I record this setting (cold lash) on tear down of engines I work on so it could be re-set for initial start up. It works well for a couple of 650hp bb chevys with a solid rollers I work on. Try it, you may be suprised how little it moves.
NO not the L-word they do vary fortunatly....Great advise will give it a try. When i say this thing wont stay adjusted, I am talking every 150 miles of moderate abuse , they will require adjustment. Funny that diesel engines with solid cams [ cat] ncan go 60K before adjustment required ! Best Mr Haney
I don't know if you can get a stud girdle for a Pontiac, but if so... This will solve your problem. We have run them on everyting from full race engines to hot street stuff. The girdle will stop all that movement that is causing your poly locks to come loose. The poly lock is only as good as the set screw. When the rocker stud deflects, the set screw looses its grip on top of the stud. The girdle not only stops the deflection, but has a firm grip on the outside of the poly lock to keep it from backing off. You will have to buy a poly lock made for a stud girdle, they are taller to allow them to come up through the girdle. The only draw back to all of this is that your valve covers will not be tall enough to clear the stud girdle and tall poly locks. Hope this helps. Later, Kevin Ooltewah Speed Shop
Kevin , My friend at Obsolete Engineering can make me up a VC spacer no problem. I hate having to wear a girdle......whats next a bra ? ? Just kiddin ! tech info understood and appreciated. Pitts64.... gotta work on mrs douglas house before buying any more speed equipment ......Hot Dammn ! Good though !
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