hello, this may be long and complicated. i have this roller motor from a wrecked car but it was rebuilt and i think the block was shaved. i had some rebuilt heads that may had been shaved too i believe a little. it would not crank without .060 shims under the stock rockers. it ran top notch with them. now i put some thumper heads on the same motor and i new i was probably going to have a problem but not this big of one. i first used .060 and tried it. no crank. then tried .030 and still no crank and all rockers were very tight so i don't think that is it. i had a backfire or 2 sometime but forgot what shims i had when it did. i tried .090 and all rockers were very loose besides the ones that were fully pressed down. i am sure those are not what i need. i think .060 is what i need or maybe a tad bit more. the rockers wiggle around just a hair like i think they should when the valves are closed. the spark is a bright blue, i put the msd box to make sure that was not it. i put the distributor both in the right spot and 180 out and nothing. i barely have any vacuum from the intake. i put some gaskets on the intake that were torqued once but never ran. not sure if i pinched the intake gaskets or not. a ran slightly used gaskets before and had no problems. i am going to throw some new ones on anyway. i am going to also check the compression or do a leakdown test. would i need a shorter pushrod size or something. only got shims for .030-.090 and only in increments of .030 so i don't have any in between sizes like .070 something like that which i think i need. how to i check lifter preload. if i find that out and it is within spec then i know it has nothing to do with the rockers and that it is a sealing problem whether it be a valve or gasket problem. can anybody help me out.
will not start, has little vacuum. rocker shimming maybe
- Thread starter dastang2
- Start date
vikingpower
New Member
I think you should switch to stud-mount roller rockers and custom length pushrods and forget the shimming business, what a pain.
When I set the preload I tighten the nut until the plunger in the hydraulic lifter just starts to collapse (zero lash), then add a 1/4 turn before tightening the set-screw on the rocker.
When I set the preload I tighten the nut until the plunger in the hydraulic lifter just starts to collapse (zero lash), then add a 1/4 turn before tightening the set-screw on the rocker.
ok i know what the problem is, i put a different carb on it too and before i had a gravity feed setup for the fuel for testing and this street avenger carb must have spring loaded jets or something. i squeezed the fuel bottle and it cranked but won't idle just yet. i need to get the fuel pump going soon. it has 150 psi of compression in one of the cylinders with the .060 shims in it. it is fixed
