I recently rebuilt my L35 and she purs like a kitten however I can not get it above 1500 RPMs. I was wondering what the fix is, I beleive I could of put the wrong size shim under the injection pump and was wondering if this could be the cause.
Shims change the timing and it would likely not run well if the timing was out much. Check you throttle linkage and make sure the throttle shaft is moving full range.
Agreed. The shims will delay the engine timing, taking longer for the fuel to reach the pintle tips of the injectors.
You may have dropped a govenor start spring when removing the assembly. Need some more details here! Also check that the fuel rack on the injector pump is not stuck.