I need help from someone who has "been there, done that".

I have a misfire that does not "diagnose" nor "datalog" so it has to be mechanical. I was sure I knew where it was coming from, ie: overshimmed hydraulic adjusters but I ran a leakdown today and the worst cylinder is 4% so now I don't know where to look.

When I installed my cams (regrinds), I took a tappet that I had blown all of the oil out of, squished in a vise repeatedly and blown out again, installed it in each hole, checked the roller to lobe clearance and placed the appropriate shim under each to end up with .025" clearance. I was told that .018 - .033 was the range.

As I drove my truck (now has 350 miles) the slight misfire seemed to be getting worse, I can hear it in the exhaust at idle and from the blower (loud) at light throttle and it makes very little power to the point that now it runs like crap.

I was sure I was going to hear substantial leakage when I leaked it but that's not the case.

Any input from somebody who has been through this??

 

Have you done or could you do a Hot cranking compression test ???

Do you have any valve train noise ??

Out of curiosity how much shim did you use?....what was the thinest one?

I know that recently you had some issues with your coil packs.....do you think there could be a problem with them since you made the wiring harness changes ??
Dale

 

I ran a compression test first, 167 low, 173 high.

No valve train noise whatsoever.

I installed a .020 shim under each adjuster.

I'm pretty sure I have the electrical problems cured, that's why I now suspect a mechanical issue.

 

All cylinders within 5~10#'s of each other on the compresion test?

Who's regrinds are they?

You sure you didn't damage any of the lifters when you compressed them?

 

Casey,

All cylinders within 6 lbs.

Cams ground by Dima Elgin, Redwood City CA. He's been grinding cams for the OHC Ford since it was introduced. 90% of his business is OHC stuff, Ferrari V-12, etc. He understands the 4V technology and requirements.

How would I know if I damaged an adjuster? I only compressed two. If damaged, wouldn't they not function properly and give me a valve tick? What I wonder (almost hope) is that they can be over compressed resulting in an erronious reading and therefore overshimming. However, my leakdown numbers indicate that all valves are closing properly, at least when the engine has been sitting for 48 hours. Actually, this is what concerns me. Could the adjusters be "pumping up" when I fire it and holding the valves open? But then, this is why the adjusters get shimmed to be within a certain range, no?

My plan at the moment is to disassemble an adjuster and remove the spring to make checking clearance that much simpler and do it all over again, unless someone comes up with a better idea.

Actually, first thing I am going to do is lift the cab off my truck, there are 32 of these suckers to deal with. Getting the valve covers off was a real excercise, getting them back on without damaging the gasket may be virtually impossible.

 

4V engines seem to have a harder time keeping the rockers on or were they are supposed to sit during a first start up. Will be interesting to here what you fined when you pull the covers.
Dale

 

Mike i have an extra set of coils if you want to try them.

Steve

 

I know your question was about drive train but I had a steady miss at low Rpm's when I built my engine this year. It ended up being the fuel tables and something to do with the big stage 3 crower cams that I had installed. At WOT it would not miss but I also did not stay in long cuz I wasn't sure.

Eric Eldreth from Billet Speed Performance fixed the problem.

God Bless,

Suavy