The intake valves are quite a bit bigger than the exhaust, are they not? I have to think it would be pretty obvious if they were reversed, right? As in leaving a decent sized gap?

 

Yes they are different sized. You'd be surprised what people do when building cars.

 

or machining the head but not the valve stems?

 

I wish I would've never taken a part the the head but nothing stood out when I put the head back together. It's my first build though so maybe I did something stupid. There was no machine work done to the block. The shop only hot tanked it and that was it.

 

if they did any resurfacing of the head, they should have taken the same amount from the valve stems, otherwise they wouldn't be able to full close.
this only comes to mind because we just had a set of heads on a 407 where the machine shop forgot to do that for one of the cylinders. car ran like crap and we couldn't figure out why.
weird thing was: it had good compression. anyway... since we're kinda shooting in the dark, i just thought i'd put it out there. it could happen i suppose.

i've been asking around but we're all pretty stumped. good luck, man.

 

try this real quick. most compression gauges allow you to remove the gauge and plug it right into your compressor hose. i would start by pressurizing the cylinder. see where the air goes. intake, exhaust or case. then pull the cams and see if it changes. i had an timing belt jump and wiped out all of my exhaust valves = zero compression.

 

I appreciate you throwing out the oddball ideas. I would be shocked if that was the case because they were told no machine work was going to be done, and it didn't look like there was.

Obviously I know it's even harder for you guys to diagnose because you aren't here, but I'm sure, because it's my luck, that it's something crazy.

 

I'll have to grab the air compressor from my garage back home to do this, but that sounds like a great idea. I'll try and get it to the garage the evo is now so I can do this and a leakdown test before Friday. If not, I'll just be taking it to Driven Fab.

 

Hmm. This doesn't make any sense to me. Resurfacing the head will have nothing to do with the valves and springs or closing/opening of them. When they are resurfaced they never go inside the combustion area.

 

Either my cam gear timing is somehow way off, or I managed to switch up my valves I would think.

If it's my timing, would going from 1/2 tooth advanced to 1/2 retarded make a big enough difference to give me 0 compression?

If it's my valves, well it's pretty self explanatory how to fix that problem.

 

So basically I don't have enough posts for my own thread, and I haven't found a good thread to ask this question in so I decided just to post it in a somewhat popular thread so maybe it can get moved or something to a better one. Sunday night I was driving and I was driving hard all night on and off around back roads, and while i was going slower, something happened. I think my timing belt may have broke i don't know but the timing belt cover now has a few cracks and holes that it didn't have before this happened. the car shut off and when i try to start it the engine turns over but won't start. Anyone have any idea how serious of damage there may be? I don't know too much about cars, but from trying to read up on similar issues people had, a broken timing belt seems to mess up a lot of other crap internally. Any input would be great, just looking for potential issues i may have after this, possible cost, and any insight. thank you very much.

 

1/2 tooth off won't mess anything up. Even with bent valves you would have some sort of compression.

To the thread jacker. If your timing belt snapped then the valves are most likely destroyed. Depending on the rpm it snapped, the pistons could have been damaged as well. 4g63 are interference motors. Take the timing cover off and look. It isn't that hard...

 

Thread jacker? Ok bro. Anyway thanks for the input, haven't gotten a chance to take off the cover yet, had it towed home at 7am and went to sleep and then had other things to do but I'll be looking today, any guess on cost? Best and worst case scenario?

 

Best case scenario you need new valves (and timing belt, head gasket, maybe get new seals, etc), worst case scenario you have to rebuild the block as well.

 

you are right, i'm sorry. i was posting in more than one thread while at work LOL. i didn't mean resurfacing the head, i was thinking about a valve job. i had resurfacing stuck in my head instead of the other machine work.

I'm gonna get some sleep before I post again LOL