valves not sealling

[govproperty]

Ok my enigine been running really rough. I checked bas timing, cam timing, boost leaks, spark plug gap, and checked my global with dsmlink. I had to go negative on the airflow just to get the car to run better. I have a small boost leak at the throttle body but it bleeds down very slowly. I asked the local ford guy for advice and he took a dollar bill out. Then he held it to the exhaust and the car would pull on the bill like trying to suck it in. He said I had a valve sealing problem. I had put the motor back together about 1000 miles ago. This was the first time I ever lapped valves. Does air sucking in the exhaust and poping from somewhere in the engine bay verify that the head is almost done? I almost forgot my vac was at 15 @ 1000 rpms but now it drops to 10 @ 700 rpms.

thanks

 

[kenamond]

How's compression?

 

[silver bullit]

If the motor has been rebuilt fresh the valves may not have seated yet.

Also do a boost leak test and compression test.

 

[->PrOjEcTGS<-]

Yea check the compression. See what you get. Also check your timing belt make sure all the pulleys line up properly. That causes low vacuum.

 

[govproperty]

The compression is 130 146 141 146 if I remember correctly. I did it about a week ago. The last boost leak check I did only found 1 small one at the throttle body it still held 15 psi for atleast 10min. I will do another boost leak check when I get off work today. I will also check cam timing again. But it was still at 15in @ 1200 before it started poping at idle. Oil pressure was 30psi at idle and 90 psi when I reved it up. I will recheck everything. I hope it is only cam timing.

 

[kenamond]

The compression is 130 146 141 146 if I remember correctly. I did it about a week ago. The last boost leak check I did only found 1 small one at the throttle body it still held 15 psi for atleast 10min. I will do another boost leak check when I get off work today. I will also check cam timing again. But it was still at 15in @ 1200 before it started poping at idle. Oil pressure was 30psi at idle and 90 psi when I reved it up. I will recheck everything. I hope it is only cam timing.

Looks like you have a problem with #1. Each cylinder is still in spec by itself, but they shouldn't differ by more than 14psi. Might want to wet test and see if it's rings. Also might want to check out the link below.
http://www.geocities.com/dsmgrrrl/FAQs/compression.htm

 

[govproperty]

I'll pull it in to the garage but won't be able to do the test until thursday. Thanks for the help. I will let you know what happens.

 

[govproperty]

I resealed the valve cover yesterday and I saw when I had prevously bent my valves the cams had got scored up but only on the cylinder closet to the trans. The scratches don't feel like they are very deep or stick out but I do only have 1 low cylinder and poping out of 1 cylinder. I did find the same boost leak as before. I know it is somewhere around the throttle body I just rebuilt but I don't think it is leaking from one of the seals. I am going to just buy a 75mm throttle body so instead of bj's smim-adapter-tb-tb elbow I will just have bj's smim-tb. The only problem with that is I don't know what bj's smim are flanged for.

 

[kenamond]

Just a note. I assumed that you listed your compression from #1 through #4. This would be from the front of the motor (timing belt end) to the back of the motor (flywheel end). So #1 is on the driver's side. Was the first compression number the #4 cylinder? That would make sense if you bent the #4 valve and had low compression on that cylinder.

Do you plan on upgrading anything while you deal with this? I always consider the price of labor and stock parts vs. upgraded parts anytime something goes wrong. If the part cost isn't much different, the total cost will probably be small enough to consider the upgrade. Just a thought.

 

[govproperty]

I wrote the compression order backwards. whoops. But I made some progress on it. I searched all over the forum for the same thing. Turns out 2g's with 6 bolt swaps have a problem with missing, so I did what they do and checked my cas for 180 out. I went magnus website where they had pics of the correct position and followed that. My car runs alot smoother and clearly shows signs of a boost leak. It still pops a little though. I going to fix the leak and tune. I think I will be good then. Thanks for taking the time to help me out. Also, does any body know what year mustang throttle body the BJ smim were flanged for?