Need a mechanic for for U20 in Pacific Northwest

[Datrock]

How good does the bolt hole in the front of the cylinder head line up with the upper chain guide's hole. From what I have seen, when a U20 head is machined on the bottom the two do not line up as they should or would if the head was not cut. Sometimes after head work you may see an oval shaped hole in the guide to get the bolt to thread into the head. Just a rough way to tell if there has been allot taken off, sure .005" would be hard to see but .065" would not...Bill

[311tony423]

Interesting, I'll look into that.

[311tony423]

Once again, I find myself outwitted by my U20. Early this year I took it out and there was a feel like the timing was off. It stutters while driving or just revved up. I messed with the elec distributor quite a bit. Then took the drive gear out and rotated it a tooth back and forth. It got to where I forgot what orientation I started with and put it back according to the book and nothing.

I got fed up and took it to a pro mechanic shop in town. Yea, they got it running again. I have the same problem I started with. Everything I can think of checks out.

Any U-20 pros in the Pacific NW out there willing to take a look? I can trailer it to you.

Thanks.

[unklpat]

Tony, take a pic from the back side of the cam gear, with crank at TDC{big mark). there is an arrow on the 1st cam tower that normally lines up with the hole in the cam gear. I've just gone thru this with mine, after figuring out what shims to get, by seeing how much the cam was retarded, degree wise. I also purchased thicker lash pads to correct the geometry. I first used .032" over, then switched to .040" over. Cam timing was corrected, as well as slop in timing chain. This is not a substitute for replacing the timing chain, but you said yours only has 10k on it,not enough to wear that much. Another pic would be looking down at the tensioner, after running the motor and shutting it off. This only confirms chain stretch, or head milling, which causes the tensioner to not be able to take up the slack. Take those pics, the job is easy, as Greg said, and then you can do his easy cold valve adjustment after. I am in kirkland, and am always looking for a drive, if you want help with diagnosis. Pat

[311tony423]

Hi Pat,

Timing chain rattle aside, My current issue with a rough surging has been resolved. I took the vacuum line off the intake manifold and it runs perfectly. I'm thinking that the elec distributor needs to be disconnected from the vacuum line. It is now running perfectly. I really appreciate your offer. The rattle isn't too bad (I think).

Back to daily driving.... .

[Gregs672000]

Where was it drawing vacuum from, the barb on the carb? I wonder if the vacuum advance canister is leaking, making timing a bit erratic. Had that happen many years ago on my Mitsu Starion, which really messed with a turbocharged engine!

You want vacuum advance on a street car. I think the only reason the Solex versions didn't have it was the carbs themselves didn't have a vacumm port, and they were meant more for racing. Vacuum advance will help with fuel economy by adjusting timing to engine load so you burn the fuel better at light load/cruising, and pull out a few degrees of timing under load. It will run fine without it, but you lose the benefits.

[311tony423]

Hey, Huge thanks for Art, Dan, Dave Greg and Pat for helping in a HUGE way. I really appreciate it.