I had my 250 started - can't get it running today
 

I finally got everything back together on my '72 250 and I had it running yesterday. Hard to start and a lot of carb backfire, but once I got it running and good and warm it ran fine. Tried to make some adjustments and I think I made things worse because today I couldn't keep it running.

Yesterday, I had some carb sync problems and I had fuel dripping from the rear carb at idle - tried to make the necessary adjustments, but now I'm stuck. Double checked my Crane and it seems fine and I have fiddled with the timing all afternoon to try and get it running. I did get it started a couple of times today, but serious carb backfire - were talking some flames here! And I couldn't get it to idle. I'm not a Zenith novice as I have fine tuned these things several times over the years. I just can't get it started this time. I'm sure redoing all of the engine stuff, new timing chain, a valve job etc. has affected everything and I'm almost certain the chokes are messed up, the timing is probably off (although I did check it and it seemed fine) and the carbs are seriously out of sync - I guess I just don't for sure where to start - especially if I can't get it running.

Any advice?

ryan

And you did chain and valves yerself? No mean feat, sure caint be easy. Pulled cyl heads but never done timing chain myself. Sorry i dont have shop manual to double check but could be TDC for camshaft at stantion with distributor mark on rim with rotor lining up = equals x degrees *retarded* on chrankshaft pulley and not the zero mark.

Double check your spark order. The only time I get "big flames" is when I have a wire crossed.

I didn't do the valves myself but I did change out the timing chain and all of the gears. I have everything timed - dead on. Checked it a dozen times. As far as the wires go, it ran well yesterday - once I got it started. I just can't get it to fire today. I have checked that I'm getting fuel to the carbs, which I am and I have spark. That only leaves a timing issue and something with the carbs - right?

ryan

Backfiring if the plug wires are on correctly can only mean that your timing has slipped. I would Check your distributor to see if it is loose and wandering.

Tom W

I finally got it started today - primarily by adjusting the timing. I think I have figured out a few things in the process. I couldn't keep the car idling so with my wife's help I was able to check and adjust the timing while she kept the car idling. I also discovered that I have massivie vacuum leaks around both carbs - I bet every single gasket leaked as I sprayed carb cleaner around both the front and rear zeniths.

I reused my old gaskets - I'm talking about the thick (phenolic?) ones around the carb base and the ones between the throttle valve housing and the float housing. The old ones looked fine and while I have new ones for the throttle body to float housing sections, I reused the old ones becaused they looked like better quality gaskets. I guess that was a mistake. I do not have the mounting gaskets - they do not come with the normal rebuild kits. In looking at them, I just can't see why - or where they are leaking.

Anyone know where I can get the mounting plate gaskets - besides the dealer?

And, is there another reason for these leaks or is it just a matter of practice to replace these gaskets?

And, would this explain my problems in getting this thing started and idling?

Ryan