I've worked on a lot of motors before but this one is giving me fits. Maybe somebody can help.

This car was running pretty good but I was having to use 12v battery to get it to turn quick enough to start. Long story short the 12v fried the points and condenser in the stock dizzy as expected. I didn't really care because I planned on installing a Langdon HEI.

I took the opportunity to convert the car to 12v w/ 1-wire alternator, 12v coil, completely new wiring harness. All electrics are good to go. I also installed a new exhaust system.

I installed the Langdon HEI and a set of 8mm accel plug wires and now the thing is running rough and sounds like it's missing or out of time. Can't get it to smooth out. I figured I may have accidently switched a wire pair so I disconnected them two at a time to see if it would smooth out and nothing happened. Adjusted the carb mix and idle still nothing. Adjusting retard and advance at the distributor... still nothing. Motor is shaking side to side like you would expect to see a motor do that's out of time. I even used the suggested spark plugs. I've never had this much trouble installing a dizzy and I'm not sure what I'm missing. I have double and triple checked the firing order and the plug wire order at the dizzy and just can't seem to work it out.

I dropped Tom an email hoping that he can notice something and tell me what the issue is. But hoping I can get some other suggestions in the meantime since I know he's busy and sometimes takes awhile to get back to emails.

I posted links to videos with sound of the engine before (without exhaust) and the engine after the HEI install (with exhaust). To view and hopefully diagnose.

One thing I do know is that the heat flapper valve is stuck in the shut position. I wouldn't think that it would creat the effect that I am seeing since it was stuck before and ran ok. Any tips on getting it unstuck would be great though.

Thanks.

Before:
http://s18.photobucket.com/albums/b117/hotrodderguy/1951%20Chevy/?action=view¤t=020.flv

After:
http://s18.photobucket.com/albums/b117/h...04-17164746.flv

Get the timing light out and set the idle, and with those 2 things you should have it

Might you have a problem unrelated to the HEI? You have mentioned exhaust/no exhaust... This sounds to me more like a vacuum leak problem.

Installed new vacuum hose when the HEI went in. Carb has been undisturbed since running well only a few days ago. Wasn't able to find any manifold leaks when spraying carb cleaner around it or the carb base.

I'm pretty sure that it's an unrelated issue, just hard to say. Still poking around at it.

Thanks.

got it all sorted out yesterday. Not sure what it was, cause I didn't do anything different. I'm thinking that there must have just been a bad connection somewhere.

The valves do need to be adjusted pretty bad, which may have magnified the issue. But it's running smooth now.

I was also able to open up the flapper valve. Hopefully that will help a bit.

Just an observation, if the heat riser is free now make sure you have the thermostat spring in good shape and installed correctly so it will close off when it warms up. Otherwise you are better off with it stuck in the closed position to prevent over heating the intake. Also, I assume you regapped the sparkplugs for the HEI.

Good luck,

Tim