Need Help - Stalling Problem

[badandy]

Hello All,

I have a '69 lemans I inherited from my dad. It ran OK the first year I had it, but since then the engine will stall if the engine speed drops below 1000rpm. It even does this when idling in park. I'm getting real frustrated and any help would be greatly appreciated.

It is a V8 400cid.
So far, I just finished rebuilding the carb with no success. It has an electric fuel pump that is working well and has a clear filter. The spark plugs do not appear to be fowled & I gapped them. It has what appears to be fairly new plug wires and boots. It has a Accel distributor that appears to be vacuum advance.

Someone installed a vacuum guage in the intake manifold. I've noticed if I crack the throttle when it is in park, it will hesitate and the guage will drop all the way to zero and then stall.

One oddity is that it has a Carter AFB 9637 on it, which doesn't appear to be stock. It is sitting on top of an adapter plate mounted to the manifold. The bores on the carb are *considerably* smaller than those on the manifold.

I have yet to check for compression on the cylinders as I don't have an extra pair of hands handy to crank it. I'm also a little fuzzy on how to correctly check for vacuum leaks. I haven't checked the timing since I can't keep it running long enough to do so.

Does this still sound like it could be a carb issue - or maybe someone overcammed it?

Thanks for your infinite wells of knowledge!

 

[Darron]

And easy way to check for vacume leaks is to spray hair spray or some other type of flamable spray around your key spots all vac lines ,intake where it meets the heads and carb, if it is a vac leak you will know when you hit it because the rpms will go up.It sounds like if its a vac leak it is big to make the car run so bad at under 1000 rpm so it will be easy to find,dont for get the tranny vac line if it has one.
If thats not it try checking the vac advance weights on the dist.you might have a broken spring or something.
Or your right it could have a 500+ lift on the cam and then you will have to mess with the timming and carb tell you get a mid point.All the after market cams I have put in on old cars have had to be tuned by ear and road test . By tightening the dist.just enough to turn by hand and takeing the car to a place to test it. And turn it, try it, turn it and try it .......its a pain but after a while you can dial it in.
I hope you find this helpful, I know how embarrising it is to be out crusing and have your ride sputter.
best wishes Darron