HELP..........!!!

The 383 in my 70 Charger came to me in boxes and and I carefully rebuilt it to almost stock with the exception of the intake and headers.

Initially, it started OK but after a few minutes running it simply kept quitting as if the ignition got turned off and was hard to re-start. After checking the 40 year old stock ignition, I decided it had seen better days and replaced it with a nice new Jegs electronic distributor and MSD Street Fire ignition.

Now the motor fires up easily enough but is hard to keep running, and after a very short time running, the headers glow alarmingly hot.
The timing seems in the ballpark and there are no obvious airleaks to cause excessive leanness and hot running.
I set the lifter preload to the required specs (with shims under the stock rocker shafts).
Obviously, something is not right, but I can't figure out what.............and it's starting to give me fits.

Can anyone put me out of my misery and give me an idea what is causing this.........???

 

What carb are you using ??? Have you actually put as timing light on it ???

 

I'm using a new 600 Holley V/S ....which should be more than adequate to run this motor up.
I can't keep it running long enough to put a timing light on the engine but I static timed it to around 8deg btdc.
I realise that the timing won't be exactly correct until I can get a light on it.....but surely it'll be close enough not to have such a dramatic effect if the timing is off a tad.....................

 

Run it at 3500 set the total timing to 35 deg

 

That's what I had in mind, TVLynn...........but as it stands, it's just not safe to run the motor for long enough to do this.
The headers start to glow after less than a minute and get cherry red after not much longer. I really don't like all this fooling about with a new motor like this as it can't be doing it much good.........it's not even broken in properly yet.

I think I have eliminated all the usual possibilities which by my reckoning are:
a) excessively retarded timing..........which may be a little off but nothing bad enough to cause this
b) massive air leak............but never had this problem with the old ropey ignition
c) exhuast valves hanging open and bleeding and igniting cylinder gases in the headers...............I went to great lengths to make sure lifter pre-load was as specified, and didn't have the overheating headers problem with the old ignition

Whilst the old ignition would quit at will, there was no problem with overheating headers even on the rare occasions that I could run the motor long enough to get it up to temperature before the ignition quit.
So it all seems to point to the only thing I have changed....the ignition.
........but it can't be off by more than a couple of degrees max, surely not enough to cause problems like this..............

 

rain -

I'm thinking lean A/F mix.
And it may not be coming from the carb (think vacuum leak).
Did you look at the plugs to confirm?

Could also be something silly like a curb idle setting that too low.

Archer

 

i told you elsewhere. easy. crank the distributor further advanced. if it not kicking on the starter it is probably not too much. performance cams need more initial advance. even a mild cam can handle 12-15 degrees. you want a real short advance curve not more than 18-20 degrees as measured at the crank. that is, 10 degrees in the distributor

 

Your timing is too retarded, late timing = red hot headers.

 

Thanks for your replies guys..........
As I mentioned in my post, I've looked at all the obvious scenarios, timing ( I added a few more degrees to no effect), air leak, etc............
...........that's what doesn't add up.
None of the usual suspects seems to be to blame here.............??

 

you are shooting in the dark. you don't know where the timing is so you don't know where the timing is