have a 70 challenger rebuilt a 66 383 bored 40 over comp cam 268 cam headers demon card performer intake new electronic distbutor car got hot idling in line at local ice cream shop turned it off when we got ready to leave it fired up never pegged the temp gauge pulled out on highway valves were rattling bad for about eighth of a mile car temp went back to normar but now no 6 and no 7 cylinders not firing changed plugs new wires checked rockers for movement no flat cam lobes any body got an
deas

 

70 -

When you say "not firing", do you mean no spark?
You did change the dist cap and rotor, right?

Archer

 

yes it has spark ive had trouble with it since rebuilt with what i thought was fouling plugs so i took 650 double pumper carb off put new 625 demon on wondering if mabey ive gotten a bad intake its e edelbrock performer its been off several times so wondering if its got a hairline crack or just blown gaskets friend said he thinks he got factory intake he will sell me any thoughts

 

70 -

Not to belabor a point, but if you're getting spark and the rockers appear to be moving normally, how do you know that 6&7 aren't firing?
There is one way, and I just want to know if you did that.

Archer

 

with engine running took tester and grounded out the plugs till founnd the ones that didnt effect the running also after shutting off those two header tubes i could touch the others were too hot

 

70 -

I would have just used an IR thermometer on the header flange.

Unfortunately, if you're sure about everything you did, the next step would be to pull the manifold and heads.
I would just make really sure you were getting spark to those plugs.
Sorry for this, but you're sure you didn't cross any wires, right?

Archer

 

archer thank you for the help we got it fixed 70 year old mopar mechanic told me put it back like it came thought he was crazy put cast iron intake back on never raun better evidently the aluminun had a internal crack on the runner that supplied cylinders 1 4 6 7 again thanks for all help and suggestions

 

70 -

Well, cool. Sorry about the manifold, but glad you got it fixed.

Just curious, with the cracked manifold, there should have been a vacuum leak.
Did the engine make any strange sounds or did it seem to be revving a little higher than normal?

Archer

 

we even sprayed carb cleaner all around intake no sign of leaks but it did idle funky when got hot only thing we can figure the runner supplying gas to cylinder 1 4 6 7 mabye something was going on inside never heard of this before but still running good put about 25 miles on it today no problems so far guess live and learn