headers glowing red
 

On our 350" NHRA stock engine we removed the crappy HEI distributor the other night and installed an MSD with a small cap.
Last year you could not stand near the car without your eyes watering. We fired up the Nova(after sitting all winter) and set the timing to 15* at 2000RPM which is idle for this set up and checking the max timing which is 31*, we just wanted to get it running and then tune the dist after.
I noticed the headers glowing red. We shut it down and I removed the carb, by the way the exhaust was not the bit irritating this time.
Our thought is that the old dist was not igniting all the fuel which caused the crappy exhaust smell and now with the new dist it seems lean and needs to be richened up. I must add there is a 1/8" hole in each primary throtle plate and the idle screw is in to where the idle circuit is not functioning. I am going to try a non modified carb but would like some direction to head towards.
The carb is one I did about 20 years ago and when last run the car ran in the mid to low 12's.
So where would you direct me to look to get this thing back on track, we are not racing it this year but would like to drive it now and then, it is street legal(more or less) . Thanks, Henry

Re: headers glowing red
 

Try setting total timing to 38 degrees. Looks like fuel is being burned after exhaust valve is opening causing extra heat. Hope this helps.

Re: headers glowing red
 

Fifteen degrees @ 2000 will sure warm them up. Put some timing in it.

Re: headers glowing red
 

Yeah, a small block Chevy is going to like closer to 36 degrees total. And at 2000 RPM, you should be at least 2/3 of the way there, if you're going to run with a mechanical curve instead of a locked distributor.

Re: headers glowing red
 

Thanks for the help, we used to set it up around 40*, never bothering to set it lower, amazing how much you forget when you don't do these thing for a while. I will clean out the carb and try it this weekend and let you know, Henry.

Re: headers glowing red
 

Lock the distributor out and set timing at 36 degrees and test moving 2 degrees at a time up.

Re: headers glowing red
 

Is it a Q Jet with primary metering rods?

Re: headers glowing red
 

Back in the early/mid '70s, the era of the most horrible performing cars on earth, a guy backed his '74 Cadillac out of his garage, got out to close and lock the door, and he left his car running on fast idle-around 2000 RPM or so. The phone rang, he ran inside to take a call, which lasted about fifteen minutes, and the car ran at that speed the whole time. He got off the phone and came out to find the cars' exhaust manifolds, the Y pipe, and the head pipe to the muffler cherry red hot. He panicked, shut the engine off, whereupon it dieseled like crazy for several minutes, and then backfired and quit. He had no idea that a by product of retarded ignition timing and a late closing camshaft was excessive exhaust heat. He's lucky he didn't burn the whole place down. Set the timing to 36-38 degrees at 3000 like everybody says, and I bet you find that the engine's idle improves significantly as well. Good luck, let us know what happens.

Re: headers glowing red
 

Agreed too little timing. SBC should stand 40 degrees of total timing. But, all engines are different set it at 36 degrees and raise it in 2 degree increments.

Re: headers glowing red
 

Thanks again guys;) As far as the primary throttle plates go what size hole do you have/ recommend, ours are 1 in each primary plate and 1/8" dia?
The throttle plates are well past the idle slots and am wondering if I should drill another hole in each primary plate to get the plates back to where they allow the idle circuit to work? Or keep increasing the size of the one hole?

We are still running the front metering rods. The car will be mainly a street car. We have kept our 69 Stocker engine but with a 2800 stall and only a 373 street gear in it now, but LOVE how the engine performs on the street:D

Re: headers glowing red
 

Sounds like a 1/8" air bleed hole through the primary throttle butterfly is about right. if you have the proper static initial timing, the engine's idle characteristics would improve to where no further mods were necessary.

Re: headers glowing red
 

piston at TDC - ON THE COMPRESSION STROKE, I know you have probally checked this. I had this happen to me 1 time, engine ran but headers got cherry hot. I was in a hurry and had the distributor on TDC #1 set on the wrong stroke.

Re: headers glowing red
 

I don't think you can get away with that much timing with that low of a stall. Breaking motor in with that much timing wont be a problem. Driving on the street I think it would detonate.

With the primary rods in it (which is fine) with no load on engine the rods are down in the lean or big part of the rod. Just not enough fuel is getting past the rod/jet for the raised RPM.

As a quick fix when breaking cams in I've just ran some duck tape across the choke area to richen it up. Cherry red exhaust will be gone. Don't forget to remove duck tape after break in.

Re: headers glowing red
 

Thanks again guys.
We finally got back to the Nova. I took the carb apart at home and cleaned/ blew it all out. We put the carb on and set the timing to 36# at 3000. The headers glowed so we put the old HEI back in ran it up and set the timing to 36 and the header glowed!!!!

We took the carb off and went to put the spare on but were missing a plug for this carb so I said lets put the 1st carb back on and see what happens.
Well low and behold everything worked fine??????????

So with the throttle plates drilled with a 1/8" hole the plate is above the idle slots and idling at 1100 in neutral, dropping to about 800 in gear.

What if we drill another 1/16 hole in each plate or would you recommend opening up the 1/8 hole to 3/16? Thanks, Henry.

Re: headers glowing red
 

I'm not sure you should need a 3/16" hole in the throttle blades to get it to idle.

Re: headers glowing red
 

Not trying to contradict anybody, & mine doesn't have a q-jet but to get my 351C with a 2bbl Motorcraft to idle decent, I currently have a 1/4" hole in each throttle plate. & it adjust's correctly now. But my cam is probably too big.:o

Re: headers glowing red
 

I am going to drill another smaller hole in each plate and see what happens. I have lots of spare plates so if I go too big I will change them.

Re: headers glowing red
 

That was my justification for experimenting that far out of the box. :D