Hi! In last posts been having trouble tuning new engine 396/350 .060 ovr crane energizer 272 .515/.515 lft 7/16 psh rds 215 hds 2.19/1.88 vlvs sprng press 100@1.940 285@1.440 CB@1.340 procomp electronics HEI dist w/adj vacuum adv. Been working on getting idle down to adjust mixure screws and ad total timing. Went out today and took some digital pics and noticed that the #1 and #4 ex header pipe was not discolored like the others and engine did seem to miss but was hard to tell with the low rpm loop SO does this mean that I need to re-adjust the valves on those ports? to tight maybe? all plugs are getting fire!

Before you go any further if your timing with that cam isnt approx 18 initial base + 18 deg mech in dist (all in by 2800-3krpm) for 36 total then start there.

Thats becasue in many cases people are not running enough base timing so the retarded timing tends to ic motor/ex temps and the excessive heat generated by the retarded timing initial & total timing can dis-color headers.

Make sure the idle i low like 600-650 rpm when checking/adj the initial/base & total timing to ensure mech adv in dist isnt affecting the base timing adj. Must also have vac adv unhooked/plugged when checking/adj base & total timing.

Make sure to also re-adj idle speed & idle mixsrews after your done setting base timing.

But if total is over 36-38 deg @ 3krpm & above dont just retartd the total timing to get that in. Thats because for every deg the total is retartded the base timing is also retarded the same amount so in that case re-curve the mech adv in the dist to get approx 18-20 max deg all in by 2800-3k rpm for 36-38 total when running 18 deg base timing.

since this seems to be a mild street perf motor you need to have a vac adv that gives you an additional 12-14 deg timing max hooked up to full intake vac all the time .

If your timing is already set to above specs then things like motor running to hot due to cooling system issues or lean fuel calibration/jetting & power valve and or vac leak/s could also be items to look for when headers are showing signs of exessive heat.

You never know as it could be some of the above mentioned issues causing the header discolor but it could also be partially due to in correctly adj valves(eps ex valve/s) adding to the problem as you questioned.

scott

Thanks scott your right I need to get that timing set right first! Could that adj vac adv do me any good in setting up my timing?