493 Header problem (dull red)

[70Charger493C.I.]

Hi, I have a 440 stroker (493) that i just got done building and i have a bit of a problem. Seeing if you guys got some good information etc about this issue. Ill tell ya the specs first. Indy EZ heads HUG 4950 fully ported to a Port matched Indy intake IND 440-I4-2D. When engine is over 3000 rpm's for less than 2 min fully warmed up 185-195F the headers glow a dull red. The spark plugs read this: Inner 2 cylinders on both sides read extremly rich and are dark black. The two outer cylinders read a dull white color. Not too lean, but its something to be concerned. The headers are hooker super comp 2inch primary tubes. And the engine has total timing at 36 degrees and is fully advanced at 3000. MSD parts. and running NGK plugs that are a good heat range. Also have tried champion plugs as well. The carb is a Quick fuel 950 Q series. I have been tunning the carb in etc and it has done nothing. idle screws have tried at 1 1/2 & 1 3/4 turns out and does not make a difference. Even tried goin with bigger jets etc. 86 in front and 88 in rear. went back to stock. 76 and 86 in rear now. Starting to think maybe the intake could be possibly be the problem. Being i do have a dual plane my intake runners are a different length goin the heads considering a single place intake has mostly all same length intake runners etc by the designs of both of them. Me and buddy have been doin some research and i dont know if this correct or not: A carb intake has grooves in the plenum portion under the carb. These grooves cause turbulence in the plenum. This turbulence causes the air/fuel to mix there by equally distributing among the cylinders.While a fuel injected engine wants no intake turbulence, a carb engine requires this turbulence. With out it, the fuel will pool at the bottom of the intake under the carb. It will then pour into the center four cylinders, leaving mostly air to enter the outer cylinders. Pull the carb off and check the intake plenum for those grooves. If it's smooth, there's your problem? There's a very good chance they were removed while porting and that ruins the intake? Hopefully you can give me a good sense of direction on this issue and also to see if this information if correct or not. Thanks for your time and hopfully i gave you enough information to use a good guess on what the problem is.

 

[FatJack]

This may sound ridiculous but check your firing order to be sure you have no plug wires crossed. I have actually done this before and it will lite up the headers.

 

[moparbob498]

what type of cam are you using...? and is there a chance valves are incorrectly adjusted--valves hangin open...?---check for vacum leak...and your airbleeds could be way wrong or plugged...air fuel screws should effect idle....is the throttle blades open too far..? the slot may be uncovered for air fuel screws..= no response when adjusted---good luck...its probably something over looked

 

[1badstroker]

I would check for a vacuum leak. Spray some carb spray around the intake and the carb base. If the idle raises when you spray an area you have a leak. Good luck.

 

[Meep-Meep]

Seems to me it's not that uncommon for the headers to glow a little at high RPM or be a little more sensitive to turning red. The wall thickness of the tube is much thinner than cast manifolds so the heat transfer is not as good. Also a rich mixture will produce hotter exhaust gas temps making the problem worse. It's absolutely true that the intake manifold must provide proper fuel distribution for both fuel and air, and if you are having unequal distribution that may be a problem, however I'm not sure I'd blame the intake 100%. Those ported Indy heads AND intake seem to mean business and at 3000 RPM you may not be at the sweet spot for good laminar flow. Just a guess but I wouldn't be surprised if your problems start to go away above 4KRPM and at WOT. Part throttle with no load is a totally different story and you may be better off with a dual plane.

 

[moparbob498]

this may sound crazy,..but..at one time i was running a AVS carb on a 413 in a 1971 Charger,..mild cam,.factory intake & hooker comp headers...now just my inner tubes on either side of my engine glowed orangish red...so having a nice stash of AVS's on hand..i played with the venturi's---and i found that the pair that cleared my problem up was that...the emulsion tubes (where air/fuel mix) all had different hole arrangements..some large orfice..some small,..ect..ect..i think the pair i used had 8 or more per tube ...cant remember for sure...its been years
but dagg i miss those AVS's----Thermoquads are the shizznit...i especially like the Competition series (on a tunnel ram)----ungodly throttle response---and hold on for dear life------LOL......................Good Luck
P.S.--as mentioned earlier,..vacum leak check,..try propane to locate leak,..works well