Thread: glowing pipes 3.9 V8

Glowing exhaust normally points to a lean mixture - what is the colour of the plugs - do they show anything.

The engine maybe running hot as a result but with a good cooling system the heat in the engine may be being dealt with - glowing pipes reflects high combustion temps - often caused by a lean mixture or sometimes poor timing.

Garry

Check the timing is actually advancing when revving. Disconnect the vac advance and check that the timing advances at least 10 or 15 degrees above 2500rpm. Or take the dist cap off and see if the rotor button moves against the advance weights and springs back again.

If the timing is not advancing sufficiently, the still burning fuel charge will be heating the exhaust manifolds( and valves) excessively.

Leanness can also cause this, so even though you say that the mix seeems right when driving, these engines are pretty dirty and need more fuel to run at their best. Trying to run them at modern car engine emissions levels with stock injection and ignition systems will kill them off...at least yours is adjustable?

Tight engines DO work harder, but getting the manifolds to glow is(Apart from a good caning on a Dyno) a sign of incomplete combustion caused by timing or fuelling IMHO .

JC

what exhaust pipes do you have? extractors?
what engine did you replace?
if the water and oil temps are normal then i would consider the heat to be normal.
if you upgraded to a bigger engine then it would be normal to assume greater heat output due to bigger engine does more work.
or else it may be running leaner than you think.
if you have done 300km since installation you can safely assume it's run in and can run safely to max rpm.
another thing to ask is has the exhaust got a blockage, kinked pipe or something?

If timing is ok sounds like its running lean.Does it knock when laboured(Lean detonation) A small air leak causeng a thermal? I thought the O2 should pick it up. With EGTs that hot be carfull you don't drop a valve or burn/break a piston.
Tony

We ahd exactly the same problem when installing the Wold ECU on Jezzaol's 4.6 coil pack conversion.. The problem in the end turnd out to be massivly retarded timing as the trigger wheel was installed 1 hole out. This ment 8deg BTDC(indicated on the ecu) was closer to 22deg ATDC. How are you verfing Acutal ignition timing versus what the ecu is telling you?

What ecu are you using? does it have an ignition offset adjustment?

exhaust is a 2.5" from the downpipes back with a straight through muffler, stock exhaust manifolds and downpipes.

Engine doesn;t knock/ping actually drives pretty well. i'm not pushing it hard though due to this getting hot.
Haven't got them glowing cherry red but if i get into it a little bit it starts to glow in the thinner down pipes. exhaust manifold doesn;t glow.

AFRs are mostly around 14.8-15:1 and swing into the 13s under acc.

Inspected the plugs and they seem really good.

will have a play around with timing/ dizzy a bit more today and see how i go.

thanks for the help/suggestions, will keep you updated.

Originally Posted by Lucus

What ecu are you using? does it have an ignition offset adjustment?

megasquirt fuel only ECU. timing is taken care of via std disco dizzy and coil

What sort of injector firing sequecing are you using?

Does the mega squirt have not ignition control at all?