Dr.E

I searched and did not find any info listing the normal range for exhaust manifold temperatures. What should a pyrometer reading be for my application? Last measurement was 300-400degF outside ports and 550-650degF center ports (where the boots burned).
I'm running a mild performance cam (hyd roller 43 deg. overlap @ .050) on my Gen 1 383 First TPI engine with 2.5 in. cast iron heads 9.1CR early corvette exhaust manifolds.
Sometime in the tuning process my EMT's must have been too high causing the sparkplug boots to breakdown. The burned boots caused an intermittent misfire and further complicated the tuning process.
Thank you!

Dr.E

Just as a little bit of additional info... I contacted the manufacturer (MSD) of the plug wires I am presently using (Super Conductor), and they said that the boots are rated at 700 deg F. They make a "high temp" boot rated at 1000 deg F.
When tuning for 128 BLM at idle the lowest pyrometer reading was as in my first post.
I did notice about a 50 deg EMT increase when a 130 BLM at idle. I also measured a slight decrease (50deg. F) at 124 BLM measured at idle.
I can just change to the higher temp boots and forget about it, but it seems that the plug wire manufacturers would have designed their product with a higher temp than 700 deg if that is the barely adequate to handle my EMT at 128 BLM and stock SA.
What are the rest of you folks measuring with your pyrometers? Stock cast iron manifolds. Any comments?

JP86SS

iTrader: (1)

I've seen cruise temps of 600-700 normally and up to 1100 WOT.
My logging ability is not good for the EGT but those were observed using my DMM connected to the thermocouple.
I haven't been able to sort out a grounding issue when using my logging setup so I really don't know if they are "good" or not with different settings etc. Hope to resolve that this spring.
Just glancing at the meter and a separate gauge that I installed, they do match up reading wise so at least I know the numbers are correct.
These are in the gas stream at the header collectors and not external temps though.

Dr.E

Thanks this is the type of info I want to start to collect.
Keep it coming!