EGT temp questions, little help please

i made the first hits today and my EGT's are reading high, in the 1350-1400 range, but the plugs only show 1/2 the cadium discolored on the face of the spark plug. it has not even gotten to the threads yet.
I have a 568 BB chevy, conventional heads, 2.375 zoomies, alky, blown, 10:1 static compression.
can this be right??? it is not just one hole but all of them read this high and do move with rpm and down track like you would expect them to do. no intake air temp, but only turning blower 20% over and 27 degrees timing.
Thanks for your ideas

 

Where is the timing mark on the plug? Sounds like to me it could use a few more degrees and that the fuel is still fat and burning out the pipes. Try making moves to lean it out an watch the temps. They should start cooling off some an then when you see them start going back up that is the lean spot. At that point put a step fatter pill in it and you should be in the sweet spot. Only move the timing or change the pill. Don't do them both that way you know which change makes the desired affect

 

timing mark is just on the electrode side of the bend on the plug

 

sounds too rich to me also, go leaner and make a 330ft pass and check, then go a little farther. Tell us more about your fuel system, leanouts, bypass,main bypass size etc.

 

How fast are you going with that set up? I would expect you to be in the 6.50 to 6.60 range(205ish mph). If you are going that fast already, make small steps, but in my book EGT's lie. Believe the spark plugs, they are witnesses to combustion temps where the EGT value is a processed number subject to many things. I agree with small single changes to identify your culprit, or determine if you really have a problem other than a high number.

 

just took it out the first time for T&T. made a 150' hit and had 3 holes hotter than the rest. changed the nozzels in those holes and changed the main from 135 to 120 because the temps were up pretty high at 150' (1250).
2nd hit to the 1/8th egt's leveled some, but had even higher egt's (1320's), but the spread was less than 100 degrees between all cylinders. pulled the plugs and noted that only 1 of them had more than 1/2 of the cad burnt off the face of the plug (none to the threads). decided to make a 1/4 hit and EGT's read 1330-1425. pulled the plugs and the same thing, no heat via the plug, but high EGT's. only went 6.85 @ 197 @ approx 2260 lbs
13.4 gallon 110 pump, no high speed, k-valve
how much timing you guys run with conventional headed motors?

 

You fattened the tune up and the temps went higher?? Makes me think my theory is correct. Lean it and read the plugs. Also i that 13.4 gpm an actual flow or just what you were told? If its real that's a helluva 110

 

i will have to look at the data logger at the 1/8th mile to get the exact temperature change. The temp difference was between 1/8 and 1/4 o nthe last 2 runs.

 

Couiple questions for you. What size blower and what is the actual boost? What mag are you running? We run a front motored dragster, conventional head BBC with 6-71, 25-27 lbs boost, MSD Pro Mag 44 with 32 - 35 degrees of timining. 1030-1080 on the EGT's and the plugs burning about 3/4 around the ring. I don't think 27 is enough timing. It is probably burning out the pipe causing the high EGT's. Plugs are the real story of what is going on.

Greg

 

14-71 SSI 20% over and 25 lbs of boost.
i run a MSD 7-AL3 , HVC coil
NGK 9 plugs gapped at .018

 

we are running a 509 with conventional heads, 10-71 producing 29 psi boost and 32 degrees timing. MSD-10+ ignition, we had a similar situation and it was as stated, ie: timing retarded and too rich. We used to run 28 degrees but went up a degree at a time and it seems to love it, we still think we have a bit to go. Cheers, Graham

 

same issue

i have the same problem but just wrote off as differences in egt. blue line in plugs is slighltly on the electrode side of the bend with 28 deg timing.

Sounds like I might try to put more timing into it based on these posts. my question is when you added timing a degree at a time, did you change the fuel or just watch the plugs to make sure you weren't getting lean?

Don't have any desire to go faster as I could spin blower faster if I wanted but just want to make tuneup most consistent as possible. Even if I were able to get more timing, I don't have any desire to get tuneup hotter that one thread so is there any point really in changing??

 

Casey,

It depends on where your tuneup is right now. If you are safe or conservative right now you can add a degree of timing at a time without any worries, keeping your eyes on the plugs after every change. If you are on the edge now, you will probably want to add some fuel at the same time.

 

bbc 14/71 14od msd-10 30degree
G MARTIN say
I don't think 27 is enough timing. It is probably burning out the pipe causing the high EGT's. Plugs are the real story of what is going on