[TPR] Spark plugs and heat range

[Asa Jay Laughton]

Are any of you running colder spark plugs in your souped up engines?

I pulled the plugs on my Pantera today and cracked one in the process, 
and found another one cracked (that I don't think I did on the way out).

Since I'm buying new spark plugs I did some investigation with regard to 
heat ranges.  I typically use NGK UR4 V-Groove spark plugs.  The number 
4 is the heat range, and that's the proper range for a stock engine.  
However, NGK recommends going one range colder for every 75-100 HP 
increase.  Now, I'm not saying I've put another 100 horse onto my 
engine, but 50 to 75 maybe?  Perhaps, but then again maybe not, I don't 
honestly know.

So before I go off and buy plugs in a one colder range, I thought I'd 
ask the collective experience of those on the list.

Also, it looks like the spark plug wires I got are for the male towers 
on the cap.  Mine is female and the only way for me to go to the male 
cap is to go to the larger Duraspark cap.  I had one on the shelf from 
the Mach I and test fit it on the Pantera.  It looks like I can get it 
on and still have sufficient clearance to the firewall.  I went with 8mm 
wires and forgot most of the time those only come for male towers on 
distributor caps.  Oh well.

I used the borescope on all the cylinders today.  It's hard getting it 
snaked around to inspect the entire piston surface since the spark plug 
hole comes in at an angle.  Overall I think the pistons are okay.  They 
appear to have a black sooty appearance; but do look a little wet, 
probably from the over-rich mixture I'm running.  I didn't detect what I 
would think melting of the pistons would look like.

The plugs all appeared to be in good shape, lightly brown and sooty.

One interesting thing.  I took the valve covers off to re-check rocker 
arm clearances.  Number 5 intake was tight, and that seemed to be very 
odd.  I double checked the crank position and the other valves I was 
checking, of them all, number 5 was tight and I thought that was really 
weird.  I've not had any back-firing through the intake, but as tight as 
this one seemed, I would think I should have.

I re-adjusted it and will crank the engine tomorrow for the compression 
testing and watch that valve to see if it's acting properly or not.

I didn't get near as far as I hoped today.  Maybe tomorrow I can get it 
all put back together, again.

Yes, again.  I got the oil temp sender in place and oil added and 
checked just in time for Sam and I to go to the car show yesterday.  
Then it was off for our haircuts and then back home.  Today after 
Church, I tore into it again. <sigh>  Seems like I'll never get done, 
but I'm working at it a little at a time.

Asa  Jay

-- 
Asa Jay Laughton - W7TSC, MSgt, USAFR, Retired
&  Shelley Marie
Spokane, WA
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