Hi All

I picked up a 76 vette two years ago, I found out the motor is not stock, Here is what I know.

1. Not orginal motor, id says 68 to 72 chevell, nova, camaro, corvette, or truck 350ci.
2. There is a aftermarket liquid filled harmonic balancer on the motor,(not something your weekend mechanic would bolt on for performance so I think the rotating assy is after market but what i dont know.
3. compresion test is 160 all arond. (I did it without opening the throttle, found out later)
4. World product SR2 toqurer heads, 202
5. Edelbrok alum intake
6. edelbrok 600cfm carb
7. MSD Ignition
8. Hooker header sidepipes

I replaced
1. the carb with a 750 berry grant speed demon.(per motor heads advice)
2. distributer with a MSD streetfire.
3. 8mm MSD wires.

I did
1. fixed all vac leaks
2. set the timing, by the wonderfull artcle i found on this site.

Now to my question. When I bought the car I put new plugs in, the ones the auto store looked up for a 76 corvette, I have black drops on the ground from my sidepipes, Not sure if it is from condensation or fuel running through the pipes, the car runs strong now with the parts i changed, strong roling on the gas but not much when I get heavy into the secondaries. My question is how hot can I go on my plugs? do you go up a heat range till you get tan plugs? mine are black now but no carbon build up. I know you can burn a hole in your piston if you go to hot, I am just wondering if with the after market goodies if I need to go hotter on the plugs. Any help here would be greatly appreciated.

Thanks
Gary

 

what plug number and manufacturer are you running now

 

AC Delco R45TS

 

That 4 heat range should be plenty hot for that motor, go back to the ibfun page where you found the timing, an look at the fuel & intake. There you"ll find the b/g set up page. Once you get the carb set up an those plugs turn back tan, (they will) might want to try a 5 heat range.

 

r = resistor 45= range t=tapered seat=s=extended tip. the 45 is one range hotter than a 44 which is probably standard issue. the s or extended tip makes the 45s just a tad hotter tip than a 45 the next step would be an r45tsx x=serrated tip which is more foul resistant. the next step hotter is an r 46........which is about as hot as is made for that plug group