Hi was wondering what plugs and gap I shuld use for my 1967 327-30 over 194/64cc heads about 9.5-10-1 comp
torker intake edelbrock carb with hei in 1980 GMC 2500 4x4.
thanks  

early heads use a gasket seat 13/16 hex plug..   R44S delcos should work.. you need to read them after a few days....

if you have later model heads R44TS.....

R stands for resister.. and causes a hotter spark...as the flash over voltage needs to be higher to  jump the gap to get to ground...

S stands for extended tip past the end of the threads...

T stands for tapered seat non gasketed plugs...

start with what ever the plugs are factory gapped at.. probably .045"

when you get much past that, rotor failures and coil high voltage leaks are a problem over extended service usages...  

the heads id# is 3917291 which would be the early ones , they do take the 13/16 size.
thanks waynep712 for the info on this and site help.
will give those plugs a try, ive got champions at .035 in it now and it runs like crap.  

go back to the basics.. sometiing else might be wrong....

and the 291 heads do use the R44S plugs...

did you check out the hei???  the coil in the cap for high voltage leaks to the coil frame??? look for circular dust deposits.. ...

make sure there is a ground strap under the hei coil.. it is flat folded metal that hooks to the center terminal fo the harness coming up from the base...

take off the rotor..... look underneith it.. see if there is any burn marks...where the hi voltage has burned throught...

while you have the cap off.. look up into the inside... see the 8 aluminum terminals that allow voltage to the wires.. look closer.. there are 4 blank round areas sticking out..  these are where the coil screws go into.. if there is any marks that look like a screw is coming through from the back side... put some silicone sealer over it... or replace the cap..  the screws between old coils and replacements are differnt legnths,,, the long screws that came with the orignal coil will stick through into the high voltage area and cause the hv to go to ground there  instead of down the spark plug wires....

test the spark plug wires...  digital volt meter... 200K ohm scale...  wire legnth in inches should be longer than the display shows when testing the wire.. so a 24 inch wire should display less than 24.. usually 10 or 12..

make sure the mechanical advance is not sticking at a full advance .. turn the rotor  agenst the spring.. release it...  try to move it the other way.. if you can turn it. farther back the shaft is seizing.. and the hei needs to come apart carefully to clean and lube...    ( to get the shaft out of the body.. turn it upside down and spray in brake cleaner or carb cleaner in and work it in and out more and more while twisting till if comes free..)

what... else.. check the timing... base timing.. max advance.. vacuum advance.. ...  

It could be the heat range of your Champion plugs is off. Champion hasn't really updated their heat ranges in a long time, so they aren't the best these days.

I'd get a standard AC Delco or Autolite plug for your '67 motor. NOW, the big difference is the spark plug gap.

.035" is the proper gap for a points style ignition, because of the HEI ignitions much stronger energy, the gap needs to be opened up to .045". Do this and I ssupect your motor will run much better. .035" is too close a gap for your motor.