Plugs
 

What plugs do you chebby guys recommend for a 12:1 SBC with iron heads? They're for a dirt track car so rpm's will be around 7k. It had Autolite 303's but a friend who is into chebbies says autolite plugs suck in chebbies.

Thanks bowties!:3DSMILE:

Chebby guys on this site!!! Grab the guns, ropes, and torches!!!

It's OK, Josh just returned from "over there" and hasn't relearned the boundaries of society yet. Give him a couple of years...he'll be OK. Of course, he is asking about a dirt track car instead of a Cobra, so maybe it will be OK.

Josh, change your signature line. You are now relocated.

Terry

That better terry?! haha

Ya, I posted it on the dirt forums also. Just thought I'd throw it out in here also. And no... I would NEVER put a chebby in my cobra!

I just adjusted all my valves and I did fine on the drivers side cause I kept reminding myself. Then when I went to the pass... I had to start all over because rather than exh, int, exh, int like a ford, they gotta make it exh, int, int exh! haha Damn chebby!

Welcome back Josh
 

fsstnotch Autolights are made for FORD motors. AC are made for GM motors. You didn't say which iron heads you have? Go with that year spark plug and drop the heat range 2 ranges cooler. That should get you in the ball park. How's everything else.:rolleyes::D Gald you are home. Rick L.

Will someone pleeease enlighten me as to what the he!! difference it makes whether you run ACs in Fords or Autolites in GMs, etc...

I recognize that one plug brand may be "better" than another but I just don't get why, given the correct electrode projection, heat range, etc., why you gotta match GM motors with AC plugs, etc., etc.

What about NGK, Bosch, Champion? What are they good for? And why?

(Or is it just me? :D )

welcome back Josh---I tried to answer earlier but evidently your post about the chevvy crashed the site!!!!

All I know is that I used to have a 68 Camaro SS396 and the only plugs I could get one time was autolite and as soon as I fired it up "2" of them would not spark. They were dead. I went to a different store an bought some AC44S, Changed them and she ran like a scalded ape. I will not use Autolite in ANY GM anymore. I also tried Bosch in a brand new 350 Chevy and it ran just ok but when I changed to AC it ran one he!! of a lot better.

Terry

they're double hump heads

They break down internally and go dead
 

TC cobra Lets stay with just Autolite and AC. I'm a 28+year master gm tech by trade. This is what I have seen and can tell you from the GM side. The high voltage coming from the coils and the long spark kill autolites in a gm car in a year. We get misfires out the ying-yang. You can look at the plug and see that the spark leaks out between ceramic upper and metal housing. It leaves a carbon trail. The other thing is by spraying water on the plugs you see spark arching to the heads. You can install any plug in any model. IMO depending on the output voltage of the coil or coils, it is either too much or not enough. This causes the failures. You can put Champions in any motor. In about 4-6 weeks of driving you can feel the power loss. Pull the plugs, glass bead them and you are good for another 4-6 weeks. Been there,done this since the mid 70's. People see these cheap tuneups with sparkplugs for sale like Autolites, Mighty Mite, Champion, and Bosch. In GM cars and trucks we get about 30% come back within 6-9 months with missfires. Ask yourself this, Why does one spark plug cost or sell for $1.99 and another for the same car sell for $4.99??? The higher price is the one that the dealership sells only. I don't manufacture the plugs, but for GM products I know what works. AC. I do like NGK's for blown applications. They seam to hold up very well with MSD systems. Rick L

Do you have a casing number??
 

fsstnotch Josh double humps where out for a couple of years in the 68-71 time and there are new heads being made. See if you can fine a casting number. 70 camero had these heads. Is it a big spark plug hole 13/16" or peanut hole 5/8". Rick

Rick, it is a big plug hole.

Over on the dirt forum guys are saying Autolite AR73's or NGK XR5 3332's gapped to .035.

The autolite 303's in it now are BLACK! When they should be a nice golden color. I should have looked at the csting # when I had them off the other day.