I have a 305 tpi engine, and I origonaly had AC Delco R45ts plugs in it. I then changed to Rapid fires, and I dont like them. According to Autozone, I need the R35ts Delcos. But I think that I get the best result from the hotter burning plugs, the R45ts. My question is will the hotter plugs burn my valves eventually, or will I be ok.
Thanks for the help,
Rob

 

Why don't you like the Rapid Fires?

 

I think that the car seems to lag a bit. It does not feel like all the power is there that used to be there when I had the hotter regular plugs in.

 

Then put your old ones back in.

Why are you asking us? You seem to have a special gift
to sence minute differences in power of different spark plugs.

Unless they are gapped wrong or are way too cool and fouling
you won't see a significant difference in power from 1 brand or design or another.

New plugs always run better. Cause they are new.

If you have a stock 305 tpi motor and R45's don't cause detonation or any other problems then they are the best overall plug for normal street driving.

If you race it and am getting a little spark knock then a cooler plug like a R42t will help. Other than that you're wasting your time and money.

Platinimum plugs last longer cause they self clean, better, but they cost more.

 

I know many don't like them but I use Autolite platnium AP-42. They work great for my stock 92 305 TPI. Fires instantly for 40k then I put in a new set just because they had 40k on them. Gap calls for .035 but .040 seems to feel a little better.

EDIT: Opps, that was AP-26 plugs

 

I wonder if my gap of .045 on the rapid fires is the reason I dont like them. Maybe I should change the gap.

 

Gap at what the book tells you unless you beefed up your ignition via coil and or msd esque box.

Use regular autolites. They worked the best for me. I had some bosch onces not even the real spendy ones and they fouled fast.

If you want a little hotter plug, use the Autolite 25s..... stock calls for 24.

I've got 24's in my S10 under a carb and a jacobs coil and they look perfect.


As for detecting minute changes from plugs, sometimes you can feel it. I had to add a ballast to my s10 and noticed a HUGE difference, so much that I'm in the market for a new distributor that doesn't need ballast.

I'm going to run Autolite 25s in my 350 TPI w/ Pro Topline heads and comp XE262 cam... until my rings seat, then I'll be back to 24s.

Typically more power = colder plug, but you have to burn the contaminants off.

 

I would gap them to .035" and see what happens. Play with it a bit.

 

Im in the mist of putting plugs in my car and opted for a Accel coil and Accel module. Part# acc-140011 & acc-35370. Now with these small upgrades (ignition wise) should I opt for a bigger gap??? and if so...why?


And yes I opted for a new pick-up....(AC-Delco)


Dan

 

Well here is food for thought. The Jacobs Ultra Coil, widly considered the best and beefiest coil available..... recommends you use regular plugs, with a gap .010 larger than stock.

Personally I like to run a .045 gap. My '85 had it, it's pretty large, and my ignitions have run good on it. I'm too lazy to get out and change it by .005 to see if there is a difference.

 

Ive been using accel header plugs gapped at .45. I need to regap at 35 and see what happens. Im running so damn rich anyways tho.

 

I think that I will try to regap to .035 as well. I just dont thimk that .045 is working for me.

 

When I first replaced my plugs I remembered the old HEI's called for a .045 gap so thats what I did. Ran great. Later I read the sticker that said .035, damn! I pulled them and regapped at .035 and it didn't run as well, less resposive and about 2 mpg less. I compromised at .040

 

The only true way is to test and tune. Try and try again.

The book is just a guideline. I'm sure even some stock motors run better with a slightly different gap than called for.

 

how is it running at .040?

 

Runs great at .040, always fires quickly. Been running that for 45k miles. .045 was a little better but I didn't want to over stress the other stock ignition parts with 120k on them. Plus I can't complain about 27mpg highway between LA to Vagas.
With a high output coil and new module I'd definately open the gap to .045

 

thanks for all your guys input.... I opted to go with .040 gap on my plugs.... MAYBE I should have opted for another .005 thousandths gap. Once I get the wires-cap-rotor on I'll decide whether or not to regap the plugs. Most likely if the car runs good...takes off good from a stop...good idle ect ect. I'll leave the well enough alone....

Stay tuned for updates.....

Dan