i know the bosch are out of the picture. NGK is a excellent plug. question is, what plug should i use with a full MSD set-up??? I am using the factory AC delcos now. Would the rapid fires last??? Also, what should the gap be set at. i was told that use regualr ac delco with a gap of .45 - .50 someones advice. look at signature for mods

 

Bosch = Rapid Fires. Both are designed just to last a long time, with not much reguard for how well they work, IMO. Neither have worked well in any of my cars.

NGK are generally too soft of center electrode, so they wear quickly. They're fine for motorcycles, and lots of Asian cars.

Delcos, or Autolites, are about the best combination of service life, and not being prone to failures.

.035 is fine. The difference in flame propagation from .035 to .045 is about 0 for all practical purposes. The larger gaps increase the min firing voltage, so they also shorten the secondary componets lives.

 

I agree with the above post, no extra power or performance have been found by increasing plug gaps, all it does is make the ignition work harder. It has been tested on dyno's thousands of times of the years, no real benefit.
Something interesting I found the other day. I have been a die hard ac delco plug person all my life until something I found yesterday. Bought some plugs for one of my cars, your basic R44ts plugs, I noticed some of the boxes were different between the plugs. I opened them up, some were the plugs I am used to seeing and have made in USA stamped on them, the others were very different looking and had "made in FRANCE" stamped on them. I started comparing, they were all R44ts plugs but the ones made in France were definately different. The france plugs were shorter, the porcelin was farther down inside the plug body, the electrode was a much smaller diameter and just overall looked like a very cheaply made plug. I was very disappointed, had to make the parts guy go through the bins and find me a matching set of USA plugs. The USA plugs had the electrode and porcelin sticking out of the plugs much further than the France made plugs etc......although they are both the same part number.
Just something I thought I should throw out there to keep an eye out for. It is something most people may not care or even notice a difference in there engine performance, I myself am very picky on my tuneups etc....it appears to me the ac delco plugs are making a change over to all plugs made in France, If that is the case I may have to start looking for a different brand plug to run, because I sure didnt like the quality I just witnessed in the store compared to the USA made plugs, Sad but true, Larry.

 

Thought I should mention also, the reason this jumped out at me, the USA made acdelco plugs are always coated black on the steel portion of the plug. The French made plugs were a very bright silver finish, this is what caught my attention so I started comparing differences and there were many. That is when I noticed the made in france stamping on the bright silver plugs.
Funny thing is, I even got the attention of a couple other customers in the store and they were also looking at them and they also could tell there was a length difference in the electrode, so I knew these old eyes were not decieving me.
Just something to watch for. Larry.