boonie

A question for the forum menbers:would you install AC Delco radid fire spark plugs into your LT1 engine?
thanks boonie

eschoendorff

I did and have no complaints.

Topload

Running them in my 94 with AFR heads - seem to work fine.....until the engine went POP!

onedef92

I never tried them. In my LT1 I run NGK TR-55 Double Platinum. I love those!

Fuzzy Dice

I ran them for a while...I have since switched to Autolite's...I'm talking the cheap, $8.00 per set jobs...I'm on the second set and they are just fine...my car runs as good, or better, than it did with Rapidfires, NGK's or Bosch's...

runner140*

Me too.

No Go

I've run the AC RF's for last 5 years and have had no issues. Works as advertised with lots of redline use.

vinnies87

same here, no problems or issues...

Louis Bartay

The GM LT1/LT4 plugs will burn of the platium disc's on the ground strap and the gap will be way too wide. So I changed to Bosch Platium Plus 4 on my LT1 TA and my 96 LT4 Vette and I noticed a little more HP just off idle. As there is nothing to block the spark with this design on a stock LT engine I think there is a advantage on running this type plug.

Years ago you could buy a spark plug shim kit to index your plugs so the ground strap was at the 12 o'clock position so the spark was not blocked if the strap was facing one of the valves. You would not loose much HP, but ever bit helps

No Go

Louis, you are speaking of the OEM platnum AC plugs that did/do have a problem of loosing the pucks during operation. I wouldn't recommend these and certainly would replace them if you have them.

Rapid Fires are different. Again, I've run them for year and many hard miles and they work as advertised-never a foul one.

I am surprised that your backside could detect a HP improvement from a plug change...I've felt a miss (due to the Bosch +4's in another car), but never a power improvement from them. Must be pretty sensitive.

Louis Bartay

Five out of eight OEM plugs were missing the pucks after just 39,000 miles. I know the Rapid Fire plug are designed like a stock plug but without the pucks. Suprised you had a miss in any engine that had a new set of the Bosch Plus 4. Were you running NOS? As this was the only time someone had a problem with the Bosch design that I have read about. I was suprised that I felt a difference with just a plug change but 5 out of 8 were missing the pucks. TPIS claims that the Plus 4 Bosch plugs will get you 2 more HP( I do not think I would feel just 2 HP) over the stock plugs but with 5 out of 8 that had the gap way too wide I was minus more than just 2 HP. I installed a set of Plus 4's in my daughters Altima and after 40,000 miles they still look and run great. I will look for the article in Hot Rod magazine that Grumpy Jenkins showed you the trick shim kit for indexing standard spark plugs (test was done in the early 1990's). Looks like we both have Tourch Red LT4 Coupes Who did your engine mod's? Good job, I bet you have fun spanking C-5's

Edit
I looked at your Home Page. Good job on your engine work. I have built several SB Chevy's (327/350 HP) I installed a 1965 Chevy II that had a 283 in it. 12.6@105MPH was my best time . I have never taken my Vette to the Drag Strip. Do not want to risk huring my ZF after talking to Bill at ZFdoc.com, Big Bucks if you hurt a Blue Label ZF.