What would you put in my 96LT4 for spark plugs, what came with the puppy (AC) or something that works better????Thanks for help!!!

 

NGK TR55. A great plug and at ~$15/set you can't beat the price

 

They are a little expensive but I have had Great luck with Bosch Platinum Plus 4 for a stock LT4 they are a good plug that will last a long time and no disc to burn or fall off like the OEM plugs did. Look at the design and you will see thay do not have anything to block the spark like regular plugs. We use to use a shim kit to index standard plugs so the ground strap was was not blocking the intake valve. Part#4458 at Auto Zone or Mid America Corvette.

 

 

Not double plats? or Iridiums? Any reason why not those?

 

I HATE Bosch anymore... it's JUNK. I have gone through THREE Bosch O2 sensors in the last 3 or so months. Pissing me off.

Bosch +4 is a gimmic... I am not impressed. Every person who has used them has ultimately experienced miss problems.

Double platinum? The AC Delco DPs are JUNK, too. The platinum puck on the ground strap burns off or falls off, resulting in the gap growing from .050 to .065. Yea, that's a good thing. Can you say "burned optispark?"

A friend tried Autolites, and he exchanged them for NGK cause they caused miss conditions (Jeep Liberty).

My personal fav is the NGK Iridium.

I have them in my 92 LT1 and zero problems.

 

I vote for the NGK Iridium plugs as well.

 

I use the cheapo Autolite copper core on my 94 LT1, which I use almost exclusively for racing. It spends most of its life between 4000 and 5700 RPM. No missing here. I change them every couple of years. They work just fine.

 

I am using Denso Iridium....$$$$$$$.....but they seem to do ok

 

I guess I have been lucky as both my TA LT1 and my LT4 Corvette have them with NO problems. We were talking about spark plugs. Some of the aircraft engine companies have used this design for years. Missfires ae usually from bad wires or a dropped plug that has the gap wrong. I checked each one before I installed mine using a vacumm hose to start the threads and not hurting the gaps.To each his own.

 

Bogus is correct.

The AC Delco double platinum plugs that came from the factory in the LT1 and LT5 are notorious for losing the platinum pucks.
Of my original plugs, only two still had both platinum pucks still on them at 55K miles.
There are many, if not most, vehicles that had that problem -- it is well documented on the ZR1 (the LT5 had that problem too) and CamaroZ28 forums too.

You couldn't pay me to put AC double platinums back in.
I've been using Autolite double platinums in my AFR heads for the last 40K miles and haven't lost a puck yet.

Tom Piper

 

Thanks people I pulled one of the ACs out this morning, that the factory suggest you run. Gap was at .065 when they are suppose to .050 so you guys are right on. These plugs were put in at 43K by the prior owner and I just turned 80K...37,000 miles is all she wrote. I want to thank you all for helping I am going to try the NGK Iridium. Regards Bob Wickham

 

let us know if you feel a difference

 

I had them... I just didn't wanna spend 14.00 a plug!

The only weakness to the Denso Iridium is the life span, they recommend a 30k mile change interval.

And be VERY careful gapping those bastards... yuck.

 

I know aircraft have used them... perhaps they are better for steady state operation and not variable rate as used in cars.

 

41,000 on my wifes LT1 TA 1994 and we run the heck out of it. It has 159,000 miles and runs fine. The only person who had a problem was a member of our Corvette Club that uses NOS at The Texas Motor Plex Drag Strip and he could not change the gap wider for what he needed. My LT4 is not stock and has been reprogrammed for a 6500 RPM Redline and I have had the plugs in for two years and 20,000 miles and I street race Mustangs, LS1 F-Body etc (SS and WS6 run hard) and never a miss fire. I am 55 and have been breaking SBC engines for years and the AC44, Champion UJ12Y or Autolite A1 that I used in my 62 Vette 327/375 (66 long block) would eat those up in just a few thousand miles. I know things have changed as a 327 was a POS and needed a overhaul every 30,000 miles( of my lead foot and we had 102 leaded gas.But my Dad was Aircrat A/P Mechanic and I have shimmed my share of plugs back in the old days so the strap was NOT facing the intake valve. TPIS has done a DYNO on the these plugs and they Rave on about them. Look at the T.P.I.S. Catalog (I want their Long Tube headers) and you will see they race with these plugs. Not trying to change your mind or prove anything just writing what I have learned the hard way.Have a Happy 4th Louis

 

My vote is NGK's TR55. They run great, so far.

 

So true......

Cost wise I did a little better than $14....but they are expensive......

My car is not a daily driver so the 30k is not a big deal for me....

Best bet on gapping is to NOT.....use as received from Denso, they do a great job of gapping and protecting during shipment...



http://densoiridium.com/installationguide.php

 

I found a set of Denso IT20's for $50 a couple of years ago. The car really ran smooth with the Denso's. But, when I changed cams last time thought I would give the TR55's a try. I really don't know if the Denso's were worth the extra cost.

 

My TR55's just arrived today, couldn't be happier to lose those puckers that were in there. Or should I say non-puckers?