LT4BUD

So you do cam, head job, headers, maybe some other mods....
thinner head gaskets..

Does the stock spark plug, or oem specified equal, still work fine? Or do you go one or two stages colder????

This question is a little bit which brand, but mostly directed toward what heat range.....or style works best...

BTW I went with Denso Iridium IT20 which is one stage colder than Denso's specified IT16 for stock. I have unconfirmed reasons to believe either I should have gone to colder range or some other style..

Help....plugs are too hard to change to go experimenting...Denso's are also big $$$

hngacurv

I use NGKs.

Nathan Plemons

I just use AC Delco R44LTS plugs. Eventually if you go through enough tables you'll find that this is the non platinum equivelent of what is supposed to be in the car in the first place.

LT4POWR

I've tried a few different brands/heat ranges, and I like the NGK TR55 the best.

STEVEN13

[QUOTE=Nathan Plemons]I just use AC Delco R44LTS plugs.


Nathan,

I purchased these R44LTS and they are to big for the heads on my 1992. Can this be right.

Thanks,

Steven

Nathan Plemons

Huh? I've put these in the last 4 LT1's I've worked on. I've got a set right in front of me to verify the model number.

What is too large? The threads? They had to have given you the wrong plug.

STL94LT1

These are the plugs I run with my heads/cam LT1, and the car runs great.

STEVEN13

Nathan, STL94LT1

Thanks for your replies.

The threads are larger on these plugs than the Bosch I took out.
Also when Autozone cross referenced the part# (on the R44LTS)it came up with a different Bosch plug part# than the plugs I have in it.

Could the plugs be stamped with the wrong part# ? Or am I losing my mind

I am going to put a new set of Bosch plugs back in.

Thanks again,

Steven

LT4BUD

Thanks for the response.......

When you say the car runs great, do you mean WOT performance or low speed cruising.......??

My problem occurs at "low" speed cruising after the engine has been run for while.....seems I get some missing and an occasional serious detonation when trying to cruise say around 1500 rpm....no problems observed if I keep revs up, say above around 1800....

I am thinking that after a while the plugs might get too hot causing the detonation...I have also observed knock retard when I start to accelerate...maybe as simple as "bad" gas....

STL94LT1

'BUD,

compared to the stock plugs, my car runs smoother from idle to WOT with the Densos.

Also, I'm running 11:1 compression and 41* total timing at WOT, with 0 detonation.

STEVEN13

Those plug are the right ones! I am so stupid.

This is what happened: The first plug I put in did not feel right so when I took it out (apparently there was) a heli core that came out with it on. What I did next was go to a easy one to put in. So now like a idiot I am trying to get this same plug with the heli core on it to the other spark plug holes.

Thanks,

Steven

P.S. I am not sure if its called a heli core

rrubel

Heli COIL... somebody stripped one of your spark plug holes and had to have it re-drilled. Downside of aluminum heads; probably tried to change plugs with the engine hot.
[RICHR]