[track73]

what spark plugs (heat range) are being suggested for a .030 455 with 9.5 compression. Brand is ok too.

[ta man]

what heads

[Don 79 TA]

there are quiet a few variables that can come into play here, one mentioned above
but as far as a stock head goes, probably what the originals called for
from there it could be trial and error as to heat range/etc
that could depend on your total setup

as for brand.... guess that comes to a personal preference (like gas/motor oil/etc)
as long as you have a functioning plug, probably not gonna notice a difference between a $2 plug versus a $20 gadgety one
again of course depending on setup of everything

gap is also going to be trial and error and dependent on your ignition system too

[track73]

96 heads from 71 or 72 400.

[Chris65LeMans]

My 400 has 96 heads with around 9.25:1 compression and a Performance Distributors DUI HEI unit.

I searched and didn't find any concrete plug recommendations, so I just went with these:

http://www.summitracing.com/parts/bch-4036

I have them gapped at .055 now (Performance recommends .050 - .055 for theirs), and am happy with how they run. I think I had them gapped at .035 -.040 (I don't remember) when I was running an "unknown source" HEI.

[Formula8]

Those should work with your 96s. I used to use R43S but good luck finding them these days. R44S were a bit too hot for my application and still hard to find. I tried Autolites and they all ran hotter than the cross referenced AC plugs and Champion seemed the best compromise and were always easy to get.

[track73]

My 96 heads use tapered seat plugs. I'll try Autolite plugs in AC 44 heat range.

[455rebel]

Been using ngk 4 , they are cheap and the dirt track boys around here run them.

[screamingchief]

Originally Posted by track73

96 heads from 71 or 72 400.

#96 head is '71 only,not '72.

Originally Posted by track73

My 96 heads use tapered seat plugs.

No they dont.

Just because there's a small bevel around the start of the threads does'nt mean those heads use a tapered seat plug,that's just there to help get the plug started in the threads w/o cross-threading.

All #96 heads use gasket seat plugs,end of story.

And FYI: The reach is different between the two plugs as well,and what that means is the plug wont be in the correct position as it relates to the chamber itself,with the longer reach tapered seat plug the tip will be protruding further out of the threads and that is not good cause the last thread or so hangs out into the chamber as well,and those get carboned up and can cause problems like pre-ignition and problems when removing the plugs.

'71 was the last year for gasket seat plugs.
'72 was the first year for gasket seat plugs.

And AC delco only does the odd heat ranges anymore,no even heat ranges.

R43S crosses over to Autolite 85 IIRC.

That's a 5 or 6 heat range in NGK.

And I'd never use a Champion plug in anything other than maybe a lawnmower or such.

FWIW ~ HTH

Bret P.

[Grand73Am]

Originally Posted by screamingchief

#96 head is '71 only,not '72.



'71 was the last year for gasket seat plugs.
'72 was the first year for gasket seat plugs.



Bret P.

Did you mean '72 is the first year for "tapered" plugs?

[track73]

Thanks guys.

[screamingchief]

Originally Posted by Grand73Am

Did you mean '72 is the first year for "tapered" plugs?

Yes,was in a hurry,my bad.

Bret P.

[72LuxuryLeMansLa.]

Originally Posted by screamingchief

Yes,was in a hurry,my bad.

Bret P.

Bret,

Sorry but you will have to be in time out for the next 4 hrs. Bad Bret!

[NO67GTO]

45S in my #96 headed 455. Gaped at .35
Changing to NGK at next oil change.

Sent from my XT1030 using Tapatalk

[Jc68fbody]

I'm trying to find a plug also. I'm running a ngk r5672a-8. My deal is I think they are to cold. They look to be getting carbon fouled. I'm running a 461 with 87 cc e heads comp cam 288xr with a 750 quick fuel blow thru with a procharger

[rexs73gto]

I have E-heads on my 413 right now & I like the E-3 plugs. They seem to good at the heat range that there at & they come pre-gapped so you just have to put them in.

[lust4speed]

I really like Wallace's section on choosing the proper heat range by reading the ground strap to determine if you have the proper heat range: Wallace Spark Plug Article

I'm kind of surprised that no one addressed how heat ranges should also match the type of driving you do. I have friends that run large cams and love the sound at idle - and usually don't get much above idle at any time. These guys have to run a higher heat range to keep their plugs clean. I have other friends that would have absolutely no problem keeping even the coldest plugs from carboning up.

Also the better the ignition, the more forgiving its going to be even with too cold of plug.

[steve25]

The large Cam street guys need to get the Carbs idle air bleeds set more for there needs, you can wash the rings and cylinder Walls out real fast if you do not watch out!

This type of thing is what always makes me think to myself the same thing about Harly bikes and such at stop lights as they always seen to need to insistently blip the throttle to the motor idling!
If it where me I would be very tired of doing that in short order and be putting in a fix for that real fast

[STEELCITYFIREBIRD]

How wide of a gap?
Curious how wide or narrow you can/should run with all the different possibilities? MSD BOX,HEI,Points,ETC .
Is there a point where you would switch to a different plug if your running wide gaps? Like late 60's gasket seat plugs with a HEI and MSD 6. You can only get so far open and the electrodes get pretty far from parallel.

???

[rohrt]

Anyone run an XT (extended tip) plug in the 96 head?

I run ngk xr4 spark plug now. They work fine but don't go into the chamber very far.