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So what's the current recommended spark plug for mark IV big block

shady

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I know everyone always said not to use Bosch platinums in my 350, and there was a few suggestions made that had worked well for others.

But I haven't bought any for a big block yet.

Normal low power 80s 454 with stock peanut port heads.
Bored .040, no idea on pistons.
Semi smooth, but bigger than RV, cam.
Stock HEI for now.

As some believe with Journey,,,,, Champion SUCKS.

What works well with no issues in these :dunno:
 

diesel4me

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I have always used AC or Autolite spark plugs in the gas powered vehicles I've owned..
 

shady

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I figured Delco. Wasn't sure if there's a certain model, or number that's been good. What the book says isn't always the best one from what I've read lol.
 

diesel4me

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I forget exactly which numbers I used on the mid 70's 454's I had,I think they were AC R45TS or #26 Autolite,just like the 350's used..

Older engines used gasketed plugs instead of tapered seat plugs,I think around 1969 or so is when they switched the heads to use tapered seat ones..

Some years like 1975-77 listed extended gap plugs with a "TSX" suffix with .060 or .080 gaps ,those proved to be problematic ,they would flood on cold starts in frigid weather ,or the choke pull off didn't open the choke after it started and the engines refused to start after stalling until new plugs were installed..GM went back to using the "T" or "TS" suffix plugs gapped at .035 to .045 to cure those issues..

I have tried using a heat range hotter plug on engines that were high mileage or used some oil,it did help them not to foul as quickly in cold weather driving I did.mostly short trips..
 

shady

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So is it still recommended NOT to play with crap like E3's, rapid fire, V-power, etc?.
 

CyberSniper

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AC Rapidfire #4 is what I use in a lot of stuff because they're cheap and impossible to foul. Otherwise I use NGK Laser Iridium plugs. Also because they're impossible to foul but they also never wear out. But $3 vs $9.
 

shady

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I looked at the NGK iridium ones. I know NGK is my small engine go to. But haven't ever heard much about their car plugs.

I used rapid fires in one of my old 350s, but it never ran right (even after changing plugs again) so I moved on from them too. That probably wasn't the plugs though, so I can't really knock em. That engine NEVER ran right lol.

That was the first I had heard about not using stuff like that. The previous plugs were Bosch platinums, and they Did keep fowling.

I don't mind paying for a proven set of plugs.
 

diesel4me

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I've seen more than one set of Bosch platinum plugs my friend installed in customers vehicles with 350 small blocks as part of a complete tune up,make the engine run like it had a dead cylinder,and replacing the plug didn't cure the issue...he tried swapping the old plug wire back on,same deal,it wasn't the wires..when he'd put the OLD spark plug back in,the engine ran perfectly again..

He never could pin down why the Bosch plugs did this--it wasn't an issue with other brands,but he figures its something to do with them being platinum and the engines were not equipped with them as original equipment..
Maybe there was just a lot of defective ones too,he now won't install any Bosch plugs in GM engines,if the customer supplied them,then he'd say I'll have to charge you if the thing misfires or runs lousy and I have to put a different brand of plugs in..

Champions seem to be the most likely to break off in the block if left in too long too,on top of never firing again once they fouled--AC and Autolite's will usually come back to life after you flooded the engine once the engine warmed up...once a Champion fouls,its dead for good..

I have had poor luck with NGK plugs in motorcycles and some small engines--surprisingly Champions seem to work OK in small engines ,other than never recovering from a flooded or fouling issue..
I prefer AC or Autolite plugs in my tractor engines,but use whatever I have on hand too--when you have only one cylinder and spark plug,it HAS to be a "good" one,as there isn't any other cylinders to share the duty of making it run..

I tried those "Split-Fire" plugs in small engines--they work great for a few hours,then cause all kinds of weird running issues ,if you can get the engine to start..magnetos can be fussy about certain plugs,some do not like resistor spark plugs..
I just stick to Autolite 295 or AC 45 plugs,or Champion J-8C or
J-17LM or J19LM plugs in my tractor & mower engines..
 

76zimmer

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Yup oem plugs to fit the head...R43 or R44 IIRC correctly?
 

shady

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So that's a couple for the r43 and a couple for the autolite 26. I'll just pick which ever one is easiest to get quick and go with em :waytogo:.

I have to buy 2 sets really, so maybe I'll get one for this truck and the other for the dually :thinking:
 

76zimmer

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Get one set and keep changing them to which ever truck you’re driving...
 

shady

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Lol. I drive either one on a whim... That'd get old quick :D
 

76zimmer

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Yeah, lol.....about 1/2 hr to change em, that would be fun!
 

shady

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Take me longer than that probably lol. Maybe not, but it'd feel like it.... And gotta figure in time for a few beers. So like an HR at least :D
 
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