What kind of plugs/gap would you suggest for my application?

[1984 Cutlass]

Ok I have been wondering this since I first did the tune up on my 403,and didn't really take this into complete consideration. For better performance, what type of plugs and gap setting do any of you suggest? I have a 403 that is "supposedly" bored .30 over with 72 Olds 350 7a heads,some sort of mild cam that the previous owner has no idea,als previous owner said something about upgraded (to what? lol) pistons?,and performer Olds 350 intake,dual exhaust with no cats. I didn't think about the fact that should I;
1. Get the plugs that were for the 403(which are in there)or...
2.Get the plugs for the 72 Olds 350?
3.Which gap setting would be best?
4.Is it all the same?
On another side note, I just grabbed a 160 degree thermostat and someone at O reilly said it could overheat running too cool? I have NEVER heard of that ever lol.
I know my stuff pretty good I guess but just wanted to ask anyone who has had experience more with a 403 or just Olds in general. Thanks

 

[Pontiac455]

Re: What kind of plugs/gap would you suggest for my applicat

You will have to get the plugs for the 350 heads. As for plug gap it fepends if yer runnin a high voltage coil. If so start at 45 and keep goin up till is starts to work shity then go down a few thou.

 

[Pontiac455]

Re: What kind of plugs/gap would you suggest for my applicat

You can gap the 4 center cyls a little wider because they get the most fuel because the intake runners are shorter.

 

[1984 Cutlass]

Re: What kind of plugs/gap would you suggest for my applicat

Oh, and also does anyone have any idea what kind of torque/hp this combo makes? I have seen many threads about how to make this combo,but no one asks or has said anything about the power it can make.

Thanks Pontiac455 for the info!

 

[pontiacgp]

Re: What kind of plugs/gap would you suggest for my applicat

if you can use a dyno start off at 30 and work your way up till to get the highest hp. Without a dyno it's just a crap shoot so adjust according to spec. I use the cheap delco plugs.

 

[Pontiac455]

Re: What kind of plugs/gap would you suggest for my applicat

Crap shoot? Always worked for me. I guess some are better at tunin than others.

 

[Pontiac455]

Re: What kind of plugs/gap would you suggest for my applicat

When ya cant have daddy there to give ya the money for someone else to tune er for ya on the dyno ya have to impervise. Another trick I use cutlass is install a 1 wire O2 in the exhaust and read the voltage it produces with a meter at differnt times. Ya can tune the carb almost perfect if ya can coralate voltage with fuel air ratio.

 

[olds307 and 403]

Re: What kind of plugs/gap would you suggest for my applicat

Get the NGK XR-5 or XR-45 for your 403. Honestly, I had regular AC, the rapid fire, Bosch Platinum and Autolite plugs in my Olds 307's, 350 and 403. The regular AC and Autolite are OK but I noticed smoother running with the NGK. The rapid fire foul easy. I have ran .060" and .080" gaps before, run .045". Try the XR-5, the higher the number, the colder the plug with NGK. I am running XR-5 in my 8.3 to 1 Olds 403, thinking a touch cold for my low compression. The XR-45 are doing fine in my TBI Olds 350 powered 94 4x4. Just under 9 to 1 but no high temp towing yet. I am betting on low 300's hp, if you have headers and more importantly pushing 400 ft/lbs of torque.

 

[pontiacgp]

Re: What kind of plugs/gap would you suggest for my applicat

Crap shoot? Always worked for me. I guess some are better at tunin than others.

Unless you can dyno it to see what hp you have with different gaps it is a crap shoot to gap it other than the spec gap. The method I mentioned using a dyno is what they used on the nationwide car and the craftsman truck a friend of mine drove. He mentioned they got the highest hp with a champion plug but they never tested it for durability. Different plugs would give you different hp at different gaps.