You stated that each time you changed optis, you changed spark plugs. Correct? Do you use the same type plugs each time? What do you set the gap at? I don't know if it is just the picture, but that gap looks really wide. Never tried the platinum plugs--I always stick with Autolite and they have a good reputation. NGK is a good one too. I think I would just stick another brand of plug in there just to try and see what happens.

Hang in there Bro, we have all been there-- thinking of going old school. Carbs and regular distributors were pretty reliable.

One thing with trouble shooting, make one change at a time to see what works or doesn't work. Lastly, the last opti I put one was the one from Petris. I know you can't go by looks, but it appeared to be a quality piece and I don't think it was any more expensive than the AC Delco. I think they really have their act together.

 

Yes for the most part, when the opti before my current one died I got new plugs. Yep same plugs and same time gap each time. I agree on the NGK plugs being a hood choice. I've got a spark tester and I'm going to use it on each driver side cylinder to try and narrow down a possible issue. Hopefully that will help get me a step in the right direction. Yea the Petris seems to a good opti, considering my options if the opti is really dead, I'll go with a unit from the Ebay seller described above since it's got the Mitsubishi optical sensor.

Thanks, Grant

 

Its been a while since I pulled the plugs on an LT1 but that gap seems huge. With added cylinder pressure from the hotcam, why not try tightening up the gap to 0.035" from the stock. When I out the 846 cam in my car tightening up the gap improved driveability significantly. Its a free fix if it works so it might be worth a try.

Also, are the plugs you're running the same heat range as stock?

 

Yea I think I'll end up tightening up the gap a bit probably, gap on those plugs are 0.045. The heat range for these plugs is a fourteen and to be honest I have no idea what stock is. I'm really having trouble finding it as well online. Is there anyone that knows the stock heat range off the top of their head?

Thanks, Grant

 

Not all plug manufacturer's use the same basis for "heat range". You have to use a conversion chart to compare brands.

Factory plug recommendation, per the factory service manual - AC Type 41-943 gapped to 0.050"

I strongly recommend the NGK Iridium plugs for normally aspirated applications. Superior to double platinum plugs. In fact, it was common for the stock AC Delco double platinum plugs installed by the factory to lose one or both of the tiny platinum pucks - mine did, and end up with huge gaps that caused misfires. Hopefully AC Delco has improved them over the last 20+ years.

Stock heat range NGK would be the TR5. The iridium plug is TR5 IX (7397)..There is also a TR55 IX, (7316) which is pregapped to 0.50" (always check gap before installing). A slightly cooler plug would be the TR6, but that would be useful for a bit more HP than you are probably making, or a power addeer.

 

Grant

NGK TR55 gap at .050 or Autolite 104

A mail order tune based on your mods would be what you need to do to allow the car to run right with the mods you hve assuming you don't have some mechanical or ignition issue Solomon or Jesus Christ can't make the car run right with a tune if there is a underlying mechanical problem

If you have never taken the cap & rotor off the look inside a opti you should to confirm it does not have any oil inside. leaking WP drive seals or the rear bearing on opti worn will get oil inside the opti and once it does get on optical sensor you will have misfire. Opti can be easily cleaned if this happens

 

Ok awesome that's just the info I needed. I knew that the heat ranges vary between each manufacturer but I couldn't find a conversion chart with AC Delco and NGK on it. I'll end up swapping over the NGK's then, what gap do you believe suits my needs best? Just the stock 0.05" gap?

Thanks, Grant

 

Yep I definitely agree, unless the car is mechanically sound completely then a tune is almost a total waste of time and money. That's why I'm trying to track down the issue before throwing any money at that. Seems at this point I've got a few places to check for issues later today. I absolutely hate doing plugs on these cars, the driver side is ok but once you get to the passenger side you can't even see crap, let alone get a spark plug socket on one.

Thanks, Grant

 

So would the sticky method for testing a bad opti work for me if the car runs? Or with my plethora of possible issues is it not very accurate?

 

Do you have one of these shorty sockets?: https://www.summitracing.com/parts/sle-30102
I've just gotten to the place where I just drop the starter out, zip tie it up out of the way and then I can get 4,6,8 easily. Takes less time to do that than fooling around trying to get them from the top. #2 is still tough no matter what--get that from the top.

 

I don't own one unfortunately, I'll see if any of my local parts stores have any in stock or I'll just end up getting that guy. Yea dropping the starter out is the best option as I've noticed. #2 is just the problem child for sure. Thank you for the info, will definitely help when I swap the plugs over real soon!

Thanks, Grant

 

Those tests are more geared for a car that is not running.

 

Ok gotcha, that was my assumption unfortunately

 

Ok gotcha, you think keep a gap of 0.05" with the cam as well? I'm going to try pulling all plugs and then going from there but I need a break from school before I can go much further.

Thanks, Grant