Hi,

I checked the old messages however I couldn't find any message specifically about my problem.

My engine is currently stock (i have a cold air intake and full exhaust without cat)
I'm going to replace my spark plugs. Bosch plugs are only ones I'm able to buy for the moment. However I couldn't decide which type to buy.

What is the meaning of +4s , +5s etc. ?
Which one would be the most suitable for my engine?

Thanks

 

Neither. Get the plain jain AC delcos. You will be much happier when they last more than a few thousand miles. If you must get Bosch stick with the single elctrode ones. No need to spend lots of money on plugs that are not a good match for our HEI's.

 

Get the regular Bosch, or the platinum Bosch. Both should be single electrode. The regular Bosch plugs are as good as the AC delco ones, but because of the past debates on this board, when anyone hears Bosch, they immediately think of the Platinums.
The platinums are very good if you want to leave them in there for 100,000 miles (yes they actually can, though I wouldn't).
The problem is that if you put an aftermarket ignition in the car, you then can not use the platinums as there is too much resistance introduced into the system. HTH.

 

The ones that say "Champion" on them. If you've waited a day to get an answer, you probably could have found decent plugs by now, and would not be stuck buying the Bosch parts.

 

You could also save a good chunk of change as the +4s are damn near $6 and standard Delcos are .99c.

And the +4 simply means that there are 4 ground straps in relation to the electrode. +2 means that there are 2 ground straps.

 

The basic bosch platinums will be fine if you have to. They will not work if you are using an MSD box or other product for your ignition.

 

The only thing I dont like about the bosch platinum single electrode ones is the damn screw on terminals. They always back off and cause big problems. Other then that theyre a good long life plug for a stock or near stock application.

 

I found that in my 91 ta 5.0 5speed tpi Bosch +4 works the best it means it has 4 prongs on the end istead of just 1 like most spark plugs the are expensive but most likely you won't have to replace them again unless one fouls out..

 

never use a bosch plus four, ive seen huge warranty claims when i was in the parts business, the plug burns uneven and chunks of porcleain fall off into the cylinder wall,

also the plus four is a gimmick, electricity takes the shortest route, it will only jump the shortest gap of the four terminals until the gap is opened larger then another gap, then it will jump another gap until its opened up

finally i don't care what you say, never put a bosch plug in anything

 

For a moment there I though Capt Picard was back around, but no, that was two years ago.

 

I don't know for sure but this guy is from "Turkey" and maybe he dosn't have a very good choice of other spark plug brands??

Auggie

 

Yes, Bosch is the most eaisly obtainable plug for me. It's available everywhere here. Acdelco and other brands are very hard to find here they're sold for 3-4 times the price of bosch plugs.

 

2 years ago i put bosch in my formula and it ran find for about 3,000 miles. after that it had performace problems. it ran like crap. I pulled the bosch out and put back good old AC delco and it ran like a champ again. I WILL NEVER USE BOSCH IN A THIRDGEN EVER..

 

bosch plugs suck... delco all the way.

in my experience small block chevys dont like anything other that regular delco resistors. even delco plantinums seem to screw them up. at least the older ones like mine

 

Well, that could be true but my NO2 fed (150 shot) 355 has NGK UR-5's that I installed in 1995 with a set of Accel 300+ wires. Hasn't missed a beat and the UR-5's are the short plugs that work great with headers.

Auggie

 

+1 I am in the parts buisness as well and all I have to say is Bosch is CRAP. Period. End of story. Go with AC Delco Rapidfires , my new favorite.

 

I'm around here somewhere!!! Escaped the Borg and now back at the helm..