1quik6

Just installed a set of Headman headers 68306 on the 64 vette. I was using AC Delco R45 spark plugs, but now have clearance issues with the headers. I've been searching on this site on which short spark plugs to use with these headers but there is no clear answer. So which short spark plugs should I use if I had been using the R45 plugs? TIA

Westlotorn

At the risk of getting schooled by fellow members I will share that some have used Lawnmower plugs to fix this clearance issue. Take a look they are much shorter and give you another 3/4 inch to work with for wires. Be sure to look at the plugs you choose to make sure you are very similar in heat range. Wrong heat range = melt down or cold blooded. If you can't find a heat range I know a guy that was the Champion Performance Rep, he is actually the one that originally told me they work and many use them. He probably has the part number in his head.

LB66383

Accel makes a shorty plug to work with headers. I believe the number for a SBC is 837, but doublecheck that. Some guys here don't like them, but I've been using them for quite awhile and have had no problems.

1quik6

Went to an ac delco auto parts store in town and the auto parts guy told me that an ac delco LM46 would be the short plug to use. It is a lawnmower plug & the package had " not for automotive use". It looked like the same plug but shorter. Was hesitant so I didn't purchase the plugs.

1quik6

I went to the Accel website and found Accel #437S. They also make a racing spark plug silver tip, don't know if it will work on stock heads. Their info. shows for aftermarket heads. Seems like that would be a better plug if it will work with stock heads?

1quik6

Westlotorn,
Could you check with your buddy (Champion Rep) on the part no. for the short plug to use? Seems like no clear answers on this topic. TIA

Westlotorn

I called my buddy, caught him boarding a plane in Dallas heading for Florida. He said Champion stopped producing the Short Header Plugs and Accel is about the only one still making them, he claimed Champion failed to market the plug to the Performance market and they failed to sell making them go out of production. I did not get to ask about the Lawnmower plugs he was out of time.

I found notes in another forum claiming the part numbers below work.

Again this info is un verified from another forum but maybe you can pull infor from this list.

A user wrote in looking for short plugs to replace the OEM AC R45 plugs.

Use Champion # RV92YC or #RV91MC for 1 step colder for your shorty plug application.

Autolite 133 or AR133 for the tapered seat. J4C champion for fuelie type heads flat seal ring.

The Short Plugs Are Accell#8197/0437