The Stovebolt Site Forums The Shop Area Engine Shop Plugs for a 235 with HEI?

I'm messing around with a 235 from the casting numbers the block shows to be a 55 w/powerglide, the head shows to be a 53. The vacuum advance is bad and I was going to replace it but decided to go HEI with it. Question being I removed AC R45TS plugs and was curious what everyone else used or recommended. Just FYI the plugs were all super clean and really didn't look like they had many hours on them.

Re gap them to .045 & reuse them.

Aren't R45TS tapered seat? Shouldn't it be R45S? Tapered seat plugs weren't used on 235 heads. (And yes... I may be all wet on this.)

Well I can tell you for sure they are R45TS and are tapered but they were in there. What made me run the numbers was the fact I had a 13/16 plug socket in hand and was surprised to see the R45TS. I'm guessing the PO put the plugs in to cure a miss, which was caused by the vacuum leak at intake and advance. BTW that little ball was fun to find for TDC but I took HRL advice and watched the valves, then I found it.

The 235 heads used a spark plug with a flat steel washer, and if you look close the hole will have a flat surface for that seal to go against.

It does, It's just amazing what you will find sometimes. I'll pick up the correct plugs and some new wires.

The tapered seat plugs will run WAAAAYYY too hot because they can't transfer heat to the head properly. They'll fail within just a few miles and give the engine an intermittent miss that's hard to isolate. R45 plugs gapped to about .040" ought to work very well with the HEI. CR45 commercial plugs will work even better, but they're almost impossible to find now.
Jerry

Thanks guys, the R45 it is then. It actually was running pretty well. The intake took care of the V-Twin shake at idle. If all my parts come in I might have it ready by the weekend and drive it to the swap meet on Sunday. LOL.

Good observation Roy. I missed that TS type plug. I still prefer the extended tip plugs like R45S.

When I got my HEI setup from Tom Langdon, his recommendation was AC R44SX's, and I believe I have mine gapped at .060. The "X" suffix was for extended gap, which is necessary for HEI.

When HEI first came out Chevy used the .060 gap plugs. We experienced some frustrating damp weather starting problems. They changed the specks to .045 & it solved the problem. They seamed to work OK on Buicks & olds.

The .060" and .080" gaps were needed because of the extremely lean mixtures they were trying to run in the late 1970's. Cadillacs in particular would develop an intermittent miss at .045", and run right at .080". There was a better chance of a little bit of fuel ending up between the plug electrodes with a wide gap. They finally richened up the mixture and reduced the plug gap in the late 80's.
Jerry

Thanks for all the help guys. The HEI is in with the R45S @ .045. She fired right up and I dialed her in at TDC with vacuum at the can she'll advance another 10 deg. Throttle response is good and no pinging under load. I guess I'll see how long I can put up with those lifters ticking before I attack them. Everyone else thinks it sounds fine and I am a little anal about it, but hey.

Just remember that "a noisy lifter is a happy lifter".

I bought my HEI from Langtons with plugs and he supplied SJ18YC6. Runs great with these.

I got the HEI off of ebay and used the R45S plugs. It all worked out fine and made a world of difference. I'm happy with the results. Since the shipping was free I have less than a buck and a half in the conversion.

If those lifters are solid, they need to do a little ticking.

Yea, they're hydraulic