Need some help or advice.  I just had my 2.0 for my sandrail rebuilt and the only pistons I could find (and afford) were a set of NOS TRW dome tops that had been sitting on the shelf at some shop for years and years after someone dropped them off  to have the rods pressed on but never paid for them.

The motor is now back together and almost ready for me to fire it up....but I've run into a problem.  My spark plugs are hitting the pistons.  

Last year before the motor blew up I had to switch from Autolite to Champion plugs because the Champion were just a hair shorter and for some reason the plugs had suddenly started hitting the pistons mid-season.  No changes to the motor but suddenly at the end of a day I'd pull a plug and the electrodes would be touching and there'd be a small scar on the piston top....that was with stock pistons.

But the motor had other serious issues (bad valve guides and incorrect rocker geometry) which lead to lots of oil in the combustion chambers and eventually blew a hole through the #1 piston.

I'm thinking about fnding some 18mm to 14mm plug adapters but the only ones I've found are sold by Aircraft Spruce for planes and they want $60 which is more than I can spend right now (Just broke the bank paying a well respected shop to build this motor!)

Anyone have any suggestions?

Tried that last year.  But since they're tapered seat plugs they won't stay tight with indexing washers added.  They work loose after less than 10 minutes.  

I just tried installing the anti-foulers to move the plugs back for a test fire and found out that even those are apparently extending into the head too far since I can no longer turn the motor over by hand once they're installed

Heck, the $60 18-14mm adapters are less than it would cost me to have a machine shop put reliefs into the pistons.  And that's not something I'd be willing or able to tackle myself.  

However things may not be quite as bad as I thought....I pulled the plugs and anti-foulers back out and still can't turn the motor.  So something else is locking it up.  Which is odd because two weeks ago (the last time I touched it) it turned over fine and nothing's been touched since then.

All I can think is the tranny may have been knocked into gear...but the rail dosn't want to move as I try to turn the motor so that dosn't seem right.

I took the valve cover off and the valves on the pistons that are at TDC right now aren't open so there's no interference there (But I already spent a full weekend putting the timing belt on after learning that the new pistons will only clear the valves when everything is right - unlike the stock pistons that would always clear.)   Long story but the machine shop had put the timing belt on - but they also lost the intermediate shaft cover.  So I had to pull the timing belt back off to install the new cover I found....and then in a fit of brilliance moved the crank with the belt off.  When I put it back on I ended up putting it on with the crank at TDC for #4 instead of #1 and then I couldn't turn it more than one revolution without the valves interfering with the pistons.  Had to carefully turn the crank a little, then turn the cam a little, then turn the crank a little to get everything back to where it should be.  And it did seem to be lined up correctly now since everything was moving two weeks ago.

This motor is really getting on my nerves  Thing has been nothing but trouble since the day I bought it.  And even after it was rebuilt it still never ran right.  But that was a special deal where I got it rebuilt for free by a friend of a friend who owns a machine shop.  But he never even looked at the head even though I warned him I thought the valve guides where shot.  This time I broke down and spent almost $1500 having it rebuilt by a very respected shop and they confirmed that the head was in VERY bad shape.  They put in new guides and new valves (stepped up to larger valves at the same time)  but they managed to loose that intermediate shaft cover  

I know the head was shaved once by a previous owner back in '96 since I have the receipt from it.  But they only took off .016" which the last two places who did rebuilds said shouldn't be a noticable difference.  And neither of them shaved it anymore.  But I still had piston to spark plug clearance issues last time

I've sunk way too much into this @&*&! motor at this time and have just about had it with the @&!&!* thing.   Just when it looks like all the problems will be solved it just gets worse every time  

It's alive!  

Yesterday I finally got the last of the wiring in place and got to give it a go.  One scary moment when the timing belt jumped on the second starting attmept (I had forgotten to tighten the belt tensioner   ) but then after a few slight tweaks to the timing it fired right up!

Sounds great too!  My motor NEVER sounded this good before even after the last rebuild.  The new high compression pistons and bigger valves seem to have made a HUGE difference.  Can't wait to let the old butt dyno have some time in the seat to tell me just how much of a difference

I was a little worried that with the new higher compression and anti-foulers that I may have some detonation.... but it sounded clean even on 91 octane pump gas.  Still hoping to track down some 18mm tapered seat indexing washers or 18mm to 14mm plug adapters so I can ditch the anti-foulers....but at least it's running again!

Need a little more clearance that that will give bday.  The one I was testing with was already fitting with the electrode in the position with the most clearance.  It would go in with a .030 gap and come out with a .0015 gap.  (And not leave a scar on the top of the piston.)

I'm looking for indexing washers (or 18mm -> 14mm adapters) not so much as for the actual indexing but for the little extra clerance they can give me.

Found a solution today!  

Short version:  NKG AP8FS (2227) plugs.

Long Version:

Called the shop that built my motor and explained the situation.  They offered to tear it down, machine the pistons for more clerance, and then reassemble it for what I felt was a reasonable price...but which was also more than I have available right now.

So I explained my other two ideas to them:

1) Find a surface fire plug like those used in outboards.  They liked this idea but doubted I could find 18mm tapered seat surface fire plugs...and predicted that they'd be expensive if I could.

2) Take the 18mm->14mm adapters I bought and put a weld bead around them then machine it down to add a taper as well as adjust the depth the adapter would sit.  The felt this was probably possible but without seeing the adapters couldn't say for sure.

So....I did some major legwork (3 hours worth) today.

First I went to a good local machine shop and asked about modifying my adapters.  No go.  They said they could probably do it but unless it was my only option didn't want to try.  

Next I hit a well stocked NAPA with guys behind the counter who can do more than just ask "what car is it out of?".  No dice, but their machinist said NKG probably made a plug that would work....and told me a couple of shops to try for finding them.

First shop he recomended didn't have them.

Next shop I tried was a marine supply place since I had found 14mm surface fire plugs from an outboard...no go they only had 14mm plugs no 18mm.

Last stop was the Import parts shop in town.  They pulled out the NKG book and tried like heck to decipher it but had no luck finding a part number for me  Their usual guru was out today and the guy who helped me just wasn't very good with the new NKG book.  But he said the store right next door which deals in domestic car parts just started carrying NKG and might have what I need.

So next door I went.  Took them two tries but eventually they found the AP8FS which is an 18mm plug with a non-projected electrode,  The result is that the bottom of the ground electrode is about where the end of the positive electrode was on my stock plugs.  Which gives me almost .060" more clerance!  Perfect!

Brought them home, put them in....and the motor turns without hittind the plugs!   Almost $2.50 a plug but that's a lot cheaper than tearing the motor apart again!  

Now I just have to put the wheels back on the rail, reinstall the electronic points conversion I stole to have as a spare for my other vehicle a few weeks ago....and fire this thing up on Saturday!

I'm SUPER hyped!  I've been waiting to fire this motor up since April and now it's finally going to happen!  

And I got my custom flanges made to go with the fuel injection computer I built for it....along with all the injectors, sensors and throttle body  Can't wait to dig in on that upgrade!  

For those who are curious photos of the Injection project are here

And photos of the motor and project vehicle are here