Earlier this week we tried to go for an evening cruise in Martina, as we often do on the nice evenings. This time though, she wouldn't start. She tried, but wouldn't catch. Before that, she had been running perfectly since the rebuild (600km before) - more power, smoother running, good acceleration, etc...

Today I finally got around to troubleshooting her and came away utterly defeated.

First I pulled the fuel line to check the pump, as it was the most recent change. It pumped fine, so next was the ignition. Checked the static timing and wire continuity - all good. Next up were the spark plugs. Pulled the #2 plug and it looked a little fouled (see bottom-right pic), but nothing an Italian tune-up couldn't sort out, or so I thought (I was going to check the compression to make sure I wasn't getting too much blow-by). Pulled #1 and the Timesert insert came out with the plug (top pic). F@#k.

I cleaned and chased the threads and attempted to install a new insert. No luck. The threads in the head wouldn't grab and the insert would just spin and spin (threads in bottom-left pic).

So here I am, back to square one, and need to pull the whole motor apart and hope the machinist can install some bulletproof inserts in the messed-up threads I'm stuck with. If not, all that head work (intake valves, porting, surfacing) was for naught... and now I'm missing all the good driving weather. Days like this are really a kick in the teeth and make it hard to not walk away from this hobby.

You can remove the head with the engine left insitu Matt. Put a jack under the sump, and remove the rear cross-member. Having the jack under the engine, and with the rear cross-member removed allows you to drop the engine enough that with a bit of dexterity you can get to the thermostat housing bolts at the front /rear of the engine, remove the housing and then remove the head. I do feel for you---what a bummer, but a GOOD engine shop should be able to rescue the head for you. Let me know if there is any way that I can help you.
Tom

So sorry to hear of your tribulations Matt. It can be really demoralizing but, chin up, don't let it get on top of you. From what I've seen of your posts you've made a really grand job and done some very fine engineering with this project, try to look on this as just another wee challenge!

I agree with the hobbler that this can be recovered by an engineering shop which knows what they are doing. A friend once had a completely stripped sump plug hole in an aluminium sump - so a very similar situation technically to yours - repaired by a welder friend by building up with weld and then re-tapping. I've also heard of the hole being enlarged and a custom made plug/sleeve (not sure what you would call it) screwed in so you end up back with the correct size for the plug threads. Bit like a large, custom made, thick walled, Time-Sert. Looks, from your photo (bottom left) like there is enough "meat" to do this I think - and shouldn't be cripplingly expensive - maybe half an hour in a lathe? By the way I think Time-Sert themselves actually make thick walled inserts specifically to deal with problems like this? Hey, I just found it, called a "Big-Sert" - what else? See here: http://www.timesert.com/html/bigsert.html

Whatever "cure" you end up with I wish you good luck and please do keep us up to date with how it all pans out won't you?
Kindest regards
Jock

I was finally able to get the motor out and the head off. Hopefully the machinist can get to it sorted in short order.

With it off, I can see it was running pretty rich with the FZD on it. For the FZD savvy folks, what kind of jetting are you running? The motor is a 595 with a 75/35 cam and ~8.8:1 compression.

Before the no start that lead to the troubleshooting that lead to the stripped out plug, I had checked the idle with the Colortune and it was spot on. The plugs were NGK BP6HS.

Looking for opinions… jetting? Hotter plugs? Thoughts?

Thanks!

Hi Matt;
The settings that I have are for a 30/24 FZD on an Abarth '595'. They are:--
Main:--128. Idle:--38. Air correction:--190. Accelerator pump:--40. Emulsion tube:--6747-6. I have found that if too big a 'pump' jet is fitted, it will look as if the engine is funning rich; you want the leanest 'pump' jet that will give you smooth acceleration. ALL the FZD carb for the 500 derivatives have the 6747-6 emulsion tube. If you can't get a '6' emulsion tune, the '1' can be brought to the same specification by CAREFULLY soldering up the top 2 holes (1 per side),making sure that the central hole doesn't become blocked with solder.

Oops,forgot to add---I also use BP6HS plugs. Your head doesn't look as if has been running too rich.

Just a thought but maybe a "Big Sert" would get the job done? depending on how much "meat" is left around the hole? https://www.timesert.com/html/bigsert_sparkplug.html

Many years ago my local engineering shop repaired the sump plug hole in a 1500 Allegro engine for me (cast ally sump) by welding extra metal around the hole, drilling it out and retapping it for me. The cost of the actual repair was very reasonable but they needed the bare casting to work with which meant stripping the gearbox from the engine (It's a bit like a "big" Mini with the gearbox "in unit" under the engine) so a lot of labour was involved - which luckily I could do myself so only gaskets etc to buy. I think now a days I'd use one of those oversize repair kits, like this sort of thing https://www.machinemart.co.uk/p/clarke-cht800-drain-plug-thread-repair-kit/

I dropped the head off at the machinist today. He's got some serrated inserts that thread in, then are staked via a punch on the perimeter. Similar to aviation spark plug inserts I believe. I'm having him go ahead and do both plugs, even though the other one didn't fail, just so I don't have to worry about it.

Fingers crossed.

Hi Jumpjet,
there are threaded solid Inserts called "Keyserts" which have Locking Pins you drive down into place once the Insert has been fitted.
The Pins stop the Insert unscrewing like what has happened.
Alan

JumpJet said:

I dropped the head off at the machinist today. He's got some serrated inserts that thread in, then are staked via a punch on the perimeter. Similar to aviation spark plug inserts I believe. I'm having him go ahead and do both plugs, even though the other one didn't fail, just so I don't have to worry about it.

Fingers crossed.

Click to expand...

Hi Matt, I had a 'slight' problem with the threads in one of my plug points so got my engine man to fit steel inserts - no problems at all and I'm running 10.5:1 CR
Ian.