AAAAAHHHHHHHHHHHHHH!!!!!!!!

Just fitted an ex race cylinderhead (I thought it all went too smoothly), anyway, it wouldn't start, lots of messing around, blah, blah, blah....

Took out spark plug to see if fuel was getting through and the electrode has been in contact with the piston head and compressed it

It must be out by about 1mm, I'm using Champion RF7YCC plugs, they don't have a crush ring on them that I have had with other cars, is this the same for all pinto plugs? do NGK have crush rings? Mine champions measure 16mm from seat to electrode tip, are others shorter?

I have the SpeedPro Pinto book and it mentions that this can be a problem, and that using 10mm plugs with new seats fitted is an option, are these seats easily available? where from?


Help appreciated.


Alex

Pinto plugs are taper seat ONLY.
Make sure you fit new ones when engine & plugs are both cold. I have know them to be nearly impossible to undo because of over tightening when fitting cold plugs into a hot engine.
If your plugs are makeing contact with the pistons then there is a possibility of valve to piston contact.

Hi alex,

Pinto plugs dont need the compression washers as they seal on a taper cut into the head.

If the head has been skimmed, the plugs can contact the pistons.

You can buy the adaptors to use motorbike 10mm plug from vulcan engineering who do sell stuff on ebay occasionally:

http://cgi.ebay.co.uk/Ford-Pinto-Spark-Plug-Adapter-Inserts_W0QQitemZ270092628124QQihZ017QQcategoryZ21654QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

But give them a call, they should be able to sort you out.

http://www.vulcanengines.com/

David

7 Mins and 2 replies!

Thanks guys, I checked valve clearance and that seems fine (granted a lot closer than Ford intended ).


Looks like plug adapters it is and they are not cheap, oh well (better not tell the wife)..... I'll try the wanted section over night, nothing surprises me with this place, might just get lucky!

Burton stock sparkplugs which are "short tip", anybody had any experience of these?

At £3.25 each they seem a lot cheaper than adapters.

Cheap trick is to mark on the plugs ceramic insulator the point where the elbow of the electrode is, make sure you can see it when its in the head, if the mark indicates that the elbow is down then it will contact the piston, 90 dgs either side and you should be ok, straight up and your well clear.
To have clearance problems of this nature means that you probably have a decked block as well as a heavily skimmed head.
What compression ratio have you got?
The plugs still have to be fully in the head, its the production tolerance that means the elbow of the electrode could be up, down, left or right. Its just luck but cheaper than the inserts, which i think are not just a screw in option but need to be machined in and ground back to fit.

[Edited on 12/3/07 by snapper]

quote:

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Originally posted by se7ensport
Burton stock sparkplugs which are "short tip", anybody had any experience of these?

At £3.25 each they seem a lot cheaper than adapters.

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quote:

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Cheap trick is to mark on the plugs ceramic insulator the point where the elbow of the electrode is, make sure you can see it when its in the head, if the mark indicates that the elbow is down then it will contact the piston, 90 dgs either side and you should be ok, straight up and your well clear.

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The head is heavily skimmed, probably by 2-2.5mm, the block is untouched, it's off an ex hotrod, I've used a Felpro Blue head gasket (thin and strong) no exact compression figure but it's going to be around 11.3:1 (octane supplement might be required )

Interesting regarding the plug tricks & different lengths, hope for a cheap solution is out there.
I've broken two of the plug ceramics so need new ones anyway, I'm going to try shorter plugs and combine it with the marking them to ensure the electrode points down as the first option.



Cheers all

Alex

another thing to investigate is to compare different bands - they surely cannot all be identical dimensions?

or a way of raising the seat - a copper or an aluminium washer say, that deforms to the taper when screwed in? (dunno if it will keep the plug screwed in tight)

or thin the electrode down 0.5 mm? (probalby not idea since the smaller amount of metal will mean it is hotter so could give pre-ignition).

or take a plug, know out the inner ceramic core, trap for smaller 10 mm plug?

or use those colour tune brass plug adaptors or turn something similar on the lather?

or ...... ???

Just spoke to Burtons, the short tip plugs are the answer, apparantly the electrode is basically flat with the top of the plug and will not hit the piston no matter how much the head is skimmed.

Part number or those interested is: NGK A7FS (for fast road use).



ps. I like the colour tune idea, cheap and effective.