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Helicoiling of spark plug threads. 1850.
Posted: Sun May 17, 2020 12:05 pm
by MIG Wielder
Is it possible to Helicoil a spark-plug thread with the head still on an 1850 ? I've seen a generic Helicoil tap that does not need a drill and there are 2 You-tube videos that show that this can be done. One by using a high pressure air-line to blow out the swarf and one by using a heavy grease on the tap to catch the swarf and doing it one turn at a time.
What do you reckon please ?
Thanks very much,
Tony.
Re: Helicoiling of spark plug threads. 1850.
Posted: Sun May 17, 2020 12:55 pm
by new to this
I think for spark plug holes your better to use time serts ,my brother had one fitted on his Stag while the head was still on the car
Dave
P,S time serts are solid where Helicoils are round wire coils
Re: Helicoiling of spark plug threads. 1850.
Posted: Sun May 17, 2020 1:02 pm
by cleverusername
My advice is be very careful. I have ruined a head trying to fit an insert. I didn't have a bench drill and tried to drill it by hand. Slightly off square meant the sparkplug could no longer gas seal in the head.
Even if there is a method that uses a tap, it must involve removing material to make room for the threaded insert. Only proceed if you are certain you can tap/drill the hole absolutely square and straight. If you have any doubts about that, take the head off and use a bench drill or get a machine shop to do it.
Re: Helicoiling of spark plug threads. 1850.
Posted: Sun May 17, 2020 1:22 pm
by soe8m
Yes you can. I have a tap specially for inserts. The first part is the original 14mm thread to follow the plug hole and centre, the following step is a roamer and the third is the oversized tap. It's a one piece tool and it's just a matter of screwing into the existing plug hole. It's "plug" size and the hex at the end is also plug size so when there's room for a sparkplug there's room for the tap.
Never use grease when tapping in alloy. Use only thin lubrication like wd40 or similar to have a nice sharp thread in alloy.
Jeroen.
Re: Helicoiling of spark plug threads. 1850.
Posted: Mon May 18, 2020 9:06 pm
by MIG Wielder
Hello All,
Thanks for your replies.
I found the combined M14 / Insert centering drill here.
Brilliant product ...
https://www.ebay.co.uk/itm/Time-Sert-44 ... SwwvZZVqLC
... but the cost is quite high and what really defeats it are the import charges
Thanks for the hint on WD40 to get a good thread ! I like the idea of the Time Serts.
Cheers for now,
Tony.
Re: Helicoiling of spark plug threads. 1850.
Posted: Mon May 18, 2020 9:37 pm
by new to this
soe8m wrote: ↑Sun May 17, 2020 1:22 pm
Yes you can. I have a tap specially for inserts. The first part is the original 14mm thread to follow the plug hole and centre, the following step is a roamer and the third is the oversized tap. It's a one piece tool and it's just a matter of screwing into the existing plug hole. It's "plug" size and the hex at the end is also plug size so when there's room for a sparkplug there's room for the tap.
Never use grease when tapping in alloy. Use only thin lubrication like wd40 or similar to have a nice sharp thread in alloy.
Jeroen.
I would put grease on the tap ,that way as you tap the thread the grease well stick to any swarf
Dave
Re: Helicoiling of spark plug threads. 1850.
Posted: Mon May 18, 2020 10:25 pm
by soe8m
new to this wrote:
soe8m wrote: ↑Sun May 17, 2020 1:22 pm
Yes you can. I have a tap specially for inserts. The first part is the original 14mm thread to follow the plug hole and centre, the following step is a roamer and the third is the oversized tap. It's a one piece tool and it's just a matter of screwing into the existing plug hole. It's "plug" size and the hex at the end is also plug size so when there's room for a sparkplug there's room for the tap.
Never use grease when tapping in alloy. Use only thin lubrication like wd40 or similar to have a nice sharp thread in alloy.
Jeroen.
I would put grease on the tap ,that way as you tap the thread the grease well stick to any swarf
Dave
You can't make a thread with grease on a tap.
Jeroen
Re: Helicoiling of spark plug threads. 1850.
Posted: Mon May 18, 2020 10:35 pm
by soe8m
MIG Wielder wrote: ↑Mon May 18, 2020 9:06 pm
Hello All,
Thanks for your replies.
I found the combined M14 / Insert centering drill here.
Brilliant product ...
https://www.ebay.co.uk/itm/Time-Sert-44 ... SwwvZZVqLC
... but the cost is quite high and what really defeats it are the import charges
Thanks for the hint on WD40 to get a good thread ! I like the idea of the Time Serts.
Cheers for now,
Tony.
Well, mine was around and similar to this.
https://www.amazon.ca/OEMTOOLS-25647-Sp ... B000CMHL1C
https://www.ecstuning.com/b-heli_coil-p ... 33414~hec/
Jeroen