Helicoil Size

The Old One · Postby **The Old One** » 18 Jun 2012 18:19

Hi all
I am rebuilding a sprint head,one of the rocker bolt holes is stripped.Could someone please tell me which size helicoil kit i will need to repair this or is there another option.

Many thanks

Tony

trickyx12000 · Postby **trickyx12000** » 18 Jun 2012 18:34

hi. without trying to sound rude...
if you don't have the tools to find out wot the thread form is, i think you would be better to go to a local engineer/ machine shop, it could be alot cheaper in the long run.

john 215 · Postby **john 215** » 18 Jun 2012 18:35

Hi Tony,

1/4 UNC is the thread size and i too would helicoil it.

Cheers John

LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC Beauty

1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6,ON THE ROAD NOW KICKING AR5E !!!!

The Old One · Postby **The Old One** » 18 Jun 2012 19:25

Thanks John,much appreciated.

Tony

Marko · Postby **Marko** » 18 Jun 2012 20:18

you take the helicoil kit of the same size as the original bolt.

drill bit in the kit is 0.5 mm oversize of the root of the thread, so it will fit even if you compleatly strip the threads.

Shauniedawn · Postby **Shauniedawn** » 19 Jun 2012 07:07

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by john 215

Hi Tony,

1/4 UNC is the thread size and i too would helicoil it.

Cheers John

LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC Beauty

1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6,ON THE ROAD NOW KICKING AR5E !!!!

<hr height="1" noshade id="quote"></blockquote id="quote">

John, I think you are both at crossed wires. Or it could be me.

I think one of you is talking about the cam cover (John), but I think he means the rocker shaft that bolts to the head. I'm at work and can't check, but I'm thinking the size is 5/16" UNC. Possibly 3/8". My gut feeling is 5/16".

Shaun

Beans · Postby **Beans** » 19 Jun 2012 08:35

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Shauniedawn

... My gut feeling is 5/16" ... <hr height="1" noshade id="quote"></blockquote id="quote">
For the rocker shaft caps your gut feeling is correct [;)]
And the thread size for the cam cover is 1/4" UNC.

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My full Weblog[/url]</center>

The Old One · Postby **The Old One** » 19 Jun 2012 17:58

Sorry if i confused anyone,it was the rocker shaft cap bolts.
Thanks for the replies
5/16 it is then

Tony

trickyx12000 · Postby **trickyx12000** » 19 Jun 2012 18:16

o for a zeus chart!!

Beans · Postby **Beans** » 19 Jun 2012 20:22

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by trickyx12000

o for a zeus chart!!
<hr height="1" noshade id="quote"></blockquote id="quote">
What's a zeus chart [?]

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My full Weblog[/url]</center>

trickyx12000 · Postby **trickyx12000** » 19 Jun 2012 21:07

zeus charts...
that will be the little book that engineers etc have in their top pocket,
and with in the little yellow and black book is all the data to work out what all most any thread is. and gives you the o/d, core, pitch, depth, radius, effec. T.P.I. and clearance sizes for a thread in question.
as well as metric and imperial equivalents,
letter drill sizes( thats sizes inbetween standard sizes).
hardness comparison table( and thats not outside the pub on a saturday night). its a table of cross over results for a test to see how hard the surface is on say your cam followers.
and much more.
and with a bit of looking you get to see things that if you havent got a 1/4 unc a 1/4 whit is very close and can be used. but if you need a 1/2 unc a 1/2 whit is no good as there is one tooth per inch more.
its a book of standards that every thing should be made to engineering wise!!

Shauniedawn · Postby **Shauniedawn** » 19 Jun 2012 22:04

Used mine only just this last weekend.

Here's a PDF version you can download:

http://forums.lr4x4.com/index.php?showtopic=4463

Shaun

dursleyman · Postby **dursleyman** » 19 Jun 2012 22:44

I remember those, we always had one around the toolbox or the garage, but can't remember where I saw it last.
Talk about blast from the past.

Russ

1980 TR7 Sprint DHC
Dursley
UK

trickyx12000 · Postby **trickyx12000** » 20 Jun 2012 06:00

Talk about blast from the past.
just like a drive in a tr7...
but still as usefull when working on a car which bounces between metric and unc/unf and bsp!

well it was the way i was taught to do things in the manufacturing group that made the cars in the first place[;)]

Beans · Postby **Beans** » 20 Jun 2012 07:59

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by trickyx12000

zeus charts... <hr height="1" noshade id="quote"></blockquote id="quote">
<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Shauniedawn

... Here's a PDF version ... <hr height="1" noshade id="quote"></blockquote id="quote">
Thx for the info guys, might come in handy in the future [:)]

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My full Weblog[/url]</center>

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Helicoil Size

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