OHC oil restrictor pin

[Alice]

I need sketch and dimensions of the cylinder head oil restrictor pin, also the diameter and depth of the hole it fits in.
I have a cyl head with the pin frozen solid in it and the outer end broken off. I'm thinking of drilling it out, since it appears to be brass, and making a new one, but don't want to risk drilling into the head casting. Help Please!

[Ian Grace]

Barry,

I suggest you contact Mike Dowley at Sports & Vintage. He can supply you with a new restrictor pin and also advise on the diameter. Mike can be contacted at mike@sportsandvintage.co.uk or mike@mmmspares.co.uk.

You should also order a new gasket for the oil pipe that bolts over the pin and I would also ask Mike to supply you with a new BSF bolt to secure the pipe at the top. This fitting has to be well sealed and tight, since the p\oil pressure can be in excess of 100 psi and this joint is prone to leak. I once had this problem and this bolt sheered off flush in the head while I was trying to nip it up, so fitting a new bolt while the joint is apart is a sound investment.

Cheers,

Ian

[martinng]

From what I remember the last time I checked the restrictor pin, it is not brass but steel so drilling out would a little more difficult.
As Ian says Mike Dowley will have all the info.
Martin

[Ian Grace]

Should be brass (or bronze), Martin.

[Alice]

Thanks for your posts, fellas. The pin in question is definitely brass. However in new developments I have checked a second cyl head, which is sans pin, and after cleaning the mud-hornet clay and oil gunge I can measure the hole. Also in amongst the myriad bits and pieces that I have I've found a brass item that I believe is a restrictor pin!
This is 2.7 inch long with 0.35 inch each end machined to 3/16 inch dia and having a cross-drilled hole. I've read somewhere about pulling the pin out "with a bit of wire in the hole in the pin end" . The central 2 inch length of 1/4 inch dia has a milled flat along its length. Calcs reveal that this results in about 90% loss of cross-section in the main portion.
Furthermore I have found that the hole in the head is indeed close to 2.7 inches deep.
So if all of this sounds like I am on track, please let me know. Meantime I will persevere with drilling out the offending item.
Cheers.

[Ian Grace]

Yup - that is the correct item! The holes each end are for inserting a wire to pull the pin out, just as you suggest. So, whichever way you put it in, you can always pull it out - always supposing that the end doesn't come off!

Ian

[martinng]

Ian, you are of course quite right. I have just checked and my restrictor pin it is indeed brass.
Sorry to add confusion.
Martin

[Alice]

Just to close this out; For the benefit of anyone who has to fit a pin in a crappy old head, be advised that at the bottom of the 1/4" hole in the head there is a 3/16" hole, to accept the small end of the pin. I found this out the hard way when my 2.7inch pin would not fit properly in a hole measured at 2.7 inch with the depth-measuring end of the vernier calipers! A few quick twists with a 3/16' drill cleaned it out and all's well.