Cosworth BDA Head Repair

[Rick Iverson]

Gents;

I bought a Cozzie head with two (2) cracks between the valve seats, #1 and #3 cylinders.

The fix: I know a gent that repairs nitro and alcohol drag heads with famously enormous success. And I might comment these heads may very well take more abuse than anything in our venue.

My thoughts:

• Have this Fella pop the seats;
• Weld;
• Send the head to THE world renowned Cryogenics specialist for treatment;
• Back to my guy;
• Blend the weld;
• Cut seat reliefs;
• Install seats.

The short story, these heads are scarce, unobtainium if you will. Thoughts?

[J Leonard]

Test the head to see how soft it is before investing time and effort.

[Rick Iverson]

James;

• To whom might I send the head to;
• What values should I look for;
• Presumably pre-welding and Cryo treatment, right?

[mark elder]

All decent head shops should be able to test hardness. If they cannot, walk away. Depending on the exact variation of Brinell testing, 90 and up is good. A good shop will test in multiple places on the gasket face. Mine come back with about 15 numbers written on various places; most heads are not uniformly hard/soft.

But many heads can be head treated to harden them anyway. Note, when someone does the heat treating have the head positioned so the valve inserts do not fall out....

I think if it was me, I would check hardness and if OK, weld, cryo and machine. Be prepared to get the seats cut again after about 10 heat cycles (they can shift and go out of round). Ask me how I know all this...

If it was soft, I would weld, heat treat and retest the hardness. If OK, then cryo. If it is soft, say 50 after heat treating, then you have a problem. Ask down stream if that happens as to what to do.

[DanW]

Contact Ken Anderson at Mountune in LA. He is ex Cosworth. Mountune now service the Cossie heads. He may advise you the hardness needed and the locations to test. A competent shop can do that for you. That might save you on shipping. info@mountuneusa.com

[jstowe]

It is always difficult to weld a head and get a decent result. A cryo treatment can help, but cannot replicate the grain structure of the original head. If you do weld, make sure you use the special A357 rod (AMS 4246E). True solution heat treating requires taking the head up to around 1000 degrees and holding it for 7-9 hrs (varies a little bit depending mag content). There is often significant movement; straightening needs to be done within a few hours after quench. The head needs to be aged after that. Every important machined surface will need to be re-machined.

If the head is going to be used lightly, you can simply peen the weld, age, cryo treat, and re-age at 325 degrees for 3-5 hrs. Peening the weld helps to reduce the shrinkage stresses. This should be acceptable for club racing.

I have been casting BDA heads for over a decade. The better the casting, the better the weld results will be. Proper chilling and solidification of the material results in closer dendritic arm spacing (DAS), which improves elongation, and it will accept the welding stresses better.

[David Clubine]

Gents;

I bought a Cozzie head with two (2) cracks between the valve seats, #1 and #3 cylinders.

The fix: I know a gent that repairs nitro and alcohol drag heads with famously enormous success. And I might comment these heads may very well take more abuse than anything in our venue.

My thoughts:

• Have this Fella pop the seats;
• Weld;
• Send the head to THE world renowned Cryogenics specialist for treatment;
• Back to my guy;
• Blend the weld;
• Cut seat reliefs;
• Install seats.

The short story, these heads are scarce, unobtainium if you will. Thoughts?

There are new heads available from a few different sources, Blue Sky Racing comes to mind.

[Charles Warner]

Contact Steve Jennings

[jkeller]

Also available new in the UK from Burton Power, John Wilcox, Ridgeway.....

[Motorsport Services]

[QUOTE=Charles Warner;625623]Contact Steve Jennings[/QUOT

[jstowe]

S Jennings Racing is still in business. They have moved...google their website; Cliff and Kevin (Steve's sons) are continuing the business in the family tradition. They have new 1600 and 2000 cc heads for sale, and a bunch of high quality parts, which they manufacture themselves.