I took the cylinder head off the old crossflow today to get it converted to unleaded, All's looking good, flowed head Burton stage 2 valve sizes, until i spot a crack,

It goes between the edge of the number 2 inlet port and the spark plug hole, it doesn;t make it to the threads in the hole and I've not got a spring compressor to check the valve seat. Is it too optimisic to hope the bloke doing the inserts for the unleaded can repair it?

ATB Dan.

Most heads can be welded, remachined and a new valve seat cut and inserted.
If he has done the job before, he will know once he sees it.

may be repairable - but gotta be the beginning of the end

Get another head and some carbide burrs you have a great example of a good head to copy

Just my 2p worth

Mark

Not a problem to repair. If you are having seat inserts for unleaded then it shouldn't be too expensive.

If your man can't do it I would advise taking it to someone else as it is a widely accepted repair.

Many good race engines are built with welded heads.

Yep it can be repaired as long as the crack doesn't go too deep.

As above, it could be the beginning of more trouble/doubt!

Again though, we have repaired some never to have problems again. Depends on the repairer really.

HTH Fozzie

Scutter

IMHO i would scrap the unit, as for the following reasons
I also run stage 3 1691 xflows for several years, and have wrecked totally 2 engines, and from analyizing all the bits that were left. the only common denomenator to both engines, was the head, that was a stage 3 V*****n head

in the last distastrous blow up, a valve has come straight thru the head, and gone thru the piston, and, the cause, from the evididence, is plain to see, I had unleaded valve seats put in, while building the first 1691 st 3 block, and one of these inserts has rattled loose, due to a crack eminating from the valve seat
This has been confirmed by V*****n them selves, but ofcoarse there not liable for any damage, All they offered was a replacement st3 head at cost price (£230 from memory)

I didnt take them up on the offer, as I was sure to get my old head back !!!

bin the fecker and get a new one

Well in his words "it's not that deep" he's doing the unleaded seats, if the crack does lead into the inlet seat he's going to replace it for the same price.

On the line of inserts dropping, If one does drop he'll do the job on the next head for a greatly reduced rate. On encouraging thing is he used to build engines for the formula ford series.

ATB Dan.

"On the line of inserts dropping, If one does drop he'll do the job on the next head for a greatly reduced rate. On encouraging thing is he used to build engines for the formula ford series. "

trust me, it wont just be a new head,
a total engine rebuild will be req

I wouldn't even consider putting inserts into a crossflow head. There just isn't enough material between the valves to hold in place properly, and when they fail it's catastrophic for the rest of the engine.

Run it on unleaded with a good additive.

Cheers Chris

I'm kinda wondering whether this is money well spent; best get another head.

I guess yoou have to sit dwon and do the sums.,

Interesting on what ^^^^^ says about inserts though.