The V8 Owners Forum -

Hi.

What an how do you recon to repair porous head gasket face for cylinder head?

Welding is not our 1st choice because it will need at least valve seat machining etc.



1. Some chemical metal. Like jb weld?
2. Custom head gasket to get wider fire ring. Current is only 3mm wide. And couple of casting fault will just go below fire ring.
3. Machine more metal for face and hope for best and porting to get correct CR?

Any good ideas?

That does need welded

I think laser welding could be done on that without the need for valve seat work.

This is a German place, but there will be somewhere in the UK who can offer it.

Slightly more time to look at those holes.
Look like they are approx 1-2mm deep and very small.
Have to tig weld those.

IF SOMEONE IS INTRESTING. THOSE ARE NEW WILD CAT HEADS WITCH I BOUGHT 2017.. Just start to finishing heads, and surprise.. argh.. Also i have got similar problem to inlet port to head bolt hole. But hole is bigger an it is welded now.

Also like to hear opinion, do i have to replace valve seat if weld those holes.? Another machine shop say maybe. And another say no. At least leak test and maybe machining if needed..

Speak to specialists who do the laser welding.

Although replacing seats isnt the end of the world, it just adds more cost.

I'd think just TIG'ing it would impart more heat as it's a slower and slightly more widespread process ? So more risk of seats needing re-done. But I'm sure it would also be a good repair.

Forgot to say. That we are finding best solution to repair those heads in Finland and also seller try to do his best. Process is still in progress. Thanks for seller also..
Hope we can repair it..

kokkolanpoika wrote: ↑

Sat Dec 29, 2018 11:38 am

and also seller try to do his best. Process is still in progress. Thanks for seller also..

Can't the seller do a swap for a good one?

What about something like silver solder.

Not a lot of heat required to do that and once sandwiched with a gasket probably zero chance of it coming out

Ian

In all fairness, Ian, something like A4 Metalset will probably work, too.
There is no water around there as long as the gasket is intact, but for a new head I'd be loath to have to resort to that.

After welding and cleaning valve seat holes we found a hole after 0.1mm machining.


Those heads are x rayed and pressure tested.

Top quality heads.

Also friend of mine has got loose valve guide holes..

Buyers beware..

What a crock of shite.

Head has been welded again. And now machined and new seat fitted.. + pressure tested.
Better than new one. Seller try to compensate only 4x inlet valve seats. But thats nothing. And they wont eaven response when i send pick of valve seat hole problem.. quite poor..

Also if we compare OE heads. OE casting have got more metal under the valve seat. Mutch stronger casting on that place. Also you cannot cut/port seat throat/bowl any more bigger than it is. Because port wall thickness will limit that.. Maybe couple of tenth millimetres.

If use 1.94" valves 90% throat is risky to use, 87% is way to go. You may have then 2.5mm alloy on port wall to water jacket if use 90% rule..
So speech for metal is only speech.

Like Friend on mine says when he compare Merlin head casting to wild cats, that they look mutch better..

I know I’m a long way from Finland, but I wouldn’t be afraid to spray weld this head

HVOF might work well

Flame spray would work

I don’t think I’d bother with twin wire, it’s not as tidy a process

good question,might be possible,as long as your not talking about a crossflow head ? but the 200 or 250 older head might have larger chambers and your compression will be reduced,but maybe some off the other boys can give the correct info.

Heads has been welded and machined. And first start yestyrday.
Took some time because bought Europian cheapest l322 4.2 SC Rangie..

Back to project. Have to adjust some fuel maps today or tomorrow. It wont idle over 500rpm because it is running lean mixture. No major fluid leaks yet..

But damn those fu.... heads are half finished. All accesory and exhaust manifold theard's are only approx 10-12mm long. OE heads has got mutch longer thread's.
Friend on mine bought wild cat guideplates and roller rocker arm roller tip will sit away (side ways) from centre of valve tip.

Rocker arm geometry is what it is. I have to fit lash caps to get it as near as i can. Roller will sit centre of valve, but slightly too wide pattern. If fit longer pushrods, rocker arm then hit poly lock at full lift. Best solution is to bought new longer valves and then pushrods..

Will see how those heads handle heat and power..

But hole packake need to design again.