Crack Head...

In the quest to stop chirping gave the exhaust manifold a nip, and whipped off a carb to try a new gasket..

Looked promising in that the light smear of Curil on the gasket appeared missing on the bottom edge..



There's a likely place for air to whistle through I thought then I took a picture down the inlet to make sure nothing in there.



Nothing apart from a crack in the head!..

Are inlet cracks there a worry and need to replace head or all fine and thrash the life out of it?...

And do I need a written permit from mods to post lots of swear words if its buy a new head (prob 2 as it's a 1800 big valve version )

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That one is big enough to allow the valve seat to loosen. I dont think I could go further with that head, all the cracks I had in cylinder heads were shallow and didnt come round the back of the valve seat like that. The exhaust valve seat next to it is probably also in a precarious position.

 

Are you sure its a crack and not just a mark in the casting ?

 

Beat me to it.

 

There were casting Mark's on the other side.. but cant find photos of there... I'll have another look tomorrow when I've stopped sulking..

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Can it be fixed with a TIG welder?

 

Could be a crack, but as above could just be a flow line in the casting.

 

When I saw the title "Crack Head" I thought you had been to East Grinstead !

 

...although it does look a crack

 

I have a head with the same marks in the same place on both ports. I thought the coincidence was too much and looking closer they look like casting marks. I’ll look again today and take some pics if it would help you make a decision ?

 

Just slap a bit of chemical metal or JB weld on it, good for another 100,000 miles stop worrying

 

Yes please..

Mrs Deefer is threatening to inspect my crack later .. shes got little fingers... before she goes looking at bridges later, she likes metalwork.

 

I've inspected a few Biffin bridges in my time

 

Deefer66, I hope this gives you some peace of mind. The photos show the casting marks from inlet side to the valve seats, as you can see these were crack detected.

 

There are some nasty sharp corners there!

 

Yes that one has been there for a while, although ive never measured it just photos, its still in the line of the casting flashing marks

 

I meant generally. The seat could do with the sharp overhanging edge blending into the port. Below that is another hard edge that softening would improve flow. That with a better seat cut and unshrouding the inlet valves are the sure fire /biggest gains as I understand it.

Are they new seats?

 

Ahh. Those pics are of uncut seats?

 

Casting marks for the win!
Cheers @Gnasha

Just had more of a look



And a v short film..



Mrs D's little fingers can feel the change in profile at this point so 99% casting


Setting up backfire though the carb seems to have made the gap for the chirp too



So quick clean up, new EMPI gasket.. bit of a reduction in footprint to make it fit easier and get it back together if to the rain stops..

Thanks all

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Those casting flashes should be blended into the port to avoid stress risers. Remove as little material as possible but smooth the whole port without polishing it or changing the shape - unless you know what you are doing.