12 replies to this topic

[Da11yn]

Hi all,

 

Upon inspection of my cylinder head I discovered a small crack between the exhaust valve and inlet valve seats. Currently this does not appear to be affecting the performance of the engine, but as with all cracks under cyclic loads i am sure it will grow until it does become a problem. currently it appears to extend to just below the valve contact area by around 1mm.

 

The head has 37 and 29.5mm valves and is an old leaded pre A+ head with 1045 stamped on the top at the opposite end to the thermostat. It appears to be heavily ported and has polished chambers measuring 21cc if i recall correctly.

 

I have removed all the valves and it only seams to be on the one set. 

 

As it is currently leaded would cutting it and inserting hardened valve seats take out the crack, is this head now scrap or do you think it is financially viable to repair?

 

Thanks

 

Paul

 

 

 

 

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[carbon]

Paul - if the valve throats have been opened out for these size valves then I don't think there will be enough meat left for unleaded inserts.

 

Also I would suggest if you're going to the expense of fitting hardened seats you don't want to be using a cracked head as a starting point. These inserts have an interference fit, and this could cause the crack to spread further.

 

But there may be others on the forum with more experience that can give alternative options.

[ACDodd]

Scrap.

Ac

[sledgehammer]

They do go wide with them seats

 

as above & not much room to get rid of the heat

 

pity there isn't a 100% way to repair cracks - it's always a compromise

[cal844]

Nice door stop ;)

[sledgehammer]

put legs on it & glass on top for a small coffee table

 

 

http://www.ebay.co.u...=item3394416c64

 

http://www.ebay.co.u...=item33957fcaeb

 

 

someone making money

Edited by sledgehammer, 22 September 2014 - 11:08 AM.

[Cooperman]

I have one on my bench which is exactly the same. It is scrap!

[Da11yn]

Not really what I wanted to hear but what I suspected. Will run it until it gives up the ghost, which will hopefully be long enough to save up for a replacement.

Who would people recommend to undertake head modifications to a good standard? As seems a shame to scrap all the valves and springs and caps when they appear to show no signs of wear.

Thanks

[ACDodd]

Keep valve sizes to 35.7 x 29.4 to minimise cracking.

Ac

[fwdracer]

Not really what I wanted to hear but what I suspected. Will run it until it gives up the ghost, which will hopefully be long enough to save up for a replacement.

Who would people recommend to undertake head modifications to a good standard? As seems a shame to scrap all the valves and springs and caps when they appear to show no signs of wear.

Thanks

 

Echo 35.7 x 29mmm sizes to ensure longevity. Try Rob Walker for great head.

[Allrounder]

Hopefully see you at the last few Autosolo's then Paul

[Da11yn]

Ross was going to be my last this season Liam as all the others clash with the off-roading championship im doing. Hopefully I'll make it to a few more next year and give you a bit more of a run for your money! Haven't seen the results from Sunday, how'd you get on compared to mike and zenya?

[Allrounder]

Some good test but finished 2nd overall to mike in his mx5 again. Maybe a few more horses and atb in the mini will sort him out. But as always in Motorsport, you have X amount of money for maintaining the car, developing it and entering events. Can't do it all.