L24 head

[JMT240KGTR]

Guys,

Can anyone provide me the height of an E88 head ie top to bottom without having been shaved.

Opened up an L24 last night and found it had notches in the pistons for valve reliefs, looks professionally done.

Also noticed they aren't the traditional flat tops we associate with L24, these had a slightly raised outer crown but was flat centre, so it isn't a true dished piston either.

I'm thinking the heads been shaved and they've fitted aftermarket pistons, or maybe even L26 pistons?

Anyway if someone can provide me with the head height I'd appreciate it, thanks.

James

[HS30-H]

James,

Its 107.137mm or 4.218 Inches.

Alan T.

[JMT240KGTR]

Thanks Alan.

You're a good man! And a knowledgeable one!

:classic:

[HS30-H]

Don't know about that.

Got a few books. The knowledge is in them, not in me.

Lately I've been checking which of my stock of heads has been shaved. That's why I had the dimension to hand.

Good luck with the engine build:classic:

Alan T.

[JMT240KGTR]

Cheers, thanks mate.

By the way, go Man Utd!:classic:

[HS30-H]

Originally posted by JMT240KGTR

By the way, go Man Utd!:classic:

Now you've blown it! Manchester is a different country altogether. My local team is Arsenal FC, and I can't stand them either.

[nixcars]

Alan,

May be of interest to you, I've measured one at 107.7mm & was told by Stewart Wilkins Rally that all standard L series heads were 108mm.

Maybe thats for the ozzie cars only but I doubt it.

Nick.

[HS30-H]

Hi Nick,

That's interesting. Slightly worrying too!

When I was looking for this information, I checked through all my Factory Engine Service manuals for the L20 / L24 / L26 / L28 engines. I have several different years, and several different market versions ( including some of the more comprehensive Japanese versions that seem to have dimensions and specs that the others do not ).

To cut a long story short, I found every conceivable dimension and specification for these engines EXCEPT that one measurement. Dimensions for the cylinder block are very comprehensive, and they go into great detail about valve, valve guide and valve seat dimensions. They mention a fair bit about head warpage and acceptable tolerances - but always fall short of quoting an actual dimension for the head thickness..............

That made me suspicious. Why would they not quote something as important to us as that? They skirt all around the subject - even mentioning chamber volume and how it is affected by skimming the head - but never actually quote the thickness.

The only reason I can think for them not quoting it is that it must be a little bit of a grey area. I wonder whether there was a Factory tolerance for this dimension that allowed a fair amount of variation? Varying thicknesses between the cam tower bore / cam tower base mounting and the mating surface of the cylinder head to the cylinder block would of course have an effect on the cam chain tension and the cam timing. Surely they must have had a tolerance to work within - but they never quote it.

I got the dimension I quoted above from the "How to Modify" book by Frank Honsowetz - which contains a lot of useful information. I cross-referenced it with my stock of heads ( I have 9 heads and two whole engines to compare to ) and came up with no dimension bigger than 107.14mm on any of my heads. The 107.14 was from a known-history ( definitely never skimmed ) N42 that I have set aside for some port work. Some of my heads were just a smidge less than this - but the majority of them seem to have been skimmed at some point in the past ( some of them quite a lot! ).

I know how to measure, and I have some good measuring tools at my disposal - but measuring these heads without a surface plate and height gauge is probably going to give a slightly different reading to me working with digital vernier calipers and micrometer - so I accept a slight tolerance for my error. That N42 was fairly consistant along its length - but some of the others measured slightly different along their lengths, which could be due to bad machining I guess.

Its worrying that a firm "official" Factory dimension seems to be so hard to find. If anyone has any better information I would be very interested to hear it. Technically, I wonder if a small amount of variation is all that important for this dimension. There are other dimensions that are more important than the overall thickness, I suppose.

Anyone else got any thoughts?

Alan T.