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John Culham

Cylinder Head 219016

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John,

It's not the fuelling system, or the cam that that dictates a head's suitability, but the compression ratio.

 

A 219016 head was used for 2.5L engines (See Chris Witor's page: https://www.chriswitor.com/cw_technical/head_applications_chart.pdf)so the chambers were originally big enough, if you plan to use it on a 2.5L engine. They will be too big for a 2L, but the 2L head was just skimmed down from the same castings as 2.5s, so a bit more of a skim and it will be right.

 

But what CR willa 70 thou skim give you. Impossible to say for sure, unless you burette the chambers. That is, measure their volumes by pouring liquid into them until they are full, doing so from a "burette" so that you can be accurate down to fractions of a milliliter. And then do the sums, aiming for a CR of no more than 10.5 on modern fuel.

 

May I modestly refer you to my article, "Skimming your head" in TRaction Issue 282, May 2015, pages 36-38? You can read if you log into the Members page and go to the TRaction Index.

John

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I do not mean to step on John's toes as his article is the correct way to achieve an exact compression ratio for a given cylinder head.

 

However, a bit simpler method that will get you close, and is useful if you're not going to push the envelop on compression ratio, is to use the deck height of the cylinder head itself. Here's a link that discusses this a bit and tells you what deck height equates to a particular compression ratio:

 

https://www.goodparts.com/shop/index.php?ukey=auxpage_tr6-compression-ratio

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I have the 016 head in use with an PI EFI system.

I bought the head because Wittor recommended

but when I had it I swapped opposite to his opinion to

the bigger outlet valves.

 

The head was modified and as I have a 77mm bore I

grinded the combustion chamber to fit what reduces CR.

Also the valves got the 3-angle valve job what puts them deeper

into the head what reduces CR, too.

 

In the end it was necessary to skim the head to 10:1

I have no valve seat inserts and use valve master oktan booster

and normal 95 oktan Super.

 

Engine runs very well..

 

Should CR become too high it can be reduced by grinding

the combustion chamber but I do not see a reaon why a swap to PI

should require that.

 

I would not even lift the head but simply bolt the manifolds and look what happens

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I do not mean to step on John's toes as his article is the correct way to achieve an exact compression ratio for a given cylinder head.

 

However, a bit simpler method that will get you close, and is useful if you're not going to push the envelop on compression ratio, is to use the deck height of the cylinder head itself. Here's a link that discusses this a bit and tells you what deck height equates to a particular compression ratio:

 

https://www.goodparts.com/shop/index.php?ukey=auxpage_tr6-compression-ratio

Critical debate involves no toe stepping, Yankee!

 

If I may, "decking" and "deck" is usually applied to equalising the height of the pistons in the block, but as the "deck" is the block/head interface, you were clear. The statement from the GoodParts site that "EVERY .010” REMOVED FROM THE HEAD THICKNESS REDUCES THE COMBUSTION CHAMBER VOLUME 1.03 CC" may be true, IF there has been no work in the chambers. But you will note all the provisos, on piston height, and valves. Doubt about the last and on chamber work is removed by buretting. However it is a convoluted and potentially messy procedure, that many will be happy to avoid by using such a ready reckoner. Bt if you are aiming for performance and the highest safe CR, accurate measurement is essential.

For horses, you need courses!

John

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Thanks for all your comment.

 

It appears head will be OK for a PI system for my TR250 with a 219016 head, when head is modified for unleaded i will change exhurst valves from 30.3mm to 32mm and skim if required.

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