cylinder head thickness

[rpurchon]

question for ntc following conversation on saturday by the rolling road at malvern.

ive measured the head thickness at 86.3mm. its a 219016 and compresion 165psi.

when i got the head i skimmed 75" off, down to a chamber depth of 525".

how much more could i take off.

cheers richard

[Guest ntc]

question for ntc following conversation on saturday by the rolling road at malvern.

ive measured the head thickness at 86.3mm. its a 219016 and compresion 165psi.

when i got the head i skimmed 75" off, down to a chamber depth of 525".

how much more could i take off.

cheers richard

 

Hi Richard

Is it a flat top block and also pistons +20 +30 +40 ?

[rpurchon]

Hi Richard

Is it a flat top block and also pistons +20 +30 +40 ?

 

+20" recessed block

richard

[Guest ntc]

+20" recessed block

richard

Edited July 28, 2009 by ntc

[Bald Rick]

Hi Richard

 

I'm thinking about going down the 219016 route (got the head) as the stage 2 head on my early TR6 is the narrow port type (516323) and so I can only fit the narrow USA type inlet manifold which I'm now convinced doesn't let the engine breath properly.

 

THis article by Chris Witor may help:

 

Triumph 6 Cyl Heads

 

Especially the second page (let me know if the link doesn't work).

 

I'd be very interested to hear Neil's opion also. I am using a recessed block but have a late 2500S block or the original USA block which I could use.

 

Cheers

 

Tony

[Guest ntc]

Tony

You have Pm

[Steve Knight]

No one needs the "ideal" head number unless it remains as a standard fitment. Any head ( including 2 litres ) can be machined, ported, and modified to give the best flow ( discounting the export USA head ) Early standard PI valves are the largest; it is debateable that larger valves will just give more shrouding. How much you skim off the face will depend on what head it is, how much combustion chamber reshaping is done, and whether it has been skimmed in the past. Really the only way is to use a burette ( CC should be equalised anyway ) but my measurements with extensive re-worked chambers and a 11.3:1 CR gives a new depth of 7/16". That is with 030” off the block / recessed then become flat top !. Try reading the tuning book from sknight@uk2.net

[Guest ntc]

No one needs the "ideal" head number unless it remains as a standard fitment. Any head ( including 2 litres ) can be machined, ported, and modified to give the best flow ( discounting the export USA head ) Early standard PI valves are the largest; it is debateable that larger valves will just give more shrouding. How much you skim off the face will depend on what head it is, how much combustion chamber reshaping is done, and whether it has been skimmed in the past. Really the only way is to use a burette ( CC should be equalised anyway ) but my measurements with extensive re-worked chambers and a 11.3:1 CR gives a new depth of 7/16". That is with 030” off the block / recessed then become flat top !. Try reading the tuning book from sknight@uk2.net

 

And is that for road use or track Mr Knight with your book?

[rpurchon]

Tony

You have Pm

 

thanks for the info ntc

looks like id need the head of to measure pistons below the block.

i smoothed/rounded the combustion chamber walls.so my chambers will be a bit bigger.

 

tony, i have the later swept manifold you mention. you will need the head skimming.about 75thou

i skimmed mine so the chamber depth was 525thou as in the moss catoluge for early pi head.

thats the only info i had,untill now.

i ground out the inlets so they were the same dia right through the port and around the bend.

fettled around the valve stem and smoothed the short radius on the bend.

also smoothed qiute a few ridges out below the valve seat. i chamferd the valve guides.

the ex ports i just generally cleaned up.

last job was to match up the ports.i had to grind quite a bit from my 631 phoenix ex manifold.

 

good god, that horrible cast iron taste is coming back.

 

any way car went ok on rolling road,probably more by luck than owt.

richard

[Guest ntc]

thanks for the info ntc

looks like id need the head of to measure pistons below the block.

i smoothed/rounded the combustion chamber walls.so my chambers will be a bit bigger.

 

tony, i have the later swept manifold you mention. you will need the head skimming.about 75thou

i skimmed mine so the chamber depth was 525thou as in the moss catoluge for early pi head.

thats the only info i had,untill now.

i ground out the inlets so they were the same dia right through the port and around the bend.

fettled around the valve stem and smoothed the short radius on the bend.

also smoothed qiute a few ridges out below the valve seat. i chamferd the valve guides.

the ex ports i just generally cleaned up.

last job was to match up the ports.i had to grind quite a bit from my 631 phoenix ex manifold.

 

good god, that horrible cast iron taste is coming back.

 

any way car went ok on rolling road,probably more by luck than owt.

richard

Hi Richard

You are not doing yourself justice you had a good result there with what you had,just need a bit more compression

love the colour of the car

 

Regards

Neil

[rpurchon]

Hi Richard

You are not doing yourself justice you had a good result there with what you had,just need a bit more compression

love the colour of the car

 

Regards

Neil

 

ive got a milling machine so how many thou would you suggest.?

richard

[Guest ntc]

ive got a milling machine so how many thou would you suggest.?

richard

 

Without the info that I sent you god knows but don't guess it

[rpurchon]

Without the info that I sent you god knows but don't guess it

 

no i wont guess it.im a bit tight been a yorkshire man.i dont want to be buying a lot of head gaskets.

something to look at after the clocks change.

richard

[Guest ntc]

no i wont guess it.im a bit tight been a yorkshire man.i dont want to be buying a lot of head gaskets.

something to look at after the clocks change.

richard

 

Head gaskets would be the least of the prob's and I am only an hour from you

[ncoll]

In my experience, be very careful of the compression ratios you use with these engines. If you are using anything above 10:1 with a fast road cam and have no problems ( detination/pinking) usually it's a sign that the cylinder head has poor airflow. To the best of my knowledge with the race engines that i was involved with, we only used a 10.5:1. If you are tempted to modify one of these cylinder heads yourself, and using the standard size valve, modifications to the chamber do not increase airflow. It is only when you use a 38 or 39 mil inlet valve that you will need to mod the chamber. For this you will need either a copper head gasket and cut it to the shape you want, or a large bore head gasket from a specialist at about £150.00 a time. The only mods to the port and valve throat are to the short side radius and the valve seat. Cleaning the bumps and ridges and tidying the ports up has no effect on air flow at all.

 

Neil Collingwood

[rpurchon]

Head gaskets would be the least of the prob's and I am only an hour from you

 

cheers il bear that in mind .going on holiday early hours so best be off.

richard

[Guest ntc]

In my experience, be very careful of the compression ratios you use with these engines. If you are using anything above 10:1 with a fast road cam and have no problems ( detination/pinking) usually it's a sign that the cylinder head has poor airflow. To the best of my knowledge with the race engines that i was involved with, we only used a 10.5:1. If you are tempted to modify one of these cylinder heads yourself, and using the standard size valve, modifications to the chamber do not increase airflow. It is only when you use a 38 or 39 mil inlet valve that you will need to mod the chamber. For this you will need either a copper head gasket and cut it to the shape you want, or a large bore head gasket from a specialist at about £150.00 a time. The only mods to the port and valve throat are to the short side radius and the valve seat. Cleaning the bumps and ridges and tidying the ports up has no effect on air flow at all.

 

Neil Collingwood

 

Sound advise Neil, don't know about the guy with the book

Edited July 28, 2009 by ntc

[Steve Knight]

My tuning book gives info on road and race. 105 bhp is not much but typical of a tuned TR. It is difficult to get a real power hike from the six cylinder. 10.5 CR is about the maximum on standard pistons, but as a cheap skate I use modified (standard) pistons on 11.3:1. with a TH6. ported and big bore exhaust manifold and various lightening, and I have to lift off at 7500rpm, but I doubt it gives any more than 180bhp. Modifying the chamber is to give an uniterupted flame front with no ridges. Air flow comes through the ports and valves; you should maintain a slight narrowing venturi effect on the inlets. There is a lot of rubbish and power claims written about Triumph tuning so I am not surprised people being sceptical. Decide for yourself.

Edited July 29, 2009 by Steve Knight

[88V8]

Cleaning the bumps and ridges and tidying the ports up has no effect on air flow at all.

I do not disagree. However, smoothing the ports may have a detrimental effect on atomisation, as the surface roughness provides a boundary reflection layer that prevents fuel dropout from the entrained mixture. With smooooth ports, you can get a layer of liquid fuel creeping along the surface of the port that arrives in the chamber as liquid and therefore is not available to be burnt, it just goes down the exhaust.

I believe that the best result is obtained by tumbling the head (after smoothing) at low speed on a lathe with small ball bearings in the ports, to reinstate a slight surface indentation.

Or perhaps this is folkloric

 

Ivor