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high compression head identification 202

Started by _m.mcarthur_ , Nov 06 2011 08:42 AM

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#1 _m.mcarthur_

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Posted 06 November 2011 - 08:42 AM

Is there any way of identifiying a head of a 202, as to whether it is high or low compression?
there are numbers stamped on the head do these identify at all. thanks.also what oil is the best to run in a 202 these days wonder about a synthetic to stop lifter rattle when cold.
comments appreciated.

#2 _stretchlc_

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Posted 06 November 2011 - 09:31 AM

Passenger side of the head....casting mark above the number 6 exhaust port on top face of head, between the rocker cover lip and the exhaust port...there should either be an L or a H cast there. H=High Comp. head......L= Low Comp

#3 rodomo

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Posted 06 November 2011 - 09:44 AM

H=High Comp. head......L= Low Comp


Blue heads are marked towards the front of the head.

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#4 _CHOPPER_

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Posted 06 November 2011 - 01:52 PM

Looks like an "L" at the back of the head, Rob.

#5 _m.mcarthur_

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Posted 07 November 2011 - 05:58 AM

thanks for that easy when you know.

#6 _m.mcarthur_

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Posted 07 November 2011 - 06:07 AM

wondering how much difference a low compresion head apposed to a high compression head in performance will have?
what will the advantages or disadvantages be?
putting in a 202 with low comp head original has a high would it be best to convert & use high comp head on transplant.
any advise much appreciated.

#7 _m.mcarthur_

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Posted 07 November 2011 - 07:15 AM

confused put me straight on this one , i checked the head which was on my u.c. it is marked with an L low comp the engine no is QL which means high comp, am i right that the motor is a high comp & head is low???
should it not be all matched the same.
dunno, can some one put me straight .
thanks.

#8 rodomo

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Posted 07 November 2011 - 07:38 AM

Motor is stamped as it left the factory with whichever head was fitted. It would have left with a high comp head.
The head is the difference between low comp and hi comp engines............................not the block, if that makes sense?
Sounds like the head has been changed.

QL isn't correct for a UC either? Is it XQL?

Edited by rodomo, 07 November 2011 - 07:46 AM.

#9 S pack

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Posted 07 November 2011 - 08:50 AM

Motor is stamped as it left the factory with whichever head was fitted. It would have left with a high comp head.
The head is the difference between low comp and hi comp engines............................not the block, if that makes sense?
Sounds like the head has been changed.

QL isn't correct for a UC either? Is it XQL?


The LJ parts catalogue lists different pistons for low and high comp 202 engines.

#10 rodomo

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Posted 07 November 2011 - 09:01 AM

Correct! I thought that but too late to edit.

#11 _m.mcarthur_

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Posted 07 November 2011 - 11:11 AM

thanks for this comment yeah i thought that the head was the governing factor as to high or low comp, the original motor in this car was stamped HL the head which i still have is stamped L bought car new & this info was orignal to it.car is a orig 4 speed u.c. what i want to know what difference it would make by fitting a high comp head to it.? performance wise etc , any advantage??
i await your comments. thanks.

#12 yel327

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Posted 07 November 2011 - 11:40 AM

As above the H and L only apply where the head is used to make a high or low comp engine (eg 149, 161, 173). 186 and 202 ( and from memory 138 also) use a different piston to make a low compression engine. 186 and 202 low and high comp use the L head. The only ones to use a H head are the XU-1 engines. If you want to work out roughly what CR you'll get on a 202 with a H head look at what LJ XU-1's were.

#13 S pack

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Posted 07 November 2011 - 11:51 AM

As above the H and L only apply where the head is used to make a high or low comp engine (eg 149, 161, 173). 186 and 202 ( and from memory 138 also) use a different piston to make a low compression engine. 186 and 202 low and high comp use the L head. The only ones to use a H head are the XU-1 engines. If you want to work out roughly what CR you'll get on a 202 with a H head look at what LJ XU-1's were.


Appears that 202 high & low comp eng's have different pistons but both use the same cyl head as the 173 low comp eng.
The 173 high comp eng had a different cyl head and pistons to the 173 low comp eng.
138 low and high comp engines use the same pistons but used different cyl heads.

#14 greens nice

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Posted 07 November 2011 - 12:52 PM

138 low and high comp engines use the same pistons but used different cyl heads.


so does this mean that there is a chamber smaller than the 39cc 149/161/173 head?

#15 _CHOPPER_

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Posted 07 November 2011 - 01:57 PM

If it was any smaller, there wouldn't be any room for the valves.

#16 S pack

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Posted 07 November 2011 - 06:00 PM

so does this mean that there is a chamber smaller than the 39cc 149/161/173 head?


No! The 138 high comp eng uses the 173 high comp head and the 138 low comp eng uses the 173 low comp head.

The above info applies only to 138 engines made from HQ release onwards and with non adj rockers.

Edited by S pack, 07 November 2011 - 06:03 PM.

#17 greens nice

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Posted 07 November 2011 - 10:19 PM

If it was any smaller, there wouldn't be any room for the valves.


almost sounds like a challenge :tease:

#18 _CHOPPER_

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Posted 07 November 2011 - 10:37 PM

Just devise a heron head and do away with the combustion chamber altogether.

#19 evl666

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Posted 11 May 2014 - 10:15 PM

I know this is a old thread but what does the number before the stamped 'h'or 'L' mean? I.e in the photos above the number 5 is cast on the head

Edited by evl666, 11 May 2014 - 10:16 PM.

#20 S pack

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Posted 11 May 2014 - 10:20 PM

Casting pattern number that's all.


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