043 Mexico heads cc

[samotorsport]

I am building a set of new heads for the Karmann .
Base is a set of Mexican 043 heads .
As per Thesamba chamber cc is 47 mm plus a 0.055 step giving a total 52 cc chamber .
But if i am not mistaking the step of 0,055 inch = 1,397 mm
1,397 mm with a 85,5 cylinder equals 8,02 ccm , so something is wrong there ...
I took out 0,8 mm out of the head , leaving me with 0,7 mm measured precisely on the milling machine .
While measuring my actual cc right now with the 0,7 mm step i come to 47 cc remaining



With the actual setup of 1,3 mm deck height i would get a C/R of 8,2/1

Dont really get it .
An i doing something wrong ?
Reverting the calculation
Stock 1,5 Deckheight
Full step in the head 55,6 ccm
Would bring me to 7,17/1 which looks a liitle low to me .
Anybody can help me ?



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[samotorsport]

I measured the chamber on it own and it looks like that has 43 ccm .
Could that be ?


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[PPRMicke]

a good volume page

http://cbperformance.com/v/enginecalc.html

A link and pictures on how to measure volume (Swedish) but good photo
http://peterclevarp.blogspot.com/2010/07/mata-forbranningsrum.html

/// M

[samotorsport]

Thanks for the links , i usually use the CSP calculator , I took out 0,3 more , so know i am at 45ccm , with Deck height of 1,3 i have a 8,5/1 CR . Enough for a CB 2280 cam with 36 Webers on a 1600 .
The Karmann got the long gearbox , so I prefer a torque cruising setup for once
 


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[PPRMicke]

I thought you would build a racer engine The cam (2280) for fuel economy
 The camshaft is very similar to the one sitting in the WBX engine
 It has very good on the lower register
A tip Do a three angle job on the head
/// M

[samotorsport]

Thanks , thats something i ve never done myself , what is the benefit of a 3 angle compared to the standard ?

[PPRMicke]

Increased flow
If you have the time and energy I have a thread on a Swedish forum how to increase the flow with easy tools
 You can translate with googel    Some pictures are unfortunately gone (
If you click on the pictures, they can open up)
 But would think it is very helpful for you
Link https://boxerville.se/forum/viewtopic.php?id=10359
/// Micke

[samotorsport]

Thanks , i will have a look at it, nice interesting thread .
I guess google translate is going to be a good friend of mine during that time  


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[Martin S.]

I was able to find the old manual valve grinding tools from a retired VW mech (started at Wolfsburg in ‘46) so ask around they were common tools years ago. The grinders flip over to give you the 3 different angles. You need a stand for the head, some machinist blueing and new or newly ground valves. It’s a good upper body workout and satisfying getting that perfect ’pencil line’ as Clyde Berg put it.

[samotorsport]

Do you maybe have a picture of the tool ? So i know a little better what to look for

[spoolin70]

Thanks , thats something i ve never done myself , what is the benefit of a 3 angle compared to the standard ?

https://johnmaherracing.com/tech-talk/3-angle-valve-job/

[PPRMicke]

Mira valve cutter
Which has a cutting steel with profile (3 angles)

[Martin S.]

Ok here ya go. This is what real men used back in the day ; )
Notice the different angles of the cutters? One has the “down the hole” angle while the other one has the 45 plus the entry angle.
There’s nothing exotic about 3 angles and you can even go further.
The shafts index the cutter in the guide.
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[samotorsport]

This looks really cool . I will keep my eyes open do find one of those things around here !
Thanks very much for pics!
What about the valves self . They usually come with only one angle . Do you rework them at the lathe ?
 

[Martin S.]

Valves are done on a valve grinding machine. Those machines are around too at some of the old school shops.
The angles can be done on valves but I’ve got no experience with that. I have re-used intake valves and had someone grind them for me but you can buy nice stainless Italian made valves for cheap (about $10 each). New valves are always recommended, especially exhaust. Stainless steel exhaust valves were a huge breakthrough for air cooled engines. The old valves were a time bomb waiting to go off!

[samotorsport]

I planned to put new ones in it for sure , i knew about the exhaust valves .
Thanks for the info , i think i have some shopping ahead of me


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[Glauco]

you can find these tools on ebay as well, not as good as the original ones used by vw, but they get the job done imo.
There is also a simular tool for grinding the valves.
not my photo's, not my tool neather unfortunately..

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Glauco

[Glauco]

valve grinding tool is from Neway (called the Gizmo). they also have realy good seat grinding tools like the one Martin S. pictured.

Glauco

[Torben Alstrup]

The Neway cutters are fine for garage mechanics that do a set of heads now and then. With a little patience you can do a very nice job.  For professionals it is too time consuming.
"We" actually still use a Neway pro set on flat heads, since it is a little difficult to get those blocks into the Serdi

[samotorsport]

Thanks , for the actual set of heads i will stick to the single angle.
Too much different projects eating the time away . But i plan on to do the heads i gonna removed from A to Z , too see what i am capable to do at home .
I got a new set of valves from CSP , still wanna modify the „upper“ surface of the valve to make them flow a little better.
Not yet sure what to use to reshape them. I dont have a valve grinder . Was thinking about putting them into the lathe . Could break the edge to the 45 degree (without touching the 45 itself) and maybe sanding the upper surface smoother with a little swirl left into the upper surface



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