Club 80-90 Forums

Thanks for those piccies.

Why have you cut the perspex out, surely some of the volume you are trying to measure is being taken up by the perspex.

Now I understand about the adjustable pushrods...... the why is beyond my understanding unless it is something to do with different ratio rocker arms ???

Good to see lot's of measurement checking taking place

Hello.

The perspex has a hole drilled in it. You vaseline seal the perspex to the head. Using food dye coloured water, you fill up the combustion chamber with water through the hole in the perspex.

The amount of water gives you the volume of the combustion chamber.....only the drilled out bit below the flat surface that the barrels seal against.

The deck height and bore diameter gives you the volume measurement of the bit below the drilled out chamber. Least, thats how I understand it. [SMILING FACE WITH SMILING EYES]

Sent from my SM-G935F using Tapatalk

Agreed - from the picture I though you had cut the perspex down to sit into the head combustion chamber, clearly an optical illusion, or my eyes

No worries....

Its always tricky to get a good, clear picture. [SMILING FACE WITH SMILING EYES].

Sarran, in one of your video's the new head you had a 12mm spark plug hole. Mine has the same. What spark plugs did you get? Can you remember?

Many thanks.

Sent from my SM-G935F using Tapatalk

Hello,

totallyconfused wrote:How do,

Have remeasured my deck height....as per Sarran's picture. Thanks for that Sarran.

Got a deck height of 1.22mm.

That gives me a compression ratio of 7.6 :1.

Thats more like it....

So you could use paper gaskets between cylinder and case, like beetles, and keep your CR..

You are getting lost with the perspex plates thing...

Like I show in the video, 53ccs fills the combustion chamber to meniscus.

Frankly that is all you need to know..

As for the pushrods...if you are using solid T2 lifters, then use beetle (shorter) pushrods..

Spark plugs: NGK 2120 D8EA, from motorcycle suppliers..

Father's Day today, so a great long e mail from Nr 2 son in Argentina, and English bottled ale on the terrace with Nr 1 son this evening...

Bliss.....

Cordialement,

sarran1955 wrote: Like I show in the video, 53ccs fills the combustion chamber to meniscus.

Are you using the exact same heads, I think the 59cc he is using came from the manufacturer??

Hello,
AA performance 500 heads
Standard combustion chamber..big valves..53 ccs

Cordialement,

https://aapistons.com/collections/stock ... ead-40x355

http://vwparts.Aircooled.net/Dual-Port- ... 00-420.htm

"Approximately 59cc"

Looks like he needs to measure his own then if he really wants to know and assess the CR for his engine (I'm not saying yours were not 53cc)

The head volume affects CR from 7.64 to 8.29 in these scenarios

Hello,

Thanks for your comments. Much appreciated.

Have got the spark plugs Sarran, they fit a treat.

I have measured the combustion chamber. With the spark plug wound in got a reading of 58cc.

This should give me a compression ratio of 7.7 : 1. I think I will just go with this. Higher than standard (7.4 :1 only a bit) and within the specs of the cam. (7.5 to 8.2).

I did try and send some pictures but have a new phone and upload failed. Not sure why?

Glad you had a good father's Day Sarran. I had a lovely roast beef dinner and some wine. Yum. [GRINNING FACE WITH SMILING EYES]

Sent from my Pixel 3a using Tapatalk

Hello,

Thanks for the update..

So 58/59 cc's it is then..

I'll have to redo my compression calcs...

Frankly I was so pleased with the performance increase on 98 RON E5....

This Summer I will be doing a twin solex project, so maybe rethink for 95 Ron E10.

I am running a SVDA dizzy at about 9° BTDC, with smooth running..

Air-Cooled Bliss.....

Cordialement,

All fired up and working now ???

Hello,

Only just saw to this.

Sadly the engine is still not done.

I have run into some problems with the build. Namely a wierd knock when you turn the engine by hand.

I am still trying to sort this. Mixture of running out of steam and corona have slowed me down.

Many thanks for your interest. Can give you more details if your interested.



Sent from my Pixel 3a using Tapatalk

Yep, people are always interested, some pictures help too