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Azu 1960
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Harley
Dropped


Joined: 26 Nov 2007
Posts: 394
Location: Braidwood - Australia

PostPosted: Thu Aug 19, 2010 1:13 pm    Post subject: Reply with quote

Olli wrote:
Yeah, you can sure find those for 2cv6, but how is with old 425cc?
Also I can go machine my cylinders to my friends place at free.
Does anyone know how much is example this 7,5:1 in bars? My
engine has only 6bar in bolth sides, and it does not mess oil so piston
rings does not leak so much.

-Olli


Calculating Compression ratio is better left to rocket scientists and witch doctors...

This article explains in-depth how and what it is: Article
And here is a calculator to accompany it: Calculator

Correct ratio pistons are more effective at their given ratio compared to shortened barrels, as this alters the combustion chambers 'squish area', a small area or ring around the edge of the combustion chamber. Some performance engineers say this area must not be messed with Exclamation treat it like your in-laws, respect it but don't f@ck with it Exclamation

Unfortunately I don't have the mind to give you the answer, but I hope this has helped. Talk to the people who machined your heads they will be able to help.

Keep the pics inc. Cool

Harley
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Olli
Soviet-Finn Photoshoper


Joined: 25 May 2007
Posts: 2146
Location: Soviet-Finland

PostPosted: Thu Aug 19, 2010 4:48 pm    Post subject: Reply with quote

Thanks Harley!

I will check those links later, but anyway I think my only change is to do
something and check what happent.

Harley wrote:

Talk to the people who machined your heads they will be able to help.


As usual, I can talk with my self Laughing

Got all rockers ready today! About 1 - 1,5h work with each.





I made one extra arm which is lighter and better polished than rest.



-Olli
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woody
Dropped


Joined: 01 Jul 2007
Posts: 151
Location: Chaudfontaine Belgium

PostPosted: Thu Aug 19, 2010 8:19 pm    Post subject: Reply with quote

woooawww Shocked
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Chewie
Dropped


Joined: 29 May 2009
Posts: 112
Location: Eggenfelden, Germany

PostPosted: Sun Aug 22, 2010 2:12 pm    Post subject: Reply with quote

Hey looks great :-)

you should sell some of theese replica RAF carburator manifolds ... I would buy one Wink
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Olli
Soviet-Finn Photoshoper


Joined: 25 May 2007
Posts: 2146
Location: Soviet-Finland

PostPosted: Thu Sep 02, 2010 9:55 pm    Post subject: Reply with quote

I'm trying to make some of those manifolds and exhausts at next winter.

Today I cleaned pair of 15,5mm's to replace those huge 17mm's what there is now.





-Olli
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dyanut
Dropped


Joined: 05 Aug 2007
Posts: 177
Location: North Yorkshire

PostPosted: Thu Sep 02, 2010 11:22 pm    Post subject: Reply with quote

Ollie,
do you know what the nominal compression ratio of your engine is?
602 pistons often have the compression ratio marked on the piston crown, but I don't know if this applied to the older models...

Fwiw, 6 bar seems quite low, as a 602 engine with 8.5:1 pistons will show around 10 bar at cranking speed, with 9.0:1 pistons producing almost 12 bar.

Using the following 'rule of thumb', it seems probable that your pistons may be the early 6.2:1 version, since 6 bar = 90 psi.
Then 90/15 = 6
"Generally, cylinder pressure for common automotive designs should at least equal 10 bar, or, roughly estimated in pounds per square inch (psi) as between 15 and 20 times the compression ratio, "

If you're worried about reducing the clearance between the pistons and the heads at the squish band, you can use plasticine to check the gap.

Another trick I used when I first started building race engines was to pour molten candle wax into the combustion chambers with the pistons at top dead centre.
Let it cool and set, then there's a nice casting available for dissection.

My guess is that you should be able to remove 'around' 0.5mm from the barrels' top spigots without clearance problems.
Whether the crankshaft will stand up to the increased output is another matter, same story for the valve seats regarding coping with the extra stress...

Ken


Olli wrote:
Yeah, you can sure find those for 2cv6, but how is with old 425cc?
Also I can go machine my cylinders to my friends place at free.
Does anyone know how much is example this 7,5:1 in bars? My
engine has only 6bar in bolth sides, and it does not mess oil so piston
rings does not leak so much.

-Olli
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Malte
Lowered


Joined: 11 Dec 2007
Posts: 534
Location: Germany

PostPosted: Fri Sep 03, 2010 12:31 pm    Post subject: Reply with quote

Olli wrote:
I'm trying to make some of those manifolds and exhausts at next winter.

Today I cleaned pair of 15,5mm's to replace those huge 17mm's what there is now.





-Olli


6pack for 440 mopar? :)
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Olli
Soviet-Finn Photoshoper


Joined: 25 May 2007
Posts: 2146
Location: Soviet-Finland

PostPosted: Fri Nov 12, 2010 10:52 am    Post subject: Reply with quote

Ok, after some other projects this continues!

Motor madness in getting deep.

Now I have some problems to install manifold:


So whats going on here is: 602cc "12hp".

I got old Ami6 case from JoZeF, thanks! So I can get old engine look
and 70mm stroke, instead of 62mm. Also 2cv6 cylinders will fit straight
on case.

But cylinders does not fit on 12hp heads. Outer diameter of 425cc cylinder
in 80mm and 2cv6 is 82mm.


I took heads to machining company. Here you can see 2cv6 cylinder
sitting on 12hp head.

Needs still some grinding to get it nicely shaped.

Also I got problems with pushrod tubes. In 12hp head they are very short and outer diameter 16mm (2cv6 18mm).


First I was thinking to extend the tubes but as they are so small I was
thinking that it may bring me some problems. So I drill old tubes off
with 18mm drill and swap tubes from 2cv6 head. I can tell that, this was
no easiest project but I'm very satisfied with result. Tubes sit really thick
in their new home.





Push rods and their cups on block seem to be usable from 2cv6.
Next step is to finnish this head bussines, see that engine rolls nicely
around, valves work etc and then case on pieces: wash and check.

-Olli
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dule
Lowered


Joined: 06 Jan 2008
Posts: 590
Location: Zagreb, Croatia

PostPosted: Fri Nov 19, 2010 7:41 am    Post subject: Reply with quote

are you still going with RAF intake replica that you've made?
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Olli
Soviet-Finn Photoshoper


Joined: 25 May 2007
Posts: 2146
Location: Soviet-Finland

PostPosted: Fri Nov 19, 2010 6:01 pm    Post subject: Reply with quote

I'm not sure yet what I will use. One I made will not fit in this engine anyway.

-Olli
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dule
Lowered


Joined: 06 Jan 2008
Posts: 590
Location: Zagreb, Croatia

PostPosted: Wed Jun 08, 2011 10:14 am    Post subject: Reply with quote

any news? I've started to think about dual carb for my 602 with that vintage looking manifold, what do you think, would a pair of single barrel stock solex carbs do the job?
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JoZeF
Grave Digger


Joined: 25 May 2007
Posts: 1734

PostPosted: Wed Jun 08, 2011 11:00 am    Post subject: Reply with quote

Apparently, with 2 single choke 2cv carbs on a 602 with a hotter cam, yes, it does
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dule
Lowered


Joined: 06 Jan 2008
Posts: 590
Location: Zagreb, Croatia

PostPosted: Thu Jun 09, 2011 7:33 pm    Post subject: Reply with quote

tnx
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PerI
Snailer


Joined: 13 Nov 2008
Posts: 85
Location: Landvik, Norway

PostPosted: Wed Feb 06, 2013 12:17 am    Post subject: Reply with quote

Found this in my parents photo album recently Very Happy

From world meeting in 1985, Cheltenham UK


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'71 2cv 6 · '74 Ami Super Berline · '70 Ami 6 Service (project) · 2(3) AZU projects · 2cv since '93 · C5 v6.24 · GPicasso 2.0 hdi · 307cc
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oliver pickard
Snailer


Joined: 18 Jul 2011
Posts: 11

PostPosted: Mon Mar 17, 2014 8:44 pm    Post subject: Reply with quote

i totally dig this project its totally awesome, any news on what has been going on with it?
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