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Offenhauser Manifold and Weber 500 carbs
Paradoxia0 - 5/11/06 at 10:34 AM

Just to show my total ignorance here...

I have a nice shiny new Offenhauser (JWR) inlet manifold and a Weber 500 (well, Edelbrcok Performer anyhow :-))

Fitted it all last night but it seems wrong... The Vac point for the dizzy is pointing to the back of the car and not at the dizzy and both throttle and choke cables point to the front of the car...

Tried it the other way around and the throttle linkage catches on the inlet manifold... (The manifold is installed with the thermostat housing pointing to the front of the car - my girlfried is insistant I have that on the wrong way around!!)

Can anyone offer advice on this please?

Mark


mark chandler - 5/11/06 at 11:50 AM

Cables are easy to sort as is the vacumn tube, the thermostat points forward which is correct.

Try using push bike cables, the vacumn tube is special so a trip down the breakers for a few yards may be in order. Tube from Halfords will tend to collapse when hot.

rgds Mark


wilkingj - 5/11/06 at 12:40 PM

Take a look at my site, I have the Webber manual on there.

http:\www.v8viento.co.ukDocs.htm




[Edited on 5/11/2006 by wilkingj]


Paradoxia0 - 5/11/06 at 01:55 PM

Well that is a relief! I was half expecting someone to say "ooh no, you can't have it that way round as the you will be fueling the wrong cylinders...." So at least now I know I don't have a major problem :-)

The cables I have are long enough just the vacuum hose I don't. Thanks for the tip on the Halfords stuff, I will avoid it

Mark


Bob C - 5/11/06 at 02:18 PM

I think this is the system I had on mine:- it's the kick-down link that catches the manifold, so just file/cut it off.
Note also, this is the "low profile" option but you will need a thick thermal inulating gasket twixt carb & manifold - if you stick a couple in you might find the linkage don't foul any more & you'll get easier hot starting!
Bob


DanP - 5/11/06 at 04:14 PM

hang on the PCV and vacuum hoses must go twards the front otherwise the carb primaries will be supplying the wrong part of the manifold. (incidentally you do have the maifold the right way round)

The JWR dual port manifold is one of the lowest manifold you can buy an can be a problem with throttle linkage clearance

I have the same setup on mine the JWR manifold and a Weber 500, the throttle linkage clears the manifold on mine using a spacer/coolling plate that I got from www.v8tuner.co.uk Rescued attachment enginedone.jpg
Rescued attachment enginedone.jpg


Bob C - 5/11/06 at 06:01 PM

Yep - thet picture looks like my old system.
BTW the finish and port matching on my manifold were dreadful (I'm talking 5 or 6 mm mismatch & very small port holes on the manifold - how are yours?
Bob


Paradoxia0 - 5/11/06 at 07:06 PM

Eeek!

So the carb is on the way round and it will cause a problem

I will take your advice and try the spacers to see if that helps. Cheers Dan

Also, when I haul the inlet manifold off again I will check the port matching and let you know what it is like.

Mark


Paradoxia0 - 5/11/06 at 07:47 PM

Dan

I can see 2 possible products on the V8Tuners website...

1" Phenolic Carb Spacer Holley/Carter/Edelbrock

http://www.v8tuner.co.uk/product.php?id=567

And

Carburettor leveling plate

http://www.v8tuner.co.uk/product.php?id=245

The first sonds like what you are recomending but but doesn't look like what you have in your picture. The second sounds more like how your engine looks in your picture but I don't know if this is what you recomend... Any other clues?

Mark


DanP - 5/11/06 at 09:13 PM

This is what I used and it clears on mine http://www.v8tuner.co.uk/product.php?id=385

I don't think the carb being the wrong way round would cause any major problems - it just wouldn't run as well tho so not ideal. The larger chamber (that runs to the lower of the two ports running to each cylinder) of the manifold is meant to be fed by the carb primaries and the smaller chamber run by the secondaries. I read somewhare that the dual port arrangement was meant to be so that the secondaries fed the engine cooler air but I'm not sure if thats true.

incidentaly the bloke at v8tuner (Paul - a very helpful chap) suggested that for non standard fittings of the RV8 ie a kit car; it may be necessary to use a wedge plate to level the carb up - I decided not to and am going to see if I need it or not.

Hope that helps!