Menu toggle

Best Weber set-up?

911hillclimber

911hillclimber

PCGB Member
Member
Separate thread to get your attention.
3.2 about bog standard with 40 size webers and 2.4 dizzy, no electronics in sight ([&:])
I have the 40/2 litre inlets (mag alloy, bog standard) which have tiny ports compared to the cavernous 3.2 inlet tracts.
I spoke to Josh Sadler at the autoSport show by chance who thought these carbs on a 3.2 would be a great hillclimb engine, all torque if not power. Sounds good to me.
When I did my 2.4 E/S engine (2.4 E cams/2.4 S p&b and heads) with mech injection (what a great little engine that was) I ported the inlets to match the heads (not much to remove) but the difference here is FAR greater.

Question:

Should I do a serious porting job on these manifolds, '2 litre' to start at the carb and then blend open to match a 3.2 inlet gasket diameter?
Or: leave them alone and ignore the diameter difference?

Secondly: are there heat insulation spacers on the 3.2 engine? I think there are as the inlet studs are very long. I will need to use the smaller insulators from a 2.4 or similar as the 3.2's are notched to allow for the injectors.

Finally, anyone have any insutation spacers for an air cooled 911?!
 
There are no spacers on the 2.4 motors, just a standard gasket. I have a spare set of 6 spacers off a 3.2, also a set of ported PMO manifolds that may well match your heads. I was going to ask £5 for each spacer but just had a look at the Porsche prices and they are just £3.25 each new! How about £15 including VAT and postage? BTW the 3.2 setup has a gasket either side of the spacer, but these seem to be NLA
 
You should definitely match the internal diameter of the bottom of your inlet manifolds to the inlet ports on your heads otherwise the 'step' to a smaller diameter will seriously affect the gas flow.
 
Andy I think it's the opposite problem where it goes from small manifold and the step is to a larger inlet port. I think this should work OK and will give some anti reversion characteristics. The question is are the manifolds large enough to support the flow from the carbs?
 
Indeed.
The holes to each venturi is quite small and with a 3.2 breathing through it the air flow will be very fast compared to a 2 litre.

The manifold holds this small diameter port in the casting which i suspect matches a 2 litre S head port a treat.

The matching on a 3,2 is a lage step BUT the air mixture from the carb will suddenly have a large head port chamber to expand to before passing at a slightly reduced speed (but cooler?) to the inlet valve and the combustion chamber.

What I can do is port the 2 litre manifold to the 3.2 head closer than it currently is to give a transition rather than a very abrupt step, and jet the circuits accordingly (it will be tuned by Bob Watson)

Nick:
I will take the 3.2 spacers and prob fit them with a 2.4 inlet gasket to cover the 3.2 injection notch. (I will send you a mail tonight with addresses etc)
All gaskets are available from the States (of course [8|] )
What PMO manifolds do you have : 45's?
 
So is that 40mm dia at the carb and out to 40 at the head side Nick?
I've sent you an email Nick.

The stock 1968 manifolds I have are 40mm carb side and reducing to 32mm head side.

I don't realy want to flow these perfect, un cracked ribbed manifolds as they must be a bit rare now?
 
You must log in or register to reply here.

Posts made and opinions expressed are those of the individual forum members

Use of the Forum is subject to the Terms and Conditions

Disclaimer

The opinions expressed on this site are not necessarily those of the Club, who shall have no liability in respect of them or the accuracy of the content. The Club assumes no responsibility for any effects arising from errors or omissions.

Porsche Club Great Britain gives no warranties, guarantees or assurances and makes no representations or recommendations regarding any goods or services advertised on this site. It is the responsibility of visitors to satisfy themselves that goods and/or services supplied by any advertiser are bona fide and in no instance can the Porsche Club Great Britain be held responsible.

When responding to advertisements please ensure that you satisfy yourself of any applicable call charges on numbers not prefixed by usual "landline" STD Codes. Information can be obtained from the operator or the white pages. Before giving out ANY information regarding cars, or any other items for sale, please satisfy yourself that any potential purchaser is bona fide.

Directors of the Board of Porsche Club GB, Club Office Staff, Register Secretaries and Regional Organisers are often requested by Club members to provide information on matters connected with their cars and other matters referred to in the Club Rules. Such information, advice and assistance provided by such persons is given in good faith and is based on the personal experience and knowledge of the individual concerned.

Neither Porsche Club GB, nor any of the aforementioned, shall be under any liability in respect of any such information, advice or assistance given to members. Members are advised to consult qualified specialists for information, advice and assistance on matters connected with their cars at all times.

Porsche
Lockton
Pirelli
Officially approved
Oracle Finance
WEX Esso
Collecting Cars
Archant Dialogue
Back
Top