Question about ITBs

[MrPerkles]

Guys how important is the transition from ITB to port ,I have a carrera 3.0 with 39mm intakes which is bit different or so im told
Jenvey have 41mm bodys in stock but will machine a set of 39mm intakes if I wait.

ps im impatient

x 2 ps should I leave the PMO spacers on ?

[Jeff Alton]

I am not going to say they must match... but we blended the Jenvey manifolds for my 3.4 to match the intake port size.....

Cheers

[ChkbookMechanic]

In my opinion of the three options you could have, this is how I'd rate them on the desirability scale (assuming you aren't going to upgrade throttle bodies anytime soon).

(1) Matched
(2) Smaller ITB bodies to larger intake port
(3) Larger ITB bodies to smaller intake port

Granted, I'm not a Porsche engine builder but I'm sure some with more experience chime in eventually.

[MrPerkles]

option 1 then as if you do things not quite right you always end up ripping it off and doing it properly.
What about the gaskets Jeff did you fit straight to the head ,I have still have the PMO carb spacer/adaptor things but I suppose ITBs wont suffer from heat soak as they have no fuel chambers so I should take them off ?
Im ordering and fitting it all this week ,jenvey is just down the road from me .

[Jeff Alton]

Are you talking manifold size or throttles? I use 48mm throttles and the manifolds are 48mm at the top and taper to 41.5 for the heads. I use PMO spacer/insulators for the 3.2 heads as well. They match my intake portd ID.

I would still keep the whole intake as cool as possible and use the insulators. I did.....

Hope this helps??


Cheers

[MrPerkles]

Thanks yep that answers my question sorry I meant the manifolds,right im purchasing today cant wait to get rid of the carbs.
I will post an update when I re appear out the garage in about a month

[Jeff Alton]

Okay, I would get undersized manifolds if they don't have a direct match. Then hone them to size.

Cheers

[MrPerkles]

OK have the set up now what do people do about the vacumn booster for the brakes ?