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Full Version: 2.7L W/ CIS to Weber 40s
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Cfletch
I am thinking of going to a more simpler setup for my 6 conversion. I found a set of Webers that are already jetted for a stock 2.7, which is what I have. I only need manifolds and linkage to make it all work. It seems like there were some different sized ports on the manifolds and I would like to know exactly what it is I need. Based off of my research it seems like I need 32>40 manifolds to bolt the two together. Is this correct?

I also am not having much luck on a source for them either. It does not seem like Pierce manifolds sells the manifolds and I see they sell some linkage, but it is more so generically labeled and so I am having issues being able to tell what it is that I need to purchase.

Any insight will be very helpful! Thank you
Root_Werks
I'm running CIS on my 2.7 and think it's simpler than carbs. CIS is mechanical and there's not much that can go wrong. Plus, you don't have to care much about E10 in fuel. Move to carbs and that becomes an issue.
Cfletch
QUOTE(Root_Werks @ Jul 27 2020, 02:43 PM) *

I'm running CIS on my 2.7 and think it's simpler than carbs. CIS is mechanical and there's not much that can go wrong. Plus, you don't have to care much about E10 in fuel. Move to carbs and that becomes an issue.



I generally prefer carbs on my cars and am not a rookie to tuning them once they are on, my family has a few English classics with various types on them so they do not scare me, if anything, older injection scares me mainly because of the pressure, the plumbing, my irrational fear of springing a high pressure leak because of how the lines attach to the pump/accumulator/filter.
TravisNeff
Tell us more about your 2.7 engine. The 74 normal (not S) has a 32mm intake port, all years of the S model have a 35mm intake port. I have a 74 normal engine and I verified it has a 32mm intake

The 75 (S and normal) and up may all be 35mm - but I do not know that for sure
Cfletch
QUOTE(TravisNeff @ Jul 27 2020, 03:08 PM) *

Tell us more about your 2.7 engine. The 74 normal (not S) has a 32mm intake port, all years of the S model have a 35mm intake port. I have a 74 normal engine and I verified it has a 32mm intake

The 75 (S and normal) and up may all be 35mm - but I do not know that for sure


Sorry! Forgot the year, it is a 74 non S model. So it seems like my initial search was correct.

Are there any vendors that sell the correct manifold for the car? It seems like Ebay is going to be my best bet unless I can stumble across the something.
sixnotfour
PMO for Manifolds = Base Gaskets/Insulators... Linkage
https://www.pmocarb.com/

CIS-flange shown
Cfletch
Ah okay I see, they will be the full source then
roblav1
I saw a set of original 911 weber intake manifolds on pelican yesterday. Not sure of size.
914Toy
Stock CIS cams are not optimal for carbs - one more issue to consider.
JmuRiz
+1 if the internals of the 2.7 are stock, keep the CIS and clock the fuel dist if it touches the rear bulkhead. If setup CIS is turnkey easy/simple w/o the fuss.

That was my plan until we got into the engine and found the prior rebuild was barf-tastic.
porschetub
QUOTE(914Toy @ Jul 28 2020, 01:46 PM) *

Stock CIS cams are not optimal for carbs - one more issue to consider.
.
agree.gif cams are very tame in these engines to work with CIS,the system has little tolerance for "flutter "of the air plate so the stock cams are what they are for that reason,I believe the piston shape in these motors isn't optimum for carbs also.
Yes PMO manifolds will work or 911 carb manifolds with inlet port adaptors ,remember a guy on pelican makes them but don't remember his username.
Hardly a system for power but super reliable in good condition with great starting ,driving and good fuel economy,an interim move before Porsche went to electronic FI and was first used on the last half year only 2.4 to replace MFI.

porschetub
QUOTE(JmuRiz @ Jul 28 2020, 02:43 PM) *

+1 if the internals of the 2.7 are stock, keep the CIS and clock the fuel dist if it touches the rear bulkhead. If setup CIS is turnkey easy/simple w/o the fuss.

That was my plan until we got into the engine and found the prior rebuild was barf-tastic.
sadly a bit of the 2.7 engine thing dry.gif the engine I looked @ was very clean and relatively cheap till the seller mentioned case savers installed on one side only WTF.gif seems the other side was fine rolleyes.gif .
Never got there thankfully.
sixnotfour
there is a guy jn CA ..looking for 2.7 jetted webers ,If you change your mind..
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