Need Advice: 2.7 into "70 T

I bought a rebuilt 2.7 (911/85) stock with updated everything and including a new 030 distributor. I have a set of 40IDA webbers, exhaust, 901 transmission and ignition from my 2.2. Can anyone tell me how to set up this engine for optimum performance with these parts without taking it apart again? How much HP can I expect? What problems are in this configuration? Thanx, adgx

I sure don't have a clue by what you mean by 'optimal' with those pistons and cams ... but I wouldn't expect much more than what a 'normal' 1974 911 would put out, 140-150 hp. If you had 2.7RS pistons and cylinders, 'S' cams, and some head work done you might be able to get 210-220 hp, but you would have to do a partial tear-down for that 'optimization' ...

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Warren Hall
1973 911S Targa

The 911/85 (77 911 50 state) was rated at
165 hp & 176 ft/lbs of torque. The Webers should improve on that, maybe 10 hp, or so.
E cams and and RS pistons ( I just happen to have a set of pistons F/S) will give a bunch more. The rest is up to the tuner of the carbs. The head work is optional according to some knowledgeable folks I've spoken to.
Opening them from 35mm to 36mm is not worth the trouble. Aftermarket pistons in the 9.5:1
range are even better than the RS jobs(hp wise).
JPIII

Actually, from the sevice manual, the '76 and '77 engines were rated at 157 SAE net hp, a reduction of exactly 10 hp from the '74 'S' with the early heat exchangers. The '77 torque rating was 166 lb-ft SAE net, down 2 lb-ft from '74 specs. I seriously doubt 'T' Webers would show any hp improvement, unless venturis are enlarged to earlier 'S' specs, and the appropriate jetting changes made on a dyno, unless you find someone who has setup a mild-cammed 2.7 engine to get the data from. The head work would not be needed with 'E' cams, but the hp gain would be limited to 15-25 hp, not 'bunches'! If you doubt the 'value' of 'S' cams and head work and port-matching the manifolds to open the ports up to 'S' or 'RS' specs, consider that those are precisely the differences between a 2.4E and a 2.4S, a gain of exactly 24 hp in '72-'73 engines! The use of 9.5 to 1 pistons in an engine without a knock sensor and ECU would be highly questionable with today's gasoline, and an extremely 'risky' proposition! The 2.7 CIS distributor would not be suitable for Webers and hotter cams, so an 'S' or 'RS' spec distributor would be a prerequisite to any of the changes mentioned!

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Warren Hall
1973 911S Targa

The carbs he described are not necessarly T Webers. The biggest difference between the IDA & IDS is a fuel enrichment circut that opens at the top end with the IDS. The rest of the stuff is variable

The 40mm IDA, IDT, and IDS can all be modified to work with any motor up to about 3.4L. That's the nice thing about Webers, They are tunable. Some assembly is required!
We're not talking about turning a couple of screws here.
For instance, PMO sells IDA's for a straight conversion of CIS, all set up and ready to go.
The info I supplied for the 911/85 was from B. Andersons 911 book.

His 2.7L special with RS spec pistons, E cams
& Webers shows around 210 Hp on the dyno graph. That is 45 Hp over stock,using my numbers,53 hp, using yours.... a bunch to me.

The E heads had 32mm ports, not the 35mm ports of the 77 2.7L motor.

Since I am presently building one of these motors, I have taken the time to investigate all the aspects of it. And no, I won't be using a knock sensor.
I do agree with your assesment of the distributor.
S cams are a bit radical for a street motor using Webers. Too much overlap for bottom end throttle response. MFI can deal with it.
Webers will give you a cloud of fuel out the stacks.
Thanks for the advice.
JPIII

I bought a rebuilt 2.7 (911/85) stock with updated everything and including a new 030 distributor. I have a set of 40IDA webbers, exhaust, 901 transmission and ignition from my 2.2. Can anyone tell me how to set up this engine for optimum performance with these parts without taking it apart again? How much HP can I expect? What problems are in this configuration? Thanx, adgx


With a 2.7 in a 2.2 car, with a 901, you can go >
2.7
Webers
early headers
901, shorter gearing then a 915,
so toss the E cams
go with Early S camshafts, or if you want more bottom end, go Solex grind,
You can open the head ports to at least 35mm, to gain more top end,
time sert it
Head stud it
The 2.2 dist will not work because the shaft is to small, I would sell the 930 Dist, and take the money and buy a 2.7 (which will leave money in your pocket) and have that dist re-curved.

But to strickty bolt on a set of Webers to a stock CIS 2.7 is not going to be much of a gain.

Roy at http://www.motormeister.com

Thanks for the advise so far guys- but I'm confused as to what cams the 911/85 engine comes with. Whatever they are is what it has. The Anderson book says it has the same cams as 911/42 ("S" cams?) as do several other engines. Also I measured the intake manifold diameter and it shows 35mm. This engine already has the stud work timeing chain upgrades, turbo covers and so on.
I'm pretty good with tools (I've been a Harley mechanic all my life), and can deal with any carb adjustments. The distributor is new and came installed on the engine. Are you telling me it won't match up with the Webbers? It has a vacuum advance attached. Tell me what to do here. The whole point of fielding this topic was to see what I could do with what I have now, and what I can realistically expect from it . I've pretty much shot my wad on high dollar parts for a while. By the way How much are those RS pistons or their substitutes. Are there pistons which will work like those without the cost of new cylinders? Thanx again, adgx