Plan to build a carb'd 2.4 - questions

[ddubois]

My restored 71T has the original, matching engine that still runs well but is tired. My plan is to put the original engine in storage and build another engine for the car. What I want to build is the 2.2 -> 2.4 upgrade/E pistons & cams described in Wayne's book with PMOs.
My question is should I look for a 2.2 or 2.4 engine to start with?
If I start with a 2.4 are there issues with the MFI heads since it will carbureted, or issues mating it to my 901/911 transmission? Do people simply plug the injector ports when switching to carbs?
Would it be better and/or more cost effective to start with a 2.2 and find the 2.4 crank/rods as well as the E cams/pistons?

[Walt Fricke]

Doug - lots of choices. I'd want the 7R case, and you won't find that on a 2.2. So see if you can get a 2.4E, maybe minus the MFI stuff.

Then buy the 2.2 pistons for the CR you are wanting.

You can plug injector holes easily enough.

I don't know about the water cooled 911s nowadays, but you can bolt a VW or 356 transmission to any AC 911, and vice versa. The four holes are all in the same place.

Flywheel and clutch are the issues. The 901 and the 911 are very different in this regard. But the 911 transmission uses the same clutch as the 915, and as a result the same flywheel. So you are OK there. You still have the funky 911 release mechanism, but it will work with your flywheel. Or any flywheel likely to be on a donor motor of the type under discussion.

[marlinaness]

I just finished this last week. I used a 74 2.7 7R case which allowed the 2.2e pistons to fit (as a later 2.7 case the spigots are too large). I also used 2.2e cams. All fit very nicely together. Probably around 9.5 compression. Started the testing with high octane and no pinging yet. Barry Hershon rebuilt the distributor to match the engine specs. Webers with headers, and M&K finished the deal. It uses an LSD 915 transmisison. Car is a 71 widebody purchased on ebay. Looks like a 964 carrera. Last weekend, I got all of the webers between 11.5-14.5 AFR at all ranges through 6k rpm. will be tightening up on the idle circuit this next weekend e.g. 55 idle jets vice 60. I will be putting regular muffler and SSIs back on the car. The current headers have AFR bungs on each exhaust so I can get individual readings. 1st test run and the engine seems a bit faster than my SC was, but maybe not faster than a 3.2. Hard to tell. Let me know if you have any questions.

[moneymanager]

Why wouldn't you do a 2.4 vice the 2.2 when doing this upgrade? For the same price you get 9% more of everything. For that matter, why not just jump to the 2.7? Now you have 22% more of everything for little or no incremental cost.

[911pcars]

Originally Posted by moneymanager

Why wouldn't you do a 2.4 vice the 2.2 when doing this upgrade? For the same price you get 9% more of everything. For that matter, why not just jump to the 2.7? Now you have 22% more of everything for little or no incremental cost.

+1
There is no substitute for cubic inches (or cubic centimeters). Start with a 70.4mm crank/rods (2.4-2.7 liter), 90mm RS P/C and some case mods. The other costs you would spend with the smaller engine are about the same.

At the same time, 3.0 and 3.2 rebuilds are viable as well and cost is comparable.

Sherwood

[Henry Schmidt]

Doug
I've done a couple of these car/ engine project for myself recently and had some of the same questions.
I would avoid using 2.2 E pistons in any rebuilt because I don't like investing in performance engines with cast pistons. The only reason for the 2.2E/2.4 crank was to increase hp and save money back in the day but now we have better choices.
With both of my projects (69 T, 71T)I chose to rebuild the original numbers matching engine.
The reason I did that is I wanted my cars to benefit from the upgrades without changing out the engine. (easy resale)
Most of the available 2.7 case are marginal at best and 2.0T, 2.2T and 2.4T cases have generally never been heated or stressed.
You can go either way.
The engines I built were both 2.45 mod S with 40mm Webers.
I took the stock case and heads and changed out the crank to 70.4.
The Ps&Cs were 86mm AA (Nikasil coated) with 9.5:1 JE forged piston. No case machining necessary.
Cams were mod S from Doughety Racing Cams.
Ported the heads to 36 mm and added twin plug for the wow appeal.
With SSI header boxes and and an M&K sport muffler the engines produce a very driveable 180 RWHP @ 6400. Comparable to a 2.7 RS and yet still the stock unmodified case. (case savers, oil pump mod, of course)

[SWS911]

2.2T heads have no injector holes. Valve sizes are the same, but ports are not.