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Thread: Rebuild Suggestions for '72 E

  1. #1

    Rebuild Suggestions for '72 E


    I just read through the posts on suggestions for a S rebuild. I have a stock, MFI '72 E that I plan to someday rebuild. It runs fine now but I plan to keep this car a very long time and want it in like-new condition.

    I have read Bruce Anderson's book several times and have a mechanic here locally who has built several 2.4's, 2.7's and 2.8's, etc., and is very well respected. I know Bruce feels the 2.7 w/ E cams and webers is one of his faves but I'd really like to keep my MFI. Afterall, it's the "E" in einspritz.

    My goal is for a very hot but very reliable street & DE performer (read ~200 HP) but not an out and out race car, and am trying to weigh the value of keeping a true 2.4 displacement E (ie, totally stock), putting 2.2 E pistons in to raise the c/r & HP, or going with a 2.7 a la RS but with E cams. I know there's no substitute for cc's but I also see the value in keeping it a 2.4 (its rarity).

    The other question then is how to feed it--MFI or carbs? As I said, I'd like to keep the MFI if possible but not sure on the cost of rebuilding and re-sizing my MFI for any of these changes.

    I'd like to hear pros and cons on both displacement and fuel system changes and your ideas on the proper marriage of the two.


    '72 E Sunroof Coupe

  2. #2
    Robert Laverty


    I recommend going to 2.7 and putting in the S cams. With that large of a displacement, the engine could use the better breathing of the S Cams and the longer stroke helps a lot with torque at lower RPMs. You will also have to ensure the ports are 35mm or so and that the carbs are jetted and venturied correctly.
    This was the configuration of the last 911 engine I built and was VERY happy with it.

  3. #3


    Thanks Robert.

    Anyone have any experience with 2.2 Pistons and the 2.4 rods and crank?

    Call me sentimental, but I think I might get the performance I want while keeping the originality of the 2.4. Comments?

  4. #4

    Re: Reply

    If you're happy with the stock 2.4 E profile, why not keep it? And, from reading your post on the general discussion page, you seem to be? If your car still has it's orginal case it's made of magnesium. IF I were going to have a 2.7 or bigger engine built I would lean more towards NOT maching the 2.4 case to take the bigger pistons & cylinders, but think more in terms of going with an aluminum "7R" case.

    C'mon, Jeff you've done the 2.7 thing...any thoughts on this?

  5. #5

    Re: Reply

    I would look to NOT machining the magnesium case is what I meant. 2.2 pistons? You want a higher compression ratio with what passes for gasoline these days?

  6. #6

    High-Compression 2.4

    Thanks. That's the kind of feedback I was looking for. Let me qualify my position on the car's current performance. I am indeed happy with it but perhaps not entirely satisfied with it.

    The way I figure it, if I'm going to spend $10k++ on a thorough, quality rebuild, I want to take as much advantage of hindsight to re-engineer more HP, torque and reliability into the motor. What's difficult for a neophyte like me is there are so many options to choose from and everyone you ask will tell you something different.

    For me, the goal is to find the right balance between performance, reliability, originality and cost--and probably in that order. I feel the right balance for me will be what performance choices can be made during the process that will not add more than say 25% to the total cost of the rebuild, not make it any less reliable than stock, and not change the outward appearance of a 2.4 E knowing that only a few people would ever be able to tell a 2.7 from a 2.4. The allure is that for me, I can certainly feel it more torque and HP.

    Another example to illustrate my point, the car already has the carrera chain tensioners. I will certainly keep those. But since I will want to have new P&C's, I want to figure out which combination will give me the desired balance between increased performance for the $. Hence my question about the 2.2 E pistons. But if the car just won't run right at that compression on what "gas" is available (octane additives or not), then I probably won't want to do that as this car will be pretty regularly driven.

    Also, as I stated before, I will be VERY reluctant to dump the MFI or change the cams to get more performance because to me, that's too much at the expense of originality. It's a '72 E primarily because of the MFI and the cams and I want to keep those qualities of the car. An 2.4 or 2.7 E with carbs is obviously not a stock '72 E (an "L" on steroids??!) but a 2.7 E built on a 7R case with MFI and a front oil cooler could be a very covert and appealing package.

    Anybody who has dealt with these issues and would like to share, I'd love to get your input. Thanks again,

    John Mackay

  7. #7

    Re: High Comp 2.4

    I have a 2.7 RS spec MFI engine in my 72S (rebuilt by previous owner) and it is wonderful to drive around town and on the track - very torquey and yet still winds up with that early S sound. It dyno'd with 210 at the wheels. Another 2.4S I know rebuilt with 2.2S pistons and mod S cam is just as fast, if not as torquey, and dyno'd at about 200 to the wheels. If it were my engine to rebuild, I would go to 2.2 E pistons with your stock E cams and MFI and leave it at that. This would give you a performance upgrade and still not be too expensive a rebuild, especially since you wouldn't have to modify your case or change your cylinders or MFI cam. You could always convert it back to stock and you would gain most of what you would with a 2.7 RS spec conversion. Also, you may want to price out a rebuild to RS spec MFI engine, as these are getting to be rather pricey conversions.

    Randy W

  8. #8

    Re: High Comp 2.4

    John...I really think this boils down to the oldest question in hot rodding. IE, "how fast do you want to spend?" The $ add up quickly when you're talking P cars.

  9. #9

    Re: High Comp 2.4


    Wow those are some pretty impressive rear wheel hp #'s out of a 2.4...I'd be interested in hearing about the specific modifications done to the engine. is there a way I could have a look at they dyno chart?



  10. #10

    Re: High Comp 2.4


    Thanks for bringing my error to my attention - should have typed "flywheel" instead of "wheels" in the above post for both vehicles. Sorry, I did not wish to mislead. The numbers were generated based on a 15% loss to the wheels. The dyno chart for my 72 RS spec MFI indicates 182.5 HP at the wheels - if you're still interested, I can mail a copy to you. The engine is standard RS spec MFI as far as I know.

    Randy W

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