73RS Upgrades - Oxymoron?

Hello,

I am still not finished chasing an elusive vibration in my '73 RS spec motor. I have been through a lot with this, but not giving up just yet. Just as a re-cap, it originated from a missed shift / mechanical overrev. Repairs to date have included the following:

1) Bent exhaust valve on cylinder number 2
2) Valve timing checked and reset correctly
3) New alloy clutch plate and new clutch disc
4) Ignition tune-up including R&R and lube of distributor, plugs, cap, wires, rotor.
5) New vacuum hoses
6) New mechanical injection hoses and clean MFI thermostat.
7) New Air Filter

Still, annoying vibration throughout the rpm range and corresponding lack of power.

So, I think I am going in. I am going to start with the top end and see if there is anything suspect there... bent cam sprocket, broken valve spring(s), broken rocker, chain problems, etc... If I find nothing there, I will go deeper... bent intermediate shaft, bearing problems, bent connecting rod, etc...

Now to my question... while I am in there, are there any upgrades I should contemplate? Based on the way this car ran previous to this incident, I have to believe it is putting out near 210 HP or better. I believe it has stock "S" cams. The MFI pump is numbered as from a 2.4S, but I have to believe it has the 2.7 space cam because it really dumps the fuel.

Bruce talks about the Andial 2.9 or 3.0 conversion. Is this safe with my magnesium 7R case? From his chart it look like they were getting around 225 horses. That sounds great, but I am wondering if it would be worth the expense.

He also talks about the 2.8 conversion, but advises against it due the compression issues and the difficulty in locating the RSR heads.

Are there any particular recommendations that would be maybe just some new pistons or cams? This motor is hard to improve on I am sure, but I figured I should check while I am in there.

Thanks fellas,

JA


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John
70/73 RS Spec Coupe

john,

i can only comment on the andial 2.9

my 2.9 andial built motor is just about 3 months old. they built it off my original 2.7 mag case.

i love my car! it has great tourqe and is quicker than most expect. like anything you get used to the acceleration and always want more but until a big pile of cash falls from the sky i will stick with what i have.

if your in the orange county area let me know, i'll give you a ride to prove it.

jim

Thanks for the comment, Jim.

One question, did a big pile of cash already have to fall from the sky for 2.9?

Also, what kind of HP are you getting? Does it leak oil at all? What all was included to get to 2.9 and what other engine components had to be modified? I assume you are CIS, right?

Thanks,

JA

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John
70/73 RS Spec Coupe

John,

Jerry Woods' 'Sport' valve spring set and retainers, and GE-60 or GE-80 cams!

Andial no longer sells or recommends the 3.0 conversion for Mg cases!

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Warren Hall
1973 911S Targa

Warren,

Now you're talking! I was wondering about that Mag case - Thanks.

What benefit do the "sport" valve springs provide? Extra support for the wild cams, I presume?

What is approximate cost of the springs and cams, and what kind of performance impact would I likely see? What criteria should I use to determine the use of the GE-60 vs GE-80 cams?

Also, any street driveability issues with those cams?

Thanks for the great info!


JA

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John
70/73 RS Spec Coupe

John,

The sport springs and retainers offer safe reving to 8000 rpm with stock rockers and swivel-feet adjusters, and I believe the price was $420 in a recent ad.

All of the GE-series cams are $1098 from Jerry Woods, and I don't know if Web-Cam or Elgin offer similar grinds. I doubt there would be any drivability issues with the GE-60 cams, as they are quite similar to 'S' cams (and 'RS' cams, too) with slightly more lift on the intakes, and slightly more lift and duration on the exhaust lobes. You would need to talk to or write Jerry Woods (email, but no website, yet) for the approximate power and torque peak rpms on the GE-80 cams ... my best guess is between 'S' and 'R' cams, low to mid-7s for the power peak.

Oh yeah, one more easy upgrade (if you don't mind serious wallet pain) is Titanium intake valves, though I haven't found any that are in the 'reasonable' price range! Twice the price of a set for a Mopar 426 Hemi is still a bit too painful for me to contemplate seriously!

I am planning on getting Jerry Woods sport valve spring set and GE-60 cams when I do a top-end job later this year.
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Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 04-25-2001).]

john,

first warren is absolutely correct . andial would only take my mg case to a 2.9.

as for cash from the sky, the 2.9 was up there but has been my personal dream to have an andial built motor. when fulfilling dreams i find that rational thinking takes a back seat.

i wish i could give you hp numbers. i am look forward to getting my car on a dyno. (if anyone knows of a porsche friendly place in orange county let me know). what the guys told me at andial is that my car should have a hp to weight ration similar to a 993. in my very un scientific nose to nose comparison i find that i am actually faster.

i have 5500 miles on my motor and i do not leak a drop of oil.

i did keep CIS but updated the CIS system to the larger runners and air box from 78-79. my understanding was that this would allow for a little more at the top end.

additional items i included were: sport muffler, most of the neccesary work for future twin plug ignition (had to limit the budget somewhere), spor t cams, 1.5 hp starter (to turn the beast over) and all the other little thinkg that andial does.

have fun with your project.

jim

We should organize a Southern California Dyno-day.

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Jack Olsen
1973 911 T (3.6) sunroof coupe
jackolsen@mediaone.net

jack,

i would love to be a part of a socal dyno day.

jim