Virgin 911 engine builder needs advice

[vwbobd]

I'm a total noob when it comes to these monsters. I bought a 71 911T targa a while back from the original owners (deceased) family with the intent on restoring back to original . I have decided to tackle the rebuild myself giving that I have been a service manager at a very large multi line dealer, and now a technical trainer for manufacturers. I feel that although challenging, I have sufficient background and mechanical experience to handle it. However, I would like to change the engine to the "S" specifications. I now have the standard 2.2L with Zenith carbs. Finally to my question: I know I need the "S" p&c's, but do I need new heads or can my heads be worked to get the results I need? I do know that my case will have to be machined to accept the "S" p&c's. Thank you for your help, I know that I'm a "noo b" so please don't harass me about that.

[Mark Henry]

Buy Wayne's book...never say you're on a budget.....even if you are.

[Kemo]

Originally Posted by Mark Henry

Buy Wayne's book...never say you're on a budget.....even if you are.

this has got to be the most truthful reply I have ever seen

[vwbobd]

Originally Posted by Mark Henry

Buy Wayne's book...never say you're on a budget.....even if you are.

I will get that book!! thank you for your support

[vwbobd]

This is what Im working on:

Bad pic from back when I first got her in 2001, Got her for $2k !!!!!! and She was complete!!!!!

[304065]

Bob,

First of all, WELCOME to the forum. It's important to remember that there's no such thing as a stupid question, and unlike seemingly the rest of cyberspace, new people are welcome here as it provides an opportunity for EVERYONE to learn. So ask away without fear of being flamed, we have all been there once, even the handful of professional engine builders who frequent this forum.

I think you're on the right track with your thoughts about the 71T build. Just to calibrate a few items--

Your case does not need machining for 2,2S cylinders- the spigot dimension is the same, it's just that the S cylindrers are Biral, meaning they are aluminum fins with a cast-iron cylinder liner, unlike the solid cast-iron of the 911T cylinders. But dimensionally, the Birals slip right in. These days, there are Nikasil cylinders available that are superior to the Birals that also offer the opportunity for increased displacement, e.g. why stop at 84mm when you can conveniently go to 86mm for 2300cc?

By 1970 the valve sizes had standardized across the T, E and S, it's really the ports that are different. So yes, your "T" heads can be ported to "S" specifications.

Of course you will need S cams-- there are modern grinds that are regarded as better, including the DC40 "Mod-S" which offers similar duration to the original but better cylinder filling.

Anyway, those are just some preliminary thoughts, others here will chime in.

[tom1394racing]

Bob

One thing to think and ask about is going with an E spec motor rather than an S spec.

If you plan on using the car mostly for street driving, you will get better all around performance and driveability with the E cams and the slightly lower compression E spec pistons.

The S motor produces most of it's addition HP right at the top of the RPM band at the expense of low end driveability.

Others with more experience should chime in here and help Bob with this suggestion.

[Fast Corners]

Bob,

Welcome to the forum and "Summer" really is a nice looking car. Start with Wayne's book as Mark said. This will really help you get organized for the build. As John stated ask questions and solicit opinions on this board it will help alot. Tom also brought up a good point in his post. If you plan on using your Targa for street driving you may want to consider building a high compression "E" motor (use "S" P&C's and "E" cams). This makes a great little motor that is much more fun to drive around on the streets than a true "S" spec motor.

[OldTee]

While you are ordering books, inlude "911 Performance Handbook" by Bruce Anderson. It offers a good background on your car and engine.

[vwbobd]

Thanks guys!!! I just spoke with Bruce Abbott about setting her up to "E" . I think that is probably gonna be my best option. I'm not looking to hot rod her, just wanted a little bump after the foot pump if you know what I mean. I certainly appreciate all of your comments . I really enjoy this site , lots of knowledge and experience here unlike other sites where you get flamed for everything and no one seems to know crap about what they're talking about. You guys are awesome!!!!

[jpnovak]

VW Bob, welcome to the board. Here are my thoughts.

If you are going to get cams ground take the time to speak with John Dougherty (camgrinder on this board). he has a Mod-E grind that would be perfect for your application. that would be my choice for a fun street car. Tell him exactly what you are looking for with respect to power band, rpm response and car usage. Cam choice should be first in your engine build specifications.

Next, choose compression ratio (pistons) to match the cams. Make sure you have good valve clearance. Higher compression pistons can be run with wilder cams based upon dynamic compression ratio and engine rpm.


for an E spec motor try to keep the compression ratio less than 9.5:1 so that you will not have problems with the summer heat on pump gas in GA. Less is more in this case. Anything around 9 or 9.2:1 would maximize your output for single plug and pump gas. Any more and you will have to retard timing to avoid detonation/pre-ignition.

Once you have set the cam spec and compression you need to tune your heads to flow in the right rpm band. The stock T head port sizes will be too small for an E or mod-E cam. They will be great at low rpm yet limit flow up high. Since you are building a street engine don't get crazy with port sizes. Too much porting will make the engine feel sluggish. In most cases you can keep the stock port sizes for an E and clean up the shape of the intake tract. Talk to one of the many professionals on the board for more assistance.

Next you need to consider your induction system. The zeniths can be made to work. The problem will be availability of some of the tuning parts. Some jets are interchangeable with webers and easy to find. Others may require drilling out. A change in Venturi size will require a lathe since AFIK, replacement internal parts are not available. Zenith's will function very well but require proper setup for the new engine configuration.

Finally, you need spark and timing. The switch to an E cam will require a different advance curve. You can purchase an E distributor (bolt in) or have your T recurved. If you have the original Marelli, consider buying a Bosch and having it custom curved. This will greatly influence your throttle response. Cap and rotor availability for Marrelli is non-existent.

You have a great looking car. I bet she likes to take her top off and go hard. I know my 71 targa surely does!

[vwbobd]

Thank you for the advise my good man. Can you shoot me some pics of your pretty lady? Also what engine set up are you using on yours? email is bldixon@windstream.net

[turbobrat930]

SO, I thought your wife had stole all of your cash out of your wallet??? LOL, so, when are you going to get the o2A trans from the good ole' vortex??? Pullin your chain...but if you are messing with that old 911...you will never have enough cash to buy the trans!!

[vwbobd]

My wife always steals my stash!!!!! She hates my VW, she loves the 911 though, so she don't give me crap about $$ on it........She thinks she is gonna get to ride in it when its done. NOT GONNA HAPPEN!!!!1 I'd hate to wrinkle my freshly redone seats or take a chance on a foot hitting my door pockets

[turbobrat930]

LOL< good to see you on here....