1966 Engine Build Suggestions/Thoughts

[Ovis]

I have a 1965/1966 911. It hasn't been on the road in 10 years, but I am currently in the process of ordering parts for the engine rebuild and have become stumped. I know these motors can be built to a number of different combinations, but as a engine builder neophyte, I'd love to hear suggestions from those more in the know.

This is my first post, but I've been a long time browser of the Pelican Forums. The case and crank (66mm counterweighted) have been at the machine shop and should be done soon, so now I am to the point I need to order parts. I've decided against rebuilding the motor with the original heads, piston and cylinders, as I'd like to produce a little more horsepower. Therefore, I need to source heads and have them rebuilt, and I plan on purchasing LN Nickies and pistons. This will not be twin plugged, so this will not be a high compression build. The motor will run Weber carbs.

If you were faced with this basic set of parameters, what would you do?

Heads: 2.2/2.4 built to S-spec? 2.7 S-spec?
Pistons/Cylinders: 84mm Jugs? I have been told that I can purchase up to 87.5 jugs with my stock spigot size.

These are the two piston/cylinder combinations I have been considering:
https://lnengineering.com/products/porsche-and-vw-aircooled-cylinders-and-pistons/porsche-911-1965-77/porsche-911-24-84mm-nickies-inc-95-1-je-piston-set.html

https://lnengineering.com/products/mahle-motorsports-cylinder-and-pistons-sets-for-porsche-and-vw/porsche-911s-22-24l-1969-1973-mahle-cylinder-and-piston-set.html

Any thoughts or consideration between the JE and Mahle pistons? Preference?

Cam suggestions?

Please bare with me as I am new to all of this and learning, but I certainly appreciate any advice and suggestions that you may have. Thank you in advance!

[304065]

Well, I asked precisely the same questions here over a decade ago. Ultimately I decided to bore the Biral cylinders to 81, fit 9,5:1 JE pistons and rebuild everything completely as stock.

That thread is here: Suggestions for warmed over 2.0 901/05?

if you do a "tag search" for 901/05 you will find a great deal of information that can guide your decision making process.

The short answer is that the 84mm and larger cylinders have a cylinder-to-head mating design that is different from the 80mm. So yes, new heads are in order.

If you are going the nickies route, yes, I would go all the way with 87.5mm cylinders and JE (mahle doesn't make an 87.5.

https://lnengineering.com/products/porsche-and-vw-aircooled-cylinders-and-pistons/porsche-911-1965-77/porsche-911-22-875mm-nickies-inc-95-1-je-piston-set.html

This then raises the issue of oil cooling, which must be addressed if you are going beyond stock power levels.

What cams? Depends on what you want to do with the car. I would start with DC30 ("mod-Solex") or DC40 ("Mod-S"). The modern cam profiles are better than the original with asymmetric ramps that give you a little more area under the curve.

Good luck!

[Ovis]

Thank you for the insight 304065.

I have considered going completely stock on the rebuild, but this car will never be a pure all original early 911. If I were to do that, I'd have the Solex carbs restored, and probably add about 100k in restoration costs for good measure to make her "original"....Alas, I think she'll be a driver for the rest of my days, which is why I am looking to get a little more power.

If I do go with the 87.5 mm cylinders, will 2.4 heads mate with those cylinders, or do I need 2.7 heads. Yes I know, probably a dumb question, but I am still learning.

If anybody else has any thoughts or suggestions, I am all ears.

[targa72e]

2.4 and 2.7 heads are dimensionally the same (different port size depending on year). 2.7 heads have a slight bevel to accommodate the 90mm bore (can be added to 2.4 heads). Depending on piston design used you may or may not need to bevel 2.4 heads if used with 87.5 bore.

john

[Ovis]

Originally Posted by targa72e

2.4 and 2.7 heads are dimensionally the same (different port size depending on year). 2.7 heads have a slight bevel to accommodate the 90mm bore (can be added to 2.4 heads). Depending on piston design used you may or may not need to bevel 2.4 heads if used with 87.5 bore.

john

Thank your for that info John, that is very helpful!

Decisions, decisions.....I just want to do things right since these motors are so expensive.

[Ovis]

Anybody else?

Bueller...Bueller...Bueller?

[tx93086]

I have a friend who loves the 2.2S motors so I had a 2.2E that I decided to rebuild and try. It has 2.2E pistons, E cams, Weber’s with 32mm ventures. I put it in my car and I did like it, but over the next year I assembled a 2.4 with 2.2E pistons (about 9.5:1 CR), E cams, and Zeniths with 34mm centuries. I like the 2.4 much better than the 2.2. I thought the shorter stroke might be smother or more snappy, but everything about the 2.4 is better. I will probably have a 2.2 for sale on Pelican soon.

[silverc4s]

I had an otherwise stock 2.4E engine with Webers in my 69 targa for years. Very fast, AND very drivable as well. (ran on 87 fuel too) If its a driver you want, look for low end torque.

[Ovis]

Thank you guys....I appreciate the input. This car will be a driver. It has been in my family since 1976 and it is my fathers dream to drive it again before he is unable, so I am trying to make that dream come true for him.

Right now I am leaning towards buying the 87.5mm cylinders and pistons on going that route.

Thank you guys!

[DaveA]

Get Bruce Anderson's book and Wayne Dempsey's book and read them. If you are going to spend the money, get a 2.4/2.7 crank and rods, 2.4/2.7 heads. Use either 2.7l 90mm or 2.8l 98 mm pistons and cylinders, compression ratio 9.8 to 1. You can even use your cams, or get S plus cams.
You'll have to have machine work to open up the case bores for the cylinders.
When you finish, you'll have a stout, reliable engine that will run very well.

Dave

[Ovis]

Thanks Dave, I appreciate the thoughts. I wanted to avoid opening the cylinder spigots being that it is an early aluminum case, hence my desire to stick with the 87.5mm or less cylinders. I have been told these are slip fit and will work with the early 2.0 case without modifications.

I will use the original crank and rods. I have solex grind web cam camshafts, with the Weber carbs. I do not want twin plug, so compression needs to remain reasonable. The case is at the machine shop now, and should be about done, oil bypass mod and pistons squirters included.

One question I do have is whether or not I should upgrade to the later 4-rib oil pump, or is my original pump up to the task?

Ovis

[tx93086]

Something to consider is that 87.5 mm pistons make the remaining cylinder wall around the head gasket very thin. I have seen this section breaking off (on 86mm pistons) and cause major damage. It was probably caused by detonation, and you may be fine, but if you go as large as 87.5 be very careful with compression and timing to be safe.