2.7 Rebuild – To bore or not to bore and other questions

[draw]

Originally Posted by cmcfaul

Will be a screamer that will want to run past 7200 RPM redline. Anything you can do to lighten the valvetrain is recommenced.

Chris
73 911 E 2.4 with 9.8 CR and DC 30's

I appreciate the input!

I am concerned about this, too. I exchanged some emails with John at Dougherty Racing Cams (aka "camgrinder") about my build and intended use and he suggested that titanium valve springs and retainers would be good insurance for any revs over 7,000. So, these are now on my build list.

[draw]

Originally Posted by lvporschepilot

Fab engine! Make sure the intake and exhaust ports are opened!

What port size do you suggest? They are at 35mm now and I'm concerned if I open them up too much more that this will become a full race motor and not streetable.

[draw]

Originally Posted by Walt Fricke

Rather than considering shuffle pins for the case halves, you ought to think of bushings - tubes around the through bolts. Like what Porsche does for the #1 main bearing. There is a trick which allows you to drill these holes larger one by one with the case otherwise bolted together, so the tubes line up perfectly. Cgarr can do it for you, as can other machinists. Pretty straight forward. A good idea for a race motor, whether tracked or not, and especially for a mag case.

Thanks! I've seen this done, but wasn't sure if it had any advantages over dowel pins.

[draw]

Originally Posted by 75 911s

Myself and a friend just had our jugs sent out, he used millennium, I used US Chrome. Both sets (his a 3.0 and mine 3.2) had one bad cylinder returned with excessive pitting. I was able to source a set of jugs for free but it still cost me an additional $220 to get the 7th one bored and plated. Just a word of caution when considering new jugs vs boring existing.

Good to know about this. Where was the pitting? Any pics? Thanks!

[draw]

Current progress.

At this stage, I was introduced to “Murphy’s Law of Wrist Pin Circlips” when I removed the first piston. This law states that if you leave any openings in the engine case uncovered, a circlip is required to automatically fly in there when removed from the piston. Fortunately, I am now aware of this law and will comply with it during the reassembly process.

[targa72e]

My friend built a engine very similar to what you are planning. It had good power everywhere. We used my 914-6 to break it in and get some miles on it. Mod S cams, Stock ports, Valve retainers and springs. Springs set at 34.5MM height. Rev-limiter was set at 7500RPM. Pulled very well and smooth to the rev limiter. His for sale post has some more details. Dynoed at 204 at wheels and probably could have got more with some tuning as we were a little lean on top. I am planning a similar engine but with more compression, twin plug and EFI ITB. I might even go up to DC44 cams.

911 Engine for sale


john

[Henry Schmidt]

Originally Posted by draw

Henry, I'm wanting to use your Supertec head studs for this build...any other suggestions?

I've been to your shop by the way...you and I chatted while your dog chased rabbits or goats or something.

Because you asked....here are is some shameless advertising.
Wide idler arms are a must. We modify stock arms for a reasonable price or you can by factory late style (wide) arms from our host.





Supertec case sealant kit, available from our host



Twin plug distributors




Custom made engine harnesses



We also make a pretty cool front pulley.


Replacement fan pulley to renew a worn pulley and retrofit late pulley with our early replica. Rivets included.

[Flat6pac]

Draw, in the pictures, the pistons are upside down that you are removing or did you drop them in place for photo?
Bruce

[draw]

Originally Posted by Flat6pac

Draw, in the pictures, the pistons are upside down that you are removing or did you drop them in place for photo?
Bruce

Holy cow!!! I wasn’t even paying attention to that when I pulled the heads off. Those pistons are still attached to the rods in the pic. That’s how they were installed and it looks like it was able to run like that, too. (I bought the motor after it was already pulled from another car and I’ve never seen it run.)

[lvporschepilot]

I run 39mm intake ports, 38mm exhaust, and a DC65 cam. Twin plug. 92mm. It is perfectly streetable. 37-38mm intake ports certainly wouldn't hurt your motor.

[draw]

Been chipping away at the teardown over the last couple of weeks and today I attacked the head studs. Wayne's book suggests using the Snap On collet tool, which I thought about but I couldn't find the Snap On CG500-43 collet on ebay and Pelican doesn't sell it any longer.

So, I went with propane heat and the pipe wrench and double nut method. Wayne's book suggests 10-15 minutes of heat, but I'm too impatient for that. I used a laser thermometer to check when the case got to about 230 degrees (which took about 3 minutes) and then I loosened the studs with the wrenches. I've got 12 studs out so far and no problems yet. I ran out of time and propane...

Originally Posted by targa72e

My friend built a engine very similar to what you are planning. It had good power everywhere. We used my 914-6 to break it in and get some miles on it. Mod S cams, Stock ports, Valve retainers and springs. Springs set at 34.5MM height. Rev-limiter was set at 7500RPM. Pulled very well and smooth to the rev limiter. His for sale post has some more details. Dynoed at 204 at wheels and probably could have got more with some tuning as we were a little lean on top. I am planning a similar engine but with more compression, twin plug and EFI ITB. I might even go up to DC44 cams.

911 Engine for sale


john

Thanks for sharing, that's a nice looking motor...

Originally Posted by Henry Schmidt

Because you asked....here are is some shameless advertising.
Wide idler arms are a must. We modify stock arms for a reasonable price or you can by factory late style (wide) arms from our host.


Supertec case sealant kit, available from our host

Twin plug distributors

Custom made engine harnesses

We also make a pretty cool front pulley.

Replacement fan pulley to renew a worn pulley and retrofit late pulley with our early replica. Rivets included.

Thanks Henry, I will definitely stop by for those wide idler arms.

Originally Posted by lvporschepilot

I run 39mm intake ports, 38mm exhaust, and a DC65 cam. Twin plug. 92mm. It is perfectly streetable. 37-38mm intake ports certainly wouldn't hurt your motor.

Thanks for the advice. I'm considering opening up the heads to 36mm for both the intake and exhaust.

[Left_coast*9]

Great thread, following intensely and thanks everyone for the valuable input!

[jess p]

Originally Posted by Flat6pac

Draw, in the pictures, the pistons are upside down that you are removing or did you drop them in place for photo?
Bruce

Maybe he has a camera that takes things upside down!

[mikedsilva]

Originally Posted by draw

Holy cow!!! I wasn’t even paying attention to that when I pulled the heads off. Those pistons are still attached to the rods in the pic. That’s how they were installed and it looks like it was able to run like that, too. (I bought the motor after it was already pulled from another car and I’ve never seen it run.)

Nothing gets past our Bruce!!

[draw]

Success!!! The case is split!

I removed all of the head studs without breaking any and without too much drama. I did have a brief magnesium fire that I was able to put out quickly. It's amazing how fast magnesium shavings catch fire.

I'm not so sure any case sealant was used during the previous rebuild. So, after I remembered to remove all of the case nuts in the various hidden locations, the case came apart pretty easily.





The crankshaft looks pretty good to the naked eye. I plan to take the crank to Marine for inspection, cross drilling, grooving, etc.

Originally Posted by Left_coast*9

Great thread, following intensely and thanks everyone for the valuable input!

Thanks!

Originally Posted by jess p

Maybe he has a camera that takes things upside down!

That's funny! The other side had the pistons backwards, too. At least the previous engine builder was consistent.

Originally Posted by mikedsilva

Nothing gets past our Bruce!!

It's amazing what experienced eyes can see!

[Mark Henry]

Now watching this. It looks like I'll be building myself a hot street 2.7 over the next couple of years. It will be twinplug, I have 40 IDA's with MSD and a Patrick dizzy OR an aftermarket EFI with ignition to choose from.

It will be for a 914/6 conversion.

[NeedSpace]

This is excellent. I am planning my first 2.7 engine rebuild myself. I'll probably keep it fairly stock but looking forward to your progress...

[draw]

I wrapped up the teardown of the engine this weekend. By following Wayne’s book, and the wealth of knowledge here on Pelican, the process was fairly uneventful and fun.

The second to last project was to tackle the camshaft housing/heads. I used my lift table for my workbench…



My Harbor Freight long 5mm hex bit didn’t fit through the rocker shaft opening, so I struggled with the 5mm “L key” until I remembered I had a Craftsman bit in my tool chest. This fit through the openings and made the job go twice as fast. I’ve seen some people cut down a longer bit to fit, and I’m glad I didn’t have to go there.



Everything came apart without much drama. Unfortunately, the previous “mechanic” trashed some of the rocker shafts on the previous installation, which gouged the housings. So, I may be in the market for new housings…

The last project was to breakdown the rods from the crankshaft. I reattached the flywheel, stood the assembly on its end, and started removing rods from the top down. Things went great until I got to the last rod (cylinder #3). When I saw this, my heart sank…





The bearing has a groove that catches a fingernail. The rod journal itself looks good, so I’m not sure what to think about this yet. I guess I’m going to be stressed out until I get the crank inspected…

Now this is done, it’s time to spend $$$...yikes!

Originally Posted by Mark Henry

Now watching this. It looks like I'll be building myself a hot street 2.7 over the next couple of years. It will be twinplug, I have 40 IDA's with MSD and a Patrick dizzy OR an aftermarket EFI with ignition to choose from.

It will be for a 914/6 conversion.

Thanks for watching! Sounds like a cool motor!

Originally Posted by NeedSpace

This is excellent. I am planning my first 2.7 engine rebuild myself. I'll probably keep it fairly stock but looking forward to your progress...

Thanks! Rebuilding an engine is certainly a worthwhile experience.

[stownsen914]

I saw you mentioned above about titanium valve springs and retainers. Some builders recommend against titanium in the valve train for a street engine. Titanium can wear, and is sensitive to failure once it does. In a race engine that is apart more frequently, it gets noticed before it is an issue. Most people will tell you the stock valve train, or some aftermarket steel springs, are easily good for 7000 RPM.

[draw]

Well, a couple of years after taking the engine apart...

It's time to take the case out of the box from Ollie's.



I apologize in advance if it's "bad form" to post how much the machine work cost, but here's the invoice.



The case was pretty twisted, so it was line bored back to standard. The case lost 0.035 during the process. I'm going to need some thick gaskets for the chain housing. Any ideas where I can get those?



Shuffle pins added.



Right side of the case.



One area I may have overlooked was not having the chain housing gasket surface fly cut.



What do you think? Should I block the gasket surface flat with sandpaper or is it good as is? Also, the studs don't seem to be the correct length. Does anyone know the correct sizes? The PET lists some sizes that don't quite make sense to me.

There's some grease left around most of the case studs, so I'm going to remove all the studs and clean out the threads. On to cleaning!