3.0 SC High Performance Rebuid

[DTW_porsche]

To tired to read back through every thing. Are your pistons brand new or did you get them refurbished?

[lindy 911]

My pistons are JE 10.5 : 1 with Poly Dyne slip coat on the sides and Poly Dyne thermal coat on the crowns bought new from Pelican. I re-used the Mahle barrels and had Arron de-glaze them. They measured in spec and the clearance worked out to be .018+-. Since this is a budget build, I used off-the-shelf pistons, not custom.

I also had Poly Dyne coat the main bearings with their slip coat that we used on the pistons. I have a good friend who is a race motor machinist and he swears by this mod especially with the fact that the Glyco bearings are not what they used to be.

Lindy

[DTW_porsche]

I had the pistons refurbished by Ollie's a while back. I still have not completed the rebuild so maybe ther is still hope for JE. Let me know what you think of them.

[Eagledriver]

I hope that clearance number is really .0018!

-Andy

[BURN-BROS]

Originally Posted by Eagledriver

I hope that clearance number is really .0018!

-Andy

Yes .0018 is what he meant.

[juicersr]

Great thread.

Just curious as to what disadvantages there would be to an identical build using small instead of large port SC heads? Would top end suffer? Would low end torque be better? I have a spare 80SC motor that is going in my 914/6 and will be rebuilding it using specs similar to yours, except with smaller port heads as that i what i have.

[lindy 911]

I'm not sure what the consequences would be with the later heads, pro or con. I do know that Henry Schmidt has offered the idea that the smaller ports can actually help the motor make more torque. He makes an intake fitting that reduces the intake port size which, as I understand it, helps to speed up the intake velocity filling the cylinder better. I don't know anything more than that.

My experience with motorcycles is that most of the time bigger is better as long as all the other parts of the puzzle support it. Big port heads with a small cam does no good. My motor is not a daily driver but more of a means to destroy rear tires on the weekend. It's my modern day motorcycle with four wheels, you know, the Saturday morning meet up with the guys and try to avoid tickets and deer while finding new limits in our 911s.

So in my opinion, the earlier heads will make a few more ponies on top, but I'm sure yours would be a kick in the pants as well.

Lindy

[BURN-BROS]

Originally Posted by juicersr

Great thread.

Just curious as to what disadvantages there would be to an identical build using small instead of large port SC heads? Would top end suffer?

Choose a different cam if you are not willing to port the heads. A DC30 (Mod Solex) would be a good match IMHO.

[juicersr]

Originally Posted by lindy 911

I'm not sure what the consequences would be with the later heads, pro or con. I do know that Henry Schmidt has offered the idea that the smaller ports can actually help the motor make more torque. He makes an intake fitting that reduces the intake port size which, as I understand it, helps to speed up the intake velocity filling the cylinder better. I don't know anything more than that.

My experience with motorcycles is that most of the time bigger is better as long as all the other parts of the puzzle support it. Big port heads with a small cam does no good. My motor is not a daily driver but more of a means to destroy rear tires on the weekend. It's my modern day motorcycle with four wheels, you know, the Saturday morning meet up with the guys and try to avoid tickets and deer while finding new limits in our 911s.

So in my opinion, the earlier heads will make a few more ponies on top, but I'm sure yours would be a kick in the pants as well.

Lindy

Henry advised me the same thing when i was building my 3.2SS last year (which i used large port heads on), but it was my intake set-up that was the rate limiting step on that motor, not the ports size. This motor will have 46's and headers, but not aiming to run the mulsanne straight or anything.

Aaron, will the performance characteristics of a small port, 10:1 3.0 motor be similar to Tom and Lindy's if one use's a DC-30 cam? Should i just port the heads, or do you agree with Henry on the 'Small port more torque' concept?

[BURN-BROS]

Originally Posted by juicersr

Aaron, will the performance characteristics of a small port, 10:1 3.0 motor be similar to Tom and Lindy's if one use's a DC-30 cam? Should i just port the heads, or do you agree with Henry on the 'Small port more torque' concept?

I agree with Henry about keeping a conservative port size for a street car. However, one must select a cam that augments port size. If your ports were above 36mm then going to a more aggresive cam profile will give you good results. Typically Henry uses 38mm ports on the 3.0 and 3.2SS with a DC60 cam. The final product is impressive.

The DC 30 has some legs on the smaller motors, but think of the DC30 as a "E cammed" type of engine when the displacement gets to 3 liters....YMMV

[lindy 911]

Well I finally got some time to start re-assembling the project 911. After a couple of dry runs to test fit the crank in the case and get all the bolts and nuts lined up, I assembled the bottom end. Turns out I had to do it twice anyway. When I tried to turn the crank after torquing everything down, it would turn but only with the use of a ratchet on the pulley bolt. So apart it came to check for problems.

I believe it was two fold; 1) the assembly lube provided in the Pelican kit is very thick and at 35F it made turning the crank difficult and 2) the over-spray from the bearing coating on the back side of the mains may have contributed. I noticed this after I took it all apart and cleaned everything up for re-assembly. There was material that you could feel so I sanded it off with 400 grit wet /dry and all is good.

When I re-re-assembled the case, everything was good to go. I could turn the crank with the snout alone and it felt very buttery. Now it was time for the Ps & Cs. Pretty straight forward with the exception of the JE cir clips. Takes some time to get a technique down but definitely more difficult than the stock clips.

Then it was time for the heads, cam housings and chain boxes. Nothing overly hard about the build so far but that's subject to change as cam timing is next. I've also included photos of a few mock-ups of the carbs and nickel plated fan.





/91+rebuild+2+0011264097546.jpg[/img]






So far that's it. More to come.....


Lindy

[911Freak]

Looking good!!

Who or how did you get the fan nickel plated? Any shop that does chrome plating could do this?

Thanks for the pics and keep them coming..

[lindy 911]

The Nickel was done in Houston and is electro-plated. Be very careful as standard chrome platers dip the fan and housing in acid before they plate and the magnesium will explode! It has to be electro-plated, not dipped.

Lindy

[T77911S]

Originally Posted by Fritter

Sub'd means I just subscribed to this thread it's a good one!

you can quietly subscribe in the upper right corner under thread tools.

along with this, posting "good job and thanks for posting" just takes away from what is a great thread. and when a thread gets really long, trying to read throught atta boys and get to the meat, gets old. lets try to keep the threads down to info about the thread. and i mean this in a nice way.

yea yea, i know, i added to the clutter, but i wanted to subscribe

[Fritter]

On a mobile phone there is no other way to subscribe.

And also, lookin' good!

Quote de Fritter

Sub'd means I just subscribed to this thread it's a good one!

you can quietly subscribe in the upper right corner under thread tools.



along with this, posting "good job and thanks for posting" just takes away from what is a great thread. and when a thread gets really long, trying to read throught atta boys and get to the meat, gets old. lets try to keep the threads down to info about the thread. and i mean this in a nice way.



yea yea, i know, i added to the clutter, but i wanted to subscribe

[snbush67]

Looks Great Lindy !!!

If you aren't running AC I would recommend going to a single belt pulley and pulley half, it saves a couple of pounds and looks great !!! After all your at least saving weight using two clamps rather than three on your air guides.

Shane

[lindy 911]

Thanks Shane.

I installed the old pulley so I could turn the crank while installing the pistons and cylinders. The pin and hole have some slop so the Z-1 mark is not accurate. I'm going to have to replace it with something. Where do I get a single belt set-up that you mentioned?

Lindy

[snbush67]

Originally Posted by lindy 911

Thanks Shane.

I installed the old pulley so I could turn the crank while installing the pistons and cylinders. The pin and hole have some slop so the Z-1 mark is not accurate. I'm going to have to replace it with something. Where do I get a single belt set-up that you mentioned?

Lindy

I put an add on here and got a used single belt fan pulley half for an SC style wrench. You can copy the below add for your own.

Wanted - Single belt fan pulley-half, that accepts an SC wrench

I found the engine pulley locally for 30$. It has the TDC 5deg. 30deg and 35 deg. as well as the other marks.

For reference the crank pulley from pelican is: 930-102-028-09-OEM

The fan pulley half in pelican is: PEL-RS-PUL2-BLK

You should be able to find both used, the diameters for crank and fan pulleys were different for different years but they all mount to the crank the same way, you will just have a different ratio, a smaller crank pulley will save a bit on the HP drag but may not cool as efficiently.

A lot of used pulleys that are still out there are warped, if they are on a shelf it is usually for a reason, be careful.

[lindy 911]

As with any first time efforts, the learning curve is still on an upward slope. I found out over the weekend that my crank pulley and the Z1 mark are not accurate with actual TDC. I am in the process of timing the cams and after going over the steps in Waynes book and trying to over complicate the whole thing, I realized it's actually very simple. With my GE 60 cams I want 5mm of initial intake valve travel at TDC on #1 & #4. The steps described to get there are confusing to me. Anyway, I was getting exhaust valve interference at TDC. The valve was making slight contact with the top of the piston with the cam set so the intake had 5mm travel at TDC.

This got me thinking and I advanced the cam another 5mm of intake valve lift and everything worked; no contact. The culprit; crank pulley that allowed about 8 degrees of movement because of a loose fitting pin and hole on the pulley. I removed the pulley and installed a degree wheel so I could re-establish true TDC. Turns out that it was off enough to be catastrophic had I not been paying attention.

Moral of the story; Make sure your TDC (Z1) value shown on the crank pulley is accurate!

[lindy 911]

More to the story: I can't read a dial indicator. I was setting the intake valve at .020" instead of .200" (5 mm) which means the cam wasn't even close to being advanced enough at TDC. This is why the exhaust valve was interfering with the piston. When I finally figured this out, I sat on my stool in my shop and laughed out loud at myself for quite some time. Bone head comes to mind!

Never the less, the crank pulley was still off by more than .375" or about 8 degrees. With the help of a degree wheel, I got the Z1 mark dead nut and we're on our way to the next part of the learning curve.

Lindy