Everyone Else Asked about a rebuild ...so will I
 

So I am fixing to pull my motor to install a lightweight Fidenza flywheel and new Sachs power clutch on a 74 / 911 / 2.7 CIS motor.
The motor as it stands now is in great shape….looks good too. It runs strong and never any problems. It does smoke
On start up when it hasn’t been run in a while. Good oil pressure. I haven’t checked the compression, but the CIS is perfect.
I couldn’t tell you what type of cylinders or pistons are on the motor.
Now while the motor is out I thought about putting some 964 cams in it….. Any problems with this?
But since the heads are off I thought about doing a re-ring also…..and replacing the rod bearings on the crank.
I will also have the heads rebuilt.
I also will have new rockers put on to eliminate the annoying tapping, I think some are worn.

Now the question,

Do I have to crack the case or can I leave it be….?

Do you see any problems with what I am going to do….?

Since the rebuild is being done, how much will the heads be and would it be advantageous to make the ports larger…?



Chris…

Unfortunatly you stand a very good chance of pulling the headstuds after the rebuild. If you don't do the timecert/casesaver thing and/or put dilivar studs in the stress from the rebuild will cause the headstuds to pull (probably). This information is from Bruce Andersons book and from information on this site.

You don't need to pull the heads off to put new cams in or replace the rocker arms. I wouldn't go any further unless you want to do the whole engine from the bottom up (line bore, case savers, etc).

-Andy

Chris,
The annoying tapping is from misadjusted rockers, some very small amount of wear is normal.
I would carefully check the compression. Rings may not be necessary.
Rebuilding the heads good move.
With decent oil pressure the rod bearings are probably ok. No need to crack the case.
Maybe take one apart, then decide.
Don't forget new rod bolts.
SC and 964 cams are 4 bearing cams. To use the stock cams you'll need a later 4 bearing cam housing.
I'd call John Dougherty about a reground cam for your application.
John is a master at matching cams to your motor and application.
Search "Dougherty" to find his web site. He's the man.
The '74 has a great exhaust compared to later mid years like my '76, which I back dated to '74.
If you have smog checks where you live, it's tough to go much further.
A '71/'72 transaxle with a 7:31 pinion and ring will make your '74 jump on the street, at the expense of higher rpm's on the freeway.

Crank main bearings get far less tress than rod bearings.
So if your rod bearings are in not too bad shape I would certainly trust the main bearings and leave the case closed.

Cams
 

I got the cams from a guy on the pelican boards, He said that they are 2.7's reground by Elgin to 964 specs.

I will look at the rod bearings, I really dont want to crack the case. But if it has good compression I might not even go that far, and just change the cams.

the rockers were adjusted, recently, my Porsche mech friend showed me the rockers get worn and shake on the rocker shaft and also cause a tap sound. . So I dont think it is a bad idea to replace them all while I am there.

Thanks for the advice, I will only go as far as I really need to.

Chris

A '74 should already have a 7:31.

Can you just install a 964 3.6 camshaft housing on a 2.7 engine? or what do you mean by that?

cam
 

you cant just take from the 964 and directly install.
I do know that you have to cut off the power steering pump end
and then installl.....I could be wrong. But no one ever talks in details about it.

Its weird to hear about this popular upgrade but no one writes about it in detail...

Thats why on another post I asked that Wayne Dempsey chime in on the conversation..

Chris