Top end Rebuild!

[AUSTmike]

Hi guys!...When it comes to rebuilding the top end meaning dismantling the heads for a machine shop service!..Basically taking the heads off the engine and taking the heads to a shop to replace the guides!

Lets assume that the heads are good valve wise and all that needs doing is replace the guides!...just a few questions regarding this type of procedure!

1. can the heads be removed while the engine is still in the car!
2. can i torque the cam casing to only 20 n/m with lock tight based glue and not 25 n/m!..some guys experience throwing the threat on these bolts at 25 n/m because of the soft magnesium!

3. can the timing chain curve enough to UN-loop the end of the cam and leaving the cam in the tower when removing the tower from the engine!

Thanks guys!.. what are your thoughts and experiences!..cheers!

[dannobee]

1. No. There's not physically enough room.

2. The cam housings bolt to the heads, which are aluminum.

3. You can't leave the cam gear on, if that's what you're asking. You'll have to remove the cam gear and shims. Carefully count the shims and jot the number down in your notebook. You can leave the cams and rockers on the cam housings, and the heads bolted to the cam housings. Then send the whole assemblies to the machine shop and let them disassemble and reassemble. They will give you an estimate on what other parts are needed. Since the valve guides are so short, the valve stems often wear and need replacement.

[AUSTmike]

Hi dannobee...thanks for your input!..I understand that the cam gear has to come off because of the cam casings need to be removed!...When you say not enough room?..do you mean the cam housing bolts to the heads are too long to get out?...or do you mean you can't slide the cams out of the towers because of the rear part of the car body!

also when you say cam housing I assuming you mean "cam tower"...cheers!

[RedCoupe]

Even if there were some way to remove the cam towers and heads with the engine in the car, I wouldnt want to. The engine isn't that difficult to remove, and with the engine up in an engine stand, you have a much better job of doing everything properly. I wouldn't want to set the cam end float and timing while flat on my back holding an inspection light! (I know it's been done, but I'd rather do it up on a stand with good light.)

[boyt911sc]

Originally Posted by AUSTmike

Hi guys!...When it comes to rebuilding the top end meaning dismantling the heads for a machine shop service!..Basically taking the heads off the engine and taking the heads to a shop to replace the guides!

Lets assume that the heads are good valve wise and all that needs doing is replace the guides!...just a few questions regarding this type of procedure!

1. can the heads be removed while the engine is still in the car!
2. can i torque the cam casing to only 20 n/m with lock tight based glue and not 25 n/m!..some guys experience throwing the threat on these bolts at 25 n/m because of the soft magnesium!

3. can the timing chain curve enough to UN-loop the end of the cam and leaving the cam in the tower when removing the tower from the engine!

Thanks guys!.. what are your thoughts and experiences!..cheers!

Mike,

Please do yourself a favor. Take the motor out and perform the necessary work with the motor on an engine stand. You are not experienced enough to do a top end rebuild in situ. Even the best professional engine rebuilders will not do it in situ.

What is preventing you from dropping the motor and performing the rebuild on a stand? I don’t see any advantage doing it in situ. Wish you luck.

Tony

[AUSTmike]

Thanks guys for all your thoughts and comments!...just starting this thread to get an understanding of whats involved and hopefully get confidence in maybe tackling this one day!...i would like to one day accomplish this task that is to take the heads off replace the guides and do a valve job!..i have done some work on my 2.7 ltre engine and that was to replace the valve seals and after taking my time and research with the help of you guys!..which i'm very grateful of your help and info in these forums!...

Having said that!..i think i can do this particular job because i believe i can do it!..and most of all i enjoy this stuff!...I guess the hardest and most challenging part of this task is the cam timing and getting the timing in spec!...To do the job all i am doing is at most replacing guides and valves!..and the only issue that i have with the engine is the guides!..I do understand that sometimes when pulling down engines and trying to fix an original issue in many situations along the line you can find other problems and issues which can cost more money!...I get that!...but i love the challenge!

https://www.youtube.com/watch?v=0t7gpEBJEf4

[mikedsilva]

If you want help with your cam timing, I am up in Brisbane and can do this for you. Feel free to PM.
Michael

[AUSTmike]

Thanks mike!..i'll keep that inmind!..Jeff from home built mentioned you on his youtube video when jeff was doing his cams on his 911...cheers!

[Mike Billings]

I've R&R heads with the engine in.

The only tense part was keeping an eye on the cylinder to head seals (CE ring) when the heads go on!

Other than that, no big deal.