Help, Engine Ticking sound - Page 2

jrflyboyVP2 · #16 (**permalink**) 02-20-2008, 06:57 AM

Thanks for the advice Jim, but at this point I am hoping to fix it without pulling the head if possible. Does anyone know if the cam bearing studs are pressed into the head or threaded into the head. The reason I ask is that as I tightened the bad stud it just seem to start pulling smoothly out. I will pull the cam off tonight and see if I can get the stud out first. I will try unscrewing it at first and depending on how messed up the hole is I might try Loctite thread repair or some other filled epoxy type stuff. It only needs to hold 14-16ft-lbs on the nut, but I don't know what that translates into tensile force on the stud (ie. how much force is pulling on the stud). Has anyone had to fix a loose cam cap stud in a 2liter head???

DoubleDawg · #17 (**permalink**) 02-20-2008, 10:38 AM

A good approximation of bolt preload is 5*Torque/bolt diameter. In this case (not knowing the diameter) I'd guess you might be looking at around a few hundred pounds of force.

slyalfa · #18 (**permalink**) 02-20-2008, 01:55 PM

I would not use glue on a striped thread. I would use a coil. and I would also bevel the hole some before puting in the stud. and check with a stright edge if it is puckered around the stud hole you might need to mill it flat. or the cap will sit on the pucker and not go on all the way. If lucky the bevel will take out the puckering.

180OUT · #19 (**permalink**) 02-20-2008, 06:27 PM

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Quote:

QUOTE=jrflyboyVP2;491548]Thanks for the advice Jim, but at this point I am hoping to fix it without pulling the head if possible. Does anyone know if the cam bearing studs are pressed into the head or threaded into the head

**papajam** · #20 (**permalink**) 02-20-2008, 07:16 PM

Quote:

Originally Posted by jrflyboyVP2

Can a stud be helicoiled? What are the threads? Do I have to pull the head, or can it be done in place?

jrflyboyVP2 · #21 (**permalink**) 02-21-2008, 07:20 AM

Thanks All, I pulled the stud and put a helicoil (8x1.25mm) in the head. I torqued the cap nut to 14ft-lbs and it held. Cranked her up and no valve rapping sound. Yea!! Now on to finish the break in process. I have about 100 miles on it so far with no smoking, should get at least another 50-100 miles on her this weekend. I have kept the rpms below 4k and throttle below 3/4 so far. I figure I will slowly work up to 5k and full throttle after 500 miles. Probably change the oil after that. I torqued the head again last night and it was right on (60 ft-lbs cold, no tightening needed). I may finally be able to fully enjoy my 77 alfa again. Then I will hand it over to my 22 YO son. It is such a pleasure to drive. I trade off between my 99 Honda Valkyrie, 73 Corvette, and 77 Alfa. Life is good!

**papajam** · #22 (**permalink**) 02-21-2008, 07:41 AM

Good show, John!

jrflyboyVP2 · #23 (**permalink**) 02-21-2008, 08:03 AM

Thanks papajam, By the way I was born and raised in NJ (Bernardsville). My younger brother and I are riding our motorcycles (Valkyries) back there and touring the NE in July this summer. I can't wait. We plan on going by the hometown of our youth which I haven't seen in about 20 years.

John

**papajam** · #24 (**permalink**) 02-21-2008, 08:08 AM

Give us a ring when you're in the area. We'd love to have you over!

slyalfa · #25 (**permalink**) 02-21-2008, 11:46 AM

I think to do the retorque you have to undo one bolt at a time and re-oil it and then retorque.
in the correct order.
others chime in if I am wrong?

jrflyboyVP2 · #26 (**permalink**) 02-22-2008, 07:24 AM

Well, I spoke too soon. I drove the car about 15 miles last night after work, and the ticking sound came back. I pulled the cam cover and the front intake cam bearing nuts were not up to torque. I tried to retorque them to 15 ft-lbs and both studs started pulling out, so I was unable to reach that torque. I removed the stud which I helicoiled last night and I could see the helicoil had pulled up almost 1/4 inch and is almost flush with the top of the head, the other stud seems tight, but will not torque up even after a full turn on the nut. So now I have several choices:

1) Tow car to machine shop (Lupton Machine???) and see if they can put a different/better insert into both stud holes, or refit step studs.

2) Remove head and take to machine shop and see if they can repair as above.

3) Have my spare head rebuilt and swap heads

4) buy a rebuilt head from somewhere like Centerline (not sure if either of my cores meet the deck height requirement 4.41", and I don't even know how to measure that)

In any case my Alfa will be missing some great spring driving weather for a while. What a mess, my head was rebuilt a couple years ago and only has about 5k miles on it since then.

alfazagato · #27 (**permalink**) 02-22-2008, 11:46 AM

Are you saying that the Helicoil was1/4" below the deck level? If so I think that the coil was too short or not into good metal. Use Papajam's stepped bolt method wth a longer coil (or two). As a previous commentator said there is not an amazing amount of force here. There are some aircraft industry two pack "glues" which appear to hold blocks together. You might investigate their use here.
Best of luck

**John M** · #28 (**permalink**) 02-23-2008, 08:39 AM

Take it to your machine shop. Have it towed. He'll have a couple of options. He could weld up the holes and retap them. Or he'll have a larger insert to install that will maintain your correct stud size....ie BigSert. I am surprised the helicoil pulled out. Your hole must have already been slop'd out or you used an incorrect drill bit or tap.

Wonder why both going south all of a sudden. This is a known head correct? No issue with warped head, messed up camshaft or something along those lines. Seems very odd that both studs now have went south. I would insure everything is straight and flat. The nut torque is not pulling the studs out. Just food for thought.

Best Regards,
John M

slyalfa · #29 (**permalink**) 02-24-2008, 10:52 PM

hmm just thinking out loud. but if something bound up the cam might pop the bolts. You might want to pull the cups and see if every thing looks OK.

jrflyboyVP2 · #30 (**permalink**) 02-25-2008, 10:10 AM

Well, I fixed my cam studs by using step studs from a VW Beetle head. Those are 10mm 1.5 thread on the bottom and 8mm 1.25 thread on the top. I had a friend turn them on a lathe to lengthen the 8mm section to 39mm long and than cut off the 10mm section to 18mm length so the studs went in 18mm into the head. I drilled and tapped the holes 20mm deep and the new modified step studs went in great. I torqued all studs to 14 ft-lbs using a very expensive accurate small Snap-on torque wrench my friend loaned me. The engine runs great, but still ticks. I drove it out to the local Alfa Guru and he said that is not too bad or unusual. Oh well, I now have 250 miles on her and changed the oil. This weekend was 80 and sunny in Austin and I drove the Alfa everywhere. Thanks for all the feedback!