I had to pull the heads off a Ferrari 308 GT4 which had never had an engine job done since 1973. Reading the horror stories associated with pulling old Ferrari heads, I lost no time in making myself a tool, borrowed from ideas in this ferrarichat Forum and othe sources of Ferrari information. The first tool, using the cam caps studs as an anchor for the plate with the screws to push on the head studs worked on one head and I was able to pull it off. The second head saw the 12mm thick plate bulging and the caps studs slowly pulling out. I used 3 clamps to hold the puller plates to the head but no results either. So I had to stop and search for another solution. I made a 320mm long central plate with 4x 16mm holes, 95mm apart from each other, and bought 4x 16mm bolts, 150mm long. The short partial thread was cut off, the front on the studs machined to take a M14 thread with 1.25 pitch , and same reach as a spark plug. Now the anchor for the puller plates was this 10mm plate bolted to the 4 spark plug holes. Some distance pieces were needed to keep the long plate tight against puller plates and the pulling began. Very easy from then on and heads are off. Using the spark plug holes as the anchor points is much stronger and saves making all those holes for the cam caps to go through. Just thought this might help others with a similar problem. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Great job, I did the same thing when I had to pull the heads of my Mondial 8. Worked like a charm. Best Jurgen Image Unavailable, Please Login
I would never pull the heads using the plug threads. Having seen how much force it took me (scissor jacks and axe handle to lever while hanging the transaxle from the head-- and praying to all gods in good standing) I would be very concerned about damaging the plug threads. I would try the rope trick while levering or be patient and give PB blaster time to get into the studs.
If you really truly have a stuck head a puller is all that works. Distributing the load over all the studs and the plug threads works fine and has been found by those of us that do this regularly to be the least destructive. Penetrants only make a mess. I also heat them up to around 300 degrees. Alfa Romeo made a puller that only used the plug threads. Worked fine. We used those a lot. The Ferrari motors have a bigger problem though so using the other studs too should be done.
Rope trick will not work on stuck 308 heads, besides why risk bending a rod? He didn't use the plug holes to actually lift the head but to anchor the plates. Now I've seen what happens when the spark plug holes are used to try and lift the head sans a plate, it's not pretty! I have a core engine sitting under a shelf that someone tried that with... stripped two plug holes, broke one piston and one of the others broke the piston and cracked the rod. If the head doesn't lift off easily then using a plate is faster and insures far less damage then many of the other crazy methods some come up with.
All Thank you for the great info... Would anyone be willing to rent a pulling tool....fee's would include case of beer of your choice!!!
please confirm the length of the bolts used for the spark plug holes also please give dimensions for the bolts used for pushing against head studs thank you!!
Rope trick worked for me. The head is designed to tolerate extreme compression forces of the ignition detonation. The piston and rods are designed to tolerate the same compression forces. If the rope is properly coiled in the cylinder most of the force is asserted on the outer rim of the piston and directly to the pin and rod, all designed to tolerate the same forces. The camshaft cap bolts (IIRC) are M6x1 and aren't deep and long enough to tolerate tension forces necessary to break the head lose. Same for the sparkplug holes. At least that's what my Finite Analysis MechE son told me. So I used the rope trick and it worked with no damage to the head, pistons or rods. If anybody has actually observed damage to the pistons or rods from using the rope trick please pipe up. I could be wrong. Further analysis indicated the source of the "stuck" was not the head/block interface, but rather the galvanic reaction between the steel head studs and the bores in the aluminum head. Because of this the resistance to removal was present until the head was at least 3cm off the block deck. Before reassembly the bores were cleaned with a circular wire brush and the studs were cleaned up and given a thin coat of ceramic anti-seize, but not the threads, which have to be torqued dry.
