Am I correct in assuming a special plate is needed to remove V12 heads ?
I have seen these, custom made, with a lot of holes drilled
They grip the cam studs, and wind down on the head studs
The plate I saw was about 1/2" thick, but it busted out the cam studs
If I decide to strip a V12 down, I will need to make a plate
I presume there is no other way ?
When I rebuilt my V12, I did not need a “plate” to pull the heads… The heads simply came off… Typically the issue is corrosion around the studs., I got lucky. If you need a plate, they show up on Ebay everyone in a while.JS
@Craig_Balzer just did this: it can be a tough go.
I used the V12 Head Removal Tool that is available from JCNA Tool Loan Program to members. I heard the caution regarding the cam studs and purchased Grade 8 bolts to use after removing the cam bearing caps.
I also purchased some pipe (1/2" dia) that I cut to ~1" lengths to make “guides” to ensure the bolts doing the lifting stayed on the top of their respective head studs.
Major caution: I was so intent on ensuring the head remained level for/aft (the length of the head) that I neglected to watch for levelness on the shorter axis.
Photos (captioned) tell the tale:
1 inch lengths of 1/2" diameter pipe as guide /
\/ I marked (clocked) the heads of the 17mm bolts with a permanent marker to ensure I was tightening each the same amount; it also helped me keep track as I sequentially loosened the bolts time and time again – easy to lose track after the 18th rotation down the length of the head . I started by tightening each bolt 1/4 of a turn to maintain even stress on the aluminum head. After a while – as the head road up the studs - I was making full rotations on the 17mm bolts, sometimes more to maintain consistent tension. \/
\/ Initial progress at 10 minutes \/
Removing the first head went smoothly – note this view (that proved my undoing on head #2)
\/ I checked the levelness of the head (on only the long axis) every few minutes ensuring level extraction. This pair of photos were taken at the end of Day 1’s work on the first head \/
\/ The second head wasn’t as pretty. In hindsight, I went too fast based on the (over) confidence built up from head #1 . . . \/
\/ And this is what can happen if you don’t watch both axis of the head for levelness as you remove it \/
The only option was to cut the bent studs and hope both ends of them unthreaded without drama
Almost extracted the studs remnants without issues:
This hole cost $US50 to properly repair by a qualified machinist
There are plans for making this lifting plate on line to make your own – I think. Obviously, the holes need to be drilled with a high degree of accuracy to avoid binding as the head is removed.
I can supply CAD files for laser cutting captive nut head puller. PM your email address if you want them since file type is not supported in private messages.