Some of you may have read Michael's (rtusnake) post on the special upgraded timing guides/pivots he made. His thread is here => Timing Guide U/G The problem with ModMotor aluminum blocks is that Ford downsized the dowel anchor where it goes into the block from an 8 MM pressed in dowel pin on the iron blocks to a 6 MM screw thread dowel on the aluminum blocks.
Here is a picture of the two pivots side by side.
When you go to higher spring rate valve springs, fast ramp cams, use a two step or a WOT box these guys take a terrible beating. To get a sense of the abuse I believe AJ (Mofasta) has a pic of his crank snout timing gear in his build thread. The teeth are all beat up from leaving on the 2-Step.
When one of these little diddy's break it typically costs you valves, guides and a fresh valve job. If a valve head breaks off, the list of carnage will include a block, head(s) and pistons. The fix is to get rid of the weak link.
To date the only source I have seen for a fix is Michael. He was motivated by one of the failures I described himself. His solution was to rebuild with better stronger pins and is extraordinarily good as you can see from the visual in the picture above.
I got a set of these from Michael a little over a month ago. I had a mill so installation was pretty straight forward. I liked the fix so much I started to look for an easier install method so it could be done without a mill for anyone who wanted to take advantage of the upgrade.
Historically the challenge in performing the modification was and is the need to drill and tap the holes parallel to the crank main bore. Not an easy task without a mill. JamesHell and I were talking about a fix and the challenge to install it. James came up with an idea production shops use when the have to precisely locate holes or fasteners and can't or don't have access to a mill. The fix is a fixturing or jig plate.
The plate is registered off known good locating points and is lightly held in place with bolts to prevent movement during the machining process. The trick to building the plate was a block print that we could pick up the timing cover dowel locations and the guide pivot / dowel locations. With a little perserverance we managed to get a print for the front of the block with the locations we needed.
James is fabricating the fixturing plate as I am typing. We are waiting for some parts to complete the first one. The plate will look like the drawing below;
The holes marked guide pin are the current tensioner pivots. The two lowest holes on the plate are the timing cover dowel pins and the other three holes line up with existing bolt holes on the timing cover to allow firmly attaching the fixture to the front of the block. The guide pin holes are precision located, reamed to take hardened drill bushings.
Two different types of drill bushings will allow you to accurately place and drill the pivot holes so they are parallel to the crank centerline. If you put a Home Depot drill stop on your drill bit you will not drill into your water jacket. After drilling the bushings are swapped out for the second set that are designed to keep your tap perpendicular to the block face as you hand tap the holes for Michael's 8MM replacement dowel/stud.
James is pretty much finished with the basic plate at this time. We are currently waiting for the drill bushings to arrive.
If you ever wanted to fix this tender spot in your block but hesitated because you couldn't, didn't or wouldn't be able to get mill time (and dollars) to do the job this is your chance to not only fix your current block but any future blocks you ever get for the car. Michael has the studs, James has the tooling and you can have a much more reliable block.
Here is a picture of the two pivots side by side.
When you go to higher spring rate valve springs, fast ramp cams, use a two step or a WOT box these guys take a terrible beating. To get a sense of the abuse I believe AJ (Mofasta) has a pic of his crank snout timing gear in his build thread. The teeth are all beat up from leaving on the 2-Step.
When one of these little diddy's break it typically costs you valves, guides and a fresh valve job. If a valve head breaks off, the list of carnage will include a block, head(s) and pistons. The fix is to get rid of the weak link.
To date the only source I have seen for a fix is Michael. He was motivated by one of the failures I described himself. His solution was to rebuild with better stronger pins and is extraordinarily good as you can see from the visual in the picture above.
I got a set of these from Michael a little over a month ago. I had a mill so installation was pretty straight forward. I liked the fix so much I started to look for an easier install method so it could be done without a mill for anyone who wanted to take advantage of the upgrade.
Historically the challenge in performing the modification was and is the need to drill and tap the holes parallel to the crank main bore. Not an easy task without a mill. JamesHell and I were talking about a fix and the challenge to install it. James came up with an idea production shops use when the have to precisely locate holes or fasteners and can't or don't have access to a mill. The fix is a fixturing or jig plate.
The plate is registered off known good locating points and is lightly held in place with bolts to prevent movement during the machining process. The trick to building the plate was a block print that we could pick up the timing cover dowel locations and the guide pivot / dowel locations. With a little perserverance we managed to get a print for the front of the block with the locations we needed.
James is fabricating the fixturing plate as I am typing. We are waiting for some parts to complete the first one. The plate will look like the drawing below;
The holes marked guide pin are the current tensioner pivots. The two lowest holes on the plate are the timing cover dowel pins and the other three holes line up with existing bolt holes on the timing cover to allow firmly attaching the fixture to the front of the block. The guide pin holes are precision located, reamed to take hardened drill bushings.
Two different types of drill bushings will allow you to accurately place and drill the pivot holes so they are parallel to the crank centerline. If you put a Home Depot drill stop on your drill bit you will not drill into your water jacket. After drilling the bushings are swapped out for the second set that are designed to keep your tap perpendicular to the block face as you hand tap the holes for Michael's 8MM replacement dowel/stud.
James is pretty much finished with the basic plate at this time. We are currently waiting for the drill bushings to arrive.
If you ever wanted to fix this tender spot in your block but hesitated because you couldn't, didn't or wouldn't be able to get mill time (and dollars) to do the job this is your chance to not only fix your current block but any future blocks you ever get for the car. Michael has the studs, James has the tooling and you can have a much more reliable block.