obnoxious001
Engine building character
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- Dec 28, 2007
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I would like to claim this as my own idea, but it's not. Gary Teague showed me this when I was doing some engines for him back in the early 90's
Keeping ignition timing stable is important to engine performance. As the cam moves back and forth, the relation of the cam gear and distributor gear changes, thus so does the ignition timing. Details are important in making an engine perform it's best, and with a regular timing cover, a thrust button can be fitted. Running a cam driven pump, you could work out how to use the pump to limit the cam thrust, or you can use a simple Torrington bearing that fits properly around the cam drive. Torrington# NTC 1427 has an ID of 7/8", perfect fit for the water pump drive that works with Neovane, Magnaflow, and I think the new CP pump that is available. The corresponding washers are TRA 1427, TRB 1427, TRC 1427, and TRD 1427. The washers are .031", .062", .093", and .124" respectively I believe, but measure them for yourself when doing calculations for machining the timing cover.
You can see my stack measures .264, make a note of how thick your particular stack is. I also measure the socket head allens as a reference when I start. It may be preferrable to face the top of the head flat for more precise measuring, but I like to keep mine at full size which seems to be right around .312". This is not part of your calculation, but you do want all three to be the same so the washer will sit flat, and later on you may need to shave them down a fuzz to get your final desired thrust. Note that measurements may be taken with a micrometer or calipers.
Next you need a good flat surface to lay the timing cover on, face down. With this Glenwood cover, I chose a small piece of steel that I could set the water pump flange on, without having any of the ribs or other surfaces of the cover keep it from sitting flat. In this case I used a depth micrometer that my friend Wheeler gave me, but calipers can be used as well, you just need to use caution to keep them perpendicular to the surface.
Then I use Gasgacinch to secure the timing cover gasket to the block, as it needs to be taken into account as well. Prior to bolting on the cover, make absolutely sure the cam is pushed back in the block so the timing gear is against the block. You can then bolt on the cover and proceed to measure from the face of the cover to the cam bolts, but to make things a bit easier, I put on two washers. The photo only shows the single washer, but it was moving around more than I liked, so I put on a .124" thick and a .062" thick, for combined .186" That .186" gets deducted from the .264" thick bearing stack that I am using. Remember, you have to use your own numbers and measurements.
I used a depth micrometer, but once again you can use calipers if that is what you have. I did it for years when I didn't own a depth mic. I also show the calipers, and used that as a way to double check myself. If the cover gets cut too far, I don't have small diameter washers to space the bolts out with. If it really got cut too far, I do have some of the .031" washers.
Now I do the calculations. I won't give specific numbers here since it may tend to be more confusing, but remember if you measure with a washer or washers in place, you would need to figure in the thickness of the bearing. You are looking at how much of the cover needs to be removed to end up with about .005" to .007" of cam thrust, or endplay.
Using the washers as I did, there was minimal clearance to the cover when measured. Calculations told me that .070" removed from the cover would mean that I could face off the bolts a few thousandths to get my desired end play without having to work at it for an extended period of time. I used a sharpie to mark it to make sure he would have the dept in front of him while he was working on it, and send one of the washers (not the bearing, don't want dirt in it) and got this back. In the past others have cut circles, Pat said it was easier for him to just do a square,, need a little clearance around the bearing and washer in case the alignment of the pump is not concentric to the opening. This recess is sometimes useful to help hold the outer washer in place while the cover is positioned on the block.
Front seal has still not been installed until final mock up is complete, including facing the three cam bolts to the proper length. I had to do it a couple of times, working slowly to not remove too much from the bolts. I ended up removing about .010", and got .007" cam thrust. Also, lubricate the bearing prior to final assembly. I used Lucas assembly lube since it's sticky and should hang around until fire up, but even oil would be good.
A drop of red loctite on the threads of the bolts, and torque to 25 ft lbs. Don't forget the front timing seal before you put the cover on with gasket sealer, you won't be happy! I use Gasgacinch on both surfaces, as I do on the timing cover gaskets. Old school stuff, doesn't fail me.
Last thing I do is make sure that the washer is still free to move after the final install.
Bob's fancy 12pt stainless steel bolts have not arrived yet, so will be installed when they get here, but now I can get the oil pump and oil pan on, and install the damper once I have those bolts in place, since two of them are blocked once it's on. The only thing remaining is to verify the new CP water pump allows the end play. It should be plenty, but don't assume anything, will know that in a day or two when it gets here.
Any questions, feel free to post or direct message me. I had a lot of interruptions writing this up, hope the continuity is OK.
Also, I have several of these sets of bearings and washers if someone can't find them easily.
Keeping ignition timing stable is important to engine performance. As the cam moves back and forth, the relation of the cam gear and distributor gear changes, thus so does the ignition timing. Details are important in making an engine perform it's best, and with a regular timing cover, a thrust button can be fitted. Running a cam driven pump, you could work out how to use the pump to limit the cam thrust, or you can use a simple Torrington bearing that fits properly around the cam drive. Torrington# NTC 1427 has an ID of 7/8", perfect fit for the water pump drive that works with Neovane, Magnaflow, and I think the new CP pump that is available. The corresponding washers are TRA 1427, TRB 1427, TRC 1427, and TRD 1427. The washers are .031", .062", .093", and .124" respectively I believe, but measure them for yourself when doing calculations for machining the timing cover.
You can see my stack measures .264, make a note of how thick your particular stack is. I also measure the socket head allens as a reference when I start. It may be preferrable to face the top of the head flat for more precise measuring, but I like to keep mine at full size which seems to be right around .312". This is not part of your calculation, but you do want all three to be the same so the washer will sit flat, and later on you may need to shave them down a fuzz to get your final desired thrust. Note that measurements may be taken with a micrometer or calipers.
Next you need a good flat surface to lay the timing cover on, face down. With this Glenwood cover, I chose a small piece of steel that I could set the water pump flange on, without having any of the ribs or other surfaces of the cover keep it from sitting flat. In this case I used a depth micrometer that my friend Wheeler gave me, but calipers can be used as well, you just need to use caution to keep them perpendicular to the surface.
Then I use Gasgacinch to secure the timing cover gasket to the block, as it needs to be taken into account as well. Prior to bolting on the cover, make absolutely sure the cam is pushed back in the block so the timing gear is against the block. You can then bolt on the cover and proceed to measure from the face of the cover to the cam bolts, but to make things a bit easier, I put on two washers. The photo only shows the single washer, but it was moving around more than I liked, so I put on a .124" thick and a .062" thick, for combined .186" That .186" gets deducted from the .264" thick bearing stack that I am using. Remember, you have to use your own numbers and measurements.
I used a depth micrometer, but once again you can use calipers if that is what you have. I did it for years when I didn't own a depth mic. I also show the calipers, and used that as a way to double check myself. If the cover gets cut too far, I don't have small diameter washers to space the bolts out with. If it really got cut too far, I do have some of the .031" washers.
Now I do the calculations. I won't give specific numbers here since it may tend to be more confusing, but remember if you measure with a washer or washers in place, you would need to figure in the thickness of the bearing. You are looking at how much of the cover needs to be removed to end up with about .005" to .007" of cam thrust, or endplay.
Using the washers as I did, there was minimal clearance to the cover when measured. Calculations told me that .070" removed from the cover would mean that I could face off the bolts a few thousandths to get my desired end play without having to work at it for an extended period of time. I used a sharpie to mark it to make sure he would have the dept in front of him while he was working on it, and send one of the washers (not the bearing, don't want dirt in it) and got this back. In the past others have cut circles, Pat said it was easier for him to just do a square,, need a little clearance around the bearing and washer in case the alignment of the pump is not concentric to the opening. This recess is sometimes useful to help hold the outer washer in place while the cover is positioned on the block.
Front seal has still not been installed until final mock up is complete, including facing the three cam bolts to the proper length. I had to do it a couple of times, working slowly to not remove too much from the bolts. I ended up removing about .010", and got .007" cam thrust. Also, lubricate the bearing prior to final assembly. I used Lucas assembly lube since it's sticky and should hang around until fire up, but even oil would be good.
A drop of red loctite on the threads of the bolts, and torque to 25 ft lbs. Don't forget the front timing seal before you put the cover on with gasket sealer, you won't be happy! I use Gasgacinch on both surfaces, as I do on the timing cover gaskets. Old school stuff, doesn't fail me.
Last thing I do is make sure that the washer is still free to move after the final install.
Bob's fancy 12pt stainless steel bolts have not arrived yet, so will be installed when they get here, but now I can get the oil pump and oil pan on, and install the damper once I have those bolts in place, since two of them are blocked once it's on. The only thing remaining is to verify the new CP water pump allows the end play. It should be plenty, but don't assume anything, will know that in a day or two when it gets here.
Any questions, feel free to post or direct message me. I had a lot of interruptions writing this up, hope the continuity is OK.
Also, I have several of these sets of bearings and washers if someone can't find them easily.
