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| JP timing set alignment https://www.slantsix.org/forum/viewtopic.php?t=51128 |
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| Author: | CNC-Dude [ Wed Feb 20, 2013 8:11 pm ] |
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Dad is on the right track, the lifter bores are offcenter relative to the lobes, this along with a taper ground into the lobe and a radius on the lifter face helps spun the lifters, so don't try to center the lobes to the bores, it will defeat the purpose of its design that is intended for it to function correctly. |
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| Author: | Rick Covalt [ Thu Feb 21, 2013 3:39 am ] |
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All good points and and well taken. So if that is true then the cam must stay in the location it is at. That means I need to machine the back of the lower gear to get it in correct alignment. As another side note, If I did nothing and just put it together as is, the cam is going to try to walk forward to "align itself" That means that without a cam stop it would come forward ..090 or close to it. One way or another, by the weekend at Pigeon Forge I will have the answer! Thanks to everyone! Rick |
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| Author: | CNC-Dude [ Thu Feb 21, 2013 8:44 am ] |
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Another possibility that you might not have considered is that this timing set is just outright defective, and might not be able to perform correctly even if you get the two gears to align properly because of other abnormalities not yet known. I have a NIB Cloyes double roller timing set from our group buy if you would rather not risk using or modifying the one you have. I can bring it to the banquet if you need it. |
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| Author: | Rick Covalt [ Thu Feb 21, 2013 1:05 pm ] |
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Scott, you can bring it along to compare to mine if you want. But I can make this one work, I'm sure. |
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| Author: | emsvitil [ Thu Feb 21, 2013 1:39 pm ] |
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Quote: All good points and and well taken. So if that is true then the cam must stay in the location it is at. That means I need to machine the back of the lower gear to get it in correct alignment.
No, you can put spacers in the recess of the cam gear to move the cam back to compensate for the spacers between the cam gear and block....
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| Author: | Rick Covalt [ Thu Feb 21, 2013 1:53 pm ] |
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Quote: No, you can put spacers in the recess of the cam gear to move the cam back to compensate for the spacers between the cam gear and block....
Yes I followed what you meant. I have .030 washers coming for the cam to block interface. And then I will put a .030 washer between the cam and gear. Remove .065 off of the lower gears back side and everything should be in perfect harmony!  At least that is my current plan.Rick |
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| Author: | robertob [ Mon Aug 12, 2013 10:46 pm ] |
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Rick what did you end up doing? I am looking at exactly the same problem with my engine right now. And it's not a block-crank mismatch issue. The block, crank and cam were all thrown together in Michigan 44 years ago. Variable X is the JP timing set (or in this case Rollmaster). |
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| Author: | Dart270 [ Tue Aug 13, 2013 3:20 pm ] |
| Post subject: | |
The set/block I had that was 0.060" off, I machined (lathe) the crank gear down that amount and it has been running fine now for about 1200 miles, with some hard use and high RPM. Lou |
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| Author: | robertob [ Tue Aug 13, 2013 3:56 pm ] |
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Thanks Lou. I'll probably do that on mine, but I think I have more than .060 misalignment. I will measure before I do anything, I'm playing with cam timing now. |
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| Author: | Rick Covalt [ Wed Aug 14, 2013 3:17 pm ] |
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Quote: Rick what did you end up doing?
I put a .030 shim between the cam gear and the block. Then Lou trimmed the back side of the crank gear .060. Everything lined up great. I also verified that my lifters were rotating I also worked the inside of the crank gear with some emory cloth wrapped around a 1 1/2" piece of pipe or a socket. I kept going so that I could slide it on by hand with just some gentle heat from my torch. Rick |
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| Author: | Rick Covalt [ Thu Aug 15, 2013 8:35 am ] |
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Also a side note. The JP timing set is a premium set as compared to the stock double roller set. I have pulled two engines apart with stock double roller units in and both had quite a bit of chain stretch. Both were relatively low miles engines. I just pulled the JP unit out of Ryan's (Seymour's) race car and it looks to have almost no play in it. It has seen some low to mid 11's in the quarter so it sees a little more severe duty than most, although not as much mileage. The current cost of the JP units are so close to the stock double roller units to make cost a non-issue Just one man's opinion, Rick |
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| Author: | robertob [ Thu Aug 15, 2013 12:23 pm ] |
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Thanks for the info, I will probably do the same. I still haven't measured the exact amount of misalignment, but it looks about the same as you are reporting. Otherwise I am quite impressed with the quality as well. I had my machinist hone mine on his Sunnen rod hone to get the right fit (around .001 interference). It still requires a good press when warm, but I bet it would drop on if I heated it with a torch. |
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| Author: | Rick Covalt [ Mon Aug 19, 2013 5:02 pm ] |
| Post subject: | Contacted Nornda |
I sent a friendly note to Nornda, the manufacturer of the JP timing sets and explained what some of us have been seeing. I got this reply. Hi Rick Thank you for your technical enquiry. As a result of your enquiry we have rehecked the gear set on our Master Block and have concluded that the alignment is correct. We also checked an Original Equipment sprocket set and found that this was correct too. We thank you for bringing this to our attention and if there is anything else that we may assist you with please do not hesitate to contact us. Best Regards Stan Huitema I was happy to get a reply and tend to believe what he is saying. Some have installed them with no problems at all, and Lou and others have checked as many as 4 different timing sets on the same block and still had the mis-alignment. So it was not the JP Timing set. Just thought I would let everyone know what happened. Just chock that up to "one more thing to verify" before assembly. Rick |
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| Author: | Dart270 [ Tue Aug 20, 2013 9:16 am ] |
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Yep, block/crank issue, not the timing sets. Lou |
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| Author: | robertob [ Wed Aug 21, 2013 11:12 am ] |
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Thanks, I have come to more or less the same conclusion. I measured my misalignment at close to .060 actual. I swapped cranks (the one I was using had a .011 thrust play) with an early crank with only .004 end play. Assembled and pushed back against the front thrust I get .946 from the face of the crank gear to the machined front surface of the block. Pulled forward I get .950. The cam gear is .900 from the face of the block. So only .045+/- misalignment with the second set. I am having my machinist take .045 off the back of the crank gear. That should give me 0 misalignment with the crank forward and .005 oil clearance behind the cam gear. Thinking about this, there are a few critical dimensions to get the alignment correct - the distance from the front thrust surface on the block to the face of the block, and the distance from the thrust surface on the crank to the end of the timing chain recess. There are at least 4 machining operations involved. Lots of room for tolerances to stack up. |
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