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Discussion Starter · #1 ·
Just a question........if you put two separate cams side by side.....1 a custom grind with a 635 lift on Andrews blanks and the other a HQ 0039 with 579 lift. The 579 lift looks visually taller than the 635. Is this possible? Also put some calipers to them and the 0039 is taller.
 

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Are both cams for the same kind of motor? Are those lifts based on the same rocker arm ratio? Maybe they have a different base circle dia.:unsure:
 

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davemhughes said:
Just a question........if you put two separate cams side by side.....1 a custom grind with a 635 lift on Andrews blanks and the other a HQ 0039 with 579 lift. The 579 lift looks visually taller than the 635. Is this possible? Also put some calipers to them and the 0039 is taller.
I'm not sure.....do all TC cams hav the same base circle size? Were the custom cams ground on a CNC. Could the program have been set up wrong? Now ya got me wondering??? :huh:
 

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Discussion Starter · #5 ·
Well the custom 635 lift cams have long opening and closing durations. Unsure about which machine was used to grind them. The Fatboy engine was dyno'd and only had 97T/93hp. CR 11.8:1, compression 215 F / 210 R, 1-2% leak down. With those numbers it should be pulling stumps. But the cams from day one just did not feel right. The dyno proved it. The cams started dying out around 4700 rpm on the dyno. Sending them back to be checked. If they check out then they were installed wrong as far as maybe off in the amount of degrees when installed. Had a 4 degree advance cam I was going to put in and see but even with it, with those kind of dyno numbers it wouldn't have been much improved.

Plan to dyno the HQ 0039 cams and compare. Was just looking at the two cams together and measured the intake lobes, the 635 lift just is not as tall as the 0039's with a 579 lift.

To add insult to injury....my new Ultra build locked up Saturday. Been making that upper cylinder tick, tore it down to check it and it came up clean.....a week later.......clank clank clank clank....locked up. Tearing it down in the am.
 

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Hello Dave, measure the base circle, then measure the lobe........subtract one from the other and this is your lobe lift.

Multiply x 1.625 and this will give you valve lift and if it is not as you describe then you have the wrong cam.

Measuring durations is much tougher to do manually but can be done and requires 2 v blocks, a dial indicator and a degree wheel................you need this setup to be able to map the cam profile as well as the durations, particularly if the lobes are asymetrical like HQ Cams.

All the best, Ozzie
 

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Camshaft or mineshaft?

You measure lobe lift by rolling the cam over between centers.With a indicator on the lobe.Kinda like when it's-- RUNNING! On a assembled engine you can also put an indicator on a pushrod that is on a lifter and roll the cam over to get lobe lift.Remember lobe lift times rocker raito equals valve lift.It is very difficult to measure from the lobe down and the base cricle down on a cast core and get anykind of accurate measurment were is the center of the shaft in relation to the lobe? And of course the base circle affects lift.The more you grind off base circle the more more you will have to adjust up the pushrod the more lift!That how early performanes cams were made from stock cams.
Big Al
 

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Discussion Starter · #8 ·
The lobe measurement issue I can now see is very complex to damn near impossible to truely figure out without all the proper tools to give you the accurate readings you need.

The HQ 0039's are in....the bikes pulls so hard with these that you no bs have to really hang on as it trys to slide you off the back of the bike. I can still tell there is much more there and the engine is not geing all it can. I really feel that this engine's output potental is huge here for a 95ci. I knew from the start of this engine build that there would probably be lots of tweeking of this or that. I am guessing but as I have had bikes in the 105T range before that right now its in the 110T range. I will dyno it again with these to just see.
 

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I have had the same experiance, A set of 600 lift crane cams had plenty of clearance than tryed some 600 lift carls speed shop cams and a lot taller requiring case clearencing,, Big Al Taylors post has hit it on the button!
 

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It seems likely that the maker of the .635 lift custom cams used a smaller base circle for clearance purposes. Don't twin cams have an issue with the lobes hitting each other at some point? This might only be on Chain Drive cams where they spin against each other.

I would ask the company that ground the custom cams. They should know more about them than anyone. You might only be one phone call away from all your answers. John
 
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