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Old 6th October 2019
rubine rubine is offline
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Default Changing From Hammer 660 Cams To 600 Cams

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Originally Posted by DonChicago48 View Post
I discussed the feasibility of switching from the Hammer Crush 600 Cam Set to the Sledge 660 Cam Set with Hammer Dan today. He indicated that in addition to making sure there was adequate Rocker Box clearance and valve-to-valve clearance, it would be necessary to switch to the earlier pinion design and shave the heads approximately .030" to add enough static compression to bring the Corrected Compression Ratio back to the mid 9 area with the 660 cam's longer duration. I opted for making all the accomodations except the head milling for now. I will try the engine with the 600 cam and decide whether to switch to the 660 cam at a later date. At that point, it will just be necessary to mill the heads to accomodate the 660 cam.
So what if you wanted to go the other way.. if your heads are set up for the 660 cams but wanted to try the 600 cams? I'm guessing the duration difference would bump the compression up a bit.. Clearancing has been done for 660 so I'm guessing they should be bolt in? Base circles are the same so pushrod geometry is all good? I have the AV&V VSK6500 springs. I get the feeling I'm missing something looking at this!
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Old 6th October 2019
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Originally Posted by rubine View Post
So what if you wanted to go the other way.. if your heads are set up for the 660 cams but wanted to try the 600 cams? I'm guessing the duration difference would bump the compression up a bit.. Clearancing has been done for 660 so I'm guessing they should be bolt in? Base circles are the same so pushrod geometry is all good? I have the AV&V VSK6500 springs. I get the feeling I'm missing something looking at this!
If you were on the edge of detonation with the 660’s, installing the 600’s could be an issue. They are talking dynamic compression ratio (of course)

Otherwise, there shouldn’t be a problem with less lift. The only caveat is if that spring needs to be set up close to coil bind at max lift to avoid spring surge at the RPM you run.

(Disclaimer: generic engine building response, I’ve never used any Hammer cams)
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Old 6th October 2019
rubine rubine is offline
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Originally Posted by Maxeffort View Post
If you were on the edge of detonation with the 660’s, installing the 600’s could be an issue. They are talking dynamic compression ratio (of course)

Otherwise, there shouldn’t be a problem with less lift. The only caveat is if that spring needs to be set up close to coil bind at max lift to avoid spring surge at the RPM you run.

(Disclaimer: generic engine building response, I’ve never used any Hammer cams)
Thanks maxeffort. I haven't had much experience in engine building. Its an engine that's coming together so hasn't been run yet. Bit of a extended time frame haha. I have to admit I don't look so much at ratios I go by CCP pressure. Was aiming 190-200 but calculator has it coming about a bit lower than that .. low 180s from memory. STD heads with big chambers that I still have to clean up a bit with a dremel. Can you run thicker gaskets to lower compression a bit if needed?

Could you please elaborate a bit more on the spring setup close to coil bind at max lift and spring surge...They are single coil springs.
Thanks
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Old 6th October 2019
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...actually I guess thicker gaskets would screw up my squish. .045 -.048 it's is now
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Originally Posted by rubine View Post
Thanks maxeffort. I haven't had much experience in engine building. Its an engine that's coming together so hasn't been run yet. Bit of a extended time frame haha. I have to admit I don't look so much at ratios I go by CCP pressure. Was aiming 190-200 but calculator has it coming about a bit lower than that .. low 180s from memory. STD heads with big chambers that I still have to clean up a bit with a dremel. Can you run thicker gaskets to lower compression a bit if needed?

Could you please elaborate a bit more on the spring setup close to coil bind at max lift and spring surge...They are single coil springs.
Thanks
Thicker gaskets are generally not a good idea. It increases quench distance and that invites detonation. It’s better to increase the chamber volume or reduce piston dome size / increase piston dish volume.

A lot of times, but not always, a spring performs best when set up .050” to .060” from coil bind at max lift. Spring surge is an out of control motion, kind of like if you had a slinky and you had one end in each hand, moving the coils from one side to the other. If the spring is set up close, it helps to dampen that motion.

It’s usually the worst at a specific RPM range because the spring has a resonant frequency. An engine that’s operated over a wide rpm range and doesn’t spend a lot of time at any RPM, may never experience spring surge, no matter how they are set up. OTOH, I’ve had expensive springs fail quickly because I didn’t match them well to the (high) RPM they were always running at, despite being set up right.
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Old 6th October 2019
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Ah ok. Thanks! What about using high lift springs on a low(er) lift cam?
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Ah ok. Thanks! What about using high lift springs on a low(er) lift cam?
Sure, .650” max lift spring and you’ll have .600” lift.
Looks good to me!

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