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Buellistic
Samba Member
Joined: February 04, 2011
Posts: 357
Location: Albuquerque, New Mexico
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 Posted: Fri Mar 16, 2012 10:53 pm Post subject: Ever had a really bad new cam? |
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The engine I've been working on for the last month or so was completed recently but it wouldn't start.
I noticed that, on #4, it was opening the exhaust valve as the piston was heading down and the intake was opening somewhere around halfway back up. To put it simply, it was sucking when it should be blowing and blowing when it should be sucking.
I'm REALLY hoping I just installed the cam gear onto the cam incorrectly. I remember distinctly lining up the timing marks but not so much lining up the gear on the cam...
Just curious what the likelyhood is that the cam may have been ground nearly backwards. I really don't want to have to split the case open to fix this. |
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65'1300Deluxe
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Joined: November 24, 2009
Posts: 584
Location: Auburn, Washington
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| Posted: Fri Mar 16, 2012 11:05 pm Post subject: |
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I don't believe you can do anything without splitting the case. If the cam gear was put on wrong, or even if the cam was ground wrong, the gear still needs to be properly oriented so that the timing marks are actually useful.
edit: that gear can be attached in one of three ways, but only one position is correct. You'll have to find some other cam to match yours up to to find the right spot.
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Buellistic
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Joined: February 04, 2011
Posts: 357
Location: Albuquerque, New Mexico
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| Posted: Fri Mar 16, 2012 11:22 pm Post subject: |
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| 65'1300Deluxe wrote: |
edit: that gear can be attached in one of three ways, but only one position is correct. |
I'm MOSTLY sure I can unbolt the cam bolts and rotate the cam within the gear while the oil pump is removed. I'll have to look at it again to be sure. If the cam is right, then I simply installed the gear wrong. If the CAM is wrong, then the whole thing has to come apart. |
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GDOG57
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Joined: March 19, 2006
Posts: 1065
Location: Gilbert,Arizona
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| Posted: Fri Mar 16, 2012 11:46 pm Post subject: |
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Remove oil pump and look at the cam/oil pump drive notch and cam gear bolt alignment. Should line up with top bolt.
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mark tucker
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Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Sat Mar 17, 2012 3:34 am Post subject: |
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| un bolt & rotate, line up the slot with the bolt hole and your good to go.Or put your carb on the end of the header and shoot flames out the top.!!. |
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baked beetle
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Joined: September 23, 2006
Posts: 1162
Location: Alberta, Canada
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| Posted: Sat Mar 17, 2012 7:20 am Post subject: |
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make sure you lined it up with the top bolt hole straight up with the camshaft
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lostinbaja
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Joined: December 19, 2004
Posts: 4036
Location: Frankfort, Illinois
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| Posted: Sat Mar 17, 2012 7:49 am Post subject: |
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If you would have degree'd the cam during mockup, this problem would have been caught long before you buttoned up the case.
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Buellistic
Samba Member
Joined: February 04, 2011
Posts: 357
Location: Albuquerque, New Mexico
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| Posted: Sat Mar 17, 2012 8:13 am Post subject: |
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| lostinbaja wrote: |
| If you would have degree'd the cam during mockup, this problem would have been caught long before you buttoned up the case. |
Don't I know it. I did that on my last engine. I was just worried about any potential harm to the lifters/cam lobes. I wanted all of the insides to be immaculate at the initial startup.
Looking at the pictures, as long as I actually managed to get the timing marks between the gear and the crank correct, I shouldn't have to split the case. Also, no one has mentioned a cam ever being ground off-center by some ridiculous amount, so I should be okay as long as I get it turned correctly. |
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mark tucker
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Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Sat Mar 17, 2012 8:43 am Post subject: |
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| the cams are cast with the lobes in the correct position.not like a billet steel roller cam with a full circle for a lobe that needs a lot of cutingheat treating then final grinding. yours looks like a cam before ever getting the grind. |
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Altema
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Joined: June 20, 2010
Posts: 2904
Location: Lower Michigan
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| Posted: Sat Mar 17, 2012 8:47 am Post subject: |
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| mark tucker wrote: |
| Or put your carb on the end of the header and shoot flames out the top.!!. |
I choked on that!
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Stripped66
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Joined: May 31, 2005
Posts: 3470
Location: Charleston, SC
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| Posted: Sat Mar 17, 2012 9:18 am Post subject: Re: Ever had a really bad new cam? |
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| Buellistic wrote: |
I noticed that, on #4, it was opening the exhaust valve as the piston was heading down and the intake was opening somewhere around halfway back up. To put it simply, it was sucking when it should be blowing and blowing when it should be sucking.
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Did you happen to notice this on cylinder #2 as well?
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| 66brm wrote: |
| Bodacious wrote: |
| Why not just make a custom set of wires with a Y splice in them. Then you could just run one distributor. |
I don't think electrickery works that way |
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Buellistic
Samba Member
Joined: February 04, 2011
Posts: 357
Location: Albuquerque, New Mexico
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| Posted: Sat Mar 17, 2012 9:55 am Post subject: Re: Ever had a really bad new cam? |
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| Stripped66 wrote: |
| Buellistic wrote: |
I noticed that, on #4, it was opening the exhaust valve as the piston was heading down and the intake was opening somewhere around halfway back up. To put it simply, it was sucking when it should be blowing and blowing when it should be sucking.
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Did you happen to notice this on cylinder #2 as well? |
Honestly forgot to check. If they are the same, what might that mean? Different? |
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Stripped66
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Joined: May 31, 2005
Posts: 3470
Location: Charleston, SC
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| Posted: Sat Mar 17, 2012 10:52 am Post subject: Re: Ever had a really bad new cam? |
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| Buellistic wrote: |
Honestly forgot to check. If they are the same, what might that mean? Different? |
You fail to say what cam you're running, but here's a cam card for an Engle 110:
The exhaust valve opens when the piston is still moving towards, before BDC, and the intake valve opens when the piston is still moving upwards, before TDC. Exactly when each valve opens is going to depend on the cam timing and how you have installed it.
If you installed the cam gear wrong, then you will be 240 degrees out of phase, either before or after the desired cam timing. Using the Engle 110, for example, if the cam gear was installed wrong but you lined up the timing marks, the intake valve would open either A) 41 degrees after BDC when the piston is moving up, or B) 100 degrees after TDC when the piston is moving down.
Likewise, using the 110 cam as an example, the exhaust would open either A) 5 degrees after TDC when the piston begins to move down, or B) 115 degrees before TDC when the piston is moving up.
Does one of these incorrect installations coincide with "opening the exhaust valve as the piston was heading down and the intake was opening somewhere around halfway back up"? Knowing the exact cam, we can determine if the cam gear was installed incorrectly based on where the valves actually open and where they should open. If you have a degree pulley, you can figure this out quite easily (remember that cylinders #2 and #4 are 180 degrees out of phase with respect to the timing marks on the pulley).
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| 66brm wrote: |
| Bodacious wrote: |
| Why not just make a custom set of wires with a Y splice in them. Then you could just run one distributor. |
I don't think electrickery works that way |
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Buellistic
Samba Member
Joined: February 04, 2011
Posts: 357
Location: Albuquerque, New Mexico
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| Posted: Tue Mar 20, 2012 9:52 pm Post subject: |
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| I turned it within the gear and it worked! Started right up and broke it in without issues. Thanks for the info Stripped66, the math was very helpful in verifying that it would work. |
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Bashr52
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Joined: July 16, 2006
Posts: 5666
Location: On an island in VA
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| Posted: Wed Mar 21, 2012 9:28 am Post subject: |
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| Buellistic wrote: |
| I turned it within the gear and it worked! Started right up and broke it in without issues. Thanks for the info Stripped66, the math was very helpful in verifying that it would work. |
You were able to re-index the cam gear with the engine still together? I often wondered if that could be done through the oil pump hole, but never tried it. Good to know! |
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