Excessive end play with Hot Cam?
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Race Director
Joined: Oct 2000
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From: N. Alabama
Excessive end play with Hot Cam?
I have installed the Hot Cam in the LT4 and with only the retaining plate in place, (no oil pump drive gear in place yet), I have a measured play of .12".
I would think that over a tenth inch of play is probably too much. How does one rectify this? also....
2nd question: the gear on the new water pump assembly has teeth the full width of the gear yet the gear that came with the extreme duty set is tapered on the end in the manner of the taper found on the timing gear. Does this matter?
Thanks in advance for all input.
I would think that over a tenth inch of play is probably too much. How does one rectify this? also....
2nd question: the gear on the new water pump assembly has teeth the full width of the gear yet the gear that came with the extreme duty set is tapered on the end in the manner of the taper found on the timing gear. Does this matter?
Thanks in advance for all input.
Drifting
Joined: Jun 2001
Posts: 1,997
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From: Lake Ozark MO
Re: Excessive end play with Hot Cam? (southern_son)
According to the Helms (factory shop) manual, camshaft endplay should be 0.004-0.012". But I would think this spec would be with the camshaft sprocket installed. Otherwise, if you didn't have the cam plug installed you could just push the cam right back out of the engine block. I think the only reason the plug is there is to have a place to knock out old cam bearings.
The oil pump gear won't mean much because it'll thrust the cam towards the retaining plate with the engine running.
Check the clearances with the cam sprocket installed and see what you come up with. This is one dimension I forgot to check when I did my rebuild.
As for the second question... I noticed this as well. I left the original waterpump drive gear in place since I didn't have the tool to remove it (and I was a bit impatient).
I may regret it later on but it's been fine for 400 miles of initial (pretty hard)driving.
If you can get the removal tool, I'd recommend going for the matched set.
[Modified by Dan Parker '96, 8:51 AM 2/10/2003]
The oil pump gear won't mean much because it'll thrust the cam towards the retaining plate with the engine running.
Check the clearances with the cam sprocket installed and see what you come up with. This is one dimension I forgot to check when I did my rebuild.
As for the second question... I noticed this as well. I left the original waterpump drive gear in place since I didn't have the tool to remove it (and I was a bit impatient).
I may regret it later on but it's been fine for 400 miles of initial (pretty hard)driving.
If you can get the removal tool, I'd recommend going for the matched set.
[Modified by Dan Parker '96, 8:51 AM 2/10/2003]
Thread Starter
Race Director
Joined: Oct 2000
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From: N. Alabama
Re: Excessive end play with Hot Cam? (Dan Parker '96)
Thanks for the reply, Dan. I have not tried the measurement with the big sprocket bolted on. I believe I will put the original water pump assembly back in (I had removed from the back side by gently tapping with a brass rod) since the shaft has no visible wear at seal contact area after 65K miles.
(man, what an adventure........) :)
(man, what an adventure........) :)
Thread Starter
Race Director
Joined: Oct 2000
Posts: 14,064
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From: N. Alabama
Re: Excessive end play with Hot Cam? (southern_son)
Dan, I realized my mistake after you pointed me in the right direction. The sprocket was not bolted onto the cam when I first took measurement. Now I realize that the end play is determined by sandwiching the retaining plate between the front of the cam and the sprocket on the other side (dummy, me).
I also discovered the difference in the water pump shaft assemblies. It seems several folks may have received the LT1 unit instead of the LT4 unit. Correct part number is GM 12551727.
I also discovered the difference in the water pump shaft assemblies. It seems several folks may have received the LT1 unit instead of the LT4 unit. Correct part number is GM 12551727.
