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Need advice 360 timing chain cam/crank slightly off

Posted By: 340challconvert

Need advice 360 timing chain cam/crank slightly off - 11/01/22 06:48 PM

Need advice 360 timing chain cam/crank slightly off

Purchased a 360 from Mabco to put into my A66 340 Challenger short term while I pull the 340 for a rebuild.
I bought a hp version with flat top pistons and installed hp cam sited as a 272 cam
Cam specs; 272-272 duration 454 lift 110 lobe separation 52 degrees overlap, 216 216 duration @ .50
Power range 1500-5200 Considered the largest "stock" cam for this engine

In going over the engine for parts install; the timing marks are slightly off.
I call the manufacturer and he stated to leave the chain as is.

Pistons are flat top 30 over, no valve notches, piston to deck measurement is not a stock (deep in the hole) 360 with the higher compression pistons it measures out at about .087 below deck with number 1 piston at TDC.

I am no expert, and I have installed cams years back always aligning timing marks; is there a reason for the manufacturer to alter the timing in this manner with this hp cam and flat top piston?
Pic of timing chain sprockets and Number 1 piston at TDC
Any thoughts appreciated.

Attached picture IMG_8963.jpg
Posted By: CSK

Re: Need advice 360 timing chain cam/crank slightly off - 11/01/22 06:49 PM

You need to degree the cam with a degree wheel
Posted By: stumpy

Re: Need advice 360 timing chain cam/crank slightly off - 11/01/22 08:20 PM

It looks to me like the cam and crank aren't in a center line. Put a straight edge from the center of the cam bolt to the cam dot and center of the crank bolt and see if they are lined. Are you sure you are top dead center?
Posted By: Cab_Burge

Re: Need advice 360 timing chain cam/crank slightly off - 11/01/22 09:18 PM

Originally Posted by csk
You need to degree the cam with a degree wheel
iagree
The first solid roller cam I bought and installed for a customer was ground 10 degrees retarded puke
I've also had 10 sets of Cloyes BB Mopar timing sets that came with the wrong cam gear shock rant puke
My message is never trust any part to be correct, especially with any Hi Po parts in your motors tsk
You'll need a solid lifter, a degree wheel and a dial indicator with 1.0 inch reading with an extension long enough to reach the lifter cup wrench scope
The quickest way to check the cam for proper lobe timing is to check the lobe separation angles at .050 before and after max lift on the lobes with the solid lifter, check the intake lobe first and then check the exhaust lobe second, if the intake lobe is correct (installed straight up) at max lift at 110 ATDC the exhaust lobe should be 110 BTDC at max lift, if the cam is installed 4 degrees advance the intake lobe center should be at 106 ATDC and the exhaust lobe should be at 114 BTDC scope
I always check the lobe lift also before checking the LSA on the cams wrench
Cloyes made a batch of BB upper cam gears that would not align dead nuts straight up and down with the crank gear, if the cam dot was to the drivers side of the motor the cam was retarded around 12 degrees and the motors would run like crap down
If you moved the cam gear so the crank gear dot was to the passenger side of the motor it is was closer to being install correctly shruggy
Take your time to make sure the cam is installed correctly on the lobe separation angles, you don't want it to hurt parts or have it run like Doo Doo tsk work
Let us know what ends up with this problem please luck
Posted By: Guitar Jones

Re: Need advice 360 timing chain cam/crank slightly off - 11/01/22 09:52 PM

Looks like you have the cam at least one tooth off.
And BTW that is #6 firing, not #1.
Posted By: BTBelvedere

Re: Need advice 360 timing chain cam/crank slightly off - 11/01/22 10:25 PM

Originally Posted by Guitar Jones
Looks like you have the cam at least one tooth off.
^^^^^ This
Posted By: Dcuda69

Re: Need advice 360 timing chain cam/crank slightly off - 11/01/22 11:37 PM

Originally Posted by Guitar Jones
Looks like you have the cam at least one tooth off.
And BTW that is #6 firing, not #1.


Agree on both points. Line those dots up, then get the degree wheel out to find out where the cam actually is. Good luck!
Posted By: GODSCOUNTRY340

Re: Need advice 360 timing chain cam/crank slightly off - 11/03/22 01:08 AM

I just lined up a straight edge on his pic from center of crank bolt to center of cam bolt and both dots are off. Looks like you have the crank spun too far past TDC. Back it up and both will most likely line up.
Posted By: AARCONV

Re: Need advice 360 timing chain cam/crank slightly off - 11/03/22 01:33 AM

They make an offset keyway
Posted By: Guitar Jones

Re: Need advice 360 timing chain cam/crank slightly off - 11/03/22 02:34 AM

Originally Posted by AARCONV
They make an offset keyway

They make them in 2°-4°-6° & 8° off sets.
Posted By: Guitar Jones

Re: Need advice 360 timing chain cam/crank slightly off - 11/03/22 02:36 AM

Originally Posted by GODSCOUNTRY340
I just lined up a straight edge on his pic from center of crank bolt to center of cam bolt and both dots are off. Looks like you have the crank spun too far past TDC. Back it up and both will most likely line up.

Cam turns at half speed, that is still a tooth off.
Posted By: TJP

Re: Need advice 360 timing chain cam/crank slightly off - 11/03/22 04:46 PM

Originally Posted by GODSCOUNTRY340
I just lined up a straight edge on his pic from center of crank bolt to center of cam bolt and both dots are off. Looks like you have the crank spun too far past TDC. Back it up and both will most likely line up.


up bow up

Actually you either put the cam in backwards or have a Chevy cam laugh2. Gods country nailed it twocents
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