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Re: What does the stock cam measure to?
Posted: July 6th, 2012, 6:30 pm
by 5-90
grainofsalt wrote:5-90 wrote:SilverXJ wrote:You can't accurately measure the lobes with out the cam installed in the engine and with lifters on it.
The journals:
Bearing Journal Diameter
No. 1: 2.029 to 2.030 in.
No. 2: 2.019 to 2.020 in.
No. 3: 2.009 to 2.010 in.
No. 4: 1.999 to 2.000 in.
Bearing clearance is 0.001 to 0.003 in.
According to KB 3.5 thou will be fine for the pistons.
Sure you can - it just takes a special jig for the dial indicator and camshaft to ride in, or you can get a full setup to measure everything with the aid of a computer (lobe lift, ramps, centrelines, overlap, LSA, ...)
Apart from measuring the bearing journals, it's out of reach of the hobbyist, tho. And if you do end up building your own measuring jig, you're just going to be able to measure lift (unless you get creative, then you can measure duration as well.)
And the cost to build such a accurate jig would take more time and money than buying a new cam!
Thanks 5-90!
Depends on how well you fabricate.
Of course, you can
buy a rig to let you measure you a bumpstick thoroughly - should cost less than fabbing up the one to automate it, and it can give you a rather compleat cam card, but it's still spendy...
Re: What does the stock cam measure to?
Posted: July 6th, 2012, 7:46 pm
by grainofsalt
Sorry I did not subtract my numbers correctly .265" is the correct number. So .424" lift exhaust and the intake is .416". I just took my caliper and measured the total height then took a measurement 90 degrees from that. I didn't have the proper lathe ends to use the dial.
What is the FSM numbers? It is different from a 2000:
http://www.jeepstrokers.com/forum/viewt ... 96&start=0
Are these numbers correct?
The stock '96 and later Jeep 4.0 camshaft is a dual pattern cam that produces more torque at lower rpm and a wider torque spread. The specs are as follows:
Advertised duration int./exh.: 256.0/260.0 deg
Duration @ 0.050" lift int./exh.: 188.0/192.0 deg
Valve lift int./exh.: 0.408"/0.414"
Lobe separation angle: 107 deg
Intake centerline angle: 114 deg
Valve overlap (advertised): 43 deg
IVO: 20 deg ATDC (0.050" lift)
IVC: 28 deg ABDC
EVO: 16 deg BBDC
EVC: 4 deg BTDC
Thanks!
Re: What does the stock cam measure to?
Posted: July 7th, 2012, 8:46 am
by gonridnu
grainofsalt wrote: This cam has less than 180k on it.
Ummmmm .... oh nevermind.
Re: What does the stock cam measure to?
Posted: July 8th, 2012, 11:01 am
by IH 392
SilverXJ wrote:IH 392 wrote: Put your dial indicator on the high side.
The lifter is domed, how are you accounting for that?
You're nitpicking a couple of thousands, if you measure every lobe you'll not get the same measurements every time, plus if you figure it at the valve you will NEVER get advertised, the rocker arms ar NEVER! correct, they are ALLWAYS short.
Re: What does the stock cam measure to?
Posted: July 8th, 2012, 3:21 pm
by 5-90
Measure at the centre of the lobe, going from side-to-side. The taper is only a couple of thousandths, and it's usually +/- from the centre.
(The purpose of the taper is to match up with the crown on the tappet, and force it to turn in the bore. This helps keep friction wear on the tappet foot down. This is also why you can't just drop roller tappets on a flat tappet cam - the ramp can wear through the roller and scrap the tappets.)
Re: What does the stock cam measure to?
Posted: October 28th, 2012, 7:57 am
by MoFo
I think you got the cam part number wrong. The correct OEM part number is 5302 0438.
grainofsalt wrote:Camshaft is PN: 53020436 , Lift is approximately .260" Exhaust and .365"Intake, Multiplied by 1.6 is .416" and .584"
Does this sound about right?