What Cam do i have?

bryrambler

Legacy Registered User
City
Tenafly
State
NJ
#1
Hey guys I picked up a 84 cj8 last year and am finally tearing it down.
4.2 automatic tranny. I dont know much about the history of the engine only that it ran on an electric pump.. after trying to get 2 separate mechanical pumps to work I realized.. (through this site) that someone had put a different cam in.. My question is.. what kind of cam could I have that doesn't work the pump?? Or is it just the wrong cam??
 

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CJ7Pilot

18436572
LIFETIME
CJ-8.com Member
City
Yuba City
State
CA
#2
Maybe a 4.0 cam? I don't know if that would be a direct fit in a 258 or not, but being made for a fuel injected engine would explain not having a fuel pump lobe. :shrug:
 

AK-RWC

Legacy Registered User
SOA Member
City
south central
State
AK
#4
Fuel pump eccentric is shot? Or maybe you're not getting the fuel pump arm on the eccentric correctly?

I'm just taking a shot in the dark here; I don't know as much about the 258s as I do the V8s.
 

Mancunian

Lifetime Member
LIFETIME
City
Bridgeport
State
WV
#6
Suggest to just buy an electric pump that will feed the carb, why did you try to replace with mechanical?
 

AK-RWC

Legacy Registered User
SOA Member
City
south central
State
AK
#7
Thanks but I've tried 2 separate fuel pumps..
The eccentric is on the cam, it's not part of the pump itself. And getting the arm in the wrong location is an installation error rather than a defect with the pump.
 

bryrambler

Legacy Registered User
City
Tenafly
State
NJ
#11
I tried an electrical pump and it works but very loud and annoying.
A generic one from napa was installed .. too loud .. so I put the carter p4594 and it was louder!
 

ag4ever

Average Nut
LIFETIME
CJ-8.com Member
City
Richmond
State
TX
#12
Maybe to get the High Output of the 4.0?

Problem with that theory is there is much more to the 4.0 H.O. than just a cam. Different heads, different stroke/piston ratio, fuel injection, ignition, etc...

The cam eccentric on the camshaft should look like the part circled in yellow between the 2 lifter lobes. If yours has that you should be able to install a mechanical pump.

CBE72E92-EF57-49F9-B8F1-F9DBDBA9B975.jpeg

The photo you showed does not have a lobe with a shiny ring around it where there is metal on metal contact. But it might not be shiny due to an electric pump being used and just accumulating oil.

I’m 99% certain your cam does not have this fuel pump lobe.
 

Mancunian

Lifetime Member
LIFETIME
City
Bridgeport
State
WV
#13
Maybe someone has a suggestion for a quiet low pressure electric pump. The one you mentions does have negative reviews about noise due to the built in regulator.
 

bryrambler

Legacy Registered User
City
Tenafly
State
NJ
#15
Ok guys.. 2 engines and not a lot of info on either except they both ran. left one is a 82 right is a 83.. the one on the right came out of my jeep and it has a different cam. One without a fuel pump lobe.. but now I'm noticing it also has a beefier chain and sprocket? The sprockets on the right also has less teath.. I was hoping to go back to original mechanical pump.. by using the cam from the left.. but the beefier chain on the right looks so much better and has no slack..... question is why? Obviously it's an after market chain and sprocket but can it be used on the original cam???
 

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bryrambler

Legacy Registered User
City
Tenafly
State
NJ
#16
Hope I'm making any sense.. I guess the question is are timing chain kits Cam specific? And why less teath on the better beefy looking one?
 
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