Hello all. Has anyone installed a Melling MC809 cam in their 4.0?
I did not really find anything here or online of experiences. So hoping to get some insight on this post.

To go on a small tangent: my cam synchronizer gear started getting wear. I heard the "barrel of monkeys" noise (if you're not familiar try searching for a video of Jeep 4.0 OPDA noise) and had no idea what it was; thought it was a pulley bearing going out. The noise happened no more than a handful of times, throughout several weeks, but would always suddenly stop making noise. Also had low oil pressure for about a week. After I found out what the noise was, I pulled my synchronizer and saw the gear was getting cut up. Camshaft gear also seems to be a little chewed up so I guess I'll be replacing.

I ordered Melling MC809 camshaft with a lifter kit. It says it's a stock replacement cam for 1994 4.0. I haven't found much reviews or information on experiences with this exact model (MC809) camshaft; aside from narrower lobes, smaller lobe base circle, different advanced timing, and possibly needing longer push rods (hopefully not). I replaced rods a month ago with Melling MPR437: length 9.639 which matched the same length as original rods.

Has anyone installed this MC809 camshaft? Did it work out successfully? Was there a need for longer rods, different springs, different timing?
When an item says stock replacement it's presumed stock engine components will work but not always true. Please help, thank you.

 

My jeep has a melling cam in it. Looks like it must have been a MC1377. No problems so far, I think I have about 2500 miles on it.

 

I remember you mentioning Melling cam in your engine but were not sure about specs on components because you had a builder for it. Good to know your cam hasn't had problems, presuming the builder used the right parts. Now I just need to figure out if my stock spec parts will work with the cam I bought... I don't expect much people to respond on this one

 

I found something that I was hoping I wouldn’t find. The rear of the camshaft has been rubbing on the rear core plug. It dug in, I’d say about, 1/32 into the plug and made a nice flat washer/donut shape. That was with 4000 miles on it after rebuilding.
The oil pump itself might have been going out due to age (low oil pressure), but now I’m wondering something else. I’m wondering if the cam was never resting as it should have and the plug had the cam pushed forward, causing the cam and distributor/synchronizer gears to bind up.
If that’s the case, well damn… Nonetheless, I need to address the core plug issue. Either it got driven in too far or the plug was made too deep and wasn’t shallow enough. I thought maybe I could try to tap the plug outward but I risk cocking it and/or driving it completely out. I thought, “what could I use to drive it out, but flush?” Then I thought of installing the old cam and tapping on the cam front face to help drive out the plug. But I’m wondering if I risk damaging the cam bearings with the hammer force; thinking the journals might rattle around inside the bearings. I’m curious if I can have the machine shop mill the rear of the cam a bit to clear the core plug. I’m trying to avoid pulling the transmission to install a new plug unless I absolutely have to.

 

My first question is what year is your jeep/ motor? Your name is 2000xj but you state that the cam you got is a 94 replacements. The camshafts are retained differently in the 2000/2001 motors. Pre 2000 has the button and spring that rides on the timing cover...the laters use something else totally incompatible with the earlier cams. I know because I have built 2 strokers with the comp cam extreme series and i had to change to an earlier block on my 01 because they state that that cam is only good up to a 98 or 99 due to the use of a different cam retainer. I pulled my 01 in its entirety so I didn't disassemble to see what the actual differences were

 

Long story short: Yes the block is a 1994 with the spring and pin camshaft bolt not the later years with cam retainer plate. A 1994 block is in the 2000 Cherokee.



Long story: My original engine went out 7-8 years ago. I went to the salvage yard for a replacement, honestly unaware WJ blocks don’t interchange; that would have been a pleasant surprise once I got the engine home and ready to transfer brackets and’s such. By luck I found a super clean ZJ (so clean that it was a shame it was in the yard) and pulled that engine. I made sure to pull the oil pan at the yard and check internals, all was good. Fast forward, I put a new timing chain kit, swapped in the cam sensor/OPDA from the 2000, etc. and I was back on the road. For a long while I recalled the GC was a 1998 but I guess my memory slipped because the block is stamped as a 1994; 53008405 casting and 408MX02 stamp.

If anyone is wondering, “Well…I don’t know why you didn’t you just get an engine out of another XJ in the first place…” (sarcasm) I looked and they were either gone or garbage. So ZJ for the win.

 

Ok thanks...that makes total sense now. And it ruins my brilliant theory on why your cam was walking..oh well . Can you actually feel the plug getting cut or is it just shiny 1/32 isn't much to measure back there. You have the head off to check? Is it possible your crank gear is slightly in too far, pulling your cam slightly back?, or the cam timing gear is not fully seated and being pulled back a hair? For unknown reasons my first stroker..92 with a 96 motor died at around 350K, with 75k ish on the motor. Would not start one day and after a week of scratching my head i found the distributor rotor slipping. Figured I needed a new one. Found the brass distributor gear in perfect condition...AND the hardened camshaft gear almost gone. Could never figure the mechanics of that. But back to your story...you explained why you replaced the original cam, but not what the issues were with this new melling 809 cam, unless the old cam made the cuts and your just now installing the new cam. Oh yea for a side note...Rockauto lists M809 from 89-95. M1376 for 96-98 and the different style retainer M1377 from 99 and up

 

Yes the old cam made the cuts on the rear cam plug. The old cam is removed, and with a flashlight I can see the groove/cut it has made on the rear plug. I can also put my hand up into the rear of the engine block and feel the cut it made on the plug. It's about a fingernail thickness of a groove. I haven't installed the new Melling cam yet.

If anyone knows the 4.0 camshaft, it has raised, rectangular nub, on the back of the camshaft, on the rear cam journal. That rectangular nub is what was rubbing on the plug. I brought up the cam rubbing on the plug issue to my machine guy. I told him I don't normally "cut corners" when I do my mechanic work, but with the engine already installed, it's going to be a heck of amount of work to get the transmission and t-case out just to change that plug. I asked if he could mill down that nub, on the new cam, just enough so it wont rub that plug. He said I could take an angle grinder, flapper disc, shave some off and it'll be fine. I trust his judgement. So, I will be doing that.

Im curious; how can the crankshaft gear be in too far? From my understanding the crank chain gear gets pushed onto the crankshaft, then oil slinger, then the harmonic balancer clamps it all down. Could you elaborate on the crank gear maybe being in too far? Maybe I missed something.

For what it's worth, I did not remove the cylinder head. I removed the timing cover, removed the threaded plug above the camshaft (that plug leads to the oil gallery for the lifters), CAREFULLY lifted each lifter individually with a magnet via the push rod holes on top of the cylinder head, and pushed a long wooden rod through the lifters oil gallery to hold the lifters up. This has to be done one lifter at a time; raise one lifter enough to push the rod underneath the lifter, then carefully release the grip of the magnet to let the lifter rest on the wooden rod. Then proceed to the next lifter, same procedure, and so on for all 12 lifters. It was meticulous but definitely saved hours of time and frustration removing both manifolds, and pulling the head, reassembling, etc.
After all the lifters are supported by the wooden rod you can pull out the camshaft. Pull the wooden rod slowly and the lifters will slide out the bottom. Install the new lifters from the bottom, held with a magnet at the lifters base, push through the lifter bore, push the wooden rod underneath the lifter, then pull the magnet off and the lifter stays put. Then the new camshaft can be installed then slowly remove the rod and the lifters will drop onto the cam lobes.

 

To be honest I have never even looked back there so I can't confirm they all don't rub a little. All harmonic balancers purchased in the last 10-15 years dont even use the oil slinger anymore. Throw a blob of assy lube into the plug. I dont know if I would shave the new cam but thats up to you and your mechanic. Ive never heard of anyone eating through it and sadly there is no way to check once installed. Good luck with it

 

To anyone that cares:
Melling MC809 is listed for lots of older vehicles from AMC and Jeep; from mid 70s to early 90s. I don't like that wide range of years. I think the MC 809 camshaft is not designed for 1994 4.0 (even though it claims to be). For a "OE stock replacement grind" it has thinner lobes and an EXTRA LOBE between the intake/exhaust lobes for cylinder 2; it's an offset round lube that looks like it might drive a fuel or oil pump?? Not present on the camshaft I removed.
https://www.rockauto.com/en/moreinfo...O5DEXkpw%3D%3D

The camshaft I removed from my engine looks a lot more like Melling MC1376 (according to the photo). The lobes look like the right thickness not thinner, that extra lobe is not there, and it has the same groove impression between the intake/exhaust lobes for cylinder 3.
https://www.rockauto.com/en/moreinfo...O5DEXkpw%3D%3D

This is very frustrating because we rely on these aftermarket companies statements that claim this specific part number fits your specific year, make, model, engine, and that's not always true. I already have the MC809 camshaft with lifters installed. So, Im going to break it in, drive it (if I can) and report back the results. I should have called Melling directly and asked specific questions about: Why the camshaft I pulled doesn't look like MC809 and looks more like MC1376? Why do you claim MC1376 will not work with my year engine? Why does MC809 have an extra lobe, when it's not used for anything in a 1994 Jeep 4.0?

 

Firstly, sorry your having dimensional issues right out of the box with your new camshaft. My best guidance would be...if you have not run / broken in the cam....CALL MELLING FIRST. Make sure the cam will physically fit/ not damage your lifters with the smaller lobe width and that you will not need different pushrods from smaller lobe dimensions. Explain your concerns with the same cam being run in the renix models and the first gen HO motors. Im mostly sure that extra lobe is made to run a carbeurated fuel pump...if so, then that cam is really not made for a fuel injected engine...something with the wrong vacuum curve, but it will ( extralobe) probably not interfere by itself being there. problem is my knowledge of the jeeps started with my first 92 HO, so I don't know the differences between them and the earlier renix motors. . You state that you are only 4000 after a rebuild...what exactly was rebuilt and done by you or someone else..what cam was in the first rebuild. Just double checking....I did my quick research on Rock Auto and they stated your 809 was good to a 95, so I went to Melling itself and confirmed the 809 was listed as a 94 replacement...Rock auto is usually fairly accurate , they list a 245mm/ 9.650 inch pushrod for every year I checked 92/96/2000 but I guess if given bad info from the manufacturers, they could be off in Cam part numbers. Even as far back as 87 they list the 809 cam and the same 245mm pushrod, so I guess it will not cause physical damage...just might not give the performance you were looking for, but thats just a guess on my part. Bottom line...double checking with them that the performance/ vacuum curve is acceptable for your 94 and if so...break it in..good luck....I wouldn't want to pull that cam out unless I had to

 

The crank was grinded. All new lower end bearings to match. New cam bearings. Bored .020 over with .020 flat top pistons. Engine was decked: i dont know how much i think he said .010. Rebuild 7120 head, not sure how much was milled off. I dont know compression nor know how to check. I assume it might be just close to stock 8.7:1 not sure. After 4000 got low oil pressure, maybe oil pump or drive gear. Cam gear was riding on back core plug and I think got pressure on the cam oil drive gear and they started chewing each other up. So decided to replace cam and lifters before it got worse. Now think I bought wrong cam.

 

87-90 83503402
91-93 83503402
94-95 33002981
96 53020438
97-98 53020438
99 53010448AA
2000 53010448AA
01 53010448AA

87-95 Cross to MC809 (AMERICAN MOTORS AMX 1978-1980 AMERICAN MOTORS CONCORD 1978-1980 AMERICAN MOTORS EAGLE 1980 AMERICAN MOTORS GREMLIN 1976-1978 AMERICAN MOTORS HORNET 1976-1977 AMERICAN MOTORS MATADOR 1978 AMERICAN MOTORS PACER 1976-1980 AMERICAN MOTORS SPIRIT 1979-1980 JEEP CHEROKEE 1979-1995 JEEP CJ5 1979-1980 JEEP CJ7 1979-1980 JEEP COMANCHE 1987-1992 JEEP DJ5 1979-1980 JEEP GRAND CHEROKEE 1993-1995 JEEP J10 1979-1980 JEEP WAGONEER 1980-1990 JEEP WRANGLER 1991-1995)
96-98 Cross to MC1376 (JEEP CHEROKEE 1996-1998 JEEP GRAND CHEROKEE 1996-1998 JEEP WRANGLER 1997-1998)
99+ Cross to MC1377 (JEEP CHEROKEE 1999-2001 JEEP GRAND CHEROKEE 1999-2004 JEEP WRANGLER 1999-2006)

Crown also lists the 83503402 for 87-95 and looks like it has the fuel pump eccentric in the pics. I bet its a rebranded melling anyway.
Im sure the MC809 will work fine. But it is listed for engines from 1976-1995, and 199 CI to 258CI. Seems to be a one size fits all "it'll work" type situation.

The MC809 shows a longer duration and less lift than MC1376. The MC1376 is also designed solely for a fuel injected 4.0.
IMO I would do so me research and see about swapping to the 96 cam, but Im not an expert.

 

Thank you for all that. I looked at the original cam and it's casting number is 8933002983. Apparently that references to 33002981, which also references to 83503402, like the Crown listing.

I was thinking the same, about swapping to the MC1376, being it's specific to fuel injection and I don't know how the MC809 will work with 49psi fuel pressure. It might work but I don't know camshafts that well and lobe separation stuff. I was just hoping to guy and oem spec cam but MC809 does not seem like it's it.
I did some measuring on the original oem camshaft lobes to get a "lift" measurement. You basically measure the lobe(s) at two different areas, find the difference, and multiply by rocker arm ratio. Unless I didn't measure well enough, the calculations came to .4048 intake and 0.4128 exhaust. On a worn out oem camshaft, those seem a lot closer to the MC1376 at .408 intake and 0.414 exhaust rather than the MC809 at 0.397 and 0.397. I don't understand how a manufacturer can get that confused.....

 

They dont have anything confused. Its just basic industry/parts manufacturer stuff, if they can make one part number and mass produce it to work in multiple applications thats what they are going to do, and any company that is smart wouldnt put their name or reputation on the line for a part that doesnt work on a listed application. Im sure the 809 woud work fine, and Im sure tons of them have been put into 4.0s with no problems. BUT, I think the 1376 is a better choice.