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Melling Sbc8 Cam

Discussion in 'Early CJ5 and CJ6 Tech' started by 53A1, Jul 1, 2019.

  1. Jul 1, 2019
    53A1

    53A1 Member

    Kern Co. Ca.
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  2. Jul 1, 2019
    Keys5a

    Keys5a Sponsor

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    Melling makes a decent stock replacement cam. If your going to the trouble, also consider a mild torque cam. The cost is pretty similar, and you can wake up the Dauntless a little bit without sacrificing drivability and economy. Melling has them too. Ask Northern if you have a choice on grinds.
    -Donny
     
  3. Jul 1, 2019
    53A1

    53A1 Member

    Kern Co. Ca.
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    Thanks for that Donny. I'm a decent mechanic but I'm not a performance guy so I'm outa my comfort area. I want to keep the cost down because good enough is what I'm looking for considering I'm just trying keep it going for a few years. Do they have tech guys that can help select the exact cam for me or do I need to know what to ask for?

    My goal is to have a mostly slow moving off-road climbing jeep with around town capabilities. It will never see freeway use. It has an auto tranny and overdrive already. The cam it has currently seems very nice but lifters are dished and one lobe is going away. I couldn't tell you the specs on it. Came with the Jeep. I bet with the same cam it has now but in new condition, the engine would be a winner.

    Maybe I could pull the cam, ID it or send it to them to match?
     
    Last edited: Jul 1, 2019
  4. Jul 1, 2019
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member 2020 Sponsor

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    I know this is Comp cams - but might give you some numbers to discuss regarding cam grinding. Comp cams has 3 different options - essentially 3 different rpm ranges for different performance targets. I used the first one on my rebuild - grind 252H. The others push the rpm range up pretty high. Its worked superb for me in both off road and on road and hwy usage. I think its just slightly more duration than the stock...
    COMP Cams - Performance Camshafts, Lifters, Valve Springs, Rocker Arms

    I know the link seems to always bring up search menu for the AMC listings, but if you look to the right on the specs, its for the Buick OF v6.
     
  5. Jul 1, 2019
    47v6

    47v6 junk wrecker! 2020 Sponsor

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    I used the northern rebuild kit. It was the cheapest out there. Everything was fine... except the main bearings were all a different undersize. Couldn’t figure out why I had no clearance. Bought another main bearing set and all my problems went away. I have had no issues with the cam or the lifters though.
     
  6. Jul 1, 2019
    todd hofsaess

    todd hofsaess New Member

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  7. Jul 2, 2019
    53A1

    53A1 Member

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    How did the stock cam work out? I figure the stock profile is setup for low RPMs. I want to order the cam kit.
     
  8. Jul 3, 2019
    Keys5a

    Keys5a Sponsor

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    Get on a tech page with Comp or Schneider Cams. Your looking for what has been marketed as an RV cam. The Comp 252 has been popular. Either way, look for an rpm range beginning around 1000-1200 revs.
    Also, look for a timing set that has multiple keyways on the crank sprocket. If you use the 4 degree advance keyway, you can pull the power down about another 200 rpm.
    A custom grind for your use is best, but can cost a lot. There are various standard RV grinds that cost little more, sometimes the same, than a stock grind.
    -Donny
     
  9. Jul 3, 2019
    47v6

    47v6 junk wrecker! 2020 Sponsor

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    I have no complaints. Works fine for me.
     
  10. Jul 3, 2019
    Chilly

    Chilly Active Member 2019 Sponsor

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    I got a Comp 252H in my 304 I'm putting together. I cannot comment on how it will eventually run, but the decision is largely made for me because the 8.5:1 CR cannot support more cam. And thats OK with me because a high CR with an angry cam that barely idles isnt what I value in a Jeep engine, either.

    Rollmaster makes a nice timing gear/chain set with adv/ret key slots. Now if cam grinders could be trusted I'd say they are unnecessary. If you are using the adv/ret slots then you bought the wrong cam. Except that when we degreed the 252H we had to go either +4 or -4 (dont recall) to get the intake centerline where the cam card advertized it to be. If you dont degree your cam you have no idea what you are getting. I did not expect this, and my buddy practically insisted on checking it. I thought it a waste of time until the results were in. Now I know.
     
    Last edited: Jul 3, 2019
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  11. Jul 5, 2019
    53A1

    53A1 Member

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    I decided I'm going stock. Melling SBC8. I'll let you know how it goes. Can't be any worse then what I have. I started a new thread. Pulled everything out and ready to replace.

    Replacing Cam And Oil Pump Help
     
  12. Jul 9, 2019
    53A1

    53A1 Member

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    Northern is a good company. I realized that the individual parts were less than the advertised "kit". I asked if I could change the order and purchase the parts separately and they just refunded me the difference. The seals seem to be the same price across the board. I like our local Autozone so I purchased them there. I ordered a conversion/bottom end kit because I'm going to pull the pan and clean it.
     
  13. Jul 9, 2019
    Keys5a

    Keys5a Sponsor

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    That SBC8 may be a slightly better grind than stock, but is still sold as a "stock" replacement. There were several odd fire grinds used by Buick back in the day, and some were better than others, but the actual specs are pretty elusive.
    -Donny
     
  14. Jul 17, 2019
    53A1

    53A1 Member

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    Follow up for anyone wanting to install the Melliing cam. I finished installing the SBC8.

    Recap... I dropped the pan, cleaned and painted it. It was not too bad, just a very little black sludge settled at the bottom. I also clean and checked the oil pump as specified in service manual. The Jeep started right up as recommended so I broke the cam in as specified in the instructions. Oil pressure was at above 20 psi in 1500 to 2000 rpm break in period. The instructions are very specific and call out the use of Rotella oil during break-in as well as liberal amounts of assembly lube. I also added additional Lucas break-in additive with zink. No engine leaks with new cork pan gasket and replaced timing cover rope seal with modern oil seal. I replaced the timing gears and chain because there was so much slop the damper was barely making contact.

    As far as the cam performance, it feels very similar to the stock cam that came out with the exception there is far less valve train noise and the engine runs noticeably smoother. I think I caught the old cam before it really got bad and look at this as preventative maintenance because two lobes were missing .070 or so and lifters were very dished out. Timing mark was very steady when setting timing with new cam and Cloyes timing gear set.

    Also purchased a Champion 3 core radiator and I think they sent me a polished one, no complaints about that. Very nice radiator for the money. Took it on a hard shake down run with a co-worker and experienced Jeep owner and he approved so as long as the break-in went ok I think it was a success.
     

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    Last edited: Jul 22, 2019
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  15. Jul 17, 2019
    Keys5a

    Keys5a Sponsor

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    Glad to hear all went well!
    -Donny
     
    53A1 likes this.
  16. Jul 22, 2019
    53A1

    53A1 Member

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    I forgot to mention some research material I used when I selected the cam. I found this very good article with the original v6 cam specs.

    Choosing The Best Cam For Your Jeep - Jp Magazine

    I Compared the stock cam specs to the Melling SBC8 cam specs.

    https://www.melling.com/wp-content/uploads/2017/03/engine-parts-camshaft-specifications-1.pdf


    Comparison
    ----------------------------
    Duration

    Stock: 285/295 Melling: 272/283 (SAE .006 off seat for both sets of data)

    Overlap (had to calculate for Melling so this may not be correct)

    Stock: 67 Melling: 55

    Cam Lift

    Stock: .250/.250 Melling: .251/.244
    -------------------------------

    This is why I went ahead and used the Melling SBC8. Seems to be very close if not better in profile. From what I've read you want less overlap and duration for low RPM torque. More intake cam lift is good. I'm not an expert but this is what I found.
     
    Last edited: Jul 22, 2019
  17. Jul 22, 2019
    Alan28

    Alan28 Well-Known Member 2020 Sponsor 2019 Sponsor

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    Very interesting. I didn't know that companies liky Cloyes existed, so specialised, but why not, if they make profit.
    It seems top quality products. The name, Cloyes, is the name of our main local city, Cloyes-sur-le-Loir !
     
  18. Jul 22, 2019
    Jeepenstein

    Jeepenstein Me like Jeep..

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    We ran a Comp 268H with a stock 1976 304, headers and a dual plane intake with a Holley 600 on it and that thing would flat out boogie.. It was in a CJ7, quadra trac automatic..
     
  19. Jul 22, 2019
    Chilly

    Chilly Active Member 2019 Sponsor

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    53A1, intake lift matters down low because you want the valve off its seat quickly. So a fast acting profile. And that requires high lift so the lifter isnt jumping off the lobe. Down low and into mid range the amount of lift doesnt really matter because its breathing as much as its gonna by the half lift point or so.

    Taken to the extreme, you can make awesome throttle response and down low grunt but the cam lobes are super steep and hard on valve train. Requires roller rockers, in some cases. And if starting at 10:1 static CR your cylinder pressures can be excessive. I built a Harley engine like this. Mean li'l bastage but it killed a roller tappet, cam, rocker shafts, and rocker bushings within not enough miles.
     
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  20. Jul 23, 2019
    53A1

    53A1 Member

    Kern Co. Ca.
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    That's interesting and didn't even know or consider that when looking at the Melling.

    I took my rig out to test again last night. Dirt lot down the street with a steep plateau graded for houses that never happened. Put everything into low and locked and it was climbing very nice. Seems like this cam likes 1000 - 2000 which is where I'm at in low and TH350 in 1st.. I was almost able to idle up at 500 and just had to bump the throttle up a little to get it climbing nicely. Dealing with an overheat issue now.
     

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