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  • you are convinced, so what can I say. That does not look like a mark on the cam gear. Looks like a bump, the way your lifters made it thru customs, who knows if that was tossed or dropped.

    I just look at every picture of every timing gear set online and the taper of the gear is on the other side.
    You look at fatguysinc picture and you see the recess of the cam gear. Same recess on the sketch of timing marks earlier in the thread.
    . Figure there would be a definite pin punch mark on the other side not just a bump. I mean the crank gear is pretty weak too so who knows. I would just be worried that the cam is pulled out a little and not running on the middle of the lobes.

    What part number was that chain? If you are going to put the 2 pc cover on, what would it hurt to take the gear off and look at the other side, and if you see definite marks, install it and see if its tighter. The mark will just be on the 12:00 position not 6:00 so you should not need to change the distributor.

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    • Aligned....straight up.

      Maybe the slack is designed into the chain for that lumpy idle.....


      With a loose timing chain your cam is slightly retarded and it will get worse as the chain wears. I've never been a fan of Edelbrock's products except for some of their intake manifolds. Now that I know they sell camshafts that require their timing gears and chains (and the chain is loose) they're farther down on my list. I'm not a professional mechanic but I've been building Chevy and Pontiac V8 engines for the last engines 58 years and have never had a loose timing chain on any new gear and chain set.

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      • I have no idea when I can get to it but that chain
        is coming off.
        I've got my Crane timing chain and the two piece cover ready but right now other business has to be taken care of.
        If I did install the cam gear backwards I don't see how it affects the chain.....the gear diameter stays the same.
        I did'nt like the chain at first sight it's links are huge.
        I do appreciate all your input and I do consider all you say important, after all I have limited experience.

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        • Originally posted by malc View Post
          I have no idea when I can get to it but that chain
          is coming off.
          I've got my Crane timing chain and the two piece cover ready but right now other business has to be taken care of.
          If I did install the cam gear backwards I don't see how it affects the chain.....the gear diameter stays the same.
          I did'nt like the chain at first sight it's links are huge.
          I do appreciate all your input and I do consider all you say important, after all I have limited experience.
          All I mean is there is always a little slack in most chain sets until you get those cam bolts tightened all the way and then they get just a little tighter. Whether that has something to do with the gear going in deeper or not I dont know. Just hoping you would get it back to TDC firing, and take the 5 minutes to flip the gear around and see if its still as loose so I can stop thinking about it. Then I would guess as long as you dont move anything and put anybodies set on at the same point the car will run the same as it is now.

          If it is loose and running a little retarded, its going to get more power sooner, where if it was advanced there would be more power later. That may be a light difference with how its running if removing the slack brings you right to true tdc timing.

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          • Originally posted by anotheridiot View Post



            If it is loose and running a little retarded, its going to get more power sooner, where if it was advanced there would be more power later. That may be a light difference with how its running if removing the slack brings you right to true tdc timing.



            this is 100% wrong. in fact its exactly the opposite--
            retarding = power later. advance = power sooner.

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            • "but my original factory spec is one and a half turns preload."

              Do you have a shop manual? I have several factory manuals and they all say one full turn. The last 2 aftermarket hydraulic lifter cams I bought recommended 1/2 turn. I've never bought an aftermarket camshaft that didn't come with specification card that specified how to adjust the valves. If the specs you show for your cam are correct that's a very mild cam in my opinion. I have a Comp Extreme Energy 262h flat tappet cam and kit .493/.500 lift .262/.270 duration in my 1980 Chevy 3/4 ton deer lease pickup. It has a lot of torque from 1800-5800 rpm. It has the original 350 engine that has been bored .030 and rebuilt. Everything but the short block is aftermarket and it has 9.5 to 1 compression. It has a rough idle but it has pulls 15 inches of vacuum at about 1000 rpm. I also have a vacuum storage tank so the brakes work fine This truck weight 5100 pounds empty and hauls ass (has 4.10 gears).

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              • Originally posted by fatguyzinc View Post




                this is 100% wrong. in fact its exactly the opposite--
                retarding = power later. advance = power sooner.
                I just heard that LT guy say it when they were degreeing in a cam over on CBS Sports channel on saturday. He is the one with no motor experience, but the others did not correct him either.

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                • Originally posted by dieselhead View Post
                  "but my original factory spec is one and a half turns preload."

                  Do you have a shop manual? I have several factory manuals and they all say one full turn. The last 2 aftermarket hydraulic lifter cams I bought recommended 1/2 turn. I've never bought an aftermarket camshaft that didn't come with specification card that specified how to adjust the valves. If the specs you show for your cam are correct that's a very mild cam in my opinion. I have a Comp Extreme Energy 262h flat tappet cam and kit .493/.500 lift .262/.270 duration in my 1980 Chevy 3/4 ton deer lease pickup. It has a lot of torque from 1800-5800 rpm. It has the original 350 engine that has been bored .030 and rebuilt. Everything but the short block is aftermarket and it has 9.5 to 1 compression. It has a rough idle but it has pulls 15 inches of vacuum at about 1000 rpm. I also have a vacuum storage tank so the brakes work fine This truck weight 5100 pounds empty and hauls ass (has 4.10 gears).

                  https://www.jegs.com/p/COMP-Cams/Com...46624/10002/-1
                  If you need to adjust your hydraulic valves again this method will simplify it and make the initial start up much simpler (it's from one of my shop manuals). It also works on solid lifter cams. It may not be perfect with an aftermarket cam but it will be real close and the engine will fire right up. You can use a more precise method once the engine is warmed up. It goes like thus:

                  1) with the engine in the #1 firing position adjust Exhaust valves 1,3,4,8 and Intake valves 1,2,5,7
                  2) with the engine in the #6 firing position adjust Exhaust valves 2,5,6,7 and Intake valves 3,4,6,8

                  It also says to tighten the adjust one turn after you have zero pushrod clearance to put the lifter plunger in the center of its travel. If you camshaft calls for one turn and you are setting it at one and a half turns or more your lifter can't compress any more and may hold some of your valves slightly open.

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