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87z !
Thanks 87Z. But I was not bothered by anything you posted. I have a weird sense of humor! I was cracking up when I realized how old the thread was. No harm done! I did start a new thread. Its all good.
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But if the Comp techs are admitting it's the cam, I think you can believe them... |
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I have a Comps XE-270-HR in my Regal with 355 SBC and it was rather noisy when first installed and before playing with the lash a couple of times. When first installed we went to zero lash plus 1/2 turn and then tried again with 3/4 turn and that quieted it down a fair bit. Still not perfectly quiet like a OEM roller but with a nice pair of mufflers, who really hears the noisy ramps anyways.
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I have a pretty big XE cam in my 69' Firebird. Its specs are 240/246 duration at .050" with .507"/.510" lift 110 cl.
Its got a awesome idle and power is good. My engine is a 400 Pontiac .030" over, balanced with KB pistons and Edelbrock 72cc RPM aluminum heads. Roller rockers and a single plane intake with a 775cfm Annular booster carb. (I had to go with the annular booster because the low vacumn from the cam) The cam was NOISY as heck when I broke the engine in, I complained to my machinist about his valve adjusting job. He said he set them at a 1/2 turn just like he does all his adjustable "Chevy Style"-Edelbrock heads are set up as. Well I READ and REREAD the instructions from Comp Cams and it says that the Adjustment is 1 FULL TURN from Zero Lash. I went back and readjusted the valves and WHATYA KNOW! They are quiet now. I also noticed that now I get better oiling at the rocker arms also....The problem is in the way the lifters are machined. The little oiling holes weren't lining up right at 1/2 turn from zero lash. When I went to a full turn the noise and the oiling got tremendously better. |
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you will make a smidgin more hp with 0 preload.
thats where mine set at with no prob. (xe274 hyd.) |
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The typical performance 1/8 1/4 turn preload was not enough. I also changed from 10w30 oil to 15w40 and that helped also. The valvetrain is not absolutely perfectly quiet at idle like a stock hyd cam. Its comparable to a well adjustened street mechanical lifter cam. The cam works well thou. I used conventional Speed Pro HT-817 lifters on the comp extreme cam. it does not sound like a sewing machine running like I've heard some fast bleed lifters create, but is not perfectly quiet either. I'll be switching it to a solid flat tappet soon. Just 'cause. I can. |
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rather be on the safe side, maybe go 3/4 and see what is up?
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But judging by what I've just read, one turn is where I would set them at. But, no- there is absolutely NO damage from one full turn- provided that you start at a correct Zero lash. Most agree that jiggling the p-rod in an up-and-down fashion will allow zero lash to be 'felt' easier than by twisting the p-rods between fingers and thumb- and is how I've ALWAYS done it, even before it was 'cool'. |
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[QUOTE=cobalt327]There is no reason to go more than one turn- if you want to try less than one full turn, that's fine too.
But judging by what I've just read, one turn is where I would set them at. Thanks again cobalt, one turn it is tomorrow.. if I can sneak out to the shop that is.. will post result |
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As far as a "loss" of power from the one full turn...I'm not worried about it. My car made 364 horses and right at 400 torque on a in ground Dynojet chassis dyno, Peak torque was at like 4900 and peak horses was 5850rpm. So that is rear wheels horsepower numbers, not flywheel.
If you tighten them too tight your valves wont close....Thats what happens if you go too much more than one turn. Most factory manuals from GM stated one full turn from zero lash as the official adjustment number for most factory 60's and 70's cars. Its nuts if Comp told you a half turn themselves, Their own literature on the instructions actually says one full turn (So they must not even read their own directions) If your adjusting your valves on a warm motor that was recently running, give the lifters time to bleed down, otherwise going from a half turn right to a full turn will unseat the valves and it will crank over with no compression for a minute until the oil bleeds down. I have in the past done Comp Cams on small block Chevy's the Magnum Series 280 cam at a half turn and never had a issue. But the XE cam was different. (Although the Magnum cam seemed more likely to bend pushrods I had to change out a few hardened Speed-pro's and eventually switched out to all 4340 Chromoly Manleys to solve that issue) I think every cam has its pro's & con's. Factory stuff is the only ones that should be expected to be perfect right out of the hole. |
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I have the comp XE as well #12-235-2. Posted on this very thread with same noise issue. I run mine at 1 full turn now, tried many different preload settings and set with engine running as well, checked geometry, have good oil pres, springs, heads etc etc. Not sure about others but in my particular application the noise is most prevalent when the engine is hot. On start up she sounds just right then once at operating temp the ticking begins and is most annoying at idle. I just did an oil change to 10W-30 from 15W-40, the heavier oil was better (helped as attested by FBIRD88). However with the 10W-30 in my case there is also much less or no noise on start up. So just a thought here...when an engine is cold the oil is "heavier" so the hydraulic pressure in the lifter has more of a effect on cushioning (for lack of a better term) the valve train. The heavier weight oil affords this principal on a continual basis even when its at operating temp so the 15-40 is best. I have had a few guys ask me if i was running a mechanical cam, my XE sounds very similar. Anyhow on my new 383 I am switching to another cam, it won't be an XE...a change is as good as a rest they say.
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