In the middle of a road trip! 2 questions! Lean cylinders and noisy rockers? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 09-24-2010, 01:07 PM
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In the middle of a road trip! 2 questions! Lean cylinders and noisy rockers?

Hi all, i had an issue before with my carb, 1 and 4 cylinders are lean while all the rest cyldiners are dog rich. I took apart my holley 750 dp and made sure all passages were clear and didnt find a thing, I put it back on the engine and tuned the 4 corner idle with a vacuum gauage. I drove around a while and all cyldiners were pretty close in color if not a slight bit richer on some. Mostly tan though. Now about 3 months later, im having the same problem!

I just checked my plugs and all are extrememly rich except for 1 and 4 which are almost white. Im in the middle of a long trip so I cant do much to the engine, but I do have all tools I need. Im at my wifes parents house which is almost halfway through the trip, we stopped here to rest.

What would make just those 2 cyldiners run lean? How does everyone else tune their 4 corner idle carbs?

Also, my roller rockers have always been noisy, but its never been an issue because of straight exhaust. I just had a nice quiet exhaust put on the car, its almost silent under under 2300rpm, so all i hear going down the highway are the roller rockers... I asked a while back how to adjust the roller rockers and was informed how to do it properly by techinspector. He told me also to do only 1/8th turn preload. Are rollers just noisy, or should I do a little more preload? Thanks!

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Old 09-24-2010, 01:22 PM
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First of all if the rockers aren't tight they will break and cause a lot of damage so make sure they are tightened correctly. I have heard of some rockers being noisy but it shouldn't be that loud that you can hear it from inside the car. As for the rick and lean mixture, it could possibly be caused by bad plugs or wires or buildup on in the distributor that will look like it's running rich but it's just that the plug isn't working as well as it should.
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Old 09-24-2010, 03:51 PM
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I know it is not stock,but the GM manual says 1 full turn so I don't see how 1/4 turn can hurt.Try it and if they get quiet you know they were too loose. I always go 1/4 turn and I have built many engines,just not many with roller rockers.
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Old 09-24-2010, 05:25 PM
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Nothing wrong with using a little more preload in my opinion. I've read lately that some fellows are using one full turn. I think that's excessive, but hey, whatever blows your skirt up.

Rollers are going to be noisier than stamped steel OEM rockers. It's just the nature of the beast.
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