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flat cam what to do next
I had my cam go bad. I looked at the oil and it was ok no sparkle at all. Do I need to bull the motor and clean? Also this is crazy. I puled the timing cover to take the cam out and the dots on the timing chain are off. the one on the crank is up and the one on the cam is up. The cam dowel is on the passenger side. when I took out the distributor it was facing the #1. Was it off. How to install the new cam and distributor. I assume dots down and dowel on driver side will the distributor go in the same. do I turn the crank one time?
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Tom, when you initially install the cam, you put the crank gear dot at 12:00 Noon and the cam gear dot at 6:00 O'Clock. This puts the #6 piston at ready to fire and the #1 piston at overlap. If you then turn the crank 360 degrees (one complete turn), the crank dot will be at 12:00 Noon and the cam dot will be at 12:00 Noon. #1 piston will be ready to fire and #6 will be on overlap. This is where you want the dots to be in order to install the distributor and ignition-time the motor.
You can, of course, install the sprockets at noon and noon, but then you could be off a tooth if you don't use a straightedge to line them up. It's just simpler to install them at noon and six to make sure you have the cam timed properly and then turn the crank one complete turn to do the ignition timing. Last edited by techinspector1; 10-27-2008 at 02:07 PM. |
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454C10 raises an excellent question. How are you going to prevent a recurrence?
In my opinion, there are two major contributors to a cam going flat. 1. Lack of extreme pressure lube in the oil. 2. Using valve springs that are too stiff. My recommendation is to use old, worn-out stock valve springs to break the cam in, then change them to the springs you intend to use. Either that, or invest in some 1.3 ratio break-in rockers and change rockers after break-in. |
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dont know
I may have flattened it at brake in 2 years ago. It always had a ticking sound but ran fine did 12.2 with 100 shot of nitrous. The sound got worse so I re did the valves and noticed on rocker looked strange. I drove the car about 45 minutes and it ran fine just sounded strange. I really dont wont to take the motor apart but if I must. I have a hydraulic flat trickflow (summit) 228/234 480/496. I guess I will always use zinc. I changed the oil allot like 100 500mi yes that sound strange. I had a oil pan leak that I was chasing down.
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your jumping to conclusions....
measure the actual lift at the rockers "one rocker looked strange" and "now it sounds strange" is not a final diagnosis for a flattened cam.... do a compression test.... |
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it is flat
no it's flat the lifter looks like a dish and I puled the cam and it is flat. It was just one exhaust.
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Flat cam
Here's an item that hasn't been mentioned: Todays motor oil has no zinc in it.
The zinc was removed from the oil because it would neutralize the catalytic converters. Zinc is required for "Break-in" of flat tappet cams (hydraulic or solid) The oil I use for "Break-in" is Brad-Penn or Joe Gibbs break-in oil. They are specially formulated for new engines. Prelubing cam and lifters, correct spring pressures, and priming oil pressure prior to starting are also necessary. Definitely dis-assemble the motor and thoroughly clean. When your timing marks are lined up on your gears, #6 cylinder is firing. (#1 is also up but not firing). Best of luck to you. Bill |
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cam
well the cam bearings look bad I guess every thing is bad. found some shavings around lifters
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I just read a article in Auto Restorer Nov.2008 mag and it says that Conoco Phillips Lubricants said that the 76 High Performance Motor oil SAE 20w-50 and the Kendall GT-1 High Performance Motor oil SAE 20w-50 both have been reformulatedwitha increased level of zinc dialkyldithiophosphate (ZDDP) for increased wear protection. They are sposed to have approximately 1200 ppm of zinc is what the article says.
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sheldonw - for what it's worth on my last build I was 140 on the seat and 370 open - I broke it in with the inner's removed, Brad Penn 30w break in oil, no other additives. Never had an issue. After the 1/2 hour break in I put the inners back in and ran it all season on Bradd Penn 20-50 with no additives and was in great shape all year. This was a solid with .573/.594 lift at the valve.
tomthecomic - what kind of oil pressure did the engine have before you pulled it out and what kind of life are you looking to get out of it? If it had good oil pressure and it wasn't a special piece I'd be tempted to just run the thing. Not the "right" way, but depends on what your long term plans are for the engine. If you plan on running the snot out of it at the dragstrip with nitrous you better do it the right way
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