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Landon S

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Long story but I'll try to keep it short. I bought a 66 tempest custom was supposed to run just needed a new coil, ended up needing a timing set. Ran fine after that for a bit then ate a cam lobe. I contacted melling they suggested a larger than factory cam, had to go to poly locks to get the valve lash correct. But it still runs poor. Its got new plugs, wires, coil, distributor. Rebuilt carb. Is the cam they suggested to big?
 

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melsg5

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Makes no sense to install that cam in an engine that I assume has small valve heads and a 2bbl carburetor and probably a two speed automatic. If my assum[tiom is wrong please provide full details on engine and type of transmission and rear end gearing.
 

Landon S

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Makes no sense to install that cam in an engine that I assume has small valve heads and a 2bbl carburetor and probably a two speed automatic. If my assum[tiom is wrong please provide full details on engine and type of transmission and rear end gearing.
Had a 2 bbl swapped to 4. Still 2 speed trans. Someone before me swapped rear with a 411
 

melsg5

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when you installed the cam why couldnt you just tighten the rocker arm nuts to 20 fot/lbs torque? Did you install non factory rocker arm studs?
what exactly is wrong with how the engine is running?
did you do a compression test?
is the distributor stock/unmodified? you replaced it with what?
what carburetor is on the car?
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Landon S

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I used the original nuts in the beginning but when tightened up they held down on the valves.
I just used locking nuts on factory pressed in studs.
It idles fine just choppy but lost a lot of low end power. Have to idle it up to 1100rpm so when it's in gear it'll stay running.
Compression test all showed around 140.
Stock new distributor from rock auto.
I think edelbrock 650. Not 100 percent sure.
 

melsg5

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With the engine running, if you hold your hand partially over the primary side of the carburetor, does the idle speed increase. If it does you have a vacuum leak.
When you installed the distributor, did you set the point dwell angle to 30 degrees and than set the timing to 6 degrees?
If you are running premium gas, have you tried advancing the timing to 9 degrees?
You are setting the timing with the vacuum advance hose on the distributor disconnected?
 

melsg5

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Another question after I did some more research. You mentioned press in rocker studs and apparently 66 was the last year they used them before going to screw in studs. So with the poly locks how did you go about adjusting the valves? Running engine and listened for valve clatter or did it cold by turning the engine every 180 degrees and adjusting 4 at a time or some other method?
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Landon S

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OK, let us know the answers to the other questions in post #6.
Had a mechanic buddy come check the timing I had him put it at 6 degrees. But he had no idea on the dwell, just never sees it. Timed with vac line attached. Runs better, was able to idle it back to 900 so it'll idle in gear.
 

cammerjeff

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6 degrees with the Vacuum advance connected? Do you know if the Vacuum advance is hooked up to Ported (above the carb Butterfly plates) or Manifold Vacuum (below the Throttle Plate)? I usually run it to manifold vacuum and time it 6-8 BTDC with the Vacuum advance line disconnected & plugged.
 

melsg5

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You do not set initial timing with the vacuum line connected just in case you have it connected to a port that is creating vacuum. You also need to set the dwell angle before setting the timing. No disrespect to your buddy but he does not seem to be familiar with pre-computer/pre-fuel injection cars. If you intend to keep the car you need a dwell meter and a timing light, preferably one with a dial back function. If you have a Harbor Freight near by or online they have a hand held Cen-Tech automotive meter that has dwell, rpm, AC and DC voltage, ohms, etc.
 

Landon S

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I'll order that. How exactly do you set the dwell.
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melsg5

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Your distributor should have a small stamped metal window in the side of the distributor cap. The window should reveal the adjusting screw on the ignition points. There is a tool, sort of like a long screwdriver but the shaft is flexible and has the correct allen head shape on the end to fit into the head of the points adjusting screw. You connect the red lead of your meter to the negative post of the ignition coil and the black lead to any metal part of the engine as a ground. Set the meter to dwell and turn on the engine. You are trying to get a reading of 30 degrees on the meter. While turning the points adjusting tool watch the meter. The link below shows you what the tool looks like and maybe a local store still has them. If you have to adjust the points it will be necessary to readjust the timing.
 
I always like to hook up a vacuum gauge to the place where I removed the vacuum advance. That way I can also adjust the idle mixture screws at the base of the carb to get the highest vacuum reading.

I like to adjust dwell first, timing second, vacuum adjustment using the carb idle mixture screws third, and when I reconnect the distributor vacuum advance I make the final adjustment to the carb idle speed stop. My old Sun dwell meter also has an induction connection to go over a spark plug wire, so you can switch from dwell to engine rpm on the meter.

Harbor Freight Tools sells the Cen-tech 95670 to measure dwell and engine rpm. If I had to buy a new meter, that would be the one I would buy. I usually can find a 20 percent off coupon in the Wednesday junk mail.
 

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melsg5

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that's the same unit I have, good for checking things in the house too since it will work with AC high voltages.
 
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