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4v Cleveland tune up question.
#1
My '73 Mach-1 currently has a 4v Cleveland with a cam, victor intake (I hate), and the original points distributer. Recently, I was driving on the freeway and I noticed some "popping" from the exhaust. I've also noticed it seems to be down on power overall. Im planning on an oil change, plugs, wires, and cap and rotor. I don't have the funds for the Petronix like I had wanted. How good actually is the points and how do I know if that is the issue?
As for 4v open chamber heads, I have heard that they are prone to detonation. Should I use a colder spark plug? I believe I am right at about 10:1 compression. Thanks in advance.
Mike
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#2
You're not at 10:1 compression unless the pistons or heads were swapped. They were 8:1.

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
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#3
Properly adjusted points are OK for a street car. However, they have to be adjusted frequently and the cam cleaned and lubed. As the gap changes (narrows), due to wear of the rubbing block, the timing also changes (retards).



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#4
Give it a quick vacuum test too...Make sure something else is not going on inside "loss of compression or rounded off cam"
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#5
According to the guy I bought my car from, the engine had been rebuilt. It was originally a 2v motor. It was rebuilt with forged pistons, 4v heads, a cam and the victor intake. It just recently started the "popping" when I get on it on the freeway. Thanks everyone.
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#6
Casper... I have a 73 q code and had similar issues on occasion. Turned out to be my fuel filter, $4.99 at advance auto and it was good to go. I always seen to think its a big problem first, driving a 40 year old car will do that to you, but I over look the simple, easy fixes. Good luck...

Sent from my SCH-I535 using Tapatalk

(01-06-2014, 11:02 PM)Don C Wrote: Properly adjusted points are OK for a street car. However, they have to be adjusted frequently and the cam cleaned and lubed. As the gap changes (narrows), due to wear of the rubbing block, the timing also changes (retards).




(01-06-2014, 07:42 PM)cazsper Wrote: My '73 Mach-1 currently has a 4v Cleveland with a cam, victor intake (I hate), and the original points distributer. Recently, I was driving on the freeway and I noticed some "popping" from the exhaust. I've also noticed it seems to be down on power overall. Im planning on an oil change, plugs, wires, and cap and rotor. I don't have the funds for the Petronix like I had wanted. How good actually is the points and how do I know if that is the issue?
As for 4v open chamber heads, I have heard that they are prone to detonation. Should I use a colder spark plug? I believe I am right at about 10:1 compression. Thanks in advance.
Mike




(01-07-2014, 06:38 AM)73StangCoupe Wrote: Cazsper... I have a 73 q code and had similar issues on occasion. Turned out to be my fuel filter, $4.99 at advance auto and it was good to go. I always seen to think its a big problem first, driving a 40 year old car will do that to you, but I over look the simple, easy fixes. Good luck...

Sent from my SCH-I535 using Tapatalk



Sent from my SCH-I535 using Tapatalk

[Image: 1_24_09_13_4_29_06.png]
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#7
Honestly, I never thought of that. Thanks..
Mike
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#8
could be a bad tank of gas also.
in the winter more water gets into the underground tanks from melt water.

if changing the filter does nothing try dumping some octane booster in the tank and keep an eye on things. if the next couple of fuel ups have the engine keep popping then you want to look at other clogs inside the carb or ignition issues.

since you have points they can drift wildly.

you want to throw a timing light on and check initial timing that it has not moved. then use a dwell meter and check the points gap making sure it is still in spec.

next wouldn't hurt to check the ignition wires make sure nothing is loose and you have good contact at the plugs, coil, distributor cap.

if the poping is happening at higher rpms, then it could be a problem with the spring on the points, it get weak and then the points start bouncing at higher rpms and cause miss fire.

Accel made a heavy duty points replacement with a double spring and larger contact point to help keep the points going longer between adjustments. it was suppose to be for racing but worked better on a street car when all the made in china points junk took over the market.
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#9
cazsper;160811 Wrote:I don't have the funds for the Petronix like I had wanted. How good actually is the points and how do I know if that is the issue?

Mike

You could always go to duraspark. I'm a big fan of stock parts upgrading.
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#10
+ 1 with 72HCODE with his response! What type of gas are you running? It also would not hurt to have a vaccum gage connected to measure your vaccum when adjusting your carb and timing settings.

mustang7173
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