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Author Topic:   Rough Running
Wes
Journeyman

Posts: 20
From: Downey, CA
Registered: Mar 2002

posted 05-08-2002 06:29 PM     Click Here to See the Profile for Wes   Click Here to Email Wes     Edit/Delete Message   Reply w/Quote
Well I've been having trouble running ever since I rebuilt my carb. I switched to a non-EGR spacer cause my old one broke. I had a big vacuum leak at the back cause the gasket wasn't sealing the spacer on all the way. Well I got the right gasket, put it on and fired it up again to see that nothing has changed. It idles very rough and only smoothes out when I put my hand over the carb, but to much makes it die. Which is different from before (with the vacuum leak). I listened in with a hose anywhere there could be a vacuum leak and found nothing. What could it be? The car ran good before this change and the carb is the only thing that I touched. Could the floats be set wrong? I set them to what the directions told me. What should they be (wet)? Please help.

It's a '73 302 C4, w/motorcraft 2bbl carb

One other thing I did was cut and crimpped(sealed) off the hard line that goes from the choke to the exhaust manifold.

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1973 Ford Maverick 302 C4 55k original miles
Life revolves around Fast Fords, Good Beer, Loud Music, and Sexy Woman

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Wes
Journeyman

Posts: 20
From: Downey, CA
Registered: Mar 2002

posted 05-11-2002 04:55 PM     Click Here to See the Profile for Wes   Click Here to Email Wes     Edit/Delete Message   Reply w/Quote
Well I had the carb flow tested today and the pump was bad on it. The guy said that it could have happened when I had the vacuum leak on the manifold/spacer. Well after changing the fuel pump, spark plug wires, checking the points and checking for vacuum leaks its all the dang carburetors fault.

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1973 Ford Maverick 302 C4 55k original miles
Life revolves around Fast Fords, Good Beer, Loud Music, and Sexy Woman

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Wes
Journeyman

Posts: 20
From: Downey, CA
Registered: Mar 2002

posted 05-12-2002 07:25 PM     Click Here to See the Profile for Wes   Click Here to Email Wes     Edit/Delete Message   Reply w/Quote
Well it wasn't the carb either. I put it back on and it still is running rough. Its not firing on all eight. It only runs smooth when the temp is way up. I'm guessing it is the distributor.

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69maverick
Moderator

Posts: 1137
From: Thomaston,CT.
Registered: Jan 2001

posted 05-12-2002 10:39 PM     Click Here to See the Profile for 69maverick   Click Here to Email 69maverick     Edit/Delete Message   Reply w/Quote
Hi Wes I have read your post but its so had to pin point something like this without being there! THATS WHY I HAVEN'T SAID ANYTHING! Have you taken a compression test of each cylinder? The ruff running could be a bad valve, Or a bad lifter! Does it still smooth out when you choke it off with your hand? Have you tried spraying some carb cleaner around the carb and intake when its running ? This will find any leak in a real hurry!!

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Jim B. 70 Maverick Grabber clone 302,c4 auto
Weld RODLITES,Holley 600,performer intake,comp cam,MSD ignition,2.5 " pipes Candy apple blue metal flake!

[This message has been edited by 69maverick (edited 05-12-2002).]

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Wes
Journeyman

Posts: 20
From: Downey, CA
Registered: Mar 2002

posted 05-12-2002 10:51 PM     Click Here to See the Profile for Wes   Click Here to Email Wes     Edit/Delete Message   Reply w/Quote
I did check the compression. #1 @ 145, #2 @ 147, #3 @ 145, #4 @ 133, #5 @ 135, #6 @ 150, #7 @ 140, #8 @ 145. When I put my hand over the carb it wants to die. I also sprayed carb cleaner and listened in with a stethoscope everywhere and everything sounds good. It runs smooth when it gets real hot.

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1973 Ford Maverick 302 C4 55k original miles
Life revolves around Fast Fords, Good Beer, Loud Music, and Sexy Woman

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69maverick
Moderator

Posts: 1137
From: Thomaston,CT.
Registered: Jan 2001

posted 05-13-2002 02:10 PM     Click Here to See the Profile for 69maverick   Click Here to Email 69maverick     Edit/Delete Message   Reply w/Quote
If I had to guess I would bet you have a bad valve or two in the #4 & #5 cylinders! With the gas that we use today it tends to couse the valves to reciede into the head and this will couse a bad seal of the valve. This inturn will make the motor stumble when its cold. It might seal up as it gets warmer??
On the # 4 & #5 valves I would try backing off on the rockers just a little bit maybe a half turn or so just to see if it clears out at all!! My guess is its making it act as if you had a tight valve!! P.S. This is not a fix

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Wes
Journeyman

Posts: 20
From: Downey, CA
Registered: Mar 2002

posted 05-13-2002 04:13 PM     Click Here to See the Profile for Wes   Click Here to Email Wes     Edit/Delete Message   Reply w/Quote
That's what I was thinking too, but I didn't want to believe myself because I just wanted to keep the thing as it is. Basically I didn't want to get my hands any dirtier than they already have become. Having an old car again after 5 years I realize that that's impossible. Well I guess the time for me too put my 351W heads and RPM manifold, cam and other expensive goodies on my car came a little sooner than I thought. But before I go that far I found a shop that will hook my engine up to a scope for $35 bucks. It might be worth it if I could track down the problem and then just fix it so I can still keep it stock for now.

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1973 Ford Maverick 302 C4 55k original miles
Life revolves around Fast Fords, Good Beer, Loud Music, and Sexy Woman

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Bluegras
Journeyman

Posts: 58
From: Easton,Pa.
Registered: Nov 2001

posted 05-14-2002 12:31 PM     Click Here to See the Profile for Bluegras   Click Here to Email Bluegras     Edit/Delete Message   Reply w/Quote
Wes, a vacuum gauge can tell a lot about the condition of valves, rings, timing and intake leaks.

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69maverick
Moderator

Posts: 1137
From: Thomaston,CT.
Registered: Jan 2001

posted 05-14-2002 04:06 PM     Click Here to See the Profile for 69maverick   Click Here to Email 69maverick     Edit/Delete Message   Reply w/Quote
I second that!! I sometimes forget some of the little details!!

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Wes
Journeyman

Posts: 20
From: Downey, CA
Registered: Mar 2002

posted 05-24-2002 02:42 AM     Click Here to See the Profile for Wes   Click Here to Email Wes     Edit/Delete Message   Reply w/Quote
Okay here's a couple more questions for you guys. When hooking up the vacuum gauge I hook it to a line coming off the manifold, right? I did it using a gauge I found in the garage that had to be as old if not older that me (I'm 25). So I'm not sure if the gauge was bad or something was wrong with my engine vacuum. I set the timing right, I had the carb adjusted right, and it was still running amiss. Could my timing chain have a lot of slack in it. I'm sure it does. I've seen a motor with 5,000 miles on it have a semi-loose timing chain. If there is something wrong with a valve, lifter, or even the chain there's no way I'm putting that cast iron manifold back on. I don't what to break my back installing the dang thing. Besides I have an extra set of heads, RPM manifold, mild cam, and many other little mods from my other Ford hot rods over the years.
Also how does an engine scope work? (the ones the automotive shops use). Also could it tell me if I had a bad lifter or a bad valve? What I mean is could it pinpoint the problem?
Thanks for you help

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1973 Ford Maverick 302 C4 55k original miles
Life revolves around Fast Fords, Good Beer, Loud Music, and Sexy Woman

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Bluegras
Journeyman

Posts: 58
From: Easton,Pa.
Registered: Nov 2001

posted 05-27-2002 09:51 PM     Click Here to See the Profile for Bluegras   Click Here to Email Bluegras     Edit/Delete Message   Reply w/Quote
I think it was you on another board that had solved you problem using a vac gauge to tune the engine.

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Wes
Journeyman

Posts: 20
From: Downey, CA
Registered: Mar 2002

posted 05-27-2002 11:09 PM     Click Here to See the Profile for Wes   Click Here to Email Wes     Edit/Delete Message   Reply w/Quote
Yep that's right!! Runs okay now. All the years I've been playing with hot rods you'd think I would have used one of these gauges. Well I guess after 5 years of not having an old car to tinker with will do that too you.

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1973 Ford Maverick 302 C4 55k original miles
Life revolves around Fast Fords, Good Beer, Loud Music, and Sexy Woman

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69maverick
Moderator

Posts: 1137
From: Thomaston,CT.
Registered: Jan 2001

posted 05-28-2002 07:53 AM     Click Here to See the Profile for 69maverick   Click Here to Email 69maverick     Edit/Delete Message   Reply w/Quote
So Wes what was the problem?

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Wes
Journeyman

Posts: 20
From: Downey, CA
Registered: Mar 2002

posted 05-31-2002 01:15 AM     Click Here to See the Profile for Wes   Click Here to Email Wes     Edit/Delete Message   Reply w/Quote
She was running just waaaaaaay too lean. It runs smoother now. I still have a flat spot off the line and it hesitates going around turns? Now that I know how to use a vacuum gauge hopefully I can fix that also. It's running to lean on start up too, so I think I need to mess with the choke.

On a good note, I'm getting some nice cragar 5 star wheels that I'm going to buy myself for my birthday. Damn, I'm so nice to myself. One I get the film developed I'll post my before after (wheels) pictures.

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1973 Ford Maverick 302 C4 55k original miles
Life revolves around Fast Fords, Good Beer, Loud Music, and Sexy Woman

IP: Logged

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