302 not firing on cylinders 2 and 3

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Olilux
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Location: Luxembourg, Europe

302 not firing on cylinders 2 and 3

Post by Olilux » Sat Apr 20, 2019 9:24 am

Hi am puzzled...
I have a 1974 with 302 and Automatic.

My engine runs fine and smooth but is not firing on cyl 2 and 3 but check this:
1. Compression is over 120PSI on all cylinders.
2. Firing order checked a million times, time checked with marks all ok
3. All valves are opening (I opened the valve cover and just fine)
4. Replaced spark plugs, wires, distributor & rotor... no change
5. removed carburator (2100) replaced all caskets and heat shield (no change...)

It looks as if these cylinders are dry. I have nothing left than to remove the intake manifold and see if there could be an object blocking but blocking both??

Anyone with a clue?
U15GLU 1974 302- Limestone Green Metallic Automatic
Export car, bought new in Iceland
Frame up restoration

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Stan
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Re: 302 not firing on cylinders 2 and 3

Post by Stan » Sat Apr 20, 2019 4:24 pm

How did you determine that #2 and #3 aren't firing?
When you come to a fork in the road - take it
Homer - " Facts are meaningless . You could use facts to prove anything that's even remotely true."

Olilux
Bfix "What's a Bronco?"
Bfix "What's a Bronco?"
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Joined: Fri Jan 20, 2017 1:29 am
Location: Luxembourg, Europe

Re: 302 not firing on cylinders 2 and 3

Post by Olilux » Sun Apr 21, 2019 2:32 am

When engine is running, I unplug one one cylinder at the time on the distributor and normally you hear a change in tune. On 2 and 3 no difference when I unplug the wires.
U15GLU 1974 302- Limestone Green Metallic Automatic
Export car, bought new in Iceland
Frame up restoration

User avatar
Stan
BFix Locked and Loaded
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Posts: 3627
Joined: Tue Jun 29, 2004 6:42 pm
Location: Boring Or

Re: 302 not firing on cylinders 2 and 3

Post by Stan » Sun Apr 21, 2019 8:40 pm

I've had varying results with pulling spark plug wires one at a time. I find it better to connect a timing light to each plug wire and then see if it " lights up " . That will tell you if you're getting spark to that wire .
One thing to check is the spark plug wire where it connects to the spark plug connector . I've seen the "conductive" part of the wire disconnected from the plug connector so there is spark to the wire but no spark to the plug.
When you come to a fork in the road - take it
Homer - " Facts are meaningless . You could use facts to prove anything that's even remotely true."

Olilux
Bfix "What's a Bronco?"
Bfix "What's a Bronco?"
Posts: 9
Joined: Fri Jan 20, 2017 1:29 am
Location: Luxembourg, Europe

Re: 302 not firing on cylinders 2 and 3

Post by Olilux » Thu Apr 25, 2019 12:22 pm

Stan thanks for the feedback.
I never found out what it was really. I exchanged threads, spark plugs, distributor and rotor. Now all is working fine. Runs like a star.
U15GLU 1974 302- Limestone Green Metallic Automatic
Export car, bought new in Iceland
Frame up restoration

brncofan
BFix Starter
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Joined: Sun Jul 07, 2013 8:34 pm

Re: 302 not firing on cylinders 2 and 3

Post by brncofan » Tue Aug 20, 2019 12:17 am

Had the same issue and that was because of a bad spark plug wire.

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