The Ford Barn

rbone · 05-11-2020, 06:40 PM

Need a little help here. Motor is 59ab, new Skip coil and distributor, new FA54 condenser. New plugs.

Motor is running very rough, especially at idle. Compression is between 85 and 90 pounds on all 8 cylinders. Getting ready to do a cylinder leak down test.

With the motor running, I pulled the plug wires off one at a time. This is where it gets interesting. Cylinders 1, 4, 6, and 7 are not firing. When I put my spark tester between those particular plug wires and the plugs, it has a big spark and I can hear the spark jumping as I lower the plug wire back on the plug. Interesting that is is every other cylinder in the firing order.

Thoughts?

40 Deluxe · 05-11-2020, 06:47 PM

Quote:

Originally Posted by rbone

Need a little help here. Motor is 59ab, new Skip coil and distributor, new FA54 condenser. New plugs.

Motor is running very rough, especially at idle. Compression is between 85 and 90 pounds on all 8 cylinders. Getting ready to do a cylinder leak down test.

With the motor running, I pulled the plug wires off one at a time. This is where it gets interesting. Cylinders 1, 4, 6, and 7 are not firing. When I put my spark tester between those particular plug wires and the plugs, it has a big spark and I can hear the spark jumping as I lower the plug wire back on the plug. Interesting that is is every other cylinder in the firing order.

Thoughts?

Jets/idle passages are clogged on one side of carb. One side of carb feeds the end two cylinders of one bank and the middle two cylinders on the other bank. Learned this the hard way almost 60 years ago. Thought I had cleaned the carb but had to take it back apart and run tag wire through the passages. Then it ran great.

flatjack9 · 05-11-2020, 07:21 PM

Yup, carburetor problem.

rbone · 05-11-2020, 07:47 PM

No way I could be that lucky. I will take it apart tomorrow and give her a good cleaning. Carb is a Holley/Ford 94.

flatheadmurre · 05-11-2020, 11:40 PM

Or intake heater has corroded and leaks exhaust gas into that runner...been there done that...almost drove me nuts since it ran open throttle but not with exhaust mix on idle...

rbone · 05-12-2020, 09:40 PM

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Thanks fellas! She purring like a kitten now.

Phil Gillespie · 05-12-2020, 09:57 PM

Quote:

Originally Posted by rbone

Thanks fellas! She purring like a kitten now.

So was it a carb problem? Useful for others if info supplied to fix problems.
Phil NZ

rbone · 05-13-2020, 10:19 AM

Yes, it was a carburetor problem. One of the small, brass idle tubes was clogged.

Mart · 05-13-2020, 10:40 AM

Glad you found the issue. It's always worth remembering how the cylinders are arranged and what can affect what.

For what it is worth, I had a similar problem once when starting after sitting idle for quite a while. In my case, it was the distributor having the identical effect. What? you say? That's impossible! Not if it is a Lucas industrial unit. If one set of points goes down, the other set work but with a screwed up dwell, and four cylinders (1,4,6,7 or 2,3,5,8) get nothing.

I also had it happen on my coupe but when trying to drive along. It was the carb, but this time some shred of sediment had lodged in one of the main jets. It idled ok.

Mart.

05-11-2020, 06:40 PM	#1
rbone Member Join Date: Mar 2016 Location: Frisco, TX Posts: 95	Interesting- missing on every other cylinder Need a little help here. Motor is 59ab, new Skip coil and distributor, new FA54 condenser. New plugs. Motor is running very rough, especially at idle. Compression is between 85 and 90 pounds on all 8 cylinders. Getting ready to do a cylinder leak down test. With the motor running, I pulled the plug wires off one at a time. This is where it gets interesting. Cylinders 1, 4, 6, and 7 are not firing. When I put my spark tester between those particular plug wires and the plugs, it has a big spark and I can hear the spark jumping as I lower the plug wire back on the plug. Interesting that is is every other cylinder in the firing order. Thoughts?

05-11-2020, 07:21 PM	#3
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: Interesting- missing on every other cylinder Yup, carburetor problem.

05-11-2020, 07:47 PM	#4
rbone Member Join Date: Mar 2016 Location: Frisco, TX Posts: 95	Re: Interesting- missing on every other cylinder No way I could be that lucky. I will take it apart tomorrow and give her a good cleaning. Carb is a Holley/Ford 94.

05-11-2020, 11:40 PM	#5
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Interesting- missing on every other cylinder Or intake heater has corroded and leaks exhaust gas into that runner...been there done that...almost drove me nuts since it ran open throttle but not with exhaust mix on idle...

05-12-2020, 09:40 PM	#6
rbone Member Join Date: Mar 2016 Location: Frisco, TX Posts: 95	Re: Interesting- missing on every other cylinder Sponsored Links (Register now to hide all advertisements) Thanks fellas! She purring like a kitten now.

05-13-2020, 10:19 AM	#8
rbone Member Join Date: Mar 2016 Location: Frisco, TX Posts: 95	Re: Interesting- missing on every other cylinder Yes, it was a carburetor problem. One of the small, brass idle tubes was clogged.

05-13-2020, 10:40 AM	#9
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 8,750	Re: Interesting- missing on every other cylinder Glad you found the issue. It's always worth remembering how the cylinders are arranged and what can affect what. For what it is worth, I had a similar problem once when starting after sitting idle for quite a while. In my case, it was the distributor having the identical effect. What? you say? That's impossible! Not if it is a Lucas industrial unit. If one set of points goes down, the other set work but with a screwed up dwell, and four cylinders (1,4,6,7 or 2,3,5,8) get nothing. I also had it happen on my coupe but when trying to drive along. It was the carb, but this time some shred of sediment had lodged in one of the main jets. It idled ok. Mart.