No fire to 3 and 4

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Model T Ford Forum: Forum 2018: No fire to 3 and 4
Top of pagePrevious messageNext messageBottom of page Link to this message  By Charles Strong on Friday, January 26, 2018 - 02:50 pm:

My new speedster doesn't appear to be getting fire to #3 and #4 cylinders. When I ground the plug wires to the head with a screwdriver I get good spark from all 4 plug wires, but there's no discernable difference in engine rpm when I ground 3 or 4. Both 1 and 2 show marked rpm reduction when I ground them. Upon removing the plugs 3 and 4 look as though there's no combustion taking place--squeaky clean. I've swapped plugs from 3 and 4 to 1 and 2--3 without any change in result. I've changed plug wires. I'm running new Champion X's, but the result is the same with new Champion 25's.
Any suggestions appreciated. Thanks.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Will Copeland - West Melbourne Florida on Friday, January 26, 2018 - 03:03 pm:

The coil box is the root of all evil, Try swamping the coils around and see what happens


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Friday, January 26, 2018 - 03:04 pm:

Do a compression test.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Rogers - South of the Adirondacks NY on Friday, January 26, 2018 - 03:08 pm:

Frank nailed it. According to your post you ARE getting fire to 3 & 4. Do a compression test- should be around 55 PSI. If not pull the head and I'll bet you find trouble with the valves...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, January 26, 2018 - 05:02 pm:

Could be the head gasket. One very common place for a gasket to blow is between two cylinders. Either between 1 and 2 or 3 and 4. The gasket is very thin in that location and you would lose compression in both cylinders if that were to happen.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charles Strong on Friday, January 26, 2018 - 05:04 pm:

Thanks. Will report back.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charles Strong on Friday, January 26, 2018 - 06:35 pm:

It was a defective gland ring in the rear intake port. Thanks to everyone for your help.


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