ac model c engines problems

The Shmunk · Mar 5, 2016

Hello everyone. I have an old model c that was my grandpas.A few years ago i had to replace the head gasket and upon re-assembly i put the valve cover stud with the oil passage in the wrong hole and ran it that way, needless to say the valves were not getting any oil and the engine kept dyeing on me. Well i ended up figuring out that the stud was the problem. Now im getting plenty of oil to the head but it keeps dying when at wide open throttle. It almost sounds like its working against itself, my question is, where do i start? did i wreck the whole engine just because i deprived the head of oil? should i just look for a good used 125 out of a b or c? just asking what everyones opinion is. after i found out what the initial problem was i ran it till the mag puked,then replaced the 6volt system/mag with a 12volt distributor/mini ac delco one wire setup. any advice would be helpful. Thank you!

teddy52food · Mar 5, 2016

When you changed to 12 volts, did you add a resistor to the ign? Maybe the coil is getting too hot.

EricB · Mar 5, 2016

Sounds to me like your problem is fuel restriction. Without the engine running open the drain at the bottom of the carb and put a container to catch the gas, you need to have a generous flow even after a good half minute. Even with good flow the main jet can be plugged and make it cut out during full throttle running. Do a carb disassemble/cleaning...it can do wonders. Your engine is likely fine even after the lack of oil at the top for a while...don't be too hard on yourself. I've had the engine cut out at high rpm more than once and it's been fuel related every time.

The Shmunk · Mar 6, 2016

you know, im not sure. i learned this lesson last summer when my case garden tractor with the cast iron kohler was running the same way after i put the wrong non restisted coil on it. it ran the same way, like it was fighting itself (timing too advanced) at wide open throttle. I did think about weather i had the right coil on. i will check, Thank you

Dick L · Mar 6, 2016

My guess would be the EricB is correct. Open it wide open with a can of starting fluid in hand and when it starts to die out spray some down the breather or in the carburetor. If it is fuel related it will pick back up.
I like to do a few tests before jumping in. As much as I have always loved to take things apart I get upset with myself when I take the wrong thing apart. Which I have done more than I care to admit.

steve(ill) · Mar 6, 2016

if you do have the original 6 v coil, don't add the resistor.......... get rid of the coil and get one built for the 12 v system.

The Shmunk · Mar 7, 2016

I have a 12 volt coil on it, just dont know if it is internally resisted. it didnt have a coil on it before because it had a magneto.

wbecker · Mar 7, 2016

A 12V coil should be 3 ohms if it does not need a resistor.

ac model c engines problems

The Shmunk

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teddy52food

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EricB

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The Shmunk

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Dick L

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steve(ill)

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The Shmunk

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wbecker

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