Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties prime cocks

prime cocks

Post Sat Oct 16, 1999 3:16 pm
don User avatar

Posts: 575
Location: Spokane WA USA
Would someone who knows explain the usage of
prime cocks.
I know the '36 VLH iron head had them or they
were optional, and the boss for them was left in the casting of later heads.
Was this purely a cold start aid?
Any truth to start it on alcohol run it on kerosine?
I don't see this topic discussed any place, except for apparently their were two different styles of valve heads.
thanks, don

Post Mon Oct 18, 1999 10:45 pm

Posts: 582
Location: meridian, id. usa
they where used primarily for cold weather starts. came with a little squirt gun to shoot hi test into the cylinders. Just recently aquired a 37 wl motor that still had the cups attached. Dont know the octane rateing on kerosene but since it is closer to diesal then it is to gasoline, doubt that u would use that. but kerosene was a recomended thinner for oil in cold weather as well as diesal. also to clean out the oil bagg. when the octane rating went up on gasoline due to the addition of tetra-ethyl lead and better cracking processes plus the higher compression-combustion ratio in the the motors starting in 38 the need for frigid weather start aids went away except maybe for police dept's or the military. i havent seen them all but all that i have seen except for this one wl motor just had the boss on the head or a plug where the boss had been tapped and drilled. early knuckleheads i have are tapped and plugged. which leads me to believe that the fatory may have belived them a nessasary addition in the beginning but found out later that it was an added expence that they didnt need to bother with due to the change from flathead to OHV.
Ronson Lighter fluid always worked for me when it got down to almost to cold to ride weather. couple squirts down the intake or pull the plugs and clika clika, put the plugs back in and whoosh light it up. dont peer down the carb when ya do it unless ya like the smell of burnt hair eyebrows

[This message has been edited by dotman (edited 18 October 1999).]

[This message has been edited by dotman (edited 18 October 1999).]

Post Tue Oct 19, 1999 1:06 am

Posts: 1038
Location: Ojo Caliente,NM,USA
Never herd of running a Hardley on kerosene but my dad had a G model John Deere that started on gasoline or alcohol and ran on kerosene after it warmed up. He said that this was a popular option during the depresion. So maybe?

Post Tue Oct 19, 1999 2:53 am
don User avatar

Posts: 575
Location: Spokane WA USA
The only top end I own that has prime cocks
is a '36 VLH, now I purchased these from Leonard Andres, and believe I asked him about
the prime cocks at the time, and thats where
I got "start them on alcohol run them on kerosine" so their may be truth in this.

Post Wed Oct 20, 1999 12:42 pm

Posts: 136
Location: oxford, NC USA

When we were kids and stone broke, and wanted to go somewhere, we used to put just enough gas in the car to start it and get it hot. Then we'd fill the tank with kero.: .07 per gal. instead of .30. We'd never shut it off until it ran dry, then start the procedure over again. Often had to clean the plugs to get it to fire.

Worked on Flathead Fords, why not Harleys?


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