The Ford Barn

hotrodmano · 04-27-2018, 01:50 AM

I have a 24 bolt 38/39 Flatty in my traditional 29 Roadster and the temp sender outlets are blocked off with a bolt. What sender/cable should I buy and where to get it? And do I need on both sides or is it sufficient with one side only?
Same goes for oil pressure.
Im pretty New to flatheads so pardon my rookie questions

tubman · 04-27-2018, 02:34 AM

There are many mechanical gauge setups available online and even at your FLAPS that come with the proper adapters to install the sender directly into your engine. Typically, when you open the package, you will find two or three thread adapters for just about any size sender openings. As an example, I bought a set of Sun-Pro gauges on close-out from Summit Racing (including temperature and oil pressure) to install on my engine test stand. So far, I have had an early hemi and two different flatheads on it and there were adapters that came with the gauges that allowed me easily connect the gauges to all of them. The only thing that may be a problem for you is if they actually used bolts to plug the sender openings. The sender openings are NPT (tapered) threads, and if actual bolts were used to plug them, they would probably have had to have been over-tightened to keep them from leaking. This may have damaged the threads in the openings for the gauges. Hopefully, they used the proper pipe plugs to close these off.

Talkwrench · 04-27-2018, 04:48 AM

Should be 3/8 NPT for the temp in the heads, the flathead has two seperate sides for cooling so one in each is advisable . The sender for the oil should go where the original sender is , you can probably use a T section and go from there that size someone might confirm ?.

tubman · 04-27-2018, 08:20 AM

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The oil pressure ports on a flathead are 1/8" pipe thread. Any auto parts or hardware store will have a sufficient selection of items that will allow you to plumb in an oil gauge. There are nipples, tees, unions and adapters of all sorts. Since you don't have an existing oil pressure gauge, you should be able to connect one directly to the opening at the rear of the block (where the filter is connected if there is one). There should be sufficient fittings with the gauge to allow you to do this. If there already is a sender and you want to retain it, then you will need a nipple (the length will depend on your situation) and a tee.

"Talkwrench" has a good idea on using a separate temperature gauge for each cylinder bank.

04-27-2018, 01:50 AM	#1
hotrodmano Junior Member Join Date: Mar 2017 Location: Klokkarstua, Norway Posts: 4	1939 Flathead temp and oil pressure question I have a 24 bolt 38/39 Flatty in my traditional 29 Roadster and the temp sender outlets are blocked off with a bolt. What sender/cable should I buy and where to get it? And do I need on both sides or is it sufficient with one side only? Same goes for oil pressure. Im pretty New to flatheads so pardon my rookie questions

04-27-2018, 02:34 AM	#2
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,320	Re: 1939 Flathead temp and oil pressure question There are many mechanical gauge setups available online and even at your FLAPS that come with the proper adapters to install the sender directly into your engine. Typically, when you open the package, you will find two or three thread adapters for just about any size sender openings. As an example, I bought a set of Sun-Pro gauges on close-out from Summit Racing (including temperature and oil pressure) to install on my engine test stand. So far, I have had an early hemi and two different flatheads on it and there were adapters that came with the gauges that allowed me easily connect the gauges to all of them. The only thing that may be a problem for you is if they actually used bolts to plug the sender openings. The sender openings are NPT (tapered) threads, and if actual bolts were used to plug them, they would probably have had to have been over-tightened to keep them from leaking. This may have damaged the threads in the openings for the gauges. Hopefully, they used the proper pipe plugs to close these off.

04-27-2018, 04:48 AM	#3
Talkwrench Senior Member Join Date: Aug 2012 Location: Perth, Western Australia Posts: 2,687	Re: 1939 Flathead temp and oil pressure question Should be 3/8 NPT for the temp in the heads, the flathead has two seperate sides for cooling so one in each is advisable . The sender for the oil should go where the original sender is , you can probably use a T section and go from there that size someone might confirm ?. __________________ *"Came too close to dying to stop living now!"*

04-27-2018, 08:20 AM	#4
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,320	Re: 1939 Flathead temp and oil pressure question Sponsored Links (Register now to hide all advertisements) The oil pressure ports on a flathead are 1/8" pipe thread. Any auto parts or hardware store will have a sufficient selection of items that will allow you to plumb in an oil gauge. There are nipples, tees, unions and adapters of all sorts. Since you don't have an existing oil pressure gauge, you should be able to connect one directly to the opening at the rear of the block (where the filter is connected if there is one). There should be sufficient fittings with the gauge to allow you to do this. If there already is a sender and you want to retain it, then you will need a nipple (the length will depend on your situation) and a tee. "Talkwrench" has a good idea on using a separate temperature gauge for each cylinder bank.