Oil Pressure Sending Unit: Converting from Light to Gauge

[pontiacgp]

that's what I am asking. I don't know if the block is metric or sae

it's neither, it's npt

 

[TomDisab]

it's neither, it's npt

what is ntp?

 

[pontiacgp]

national pipe thread

 

[Texas82GP]

The threads in my block (350 SBC) were definitely NPT. Not metric. I think they were 1/4" NPT near the oil filter and I used a bushing to reduce it from 1/4" NPT to 1/8" NPT.

 

[Bonnewagon]

TomDisab- NPT is a tapered thread. As it engages the threads seal by an interference fit. You never want to force the fitting because it will break or strip for sure. Forget thread dope or Teflon tape. If the threads are sound they will seal. Lubrication helps but be careful you don't accidentally force the fitting.

 

[pontiacgp]

Mark, the problem is he has tapped the whole in the block with a 1/2" saw tap

 

[Bonnewagon]

Tom- did you "test" the threads with the tap- or did you chase the threads forcibly? If you re-tapped them to 1/2" straight threads there are a few options. You will need to start with a new NPT fitting and GENTLY insert it. Maybe it will take. If not you can try it again with another new one but this time use some epoxy on the threads. GENTLY insert it and let the epoxy cure. But if the threads are totally not working then you can try epoxying in a straight thread fitting. The epoxy will make the seal. Of course that will mean the fitting is in there semi-permanently so be sure it is what you want. Or perhaps it would be best to put a pipe plug in and use another location?

 

[pontiacgp]

TomDisab....I think I found the fix, page F13 under F50G

https://www.parker.com/literature/Tube Fittings Division/Pipe_Fittings_&_Port_Adapters.pdf

 

[pontiacgp]

could you tell me what size brass fittings you used to convert. I am swapping out my sending unit on my SS and the bushing seems to be stripped out. I went out and bought another 1/2" brass fitting but the same thing happened. I checked the block with a 1/2" tap before I installed the new brass bushing and it was fine but when I installed the bushing it stripped out. Is the block side metric and the sender side SAE??

where did ya go?.....there is a few of us who are trying to help you out

 

[Bonnewagon]

Hey Steve- great link. I use a Racor fuel filter system on my boat made byParker-Hanniflin. Top notch USA stuff!!! Um, maybe the OP is actually out wrenching rather than typing?