Dozerman51 Posted March 25, 2011 Report Posted March 25, 2011 Hello All, I will be installing a 1958 Plymouth 230 head, casting #1676337-2 on my late 40's Dodge 230 block. Does anyone know what the thread size and pitch is of the hole where the temp. gauge nut screws into the head on my Dodge head? The hole on the Plymouth head is smaller. I believe it to be 1/4" pipe. Do they make an adapter that screws into the 1/4" hole on the Plymouth head then bushes up to the larger size I need to screw in my temp gauge to it? If not, I guess I will have to drill out and tap the smaller hole to whatever size the temp. tube nut is. Thanks for any advice. Quote
greg g Posted March 25, 2011 Report Posted March 25, 2011 The later car was set up for an electric idiot light. On mine (56)it was screwed into a stadart temp gauge gland nut. Can you post a pic of what your have? Quote
Dozerman51 Posted March 25, 2011 Author Report Posted March 25, 2011 Hi greg g, I don't know how to post pic's yet. You are right, the Plymouth head is drilled for an electric sending unit. My Dodge head looks like it is a 1/2" pipe thread, but I am not sure. All the Mopar heads were drilled using the same hole for the mechanical temp. gauge as far as I know until they went to the Idiot light set up in 1956. I'd rather not drill out and tap the hole, but I will if I have to. Quote
greg g Posted March 25, 2011 Report Posted March 25, 2011 You need to get the sensor bulb into the head, It won't through a 1/4 hole you sumtin gotta give. Where are your pics on your puter or o the web. If they are on your box, use the manage attachents tool and add as thumbnails, If they are on a service just copy their url to the box that pops up when you click on what looks like the postcard leaving off the Http: as its already there. then use the go advanced button at the bottom and hit preview post to see if the links is correct. Quote
Plymouthy Adams Posted March 25, 2011 Report Posted March 25, 2011 most big box auto parts stores have a selecion of fitting for this in the back..they do have adaptors..of course like Greg said the diameter of the bulb is a consideration..ask the guy at the counter to see the Stewart Warner selection of fittings..last oine I did I found the Stewart Warner line at my local NAPA Quote
Joe Flanagan Posted March 25, 2011 Report Posted March 25, 2011 I have a good-sized assortment of these things due to my adventures with my own temp gauge. Let me know what you need and if I have it I will send it to you. I've got several gland nuts, each with different sized internal threads. Quote
Joe Flanagan Posted March 25, 2011 Report Posted March 25, 2011 Just read your original post a little closer and see that what you need is likely smaller than what I have. You say it looks to be about 1/4"? Quote
Don Coatney Posted March 25, 2011 Report Posted March 25, 2011 Just read your original post a little closer and see that what you need is likely smaller than what I have. You say it looks to be about 1/4"? That is 1/4" IPS (Iron Pipe Size) size. The actual hole is a lot bigger. Follow this link. http://www.carbidedepot.com/formulas-tap-pipe.htm Quote
Merle Coggins Posted March 25, 2011 Report Posted March 25, 2011 That is 1/4" IPS (Iron Pipe Size) size. The actual hole is a lot bigger. Follow this link.http://www.carbidedepot.com/formulas-tap-pipe.htm That would be 1/4" NPT (National Pipe Thread or National Pipe Taper) Quote
Plymouthy Adams Posted March 25, 2011 Report Posted March 25, 2011 This stuff gets confusing very quick while the thread count and OD size stays the same..the intent of use makes the difference..see if the follow can shed a bit of light... Tapered Pipe Threads FIP, MIP, NPT A standard kind of thread used normally on Iron or Brass pipe and pipe fittings. For example: A 1/2" FIP thread fits standard 1/2" trade size Iron pipe (1/2" ID-7/8" OD). Same as 7/8"-14 NPT. Tapered pipe threads do not need a gasket or cone seal, but a thread sealant must be applied to the male threads only, before the joint is assembled. Use care to avoid getting sealant inside the pipe. Unlike straight threads, tapered thread joints seal better the more they are tightened, making them essential for leak free Iron Pipe joints. A female straight thread fitting or slip joint connection may be attached to a tapered male thread, as long as a gasket or seal is incorporated into the female fitting design. A thread sealant alone would not seal. In this case, a thread sealant may actually interfere with proper installation, causing the joint to to leak. Female tapered threads are not suitable for Faucet or Toilet Connections. Even if you use a thread sealant, a female tapered thread fitting will not seal if it is attached to a male straight thread like a faucet or toilet connection. Generally, do not mix Tapered with Straight Thread pipes and fittings unless special seals are provided. See: Straight Pipe Threads Quote
Don Coatney Posted March 25, 2011 Report Posted March 25, 2011 That would be 1/4" NPT (National Pipe Thread or National Pipe Taper) That would be 1/4" IPS. I am showing my age:rolleyes: Iron Pipe Size (IPS) refers to an old pipe sizing system still in use by some industries, including major PVC pipe manufacturers, as well as some legacy drawings and equipment. The iron pipe size standard came into being early in the 19th century and remained in effect until after World War II. The IPS system was primarily used in the US and the United Kingdom. In the 1920s, the Copper Tube Size (CTS) standard was combined with the IPS standard. During the IPS period, pipes were cast in halves and welded together, and pipes' dimensions were sized by reference to the outside diameters ("ODs") of the pipes [1] . The ODs under IPS were roughly as we know them today under the Ductile Iron Pipe Standard (DIPS) and Nominal Pipe Size (NPS) Standards, and some of the wall thicknesses were also retained with a different designator. In 1948, the DIPS came into effect, when greater control of a pipe's wall thickness was possible. CTS diameter always specifies the OD of a tube, where pipe diameter specifications only approximate the pipe ID for sizes of 12 inch or less, and STD wall thickness. The IPS number (reference to an OD) is the same as the NPS number, but the schedules were limited to Standard Wall (STD), Extra Strong, (XS) and Double Extra Strong (XXS). STD is identical to SCH 40 for NPS 1/8 to NPS 10, inclusive, and indicates .375" wall thickness for NPS 12 and larger. XS is identical to SCH 80 for NPS 1/8 to NPS 8, inclusive, and indicates .500" wall thickness for NPS 8 and larger. Different definitions exist for XXS, but it is generally thicker than schedule 160 Quote
Plymouthy Adams Posted March 25, 2011 Report Posted March 25, 2011 ..in the case of your guage gland nut..is not usually a standard pipe size so the adapter is needed..that is why all that stuff is in the guage kit... Quote
Merle Coggins Posted March 25, 2011 Report Posted March 25, 2011 Thanks for the history lesson Don. What really gets confussing is when you throw BSPT and BSPP into the mix. (British Standard Pipe Taper and British Standard Pipe Parallel) BSPT is very similar to NPT but is usually 1 or 2 thread count off. I have to work with these fittings on a regular basis. I also deal with hydraulic fittings in SAE, JIC, JIS, ORFS, Metric Straight Thread (why don't they get an acronym?) and DIN, as well as BSPP with an inverted seat. Trying to keep them all straight can be challanging. Merle Quote
Dodgeb4ya Posted March 25, 2011 Report Posted March 25, 2011 The plain simple answer is the thread size is 1/2" NPT. NPH National Pipe Thread. Bob Quote
Jerry Roberts Posted March 25, 2011 Report Posted March 25, 2011 You might call a couple of machine shops in your area to ask how much they would charge to drill and tap the hole to the larger size . They might be reasonable . Quote
Dozerman51 Posted March 25, 2011 Author Report Posted March 25, 2011 HI Guys, Thanks for all the advice you have given me. From this I can see that the best method will be to have a machine shop drill out the 1/4" NPT hole to 1/2" NPT hole and tap new threads. Guess they don't make fittings to bush out from 1/4" NPT to 1/2" NPT and still have temp gauge bulb fit. Again, thanks everyone. Don't hold it against me, but the head will be going on my Dodge 230 which is installed in my 41 Dodge Military WC-12 4X4. Quote
TodFitch Posted March 25, 2011 Report Posted March 25, 2011 HI Guys, Thanks for all the advice you have given me. From this I can see that the best method will be to have a machine shop drill out the 1/4" NPT hole to 1/2" NPT hole and tap new threads. Guess they don't make fittings to bush out from 1/4" NPT to 1/2" NPT and still have temp gauge bulb fit. Again, thanks everyone. Don't hold it against me, but the head will be going on my Dodge 230 which is installed in my 41 Dodge Military WC-12 4X4. I'm surprised that you have do to that. Seems like the assortment of bushing that came with the last "mechanical" temperature gauge I purchased at the local "bubble wrap" auto supply had one that worked on my 1933's head. And I was under the impression that all the L-6 engine heads had the same size bushings for the temperature sensor. Quote
Young Ed Posted March 25, 2011 Report Posted March 25, 2011 Tod the hole became significantly smaller when they switched to electrical sending units. Quote
oldodge41 Posted March 25, 2011 Report Posted March 25, 2011 When I replaced the 218 in my '41 with a 230 from a '48 the temp gauge bulb from the '41 was too large for the hole in the '48 head. I used the '41 head on the '48 block because of this. I did have an aftermarket gauge that worked on the '48 head but the original would not................Tim Quote
Dodgeb4ya Posted March 25, 2011 Report Posted March 25, 2011 The bulb also needs to protrude all the way into the head for proper temp readings. Also you should take the bushing you are going to use so the machinist can tap to fit for correct thread depth/fitting. Bob Quote
Don Coatney Posted March 25, 2011 Report Posted March 25, 2011 HI Guys, Thanks for all the advice you have given me. From this I can see that the best method will be to have a machine shop drill out the 1/4" NPT hole to 1/2" NPT hole and tap new threads. Guess they don't make fittings to bush out from 1/4" NPT to 1/2" NPT and still have temp gauge bulb fit. Again, thanks everyone. Don't hold it against me, but the head will be going on my Dodge 230 which is installed in my 41 Dodge Military WC-12 4X4. I, using my best memory, do not know of anyone ever having to have the head re-drilled to make a temperature gauge gland nut fit. Something is a-miss here. Quote
greg g Posted March 25, 2011 Report Posted March 25, 2011 Don my 56 motor had the electric sender screwed into a standard gland nut deal, Perhaps the later engines did away withthe gland nut and went ot a smaller tapped hole with the sender installed directly ito the head. Maybe the answer can be found on the ofrward look site. Quote
Dodgeb4ya Posted March 25, 2011 Report Posted March 25, 2011 (edited) 12 volt cars use a 1/4" NPT electric sender. No bushing reducer used. Edited March 26, 2011 by Dodgeb4ya Quote
greg g Posted March 26, 2011 Report Posted March 26, 2011 This looks like a n x230 engne # so late 50"s, this is what my 56 head looks like. Are you sure you ar not trying to install the sender into the taped hole forward of the sender that holds a bracket on some engines? Quote
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