[70RAlll]

I had this same problem years ago. Bought one from Electric Limited or H&H..can't recallw ho it was, and it was still wrong.. The difference is "with guage package" cars(TA"s and Formy's) have a different sender. Most repo senders just use the more common dumb light sender which reads wrong. Maybe the repo's are correct now.. But there is no "calibration" with these, they are not adjustable. Either they aremade correctly or not. Look at one, you will see...there is no way to open it up and change things out.. I suggest finding a used one on Ebay or finding a NOS one.. I bought numerous NOS ones for $75 or so.. I think I have 3-4 now, just to make sure I will never go through that again.. Maybe the repo's have changed the resistence, but yea ago they had it wrong.. Just my opinion and experience..Not trying to bash one company over another..

[njsteve]

Anyone know the correct part number for the original sender?

[njsteve]

Well, I bought one of the $25 Lectric Limited senders, installed it in the cyl head in the factory spot and it reads 25 degrees higher than the radiator water temperature measured with an accurate thermometer dipped into the coolant.

So much for the accurately calibrated reproductions.

On another site one of the guys opined that that the cylinder head mounted temp sensor will give a higher temp reading than the block location. This may be true, but that doesn't explain the accuracy of the original factory senders. Were they undercalibrated to compensate for higher cyl head temps?

[70RAlll]

Originally Posted by njsteve

Well, I bought one of the $25 Lectric Limited senders, installed it in the cyl head in the factory spot and it reads 25 degrees higher than the radiator water temperature measured with an accurate thermometer dipped into the coolant.

So much for the accurately calibrated reproductions.

On another site one of the guys opined that that the cylinder head mounted temp sensor will give a higher temp reading than the block location. This may be true, but that doesn't explain the accuracy of the original factory senders. Were they undercalibrated to compensate for higher cyl head temps?

Steve-

I hate to say it...but you know what is comming.,.."I told you so"... I tried one of these "calibrated" senders and same result. We must remember, the "guage" option was just that, an option. Our cars sold in way lower numbers vs total FB sales in any of the 70-73 ,model years. So , these manufacturers, are looking at the spec's for the majority of sales and calibrate to that. This is my opinion why they all have it wrong..

Steve, I told you that buying an original used one or an original NOS unit was the only way to go.. Now, with shipping, tax etc.. you are probably out another $40 or so.. This needs to be a constant thread on our board warning others not to waste the money. I will be suprised if the sender is returnable.. ANyway, shoot me an emaiul and I will find the NOS and used ones I have. Hopefully I have an extra used one. I seriously doubt I am letting go of the nOS units I have..

[njsteve]

No problem. It was around $30 so I figured I would be the guinea pig so nobody else would have to waste their money on an inaccurate sender. It's the least I can do for the site - in my role as official dubiously accurate parts tester.

I sent you a PM. A used original would be fine if you have one.

[Norwood]

Originally Posted by njsteve

Anyone know the correct part number for the original sender?

Best I can figure group 1.150 pn 6490384

[317th FMS]

APT instruments knows about this problem. I got the correct sender from them. It was NOS GM but had a threaded post instead of the spade button type. I cut the spade part off another and drilled and tapped it and screwed it on the threads. Looks original now and hope this makes sense and is understandable. If I knew how to post a pic on here I would. Chad