Hitman's Pontiac Trans Am Forum
Trans Am Information => Restoration => Topic started by: Wallington on April 08, 2012, 09:48:21 AM
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This is a common problem that comes up for anyone trying to piece together a 350 or 403 in an F-body, the original loop-bracket holder that supports the smaller original oil pressure senders. Of course, no one makes them this size now, been searching for years and chasing leads that went nowhere of the 1-1/2" bodied senders. The only type available these days is the standard 1-3/4" body which doesn't fit into the original loop bracket. This is why many are long disappeared; replace sender unit, bracket doesn't fit anymore, chuck it.
But the problem doesn't finish there, the newer oil units also have a much longer threaded stalk which pushes the completed setup beyond the mounting hole in the block. Even if the bracket fit over the unit, it wouldn't be able to slide along enough to locate.
Not the best angle, but here's an early shot showing standard length tube. The large rib around the body of the sender is right about the bracket hole, far too long:
(http://i72.photobucket.com/albums/i195/Aus78Formula/403oilpressuresenderlinechecks7_11.jpg)
I had an assortment of original extension tubes in worn and damaged condition so decided to source the repro tube by Inline tube. Of course, this turned out to be slightly longer than stock, making the problem worse. I eventually ordered another, a spare as I wanted to modify one. It was also a touch longer than original, but again had slightly different angled bends to original. Neither of the repros would have been a bolt-on fit without adjusting the angles regardless.
So this is what I did. I wanted to both support the new, larger-bodied sender unit but also keep the original appearance. I needed to shorten the tube by approx. 20mm but taking the end flare into account shortened it by 15mm. It turns out I could have gone 10mm as I lost another 5mm just when tightening the threads up along the length, but still fine.
To reflare the end I had to straighten it, not easy in stainless, and rebend without kinking once done. As usual I had mine perfect but decided to go just a touch more when it creased the wall a little. I managed to smooth most of it out, but out of sight when fitted anyway.
Here's the repro tube and the shortened and rebent tube below:
(http://i72.photobucket.com/albums/i195/Aus78Formula/Oilpressuresendertubestockvsmodified.jpg)
I also cut up some 1-3/4" pipe to suit from some old exhaust stock and cut the wall through. I also made some small angled tabs, bolted through to allow easy placement when tig-welding them on. You can see the diameter difference here between original bracket and what was actually required, yet to be welded on:
(http://i72.photobucket.com/albums/i195/Aus78Formula/Oilsenderbracketsstockandlarger.jpg)
And all installed. It is clear of the oil filler but not much, not that it can move either. An extra 5mm longer would have been better, but any longer and the other end starts to foul the fuel line. Does the job though, and looks original for those who don't know otherwise!
(http://i72.photobucket.com/albums/i195/Aus78Formula/403modifiedoilpressuresendersetup4.jpg)
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Very nice!
Thanks for sharing
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looks fantastic.
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Great info. Thanks for posting. You do awesome work! ;)
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Older thread, had some pics of used original sender unit that may assist. The finish is not accurate as appears to have been cleaned up with blasting.
(https://farm2.staticflickr.com/1771/43038634954_e1f9347353_b.jpg) (https://flic.kr/p/28zbfJf)403 Firebird oil sender and bracket 3 80psi (https://flic.kr/p/28zbfJf) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
(https://farm2.staticflickr.com/1795/29883605698_0498bf0a43_b.jpg) (https://flic.kr/p/MwHhR1)403 Firebird oil sender and bracket 2 (https://flic.kr/p/MwHhR1) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
(https://farm2.staticflickr.com/1780/43038635294_7ac4171cf6_b.jpg) (https://flic.kr/p/28zbfQ7)403 Firebird oil sender and bracket 1 (https://flic.kr/p/28zbfQ7) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
(https://farm2.staticflickr.com/1799/43038635654_cdff224844_b.jpg) (https://flic.kr/p/28zbfWj)403 Firebird oil sender and bracket 4 (https://flic.kr/p/28zbfWj) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
(https://farm1.staticflickr.com/937/43038635674_f668973450_b.jpg) (https://flic.kr/p/28zbfWE)403 Firebird oil sender and bracket 5 (https://flic.kr/p/28zbfWE) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
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Nobody making these yet?
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Great job!
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Nobody making these yet?
What they make is incompatible with original or reproduction parts. It will work, but since none are correct and the parts required to use them are not available, the retainer size and location are affected so they also can't be used without mods. The original small oil pressure sender is not available, even the NOS items with the same part number are the larger replacement. An incorrect larger sender will require the retainer tossed or opened up to fit. Most senders are now longer in that threaded area so often would also make the bracket not an option as it can no longer line up. The repro extension tube is also far too long and makes the issue far worse again. There's no combination that simply fits. Yet, they happily sell them all day long.
I previously had a custom made loop bracket from exhaust pipe and tabs. But my ever growing collection of modified original brackets saw me open one of them up and then replate, even though originally blackened. Does the job. Gives you an idea of how much larger the regular senders are with the crush tube added. The bolt needs to be swapped with a longer thread than original too.
(https://live.staticflickr.com/65535/49620312038_132b0fe274_b.jpg) (https://flic.kr/p/2iAM52m)Firebird 403 oil pressure sender bracket plated (2) (https://flic.kr/p/2iAM52m) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
(https://live.staticflickr.com/65535/49621096582_1834892105_b.jpg) (https://flic.kr/p/2iAR6eY)Firebird 403 oil pressure sender bracket plated (1) (https://flic.kr/p/2iAR6eY) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
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I cleaned up an original setup.
(https://live.staticflickr.com/65535/49889048058_04ef5748dc_b.jpg) (https://flic.kr/p/2j1wpT1)403 Olds oil pressure extension setup Firebird original (1) (https://flic.kr/p/2j1wpT1) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
(https://live.staticflickr.com/65535/49889566166_275e9c30a8_b.jpg) (https://flic.kr/p/2j1z4TU)403 Olds oil pressure extension setup Firebird original (2) (https://flic.kr/p/2j1z4TU) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
(https://live.staticflickr.com/65535/49889875892_201dfced8b_c.jpg) (https://flic.kr/p/2j1ADY1)403 Olds oil pressure extension setup Firebird original (6) (https://flic.kr/p/2j1ADY1) by Aus78Formula (https://www.flickr.com/photos/53057445@N08/), on Flickr
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Great write up, Aus. I’m dealing with the same issue. Thought about making a cut through the back side of the original bracket and bolting in place. But I haven’t had the nerve to destroy my bracket. Opening it up and using a spacer with longer bolt looks to be a great solution.