Gas tank installation
 

This fuel tank certainly is a pain ... if the Ames straps were 1/2" long it wouldn't be bad at all. Maybe the OEM tanks were a bit slimmer? Can get the long bolt in the hole, but just short of the threads on the "tower" style clip on nut.

Using a floor jack to hold the tank in place. I've got the rubber insulator above the tank, and the strap isolators, sure that's not helping.

Any tips on getting that bolt in?

Also ... jeez the tank and fuel lines seem close to the exhaust, in areas probably less than 1" clearance ... normal? I'm using a 2.25" OD Gardner set up pipes. Thinking I might wrap the rubber sections of fuel line in some kind of heat shield.

I had removed the tar paper, and purchased the rubber sheet from Ames, and original bolts were too short. So I went to Ace hardware and purchased longer bolts. Also I had no luck in finding a build sheet, Baltimore plant 69 Gto,

Are these the black straps? I don't recall having an issue with this. I know I had to shape the straps a bunch to conform to the shape of the tank & then the bolts reached. I might have started them with longer bolts & changed them but I don't recall doing that. very little room between the bolts & the exhaust pipes. I will measure somethings this morning. I still have the factory style repop insulator & decided not to use it. I used two insulation strips on the mounting areas & they were the same thickness as the insulation "sheet" so that should be the same. Do you still have an original strap to compare overall length of them?

Original straps are long gone.

Yes I am using that black straps ... they are very very close. I don't really think it's a problem with the straps ... just wish they were a tad longer to get the bolts started, once the strap has had it's first stretch they would probably go on easy. The rear area where you have to bend them to get them around the tank needs a good stretching.

For some reason I didn't even think of using longer bolts first ... I probably have some lying around ... guessing 3/8 - 16.

Doesn't help that I'm on my back under a car that isn't even jacked up ... not a lot of room to get leverage. Quickjack will be here in a week or so :)

rummaging through my gazillions of photos & realized what I did. I had the body on the rotisserie upside-down & fitted the tank and straps way before paint. I am sure I used the wrong & longer bolts at that time. But I had gravity helping me at the time. I am going to bet longer bolts will work for you to pull it closer so you can install the correct ones after.

Here is what I ended up with. Not saying everything you see is 100% correct. I took all the information I could get at the time & I really don't recall the details of what I might have altered from there. There were several things with my car I changed a bit for personal preference, but I always started at original. Not sure if what you see is one of those situations. I am forgetting some of that stuff seeing I am a couple years from completion now. ;)

I will say that the space between the tank & pipes is almost non-existent. Gardner system, but not their most recent one. I know there have been some changes to make them more correct since I bought mine.



https://forums.maxperformanceinc.com...1&d=1631970186

https://forums.maxperformanceinc.com...1&d=1631970176

Yep, pretty much the same as mine.

I'd feel better if I used a bit of heat shielding between the pipes and tank, and fuel lines. Not so much because I'm worried about fire, but that's got to heat up the fuel pretty good. All that exhaust heat rising into the space between the tank and body where the fuel lines are. Glad those are suction lines and not pressurized :) Certainly wouldn't be stock looking, but not many people are going to be under my car :)

Come to think of it ... wonder how hot things get that far back ... steady driving at 70-80 there is probably enough air flow to keep it pretty cool, putting around town probably not enough exhaust flow to get it real hot.

Your car's looking fantastic, great detail.
Hard to tell from that second picture but I know the straps should locate in the tanks third creased indent. Picture's not clear but is the strap sitting on the raised portion?

Edit: I think it's just the reflections distorting the image.

If it's like the tank I recently got there is a wider indent where the straps go compared to the indents on either side.

Late commenting on this but, as you guys suggested, l used longer bolts to cinch the tank up tight and was able to get the correct bolts in afterwards. Those straps are just stiff and require some persuasion.

Ditto. I replaced mine 12 years ago and it was rough getting it all back in, long bolts helped get things started and tensioned into place.

Well .. got the tank all buttoned up, used the longer bolt method, everything was looking pretty good. I go to hook up the ground wire from the sending unit ... it pulls right out of the unit, wasn't even soldered. So .... out it comes again. Glad I just got my Quick-Jack yesterday.

Got right right side exhaust adjusted so there is plenty of clearance to the tank, but the left side is still very close to the fuel lines, like almost touching close. So far I'm not seeing any more wiggle room moving the muffler farther forward ... I've got a brand new Gardner system .... do these ever have to be trimmed? If I could take 1/2-3/4" out of the long pipe it would make everything fit pretty nice.

Is the sending unit original?

My ground wire was cut, how long should it be?

I recall cutting just a thin slice off the front of one of my tailpipes from Gardiner many years ago. Maybe 1/2" just to gain a bit of distance between the pipe and the front of the fuel tank. I think it was the left side also.

Sending unit was from Ames, wire was right about 12" long ... I can measure it if you want. Tank was being a REAL pain so I put a terminal on the factory ground wire that was still screwed to the body and drilled a hole in the flange of the tank outside the sealing weld and used a self tapping screw. Checked the ground of the tank and it's good ... of course it was also grounded before I even put the wire on, probably through the straps.

north .. yep, thats all I need, about 1/2" ... with some wiggling I was able to get it far enough away from the fuel lines ... but still closer to the tank than I would like. I think Gardner may have the left/right muffler offset a bit too much.

BTW .... was there a factory clip/tab up by the downward turn in the fuel lines that held them up against the body right before they terminate by the tank? If I push my lines up there it produces plenty of clearance to the pipes, like 2" .. I was thinking I need something to hold them there when I noticed what looks like the remnants of a broken off factory tab that would have held them there. I'm picturing one of those bend over metal tabs.

Same here. Remnants of a fuel line clamp.

I think I'm going to clean that area off and weld on something that will hold the lines ... maybe a small "C" shaped channel with the legs welded to the body, drill a hole in it and see if one of the normal dual size fuel/return frame clips will work. If it doesn't ... I'll zip tie those suckers up there :)

Wonder how many "vapor lock" issues with modern fuel are assisted by the exhaust pipe preheating the fuel if that clamp isn't there and the fuel line is a 1/2" from the pipe.

OG ... correction on the wire length, it's 18" long almost exactly.

Checked the 69 assembly manual, it shows the bend over type fuel line tab on several drawings in the exact location we suspect. I assume 68 is very similar. Even credits "Fisher Body" for the tab because it's part of the body :)

This is how I did mine. the two clamps on the spring pocket area held them very rigid. then a clip near the end the keeps the lines together, but doesn't attach to anything. The one thing that I did, was made sure the lines where tweaked upwards a fuzz before I set the body on. They sit right up against the trunk braces now. If yours where bent downward at all I am not sure you would have a way of doing this now that your body is installed? :(

We had thread on this topic years back & I think there were o lot of original pics posted. some showed the lines going in front of the spring pocked, but there was no way I could do that. I had to go over the top as thats how they were pre bent. worked out just fine & almost impossible to see now.

Do you have the clamp on the frame right before it makes the 90 degree turn towards the tank?

https://forums.maxperformanceinc.com...8&d=1527888561

as far as shortening the pipes a bit, my only fear would be altering where the tips exit under the rear bumper. Not sure if mine are exactly in the oe location, but both angled / cut edges of the tailpipe are the same distance from the lower edge of the bumper. I can post pics of that later or measure something if it would help at all.

Data, you have this kicked into high gear! up thinking about it at 4:15am your time? :)

This is how the lines were run on my Fremont car. And how I finished it.

68ragtop ... here is a pic of mine, yes they go in front of the pocket ... like you, did mine the way they are because that's the only way I could get them on. I do have that last clip installed.

I tried bending them up after the body was on ... just can't get enough wiggle room to do it. I'll have to fabricate something to replace the OEM tab that holds them up to the body.

Got the rear bumper mounts installed last night and realized I'm going to have to put the bumper on before I make any final call on the exhaust, can't tell if they are in the right spot without the bumper on.

I do my best work between midnight and 4am .... so I often post my thoughts and questions after that :)

Thanks for the discussion and photos regarding the straps being difficult to start.

I am ordering parts to install my tank (Spectra) and I hope it isn't a bear.

Great suggestion about using longer bolts to encourage strap cooperation.

I saw this online somewhere and found it interesting. The bolts I removed were not flanged and as a result, were difficult to get a socket on. None of the online suppliers show flanged bolts so I'm wondering if they were used originally or not? If so, anyone have a source?

http://forums.maxperformanceinc.com/...1&d=1665955954

Thanks,

Mike

The original bolts on my 68 had flanged heads. Available from AMK.

Thank you!

I'll chase them down. The ones I pulled out were dog-point but no flange... same as all the repro hardware kits I see online. My tank had obviously been out before. The sending unit had no o-ring/gasket and the signal wire had been patched.

I don't care so much about correct but in this case, the flange will make it easier to install/remove.

Mike

Could not find flange head bolts.

AMK shows the same hex head bolts as all suppliers I've found online. I'll declare this good enough and use a washer if there isn't enough clearance.

https://forums.maxperformanceinc.com...1&d=1666058749

3/8-16 x 3 3/4

Just cut lengths of 3/6 x 16 threaded rod and pull the straps up with washers/nuts

Sure, that's an option, thank you. And all-thread might be a good way to get the straps stretched out to avoid the hassle described by others in this thread.

I have new hex bolts and nuts coming from Ames, but I was just wondering if a flange-head bolt was actually "correct" and if so, where to get them. So far, it doesn't matter as I haven't found a source for flange-head dog point bolts.

There are lots of sources for hex-head dog point bolts - AMK is one source. Lots of places to buy "gas tank strap hardware" but they all currently sell hex-heads as "correct".

Would definitely help to stretch the straps some first.

If I recall ... think twice before securing the loop on the rear of the strap to make sure you don't short yourself up front.

Strap hardware from Ames on the right, what I removed on the left (don't know if original). I think I'll re-use what I had, as it's in good shape after a bath in Evaporust.

http://forums.maxperformanceinc.com/...1&d=1666983516

Those original clips look way stronger .. actually a captive nut instead of threads in stamped steel.

Yes and no, those captive nut still clips have a tendency for the weld to let go between the nut and the clip

Good points..

From a manufacturing and finishing perspective I was surprised to see a nut welded to spring steel. It's easy to see why the "extruded" design would be more attractive.

OTOH, the nut style probably distributes clamping loads better and after they both rust, I'll take the nut remaining vs nothing remaining. GM couldn't afford to have gas tanks falling off after a few years on salty roads.

Both will work fine for me, but if the nut style is original, the repro really isn't.. nothing new there.

Mike

I'm happy.. tank went in without any hassle. I was worried it would be harder than it was.

Thanks again to Sidponcho for suggesting the threaded rod. It worked great!

http://forums.maxperformanceinc.com/...1&d=1668042840

http://forums.maxperformanceinc.com/...1&d=1668043044

A couple more questions came up, will follow in another post.

Mike

Questions remaining:

1. How tight should the strap bolts be? Any guidelines or just wing it?

2. The vent hose from Ames included a foam cylinder to use as a breather/anti-splash filter but it's diameter was too small to be secure in the rubber hose. What have you used to stuff in there?

3. When I connected the new sender wire, I found the connector in the trunk had a mounting clip but was not attached to anything. I could not see any obvious location for the clip. Where does it go?

http://forums.maxperformanceinc.com/...1&d=1668043590

Mike

Mike -

I believe your original hardware is original....and correct. I've never seen flanged bolts used on the two forward positions of the tank straps from the factory but who knows......maybe there was some variation in what was supplied to the factories over the years. I have a lot of original tank strap bolt sets and none are flanged. The AMK bolts are correct as well.


1)You want the bolts nice and snug.....reasonably tight but don't crank them in SUPER hard.

2) You might look into getting some breather material...typically a white scotchbrite pad looking material and it comes in various shapes and sizes. I've found it at O'Reilly's Auto Parts before. Used on valve cover breathers inside the air cleaner, etc.

3) Look for a exposed edge of metal somewhere near that clip (I'm assuming nothing has been changed in length on the wires) and that's likely what that clip will slip over. Maybe someone has an Assembly Manual and can look up the placement. In your pic it looks like there are two oval(?) openings, with exposed edges, behind the terminals/clip assembly.....see if it will get to one of those exposed edges without unduly stressing/pulling the wires. Then again, if that light green wire was curled up originally, they may have just left the wires that way originally.....and not slipped the clip over any exposed metal edges. It almost looks like the light green wire is too short to allow a "relaxed" stretch to a clip mounting point. Factory wiring tends to take a "set" when its bent into various curves and shapes and then sits that way for decades.

Thank you for the info on the bolts and nuts Patton! My tired car is far from "correct", but I try to keep it close just because.

And your insulating pad worked great. Thanks again for that.

I'll chase down some filter material... like used in PVC filters going back into an air cleaner.

As to the clip on the sending wire harness, I probably missed it. There are 2 welded tabs along the back wall where connectors for the tail-light harnesses clip but nothing near the latch where this tan sender wire comes through. The sender wire is new from Ames (M&H) and was very accurate and high quality. The two "oval" openings you pointed out are larger clips that hold the tail-light harness. There may be a way to attach the smaller sender connector clip, but I probably just don't see it. The other option may be the sheet metal that supports the trunk latch. Again, it's not obvious to me.. I will pull out my repro assembly book and see if this detail is there. Not a big deal, just curious.

Mike

Thanks Mike.

Another idea is to grab those connected wires/terminal housings and start pulling them in different directions toward ANY metal edges....that might lead you to the most possible clip point and maybe there are some scratches on the metal where the clip was slid on to/pulled off.

I don't have a wiring installation page for Tempest but the attached sheet for Grand Prix doesn't show the clip.

You can see in the photo that the rear harness has been hacked by a previous owner so perhaps something got shortened in the process.

The gas tank page I found says tighten the strap bolts to between 80? and 110 INCH-LBS if I'm reading it correctly... so roughly 9 to 10 ft-lbs.

There are also some features shown in the drawings I don't remember seeing. I'll have to check them out when I install the big breather hose.

Fastener Trivia
 

Sorry for the trivia dive but can anyone explain the logic here?

I thought it curious the rear strap screws are intended to be driven until they spin freely:

http://forums.maxperformanceinc.com/...1&d=1668182792

When I removed the tank, I still had one original fastener and found it was quite weird but consistent with the installation instruction:

http://forums.maxperformanceinc.com/...1&d=1668182952

http://forums.maxperformanceinc.com/...1&d=1668183000

The repros from Ames were definitely not these and I just tightened them down, which clamped the strap to the nut and mounting bracket.

So why would this be designed this way?

And is the original screw reproduced if it's important for the strap to not be clamped tightly?

.

As for those free spinning screws I’d imagine it’s to allow for the thermal expansion and contraction of the tank?

As for the clip on the wires near the trunk latch I suspect they were never used. I’ve got many survivor 69 A bodies and I’ve never seen any mark indicating it was attached to anything. Perhaps it’s the same wire used on 68’s or some other model and they just never bothered to delete the clip from the design?

My '68 has what appear to be the original plugs at that location near the trunk pass-through and no clip.
As for the vent tube filter, I like Patton's idea of using the breather vent material. I rolled up and inserted a piece of Scotch-Brite pad for mine.

Thanks to both of you.

I'm not sweating the clip and don't even know if it's original... was just curious.

As to the tank strap fastener, clearly they wanted the strap tension transferred to the rear bracket by the strap loop and not by being clamped. My guess is they simply didn't want it to slip after it was tensioned by the front clamp and bolts. I think it's pretty clever - retains the loop but doesn't clamp and installation is no different than any other fastener.

Apparently it was important enough to tool a special bolt. Like most of this stuff, I'd love to know the back story on this decision. Must have involved rattling tanks or worse..

For the vent, I am following this photo posted by 85_SS in this thread:

http://www.forums.maxperformanceinc....d.php?t=398479

http://forums.maxperformanceinc.com/...1&d=1668192243

Yesterday I asked the guy at O'Reilly's for a fuel-resistant filter material. He walked to his shelf and grabbed a breather just like it. Then I found this photo on the old thread and made me feel a little better.

Should have the tank install finished soon and I can move on to my next adventure.

Mike

You can do like the factory did and slam a deep staple into the hose to prevent the breather material from moving.

The rear-strap screws are designed that way so there is a smooth surface (on the bolt shaft) where it passes through and contacts the FIRST HOLE in the strap. If the screws were fully threaded the threads would grab into the first hole (as well as the second hole) and end up SPREADING the strap as the threads worked against the first hole.

The smooth part of the screw shaft prevents that from happening......you only want thread/thread contact with the SECOND HOLE in the straps.

That’s exactly it P Glade, forget my earlier opinion, too long since I looked at that arrangement!

That's a good point but I'll have to think about it as my interpretation is different.

The assembly note clearly says "until the screw spins freely", which to me means the threaded section passes completely through both holes. I think the fastener may have a smaller diameter section that is long enough to pass through two thicknesses of strap.

If it were only about avoiding "pushing" the tail during assembly, a clearance hole in the strap would accomplish this. In fact, the repro straps I bought did have a clearance hole. But with the supplied "normal" (fully threaded) screw, the strap was clamped. Getting it to spin freely would mean stripping it which would not be a good idea IMO.

I'll have to go run this special fastener through the old strap and watch what happens.... stay tuned.

Yeah, that's the way l interpreted it.

The fastener is indeed designed to spin freely and NOT clamp the strap.

I could not say if the straps I removed were original or aftermarket. The only marking I found was "W". There definitely was a clearance hole on the fastener entry side of the bend:

http://forums.maxperformanceinc.com/...1&d=1668278218

The start of threads on the bolt is ~0.7" from the flange. The strap is ~0.095" so there is about 1/2" of "thread-free", reduced-diameter bolt.

3 washers are thicker than the bracket on the car. When I started the bolt, it cleared the outer hole:

http://forums.maxperformanceinc.com/...1&d=1668278466

When tightened, the threads pulled through the strap and then "exited" the far end without fully clamping the strap. The bolt clearly "spun freely", effectively being a "self-stripping" fastener. The threads that were formed in the strap allowed the bolt to be removed easily:

http://forums.maxperformanceinc.com/...1&d=1668278612

Net:

- The strap is not clamped "by design"
- The special fastener makes it all happen
- The repro fasteners with full threads don't accomplish the assembly as intended by Pontiac

I'm not too worried about any of this, but as I said, I see this as a very clever system to assure the strap tension is held by the bend and not by the clamped connection. Why? Dunno.....

I can't read the part number for this fastener (#13 on the 1970 assembly drawing). It looks like 399782 ??? Anyone have a clear PN for this?

Mike

Wonder if the idea was to limit the bend radius in the strap?

If so, fully clamping the strap with the aftermarket screws may "overstress" the strap at the bend? I doubt it would cause any damage but just a thought... I think a general guideline for forming sheet steel was to keep the radius greater than 3 times the thickness ??

Mike