Find answers to Frequently Asked Questions for First Generation Firebirds that have been asked on First Generation Firebird-L mailing list. Special thanks needs to be given to all the Firebird-L owners that took the time to respond to other subscribers questions. These pages are continuously updated as new information is posted on the mailing list.
|Q:||Gas Tank Sending Unit|
|I'm replacing the gas tank on my '68 Firebird 400 and have located a sending unit. However, I'm being asked to select between a one or two tube unit. Can anyone help me with this selection without first removing the gas tank ??? I'd like to have all my parts before I remove the tank.|
|A:||Look under your car near the front of the gas tank. If there are two lines coming from the take you need the two tube unit... If one line, the one tube.|
There is multiple ways you can tell which sending unit you have in the
car right now. The fuel lines connect to the sending unit on the
right side of the tank new the front of the tank. Now, look there and see if
you one or two lines coming back from the engine compartment. Cars with two
lines require the two line sending unit, (one line is fuel, the other is
a vapor return. If you don't want to crawl under the car, look under the
hood a the fuel punp. If you see THREE connections on the pump, you
need the two line sending unit. (Connection 1 to the carb, connection 2 is
the fuel line from the tank, and connection 3 is the vapor return line to
the tank). If you see two lines connected to the fuel pump, you need the
one ine sending unit, (Connection 1 to the carb, connection 2 is the fuel
line from the tank.)|
I hope this helps.
|Q:||Fuel Sending Unit|
|I'm in need of a two tube fuel sending unit for my 68 Firebird 400. Does anyone have a used unit for rebuild ? Suggestions for locating a unit ? What was the original part number ?|
The original part number for the 400 Firebird Fuel Sending Unit was...
6427857 Gauge, Fuel Tank Unit (Sending Unit)
67-8 F/8 w/A.C. and 67-8 F/8 "400"
This is from a '69 Pontiac Parts Book.
Big diff. between this and those being sold as replacement units is the Vapor Return tube.
|Q:||Removing Fuel Sending Unit|
|I have a leak around where the fuel lines come out from the fuel tank. How do I remove the fuel tank sending unit? Do I need a special tool?|
|A:||You don't really need a special tool to remove the sending unit lock-ring. First clean off the area around the unit, (I like to use a shop vac and a brush). The ring should have 3 or 4 tabs; using a small brass drift, tap the ring around to the un-lock position. I try to use the tabs evenly so as not to distort any 1 tab. When removing the s/u, do so carefully, the filter element is usually fragile with age. Under the sending unit flange is an o-ring. Make sure this isn't damaged and clean prior to installation. In my case I had a gauge problem and decided to repair and replace the s/u. I couldn't find a new or rebuilt anywhere. So, disassebled it and carefully cleaned it and it has worked fine ever since.|
|Q:||'68 Fuel Sending Unit for 400 (2-Line)|
|I'm getting conflicting stories about a sending unit for my '68 / 400 / TH400 / air car. Some say only 350 is available, some say only no a/c available, some say it don't matter. Anyone had to replace one? What can I use for this combination?|
|A:||The difference is the ones with 400 engines and all a/c Birds used a 2 line sending unit, a 3/8 fuel line and a 1/4 return line. The only one available is a single line which they used on 326,350. Someone on the list said they where being reproduced, but I have not seen the name or any information on the vender.|
I am the one who said they are being reproduced and I have not had time to
post all the info but here it is:
Catalog page 65 part number 6428846 67-69 dual line sending unit price is $175.00 plus our tax of 15% this price is Canadian. They do their shipping through UPS but expect it to take an extra day for a border crossing. Also the exchange rate right now is about 50 cents on the dollar so an American dollar is worth about $1.50 here so you can figure out about what it would cost.
also just a note we had ours rebuilt by a gas tank repair shop for $181.00 they sandblasted our tank , flushed it, painted it and rebuilt our sending unit. So maybe you would want to check that out also
|Q:||Fuel Guage Sending Unit Sock|
|A few weeks back I was looking for information on how to replace the sock on the fuel gauge sending unit. Anyone ever done it? Is it hard to do? Got advice????|
|A:||This weekend, I took a look at my sending unit. The sock was missing, so there was little filtration going on in that fuel system. But the retaining ring that held the sock in place was still there. There were traces of the sock mesh on the edges of the ring, so it looks like it had been torn off. No sign of the sock in the gas tank. Judging by the ring I saw, and pictures of the sock in various catalogs, it would appear that the sock simply slips over the end of the pick-up tube. The sock has a built in ring at the open end. I was able to remove the sock ring with no difficulty at all. Installation should be a simple slip fit.|
|On my '68 Firebird 350, is lead substitute added to gas recommended?|
|A:||I add it to my 350 and use octane 92 gas. I do both to increase the octane levels the engine was originally designed to run on. This recommendation started when I started having acceleration and knocking problems when I finally had to switch to unleaded back in the mid 80s.|
|What octane rating should I use in my Firebird? I've always been told to use the lowest octane fuel available - seems to work for me.|
The thing to do is to use the lowest octane possible that does not cause
detonation (pinging). There are too many factors that control this some being
distributor advance, compression ration, carbon build up in the combustion
chamber, carburetor adjustment, plus a bunch more. Each car is different so
you have to either start at the bottom and work your way up or start at the top
and work your way down.
Today's cars have microphones attached to the blocks that listen for detonation and adjust retard accordingly via the computer. Our cars don't so you need to use your ears.
You certainly won't hurt it by using 92 (or higher if available).
You are on the right track, but it would make more sense to use the
lowest octane fuel that doesn't make your engine ping or knock. You
will eventually break something if you used a lower octane fuel
just because it was available.
There is no hard and fast rule saying that you must run a certain octane fuel in your 1st gen car. You must experiment and see how it runs with what's available. If it knocks with 85 octane, then try 87. If it then runs fine, stay with that grade fuel. Using a higher octane than necessary will not benefit you car, and will even raise it's pollution output.
|Q:||Premium Gas Usage|
I got to thinking about octane while I stood and watched the $$$ go by
on the gas pump today. What determines the need for a higher octane? Is
it the compression ratio? The HP? Torque?
I was wondering if using premium fuel is necessary. Maybe someone has some knowledge on the subject. BTW, I have a 350 with a 4-bbl, and I have been running 92 octane in it ever since I've has the car. In its original 2-bbl configuration, it is billed as a "regular gas" engine.
Compression ratio determines the need for octane
John Sawruk spoke on this at the POCI nationals. He qualified all the Pontiac V-8's as a Pontiac engineer. He said the pre 71 (10:1 compression range) engines were qualified on 100 research octane. Sunoco Ultra 94 (pump rating) is about 98 research. He felt 94 plus a can of booster was about right. He said to be careful about preignition that you can't even hear. He also strongly recommend changing all hoses that come in contact with todays gas and/or vapors.
|A:||The engines that required Premium fuel in '68 must have the hights octane put in plus an octane booster. These engines included the HO, Sprint, and Ram Air engines.|
|I have an HO engine which requires premium gasoline. Now that gasoline has lower octane rating and no lead, I want to possabley use Aviation Gas. Doesn't AVGas burn pistons over time? What about Cam 2 or 3? I've heard Sunoco has a higher octane fuel for this application.|
You may have wanted a simple 'yes' or 'no' answer, if so: 'no'. But since I have done a fair amount of research/experimenting with gasoline and find it a very interesting topic, here goes!
AV gas itself will not burn pistons. But this is not to say you cannot burn a piston with AV gas. AV gas is higher octane than typical pump gas but it is typically formulated to burn at higher elevations. Also, the vast majority of aviation gas is unleaded or "low lead" (nearly unleaded). As with any fuel, you need to jet your carburetor (or fuel delivery system) to correspond with the specific gravity and other characteristics of the particular fuel. Simply adding higher octane fuel to a properly tuned car will rarely increase performance, any usually degrade it. The reason you can make more horsepower or go faster with higher octane fuel is that you can tune your motor to take advantage of the particular fuel. That is, you can run higher compression and more advance with higher octane and, thereby, make more power.
If you've even seen Chevron's commercial where they say something like you can make more power with their Supreme gas, you will note A LOT of disclaimers at the bottom of the ad. Basically, this only applies to cars with fairly sophisticated engine management systems. That is, ones that increase ignition advance until the sense knock and then slightly back off. With this sort of engine management system, a higher octane fuel will actually more the car go faster. While is seems counter intuitive, a typical engine will make more power using the lowest octane possible fuel (lowest so as to prevent detonation, that is). Once you exceed this level, performance will actually drop off. Many people will argue this, and may even produce time sheets showing better ET's, but when driving on the street, there are far to many other variables. You will not see an improvement on a dyno, only a decrease.
Another concern is that AV gas is not taxed for use on the street and thus using it on the street is illegal. No FBO will pump AV gas in your car. While they will pump it in drums and you can transfer them to you car, it will still be illegal to use it on a public road. Should be o.k. on a race track but you will be far better off buying a race fuel specifically formulated for your application.
AV gas used to be a more viable alternative, but still not the best choice, when it was leaded. This is because it got most of its increased octane due to the addition of tetraethyl lead ("lead"). When mixed with pump gas or even real race gas, a significant increase in octane would occur, thereby allowing the use of higher CR's and more spark advance.
Contrary to someone's earlier post, there is no magical compression ratio cut off for running on pump gas. Your engine's octane requirements are dependant on far more variables that just CR. Squish band, combustion chamber shape and layout, timing as well as even the material of your head (cast iron vs. aluminum) all make a significant difference. There is no reason you cannot set up an engine to run 10:1 on pump gas (I believe Jim Hand has done this with his wagon but an not 100% confident on this and too lazy to check right now!!). Obviously there WILL be an upper limit but it is unique to each combination. I probably would not encourage someone building an "average" street motor to go much higher than 9.25:! but this is based on the complexity, care and expense necessary to set up an maintain a motor running a higher CR on low octane fuel. Also, there is not that much power that will be gained going from a 9.25:1 to a 10:1 CR.
Sunoco does sell their GT100 fuel in some areas (check out www.racegas.com). This site also lists specifics details on their race fuels as well. VP also makes a variety of high quality fuels. If you are looking for high end race fuel (gasoline, not nitro methane) you can also try Elf or Nutec.
Fuel technology is incredibly complex and very interesting (at least to me)! If you go to a GP (car or bike) you will notice that the top team have fuel technicians that 'brew' fuels for not only each track but to correspond to the environmental conditions change through out the weekend.
|A:||As a Petroleum Engineer I can only say, "very informative and well said."|
|Q:||Gas Tank Venting for 1968|
|Does anyone know how the gas tank vents on a 68 convertible with a 350/auto??|
|A:||It used a vented cap.|
|Q:||Gas Tank Venting for 1969|
|I just picked up a 69 Firebird w/ a 350 2bbl, 350 turbo Trans, PDB, PS, & A/C. This is the third 69 I've owned but the first 350. I was removing the gas tank to replace the trunk and noticed that this tank doesn't have the little vent tube that the 400s had just below the cap. Is the vent tube unique to the 400s or the H.O.s?|
|A:||I have an original 350 2-barrel car (convertible) and I just checked it today. There is a small tube which connects to the filler tube just below the cap. The tube is about 6-8 inches long, it turns around in a "U" and then connects to a fitting just above the filler tube on the body. Hope this helps.|
|A:||I have had a few 69s with and wthout the tank vent, checked my friends OHC-6, A/C car and it has one. So not just 400 cars got this I think its a production change early in the year but I believe that a/c cars got it (never say ALL) regardless of motor.|
|Q:||Gas Tank Paint|
|I have the gas tank out of a '69 Firebird which I'm replacing the rear end on. I want to clean it up nice before putting it back in. Question is, how is the gas tank supposed to be finished? Body color paint? Black paint? Undercoating?|
|A:||Original color was silver (galvanized). Eastwood company sells a close duplicate color.|
|Q:||Fuel Line Routing for '67|
|Can any one tell me how fuel gets from the right side of the eng compartment where me fuel line stops to the left side where the fuel pump is..thanks it's a 67|
|A:||The fuel lines on a '67 run along the inside of the right sub frames from the rear of the car and cross over to the left side of the car along the crossmember of the front subframe. Unfortunately, the Firebird service manual does not have a fuel line routing diagram in it which shows the exact placement.|
|A:||There is another fuel line that follows the crossmember under the engine. It joins the "camaro" fuel line with a short rubber hose, and there is the usual hose to the fuel pump. This fuel line is held by the same clips as the brake line for the right front wheel. Mine's a 68, but they're probably the same.|
|Q:||Fuel Line Replacement|
|Where do I find replacement fuel line for my Firebird?|
If you can't find a used/new
line, consider the mandrel tubing bender in the Sears Automotive catalog. It
costs about $60. then just by fuel/brake line at the parts store and build
your own. I bent the fuel lines for my Firebird and Bonneville with this
(fuel pump to quadrajet). Looks exactly like the factory line. By bending
one for each car, I figure the tool paid for itself.
Warning!: If you're like me, you'll probably need several pieces of this line just to get the hang of how the tool works. You know the old saying, "measure twice, cut once." Holds very true with this. It may be your only source for a correct type fuel line. Besides, it's a lot of fun, really!
|A:||Fuel lines are available for 67-9 repro or you can do as Greg says and make your own. You can buy the steel line in 25' roll at auto parts store(look around someone will have it ) Roll the required length out before starting, add a couple of feet extra and cut off the roll. I get my line straight by rolling out on the garage floor using a friend to hold end for the first couple feet, push down while rolling and you wont get any humps. Just curious but how did you barb the ends where the rubber lines are attached? This is necessary to insure that rubber line doesnt slide off and seals properly. I've been looking for the swedging tool to do this. Also if you buy repro line make sure it has this feature.|
|A:||To barb the end of the tubing, use a double flare kit. Insert the reverse flaring die into the end and tighten just enough to create a bulge. Hose will not slip off.|
|A:||The barb on the ends is easily made if you have a flaring tool with the adapter for double flares for brake lines (you must use double flares for brake lines!) Just do the first step of the double flare and you have a barb. As for the shape, just follow the existing brake line on the cross member, and get within 3 inches of the Camaro line so the rubber hose isn't too long. Have fun!|
|Q:||Gas Tank Strap and Finish|
|I dropped the tank off to get clear coated. I read they came un-painted. As well as straps. True?|
According to the "Camaro Restoration Guide, 1967-1969" by Jason
Scott, the gas tank should be natural galvanized steel, while
the straps ought to be either natural steel finish or gloss
black. Given that the Camaro and Firebird share so many common
parts, the fuel tanks and straps among those, it would be safe
to assume the finish is the same. To cross reference, I checked
my GTO restoration guide by Paul Zazarine, but is is silent on
the subject of 68-72 fuel tanks.
You can get some spray can galvanized coatings for the tank, or Eastwood's own tank coating. Watch out for some of those galvanized look paints. One type I bought at the hardware store went on very dry and looked terrible. I ended up recoating with something else. For the straps, try base coating with POR15, then top coat with Eastwoods "Fresh Steel" paint, or a gloss black.
It was my experience when reinstalling the fuel tank, that the new rubber strap insulators didn't want to cooperate in staying in place while raising the tank and bolting it in. Try using an adhesive such a the 3M weatherstip cement (Gorilla Snot) to keep them in place.
The reason the rubber on the straps doesnt work,is
because is not the way the factory did it.
The factory used a tar impregnated material just like thick tar paper.
It would stay in place when the straps were tightened where as the
rubber tends to shift around. Also the rubber may be a source of squeaks
whereas the tar paper stops squeaks.
The correct finish is bare steel straps and galvanized tank.However clear coat would be a way to keep lookin fresh. I removed my original 68 tank for a clean up, and it was coated with a paraffin based under coating when new. It wiped clean with mineral spirits and looks like new. I also found some green crayon markings that the factory used for assembly identification.
|Q:||Additional Information in Engine Fuel System Section|
|What is the difference between this section compared to the Engine Fuel System subsection?|
|A:||They both blend into each other but this section is focused on the gas tank and delivery system portion while the Engine Fuel System subsection is more focused on the engine compartment portion of the fuel system.|