63 340 HP carburator

[Richard S.]

I have a 63 coupe with a 340 HP engine. I am in the process of updating the car/engine. I recently installed new chrome fuel lines and filter between the fuel pump and carburator. The problem I am having is getting the fuel line between the carburator and fuel filter to line up for proper mating. I have tried moving the filter, fuel line and fittings but I can not get a good mate.

Can anyone tell me if the carburator requires a spacer between the aluminum manifold and the carburator base? If so this might correct my problem.
In looking at the Long Island Corvette catalog I see no picture information (detail) on the 340 HP carburator fuel line to fuel filter installation. In a like way in the shop manual and assembly manual I see no detail information.

Any advice or picture detail on this installation would be greatly appreciated.

Thanks
Rich

[jim cear]

Re: 63 340 HP carburator

Rich, I have the same configuration 63. My advice is install the carb, but do not install the manifold nuts yet. With the "wiggle" room that provides and keeping the fuel line connections loose, after much trial and error, I can get the threads to line up corretly(be careful of crossthreading). I often find the line from the filter to the 45 degree connector on the carb the most tedious to thread properly. If the 45 degree connector is not positioned properly its very frustrating, keep trying (fyi, often after market parts such as these are a poor fit and its necessary to try another supplier) Good Luck! BTW no spacer should be needed for your car.

[Duke W.]

Re: 63 340 HP carburator

The 300 and 340 HP fuel pipe segments from the filter to the carburetor inlet have a different OE part numbers (see the AIM Sect. L/75/L-76 Sheet 3). This could just be a finish issue as the 340 HP part was chrome plated. I'm not sure about the 300 HP segment. It may have been zinc plated steel early on and chrome plated later in production.

In any event, there may be a difference in geometry due to a difference in relative carburetor placement.

The 300 HP engine has a phenolic carburetor insulator. The 340 HP engine does not due to the slightly higher manifold, and the net change in relative location may have dictated different geometry for this pipe segment.

My '63 340 HP engine has the original chrome-plated pipe segment and the longer straight section is toward the carburetor end.

Make sure you have the correct part!

It can be difficult to start the threads. The elbows must be precisely aligned. Don't force the threads with a wrench. If you have the right part and it's correctly oriented and everything is properly lined up, you should be able to start the B-nuts with your fingers and run them up until the flares butt up against the seats in the elbows. Then snug the nuts with a five sided tubing wrench.

For new flare fittings I find it best to snug-loosen the nut about three times. This allows the taper in the elbow and the flare on the pipe to form to each other to create a tight, leak free seal.

Duke

[Richard S.]

Re: 63 340 HP carburator

Thank you for the insight and informaiton it is appreciated. I have been able to align the tubing and thread the fittings together. The issue I seem to have at the moment is that with tubing and attaching nut in place I am unable to seat the carburator. It has a small gap between the manifold and carburator base. I have tried tubing/filter from two different sources but same result. Perhaps it is associated with how the filter clamp attaches to the manifold. I have a threaded stud with nut securing the manifold then the filter washer and second nut securing the filter to the manifold.
Does this seem correct.

Thanks
Rich

[Richard S.]

Re: 63 340 HP carburator

Thank you for the feedback. I was able after some time with attaching nuts loose to arrange and connect the fuel lines to the carburator. And with the carburator attaching nuts loose align all fittings. The issue I am having at this point is that the carburator has a small gap and will not seat down on the manifold. I have tried two different fuel lines and fuel filter from two different sources but no luck.
Your help is greatly appreciated. If you have any close pictures of your installation I would greatly appreciated seeing them.

Again thank you and have a happy christmas

Rich

[Duke W.]

Re: 63 340 HP carburetor

Your configuration sounds correct. The AIM is your best reference.

Install the pipe with the filter bracket not snugged to the stud and the pinch screw loose.

You should check all vendors to see if they show different pipes for 300 and 340 HP engines. I still think that is the source of your problem. You have the wrong part.

Duke

[Richard S.]

Re: 63 340 HP carburetor

Thank you Duke for the response. It may be that another part may work for my installation.

Rich

[Timothy B.]

Re: 63 340 HP carburator

Rich,

I know Duke suggested the long end of the tube toward carburetor but it will work either way so try it to see if this allows a easier assembly.

Merry Christmas to everyone! Tim

[Richard S.]

Re: 63 340 HP carburator

Thanks, actually I did try reversing the position of the long and short bend. I could still not get the connection to work properly. It could be the fuel lines I have are wrong. To find out I could really use information on the length of the fuel line that connects the carburator and fuel filter. I do not suggest anyone remove there fuel line but if someone could measure the length of there fuel line it would be very helpful. The measurement of either the inside or outside bend of the fuel line to the connecting surface of the fittings installed in the carburator and fuel filter would be of great help to determine if the line length is incorrect.

Thank you again
Rich

[Richard S.]

Re: 63 340 HP carburator

Thanks, actually I did try reversing the position of the long and short bend. I could still not get the connection to work properly. It could be the fuel lines I have are wrong. To find out I could really use information on the length of the fuel line that connects the carburator and fuel filter. I do not suggest anyone remove there fuel line but if someone could measure the length of there fuel line it would be very helpful. The measurement of either the inside or outside bend of the fuel line to the connecting surface of the fittings installed in the carburator and fuel filter would be of great help to determine if the line length is incorrect. Any suggestions in suppliers of the fuel lines that work is apprecaited.

Thank you again
Rich