just got a thought...

and how do you feel about this issue, N8? (IMNSHO, get louder mufflers)

mufflers are fairly loud; can still hear fuel pump... actually sounds kind of embarassing.

nate

R series fuel pumps have provision for a return line back to the fuel tank, non-r series pumps do not. A friend of mine has a Super Hawk and explained this to me once, and why it's there. Beats the hell out of me if I can remember why though. If the pump is securely mounted to the timing gear cover, the level is resting securely on the cam lobe on the timing gear, and there is no obvious object tapping against the pump, you can always poke some holes in your glasspacks. Guaranteed to drown out the fuel pump racket :-)

-George-

It's there to keep the fuel from boiling and causing vapor lock, basically. I do NOT currently have the return line hooked up on my car because, well, it's a '55 and I haven't gotten around to running one yet. Would the lack of the return line cause it to be noisy?

The only other thing I'm not sure about was the "lever resting securely on the cam lobe" thing which was why I was asking my original question. Alternately I will probably have to swap with a "known quiet" pump to really get to the bottom of this, and that doesn't sound like fun - all the "known quiet" pumps I am aware of are on other cars, so there'd be a lot of pump swapping going on. Basically this engine was built from parts in a service block, and the pump came out of a box of parts and was kitted by yours truly, so I can't say anything like "it was quiet before..."

nate

reichsrundfunk wrote:

The "return line" has a .050" restriction in the sediment bowl port. It's so restricted that I doubt there is enough flow for useful cooling. AC sometimes called it a "vapor diverter". It also allows pressure to the carb to bleed off when the engine is shut down; which prevents flooding. I understand early Avanti's that had the return at a "T" on the pump, had a restriction too. It's not shown as used on the "R" pumps, but similar pumps sometimes have a piece of foam behind the outlet diaphragm, in the pulse chamber. I thought the foam, and the outlet diaphragm itself, were to smooth out the pulses in pressure to the carb; but it might have to do with noise, too. I think Carter had a patent on their "Pulsator" pump. I'll mention the spring on the operating arm; although you probably didn't forget that. Mike M.

Not a expert by any means about Stude engines,Nate but I'll toss this out anyway.I had a similar experience with a big block Ch**y engine.Replaced 2 fuel pumps until I investigated and found there were 2 fuel pump rods available and 2 different lengths.I had the short one in my engine and as soon as I switched to the long one the noise quit.Cant recall exactly the reason for the 2 sizes but it had to do with fuel flow numbers and different rate springs.

Bob40

Bob,

sounds like you experienced the exact same thing I am. Unfortunately a Stude engine doesn't have a FP pushrod after 1954, so if there is an issue outside the FP, it is with the cam.

D'oh.

That'd make only the second time the timing cover has been off this engine since it was built, if I ended up going that road.

Unfortunately, SASCO does not show the R1/R2 fuel pump cam as an available item, otherwise I'd just order one to eliminate the possibility that this is the problem.

nate

Bob wrote:

it's an original fuel pump, so unless the arm is bent, that's not the problem.

IT seems to get *louder* when there's no fuel in it.

nate

GTtim wrote:

Any chance that the blocked return line stops the lever from retrning to rest on cam? (I have no parts that are not on car and haven't had a R1 for 34 years!) (This sounds silly even as I type it!) Unplug line - Tygon it into a milk bottle!

Karl

It's not that it's blocked... it's that it's not there at all! I don't have the R1 filter/return line deal at all, it's plumbed just like a "normal" car at the moment.

I guess next time I get over to JP's I will just have to start swapping fuel pumps. I have a '55 fuel pump that didn't make noise, and JP has an Avanti that has a good fuel pump on it (I'll have to be nice to him...)

nate

I have seen narrow (same width as arm) 1/8 or 1/16 inch thick plates Tig welded to the contact surface of brand X fuel pump arms to take out slop.

Freddy

N8N wrote:

Take the fuel pump off and clean the sand and junk out of it

Nate , Pull the pump and see if the spring that goes between the pump body and the arm of the pump hasn't fallen out. While you are at it check the pin that the arm rides on, and make sure it isn't trying to work it self out of the pump body. Sometimes that little aluminum rivet can work its way loose and fall off of the pump and the shaft will start to work its way out and the arm will make noise. Don't ask me how I know that. I tapped and threaded the spot where the rivet goes and now use a bolt and permatex.The shaft can not come out and it seals well ,and giving me peace of mind. Also if you need to rebuild it again in the future you don't need to peen the pump body to hold the rivet in place.Pull the pump and examine it.There is no reason for it to be noisey. Joe Flannery