318 lags over 55mph
 

Hi folks, I just brought my 1967 Fury 3 home from the paint booth and stepped on the gas a little and at 55mph the engine began to lag, kind of like a governor does. Once I dropped below 55, the issue went away. That was the first time I had got the car to that speed since I bought it 2 months ago. I'm curious if it could be a carb issue or possibly a fuel delivery problem. Any ideas?

Hi mate.
Nice car by the way.
I just got my 68 convert on the road after painting and its suffering from exactly the same on its 318. I will be investigating it shortly when I have time.
I suspect a fuel delivery problem and the first place I'll be looking is the mechanical fuel pump since my car has been standing for a long time and I think that the diafragm may be holed or torn. It would still pump sufficient fuel to run the engine under moderate fuel demand conditions but when engine demand gets higher, the pump runs out of steam.
I'll let you know how I got on if I get under the hood of my 68 before you do. If not perhaps you'll let me know how you got on with your 67.

Terry.

Hi guys, I had a simaler prob. on a 67 dart. 318. first I thought it was the pump tto, then the gas gauge, still no fix. it ran great at low speeds , at 50 plus it hesitated, then died, you wait 10 min. then it`d start, found out it was the sock in the tank that goes around the outlet tube. replaced it and prob. solved.hope this helps.

sounds like i need to drop the tank and check it out. The fuel sender quit working a week ago as well. I think before I got the car it sat for way too long. Thanks for the tips.

what rpm was the engine at around 55?

dang, I should have noticed. I will take her out again and write down any diagnostic info I can. My dad thinks tranny but the fluid level is fine.

can you be a little more specific on the "sock" part? I'm not that savvy on terminology, thanks.

I also meant to ask how difficult is it to drop the tank? I assume you need little to no fuel in the tank, a way to temporarily stop the line up so the fuel in the line doesn't flow out when you disconnect the outlet line. What am I forgetting?

i dropped the tank on my 1967 sport fury fast top this last summer...wasnt bad...lots o dirt so wear some safety glasses to save your eyes..lol. the biggest problem i had was the strap bolts. the nuts were pretty much rust fused to the bolts, so i ended up having to break em. now came the hard part....finding the jbolts. i couldnt find them anywhere locally. i ended up having to order them from someplace i found online and they arent cheap. i think i paid like $30 for the pair.
i just used a big ol floor jack and a board to lower the tank which was about 1/3rd full and then it was no big deal.

if u decide to go ahead and do it feel free to ask questions and ill answer them best i can.

ok babe, real simple, spray knoker loose or wd40 on the 2 strap nuts on the straps for the tank, then take the nuts loose, support the tank with a board or somthing else 6"/6" at least with a floor jack. lower the tank, there are 2 hoses going to the tank and a wire, pull the wire off, then cut the 2 hoses, will be a 5/16`th hose and a 1/4 " hose , the 5/16`th is the fuel line the 1/4 " is the return or vapor line. then youll have a metal clamp hooked to the metal tube by the fuel line, thats the ground for the gauge, just spread the ends open on it and pull it off. using a screwdriver and hammer knok the twist lock off the sending unit. then the whole thing comes out, as you pull it out twist it to the front of the tank, youll feel the tubes, and see how you need to twist it to get it out. when you pull it out youll see a white sleeve(sock) fit around the end of the tube. pull it off then slide the new one on, you can get a new sock from year one or other resto parts co.blow the tubes out w/ air, to clean out debris. put the unit bacl in the tank then put the lock back on then reverse the order of taking the tank out, put new hoses on, then reinstall the ground strap for the gauge, make sure that the clamp part touches the metal tube. then hook up the wire . thats the gig.

I agree with everyone else that this sounds like a fuel delivery issue. With a ride of that vintage (very nice btw) you cannot go wrong with cleaning out the fuel tank. Just make sure you've got all the parts you'll want before you start; it'll make your life a lot easier.
The "sock" that rr69half6bbl is talking about is simply a strainer on the end of the fuel line inlet there in the tank. Its sole job in life is to prevent sediment from being pulled into the fuel system. Considering how long it's probably been in there it should be replaced, whatever its condition. It'll be easy while you've got the tank removed and everything taken apart anyway. If this doesn't fix your problem then change the main fuel filter, if that doesn't correct the problem then change the fuel pump, then lastly have the carb rebuilt.
The only other thing I can add to it is to have a look at hat condition the fuel lines themselves are in. Are the lines rusted? If there is anything more than a little surface rust on the lines then you should change those too. Good luck with the fixes, let us know what does the trick.

Thanks for the step-by-step! I have a new fuel sender enroute from Rock Auto along with a filter. Adjusted the timing today, it was waaaay off, like 26-27 BTDC when the book says 10 BTDC. Engine obviously sounded alot better. Pulled the dash off as well, i was replacing the dash pad, and checked the gauge itself, no problems there. I think you fellas are going to be proven correct after I change the sender. I'll let ya know the results.

did you find out the revs at 55?

i thought of a few things
check over your ignition system
check the cap, plugs, wires (make sure they are on the right plugs)
if your car is points, did you change them? did you change the condensor?
could be a vacuum leak
tighten down the carb. itself and where it meets the manifold

how does the car idle?
yours is a fury, so the rear is probably a high ratio
when going 55, your revs are probably 1800-2000
the engine wont require much fuel at that speed
that means if there is any restriction, you wont be able to rev

double check your distributor
check over your fuel line
make sure there are no kinks in it
make sure your fuel pump is properly functioning

Having driven my '68 a bit more now, I'm more certain that the fault lies in the 390Holley 4bbl that's on top of my 318. The problem occurs far too quickly to be sock related or even probably pump related and to a point, can be driven through.
I think that 390 is big enough for an otherwise stock 318 so instead I'm going to check out the accelerator pump adjustment and power valve in that order.

At present, I'm still having way too much fun driving the big old thang about to be finding time to work on it........................!!!!

Swapped out the fuel sender today. The float was full of fuel so that should fix the guage issue. Gotta get the carpet finished and seats back in before I take it out and check it. Also going to pull plugs tommorow and check gaps. more soon.

well, new fuel sender is working great. I also found a vacumn line that was torn and replaced that. Re-timed the engine, new plugs, drained tranny and put a new filter in and man, those dual exhausts sound friggin sweet! All in all, a good couple of days. Thanks for the advice yall.

hows the engine?

Well, i've had a very successfull couple of days working on the car. All filters and fluids are changed, new plugs, re-timed, new valve cover gaskets, new thermostat, new vacumn lines, finished the carpet and got the interior back in as well. The engine sounds great, even for a 318. The dual pipes add to that throaty rumble. Last item is getting the rear glass back in next week and going to the DMV for resgistration. The month off from the Army I have has been well spent I think. I can barely wait to take my kids for a spin.

have you gotten the car above 55 yet?

yep it did just fine. I think the combo of the fixes did the trick. Thanks for the help.

no problem
keep us posted

I took her out today and really got on the gas and no problems whatsoever! I feel so lucky to finally have a bada** car to cruise around in. Now if I can only figure out how to convince the wife we need another one......

haha
good luck with that