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Veteran
Posts: 201
Location: Fremantle, Western Australia, Australia | Hi all, Just want some info, I had a stock standard 1958 Plymouth V8 318 2 barrel Carb, The engine has now been stripped
and the engine has been rebuilt but with a 2X4 setup with the original manifold with 2x4 Carter WCFB 2631S and 2632S.
All Carbs have been restored as well
The car still has the original Crankshaft and camshaft and the carbs have been jetted down. The engine runs really rough and
also some backfiring when you put your foot down and if you put the accelerator down really quickly the carbs kind off gasp and then the car accelerates.
My question is for this engine to work correctly would I have to change the Crank and Cam to suit this new setup or is there
some sort of carb problem or another problem...Any help would be greatly appreciated....very frustrating
cheers
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Expert
Posts: 1740
  
Location: Alaska | If the engine is "backfiring", that is a sure sign of too lean of a mixture. Also sounds like accelerator pumps (one or both) not working or adjusted correctly. Your engine should run OK without having the Fury cam because 2 WCFBs are not a huge amount of air. I would look for vacuum leaks. |
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Expert 5K+
Posts: 8947
 
Location: WHEELING,WV.>>>HOME OF WWVA | is that the vacuum brake hose behind the throttle linkage ,,,,,,,,,, no clamp ? ---------------------------------------------later |
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Expert
Posts: 3400
Location: Chestertown, NY ( near Lake George) | Assuming no vac. leaks, the carbs are balanced and the timing is correct then these carbs maybe shouldn't have been leaned down. Did you adjust per shop manual the metering rods and accel. pump settings? To add can we assume this not an ign misfire, also these carbs can have isue with the secondaries not closing all the way. Lots of possibilities here.
Edited by Shep 2014-09-27 6:17 PM
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Expert 5K+
Posts: 8444
Location: Perth Australia | If thats supposed to be progressive, it looks like the linkage for the rear (primary) carb is in the wrong spot
I think its supposed to be in the top hole.
At rest (idle), the slotted part of the linkage should be about 1/2 way through the slot (this is as an idea, you have to work out the adjustment to wide open throttle), and as you accelerate the linkage should bottom out in that slot and then start working the secondary carb.
the reason for using different holes on the carb, is the secondary throttle plates have to rotate faster than the primary ones, so w.o.t is achieved at the same time.
The way that looks now, it looks like its hooked up for both carbs to work at the same time (speed)
It would be interesting to see how your car is working, as I have some issues with mine which I think is leaning out, but I havnt bought the jet kits for mine yet (might do that now while I am thinking of it) to really play with it, but basically, when you floor it, it roars like hell, but really doesnt accelerate and it pings, does that sound like yours?
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Extreme Veteran
Posts: 444
Location: North of the 49th | Hi
From your pictures I can see you have a few issues to deal with:
1. Your progressive linkage is not progressive and has been set up for both carbs to open at the same time, the dual quads were originally designed to allow the engine to start and idle up on the rear carb's primary thats why the choke is there.
2. Change the return spring for the rear carb and make a bracket to get it off of the linkage
3. It appears you do not have a choke heat stove but yet you have the choke pot in place is the choke mechanism intact?? a heat stove can be made and installed to allow full operation of the automatic choke.
4. Where is the distributor vacuum advance connected to as it appears the vacuum advance port is plugged on the rear carb.
Fix all the above and return the carbs to there original jetting which will work fine with the 2bbl camshaft , The Fury cam was a "Highway" cam in other words a "top end" cam making it a real p***y cat at idle.The WCFB's are small carbs and if you drive it easy you should be ok you just won't have the top end performance of an actual Fury 318. Set up the carbs for correct idle mixture using a Dwell Tachometer and a vacuum gauge set proper idle speed using the air bypass screws at the side of the carbs. Trim idle mixture on both carbs using the idle mixture screws. Check for correct base timing (5 degrees before top centre should work). Re-adjust idle speed if the timing has been adjusted any. All of this should work if your carbs are metering correctly, ensure your accelerator pumps are working and provide a good squirt of fuel . Check for Distributor vacuum advance operation after setting base timing at the damper using the timing light , as you bring up engine speed the timing mark should walk away from the timing plate... In all of this I'm hoping your distributor is in good shape and your breaker points are adjusted correctly (.017" ) and in good shape along with your spark plugs and wires etc. I've include pics of my Fury's engine for reference as well as a shot of the choke heat stove. Hope all this helps....
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Veteran
Posts: 201
Location: Fremantle, Western Australia, Australia | Thanks Everyone for your help, I will go to the workshop tomorrow and get the Carbs sorted out, and thanks to grunau for all that great info and photos thats really helped me a lot. Would someone know where I can get a choke heat Stove from because when I got this setup it didn't have that part. Cheers |
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Extreme Veteran
Posts: 444
Location: North of the 49th | Hi roblun!
More pictures for ya...keep in mind I did this engine about 16 years ago and I drive this car! The air cleaner wing nuts are Cal Custom pieces I had laying around and yes I added Chrome ...at the urging of my son. (:
Edited by grunau 2014-09-30 3:26 PM
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Expert 5K+
Posts: 8444
Location: Perth Australia | I think I have a stove here that you could copy, just not sure where it is (my carb has an electric choke)
Grunau
Looking at your linkage, I wonder if your getting full throttle on your front carby as well?
I thought for a progressive set up that the linkage pivot points for the 2 carbs had to be different, so the front carby opperated at a faster ramp speed than the rear, yours (like Robs) look to be in the same hole as each other.
I think the link for the carbs should be top hole on the rear and bottom hole on the front and you adjust the linkage so that when the rear carb is at WOT, the front one is as well, the rest (front opening time ect) looks after itself
Be good to know if I am wrong, because people can reference this in the future and these are great shots of a 2x4 poly setup
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Extreme Veteran
Posts: 444
Location: North of the 49th | ttotired - 2014-09-30 5:07 PM
Grunau
Looking at your linkage, I wonder if your getting full throttle on your front carby as well?
I thought for a progressive set up that the linkage pivot points for the 2 carbs had to be different, so the front carby opperated at a faster ramp speed than the rear, yours (like Robs) look to be in the same hole as each other.
I think the link for the carbs should be top hole on the rear and bottom hole on the front and you adjust the linkage so that when the rear carb is at WOT, the front one is as well, the rest (front opening time ect) looks after itself
Be good to know if I am wrong, because people can reference this in the future and these are great shots of a 2x4 poly setup
Hi ttotired
I should have discussed this whole thing with roblun in my instruction about Carburetor adjustment so we'll discuss it now... with the linkage pivot locations in either the upper or the lower positions (not mixed as what you had mentioned), WOT is possible on the front Carb when the rear carb is also WOT . But you need to consider the volumetric efficiency of the engine ; you have restrictive exhaust manifolds on the stock job along with the stock exhaust system and despite the marvels of mass production each camshaft is slightly different etc etc. Sooo... there is a difference between blind adjustment and tuning , with the service manual or the Carter info sheet giving you primary instruction the next step is real world performance and with that in mind things are "trimmed" or readjusted to suit the engine. With basic timing where you want it (slightly advanced or retarded depending on available Octane) considering that the Fury 318 is a 9.5 to 1 engine so its borderline as to it requiring premium fuel (timing can go 2 degrees advance or 2 degrees retard as an example) base idle speed and mixture are adjusted as I mentioned with two primary tools (Dwell Tach and a Vacuum gauge) You hit the road and see what it does... smooth steady acceleration is a goal as well as no significant "BOG" when you put your foot in it consider too that the WCFB has counterweighted "Velocity valves" on the secondary to assist in giving the engine only what it needs so if the front carb ends up not being at full WOT but your performance level is where it should be life is good close the hood and enjoy the ride. My Fury performs as it should with a timed top speed of 115 MPH which I figure is just fine considering the car has the aerodynamics of a Bungalow! The only reason why there are two four barrel carbs on this engine is that at the time a single carb was not available that could provide the fuel flow for the anticipated performance level. The Carter WCFB was superceeded by the AFB and the AFB by the AVS and then the final culmination the ThermoQuad.... |
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Expert 5K+
Posts: 8444
Location: Perth Australia | Geometry says that the pivots need to be mixed to get WOT
With the slot in the linkage, the front carby needs to ramp faster than the rear, because, the rear carb is already at a partial opening (lets say 1/4 throttle) before the front starts moving.
If you adjust the slot out of it, then it wouldnt matter which one (top or bottom), but would have to be either one (the same hole) on both carbs and they would then not be progressive
I have mine set up to work in unison right now, but will make them progressive again later
I have a bit more than a dwell/tach meter and I do understand tuning a bit, but I do have tuning issues with mine at this time, but its looking like a jetting problem, so I have a couple of carby calibration kits on the way, but yes, road performance is the best way to fine tune an engine
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Veteran
Posts: 201
Location: Fremantle, Western Australia, Australia | Thanks Granau for the photos and the info at least Ive got some references to work with and to Mick as well....Cheers |
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1958 plymouth 250 h.p. fury v8-318 2x4 carb specifications
