hi all, I have a 74 F600 with a year unknown 460 in it.. I would say it's between 76-79.. Anyway.. It had the stock Motorcraft 4350 on it and it was running VERY rich, and was blowing flames out of the exhaust. I decided to replace the 4350 with an Edelbrock 1407 750 CFM carburetor.. It runs much better now but doesn't seem to accelerate like it used to. When I step on it, it lets out a loud moan and just takes it's sweet time getting upto speed. It feels like it's stuck in a higher gear. I even put the trans into 1st and shifted it manually from 1st to 2nd, to "D".. same problem. It also will not crank up while climbing hills, i floor it and feel the trans downshift, and all it does is speed the engine up, and not the truck. Is there something that I need to reconfigure on the new carburetor?

 

Out of curiouity have you checked your timing? I would say it's safe to say that the carb swap has isolated the fuel delivery. Blowing flames out of the exhaust would suggest that the timing is way off from where it should be. Before you use a timing light though pull your spark plugs out, take off the distributor cap off, rotate the engine with a braker bar and socket on the crank then go the other way and check to see if your timing chain is worn out. While the plugs are out check the compression on all the cylinders. If they are all OK, reinstall the spark plugs and check for timing with a light. If the timing is still around where it should be lets move on. You didn't mention if you have a EGR valve on it or not. If you do try to move the diaphram with your finger through the back of the housing. They sometimes stick from carbon build up on the plunger.

For the engine reving up but not moving the truck any quicker check to see that you have the correct amount of fluid in the tranny. Low fluid will allow the tranny to slip like it's cool. Let us know if anything was out of specs and helped.

 

mebe2k

Also make sure the secondaries are actually opening up. When I installed a 1411 Edelbrock on my 460 the carb mounting gasket caught the edge of the secondaries and would not let them open. When I finally figured out what was going on I just loosened the carb and shifted it a bit while holding the secondary butterflies open, then tightened it.

I am not saying this is your problem, just throwing it out there as something to check.

 

Hi and thanks for your replies.
I checked the timing and it was at 10 degrees BTDC/w the vac. line disconnected and plugged, i have not checked the compression or the timing chain yet.. The engine isn't equipped with EGR.. I also checked to make sure the secondaries were opening like Superdave said and they are.

It always ran pretty rich with the old carburetor, but accellerated very well. Until about 3/4 way through Ohio it decided that it wouldn't run with the air cleaner in place. I could'nt get it to idle with or without the air cleaner. After that it would hesitate, and it was sucking gas like it was free... anyway, I had to speed up to get out of the way of a truck entering the highway, I stomped on the gas, it hesitated VERY bad and backfired a couple times (exhaust) after that it ran VERY VERY badly..I decided to rebuild the old 4350 carburetor as that was cheaper than buying a new one. I also replaced the spark plugs, and the dist cap/rotor. After the rebuild I noticed the flames shooting out of the exhaust. That is what prompted me to go for the edelbrock carb.
I wonder if I screwed something up when I floored it to get out of the way of the 18 wheeler entering the highway.. Because after that, it ran terribly with barely any power..

 

With all of that said you definately need to look at your timing set and a compression test to make sure you didn't torch your valves. You jumped timing if I had to bet the farm on it. I would honestly pull the timing cover at this point and check to make sure my timing marks are aligned correctly. You'll be luck if you didn't damage any of the valves when it was blowing flames out of the exhaust.