I just installed a rebuild 300 into my 84 f150. When it idles it is fine. When I give it gas in neutral or with the clutch in it revs great. But when I go to take off it just falls on its face, and then after a minute and then it will take off untill I shift again and it starts all over. And it is gutless also. It won' keep it's speed up at all. Motor in stock except for offy intake, and efi exhaust. Also has an edelbrock 500 carb. The motor I pulled ran good with this setup. But it was an efi block with an electric fuel pump. I have the mechanical on hooked up now.

anyone have any ideas?

 

Each motor even built with the same parts needs to be "tuned" a little bit differently.
First 2 things I would check is fuel psi. Is it what the carb calls for? I hear Edel. carbs like a little lower psi thanother carbs.
The other is the accel pump squirter lack there of. Oh maybe the float level as that can play into the pump squirt.


What is the timing set to? I am thinking it could use a little more. So if say it is at 8* BTDC bump it up to 10* BTDC and see how it runs.


I am not a big fan of a v4 carb on a L6 motor just for the reasons you have and even more so if it is all stock.
Dave ----

 

What have you done to check it? It's not hard to check the fuel pump for output and another good idea is to use a vacuum pump and catch jar at on the fuel line going to the tank. Often a rubber hose rots and allows the pump to suck air, which you would see as bubbles in the catch jar. If you don't have a vacuum pump kit, go get one. You can't diagnose and tune a carburated engine without this tool. They are cheap. Mighty-vac makes a good hobbiest quality kit, sold in any parts store.
Also, are you trying to pull fuel through the old electric pump with a mechanical pump? This might be a problem.

 

I'l look at it tonight when I get home. It' only running thru the mechanical pump. I took the electric one off. I'm starting to think it' more to do with timing. Maybe it does need a little more advance, maybe I had a plug foul out on me..

 

If the previous engine was an EFI block [and head?], the EFI head has fast burn characteristics, requiring less overall timing. If the present engine does not have the same head and has been set to the same initial timing, then that might explain the need for more advanced initial timing.

 

Make sure your distributor is advancing. I had those exact symptoms on my old 300 when the vacuum advance hose fell off.

 

I fiddled with it for a few hours last night. Nothing I did really helped any

when I have it setting on tdc on the compression stroke where should my distributor be pointing? And would it be possible for the cam timing to be off and it still run?

 

Eddy carbs don't like more that 7 psi, get a fuel pressure regulator and see.

 

I have my regulator set to 5 psi.

It's idling great and it revs great. But when you take off it is really sluggish and then it will take off. 2nd and 3rd gears are better than 4th. When I shift to 4th I can barely hold my speed and I really cant accelerate. If i have any incline i can barely make it up it. Im having to put it in 1st just to get up my drive way.

 

It is strange other than a motor change this happens with everything else the same.
Why was the motor swapped?
Did you build this motor or you bought it and if bought it short or long block?
If I had to guess it is something with the cam or cam setup as that is all I could think it could be.
Well compression lower on this motor could cause it too.
Dave ----

 

The other engine had a bearing go bad and chewed up the crank. It's all the same but the engine. I'm really starting to think the cam may be out of time. But the think will run like a scalded dog once it gets going in 2nd and 3rd

 

Okay, but have you checked the actual fuel pressure, as others have previously suggested? There is absolutely no guarantee your regulator is accurate. I'd hate to see you chasing your tail with other possibilities, when the root cause could be as simple as a fuel delivery issue. In addition to pressure, you'll also want to check the delivery volume, too.

 

but he said it runs good once he is in 2nd or 3rd gear where it would want more fuel.
It is when he is trying to take off from a stop I am guessing.
Dave ----

 

It's is the initial takeoff. Once I'm going good in second it runs great. If I can shift quick enough and keep the rpm's up in 3rd then i can run third out good too. But once I get into 4th it's terrible. I can't accelerate and it just Boggs down if I try to get hard into it. And if I have any type of hill then I can forget about it. My drive way is maybe 35 degree slope, and I have to be in first to make it up it. Which is a granny first(np435).

 

I have a pressure gauge. I'll throw it on it tomorrow just to make sure. Gonna double check everything again before I pull the timing cover to see if they are out of time.