Hi everyone,
I'm new to this site, this is my first Ford Truck. I have a 1984 F700 4X4 dump truck. It has 12,000 miles on it but it was sitting for 6 years. NO POWER! It has compression between 158-160 psi in all cylinders and runs fine until the rpm's get up there. It starts popping rythmicaly through the carb (holley 4190) I suspect valve float/worn lobe. (slight clicking on pass side)
Vacuum is steady at idle around 16 in. no bounce in the needle.
Timing is as per sticker on valve cover.

My questions are: Is this 429 like any other 429? Is it an FE, 385 ...etc?
I purchased a speed pro cam and lifters from Northern auto as well as valve springs. The guy on the phone said he could not find any difference from truck to non truck engine.
cam site:
Speed Pro performance camshafts for Ford 429 - 460


ANy help would be awesome guys
Thanks,
Alex

 

Welcome to FTE!

First, the 429 "Lima" is a 385, same as 370/460 as far as the basics of the block and the bell pattern.

"runs fine until the rpm's get up there."Define "up there". Over 3500 rpm?

You could compare the pushrod/rocker travel from one cylinder to the next with the valve covers off. That might confirm one or more rounded lobes methinks.

 

Sorry it happens around 2,000 rpms. According to the manuals, redline is 3400 rpms.

 

I think it sounds like it is starving for fuel....when you start reving it up like you say.

Th cam you listed is a lot like the stock cam. if you think it has wiped a lobe pull the valve cover(s) and start it up. all rockers should move about the same amount. if you have one parked and it is somewhat still set right, then the lobe is gone.

 

With 12k miles on the engine cant be to much wrong with it,,,,other then sitting,,,should be like new!

Have you changed fuel filter,,
Installed New plugs,,,Some ford engines are finicky about plugs,,need the right ones,,
carb been cleaned,,,
what about ignition,, cap, wires, rotor, etc,,,have fun should be a nice truck,,,4x4 and all !

 

Filter changed, new cap rotor wires plugs fuel pump and carb rebuilt. I will check the lobes next. Also I was told by a local that if you do cam work you need to add zinc for cam breakin is that true?

 

From your description it sounds like lean missfire which can also pop back through the intake. Does it do this when you rev up the engine while in neutral as well, or only while driving?

I realize on that truck it's probably really hard to get to the engine, but one way to check for a lean mixture is to partially close the choke and then see if the problem is still there (just because the carburetor has been rebuilt doesn't mean it still couldn't have an issue).

If it's an automatic choke, you can either loosen the screws on the choke spring housing and rotate it to close the choke, or wire the mechanism partially closed (or if it will do it in neutral and you can get into the engine compartment, use one hand to hold choke lever and other to rev up the motor, being very careful to not be over the top of the carb if the air cleaner is off in case it pops back at you).

If you have any means of monitoring your firing voltages (they make clamp-on portable KV testers which are very useful, I have one and use it quite often), a lean mixture will cause very high firing voltages.

If you do find out that it is lean, next step is to figure out why. Your high speed and/or power circuits in the carb may not be working properly. Or, you could have low fuel pressure (put gauge right at carb inlet and check at high rpms). Or the float level could be set too low.

On the ignition side, you could have a weak spark which manifests itself at higher engine RPMs (higher load on the ignition system).

Keep at it, it's something simple, you haven't found it yet but you will. If it was a newer truck, you'd be at the service counter right now writing out a big check, so be thankful you've got a simple engine to work on.

 

Thanks guys. I will be trying these things Monday. I'm on the road as the user name implies. Will keep everyone posted.

 

dumb thought , setting for 6 years , did you check for squirrel , rats nest inside the exhaust ? all the filters should be changed , fuel , oil air ! and did you put new gas in the tank ? hows the emission stuff , the clicking could be an exhaust leak !

 

It's been raining here so no time for truck. I will keep you guys posted. Thanks
Alex

 

Verdict:
Added a GM HEI converted for Ford. Awesome piece! all the wires (minus duraspark ****box) simple hookup well worth the 50 bucks on Ebay. Pulled the valve covers off and sure enough, number 4exhaust valve barely opening and, #4 intake valve pushrod bent?!?!?! Bottom of exhaust lifter was concave (badly)
Swapped the cam, chain, lifters, pushrods and fired right up. Broke the cam in and now idles like a dream and nice smooth acceleration. pulls pretty good for 14,000 lbs empty.
One last question fellas,
there is no sticker on the valve cover... any ideas on timing? Base and total??

Thanks in advance to al you guys.
Alex

 

I've been fighting a similar issue. Runs rough, backfire, bogging. After a month and replacing ignition components and rebuilding the carb I pulled it apart to check the timing on a Cloyes gear set I put in last summer. The chain had 1/2" of play, distributer gear slightly worn and the front cam (iron) lobes are showing porosity. Guess who is doing the top end hoping the bottom end doesn't fall apart.