I need some advice,
I have replaced the timing chain, water pump, Egr, radiator, plug wires, plugs, distr. cap and button, coil and many more items.
The problem I'm having is the 351 seems to bog when I first take off. As the rpm increases you feel the engine slightly surge with power and then the tranny shifts and it seems to bog again.
Not sure what to do now.
The 351 idles smooth, cranks everytime.
I do have a leaking Egr tube but not sure how to get to it to change it out.
Would that make it bog?
I also need to change out the smog pump it locked up and I bypassed it with a shorter belt.

The van needs to be able to pull my camper and its 4435 lbs.
Not sure if it will do it in this condition.
Thanks

 

have you verified timing and vacuum?

 

Interesting about the smog pump, the vacuum operated valves that control air pump system are still working but without air pressure from the pump, the operation of the engine under load could be affected. Smog stuff is mostly off at idle.

 

Any codes present? Doesn't matter of the check engine light is on or not.
Does the motor stumble right at throttle tip in? If so that indicates a vacuum leak.
Does the trans seem to upshift unusually early or about when it should?

EGR tube is right on the front of the motor, is that the one leaking or is it the one at the back? That is an air injection line. A leaking EGR tube will let fresh air in where there should be none, and that can cause a high idle or other problems but it won't cause a stumble. A leak in the air injection system will cause the engine to run lean after it reaches closed loop so that is more significant, and the clue is if the stumble problem is not present when the motor is stone cold but appears after it warms up.

 

Thanks for the help guys,
No I haven't verified the timing or vacuum.
Any pointers on how, I'm out of practice and getting close to my knowledge.

I plan to replace the smog pump but money has been tight.
But that will effect the pulling power?

 

Conanski,
I need to check for codes.
It does stumble from idle if you punch the throttle,
The trans shifts good, Id say where it should.
I did notice sometimes it doesn't like to drop down if you punch it.
But actually I think it's doing good.

 

Meantime, you could remove and gut the vanes from the smog pump and reinstall it with the correct belt. Plug the vacuum lines going to the TAD and TAB valves. That would remove the smog pump operation. Look for a vacuum routing sticker under the hood like this:

 

You said you replaced the timing chain, did that include new gears, and if so, did you line them up dot over dot? If so, and you didn't retard the cam by being off on your dots, you warm engine, plus any vacuum advance line from carb to distributor on the carb side, and point timing light down at pass side of van towards pointy end of timing tab (which is near crank), and if you've marked 10 degrees BTDC on your harmonic balancer in advance, keep turning the distributor until your line matches up with the timing tab pointer in the strobe of your timing light. Harbor Freight sells an inexpensive vacuum gauge you connect to a vacuum port on your intake and you hope to see a fairly solid needle and hopefully as close to 20" vacuum as you can get, which is affected by vacuum leaks, timing, fuel mixture.

 

I meant to type "plug", or cap with a rubber vacuum cap, any vacuum source from carb to distributor.