[scavenger]

Hi, all. I have some questions,What is the actual differance between the 6.9 and 7.3 cylinder heads, other than the head bolt holes? can a 6.9 be modified to work on a 7.3. also, I have a 7.3 that is giving me fits, at lite load it lopes at around 8-900 rpm.If I go heavy on the throttle, the lope goes away. It shows up a little in neutral. engine has 50.000 mi, new injectors, injection pump, fuel pump, timing has been checked 4 times, All this happens warm or cold. any help would be appreciated.

7.3 in a 73 f350, 3sp aux, dana 70u rear, soon to have an allison 545.

 

[KAAAB4]

Have you checked to see if air is entering the system?

 

[hesutton]

You could have a machine shop bore all the headbolt holes to 1/2inch but that will be expensive and they have to be careful not to screw it up. I wouldn't try to do this at home. The valve guides are different, but that won't make a difference with it woking on a 7.3.

What do you mean by "lopes"? I've only heard that term used to discribe an irregular idle on motors with large cams. At 800 to 900 rpm, I'm having a hard time picturing what the engine is doing in my empty little head. Is it missing, stalling, or ????? /ubbthreads/images/graemlins/shrug.gif

Heath

 

[scavenger]

The lope could allmost pass as a dead miss on 2 cylinders, haven,t been able to isolate which ones, tho.

 

[hesutton]

I don't know man. I have a feeling that one or more injectors (even new can be defective) may be the problem. It could also be the IP (again, new can have problems). /ubbthreads/images/graemlins/shrug.gif That's a tough problem. Sorry, but I'm at a loss. Hopefully, someone will be along with some better answers for you.

Heath

 

[agnem]

Get your injectors tested. New ones are just as suspect as old ones.

 

[Mike Lewis]

My truck has a similar issue to your lope. Dealer mechanic said not to worry about it... all IDIs do it to some degree.

Hmmmm....

I have noticed that the lope is more present some days than others. Today the truck had a bit of lope while I was stopped at a light. Yesterday the truck idled smooth as silk.

It seems to be related to how much I've been driving the truck. Yesterday I put about 15-20 miles on the truck, 2/3 of which were on the highway.

I think it is a small air leak since it seems to go away after several miles of highway driving...

Mike