I have a 68 with a 351 w. I swapped the stock air filter housing with a open chrome one. Now have a lag at acceleration that was not there before. Any ideas as to what might be going on? I checked the throttle linkage and it is not hanging up so I am stumped. Thanks

 

Did you disturb any of the vacuum lines going to the carb? Or maybe a plug wire?

 

You may have been running slightly lean and the much less restrictive air cleaner made it much more so. I think a good carb tune is in order.

 

Will do. That is what I originally thought. Thanks

 

yep, it may need more jet,pump shot,powervalve etc.....try bumping the timing about 2-5 degs, if it gets worse you need more fuel.

 

Might want to make sure the accelerator pump is working... might just be a coincidence..

 

imma have to agree with the others i would suggest the acc. pump not working properly.

 

AHHHHH so that is what a 351W will look like in my 67, fits pretty decent.

 

It may be lean because if you are running gas that has ethanol the float valve is breaking down, and or, the carb jets need to be increased in volume because of the effects of the ethanol. I just read this months edition of Mustang Monthly and it goes on about the eefects of ethanol in our older cars. It struck me because my 70 Mach 1 has been giving me fits recently with "stuck" floats and abnormal atomization from the jets. I'm betting that ethanol is the culprit. The article recommends changing out the float valve every 6 months. Either that or drive the car everyday. I know I have lost about 3 miles per gallon in my vehicles since the introduction of ethanol. It makes sense that the only vehicle suffering performance effects is the one that "sits" in the garage most of the time. Up until now, I've never had a problem.