OK so I need some help. I have come across an 88 f150 4x4 with a 351. the motor has issues so im going to rebuild it. i want to put a cam that can be noticed when idling, but how big of a cam can i go before having to modify heads? oh and this motor is stock so any suggestions would be appreciated. thanks

 

Anything with a noticeable idle will run like crap because the EFI system cannot compensate for a cam like that.

 

I'm sorry I wasn't a little more specific earlier. The 351 was actually a swap out so the engine actually has a carb