Here is what I am doing. I have a 1990 F250 4x4 with a 7.5l. I already have headers and true dual exhaust so I want to make it breathe better. My factory airbox is cracked and needs to be replaced. I have orderred the airfilter for a K&N cold air intake. Its costing me around $50.00. I used a K&N oil breather that replaces my factory oil cap by screwing into the oil cap hole. I plugged off the factory oil breather tube on the valvecover. Now I want to eliminate the plastic coupler that connects the hoses from the throttle body and the hoses from the airbox. The plastic coupler has a hose that connects to it from the plenum. The K&N filter has a nipple that I assume would have connected the oil breather. Here is my question; Am I correct in thinking I can eliminate that plastic spacer and run a hose from the plenum to the airfilter. I believe it will work that way but I would prefer some input on this. Thanks.

Rich

 

A picture would help!! Are talking about the helmholtz resonator for making the intake quiet? I would use the connection for the crankcase breather onthe new filter or else the unburnt fuel and acids and other crap might just sit in the motor and then condense back on your valvetrain and eat it up, You could leave the filler cap but at least hook up the one to suction out the bad stuff. What are planning on using to connect to the plenum to air filter? The thicker the material the better to prevent heating upthe intake air. If you could run it inside another pipe even to insulate it will
help. I would use some sort of barrier to keep engine heat away from the filter and use some dryer duct to bring cold air to the filter area, I have some in the bottom opening of my grille then it drops down a bit so water can settle there and drain out of small hole, then it goes up and is about 4 inches away from the stock filter box opening, Just to get some high pressure air to it but not bring all the junk directlyto the filter.

 

Yeah, I guess I would be refering to the helmholtz connector. I was going to eliminate that starting with two exhaust pipe couples (2.25 od). I was going to connext the pipe coming off of the plenum under the IAC to the nipple coming off of the K and N filter which is intended for the oil breather. I was thinking since I put the K and N breather cap on, I could elimintae the need for an oil breather hose ,and I could connect the plenum to the air filter instead.

This setup with the exhaust pipe couplers would be temporary. I have a customer that builds sick rx7 mazda's and custom makes his own parts. I was going to talk to him about building a nicer air intake system for my truck using the k and n filter.

I cut the baffles off of the helmhotz connector last year when I redid the upper end of my motor. Do you think I should just reinstall it or will the setup im prosing work?

 

..I would be refering to the helmholt connector as you said. I was going to eliminate it by using 2.25 od exhaust pipe couplers. I was going to keep the origional hoses for now. I was going to wrap them in a high heat insulating tape like for headers and intakes. I was going to use the nipple on the k&n filter to connect to the nipple on the plenum under the IAC.

Rich

 

It will just be a bit louder without it, I like the sound of a good breathing intake myself
especially when you punch it!! There are a bunch of k&n options out there head to the website you'll find something, make sure you isolate it from engine heat. I would be worried about deleting the crankcase breather completely you need at least one in the intake to remove the blowby out of the engine by suction, eventually it will rust the motor from within.

 

The blow-by should remove itself. Blow-by is pressure. You dont NEED it connected to the intake piping. There are lots of older cars and trucks that just have a small filter and nothing else.

 

Thats what I thought. I will let you know how it worksout. I will hopefully have pics to post too.

Rich