Make sure the cams you choose work with speed density, many big cams only work with mass air.

 

Well I hate to rain on your parade but there is really no cam that will work with the speed density injection system...actually they will "work" but you wont get the horsepower your hoping for without converting to the mass air system. Any kind of engine modifications on these engines almost require the conversion. You'll just run rich...speed density has no modification built into it whatsoever so your kind of SOL when it comes to putting bigger cams or anything like that in. I did the same to my truck... an 89 150 with a 5.8, and put a comp cam in and ran with the speed density for 10000 miles. But its always ran rich, it ran better....but now that I've got the maf conversion done....its like a new truck.

 

speed density and mass air how do you know if you got speed density im sure i got mas air ? and comp sells a cam for 200 but you have to buy new lifters thats 80 plus new springs thats 80 and retainers for 40 so 400 dollars for a cam plus you got to replace the seals for the front and top of the engine . . . and you have to make sure you have either flat tapped or roller cause there not interchangeble i was told i had roller in my a7 302 turns out its actualy flat tapped roller existid but on some engines i believe the HO is roller so unless you have a roller i wouldnt get that cam! you cant use the factory lifters unless there roller when you put a cam in you change the lifters and you will have to get stiffer springs good luck

Tom

 

dont mean to hijack the thread, but who makes a good mass air conversion.

 

Well undoubtedly you have speed density....unless someone converted it already, 86 to 93 trucks have the speed density system. You can easily tell by looking at your intake tube from your air filter and see if theres a big aluminum housing that has a sensor on it. Thats your mass air sensor. If you dont have that your speed density. Anytime you put a new cam into something...always put a new set of matching lifters. Chances are your engine isnt a roller motor, as far as I know only the mustang HO motors were. But I have been wrong before. Really the only positive way to know is tare it down and see before you order anything.


As for a mass air conversion...I used massair.com. They hand build every harness that gets orderd, and it comes as a kit with everything you will need to do the conversion. Ford racing discontinued there mass air conversion...which was a huge mistake if you ask me. Their kit was wayyy cheaper like 700 bucks vs. 1500 for the massair.com kit.

 

well my 1991 5.8 has the two separant air tubes. would that speed density also. there isnt any sesors on the intake tubes any where. ive got a prime performance short block asembley. .040 over, fordge pistons, balnced crank and rods, compcam extreme 4x4 camshaft, comp lifters, proform 1.6 roller rockers, full msd ignition w/ a 6al box. i should be able to tell that ive got a mildly build motor with the cam i have. rough idle ya know. i canit tell anything. i called jegs and talked to them about it and they said the only way to get the rough idle is to covert over to a mass air system. is that correct? thanks

 

They are right....and you do have speed density. It also depends on how big the cam is you put in, that'll depend on whether you have a rough idle or not. I didnt go to wild with my 5.8 and it runs damn good. I've got a 94 F250 service truck with a 5.8 and my truck will eat that thing for lunch. If I had the money I;d just buy an edlebrock stroked 5.8 thats 450 horse....I wish.

 

where is the speed density sensor located

 

Well there isnt actually a "speed density" sensor itself....its just the combination and the way that it works, these systems fire 2 banks of 4 injectors at a time and use the map sensor to measure engine vac. and the intake charge temp. Theres just no actual measurement of air going into the engine. Now I could be wrong if someone else reads this and I'm wrong go ahead and correct me, thats just what I've learned on my own.