The Inline Six Cylinder (4.9L 300CI)
 

I have sooo many concerns with this engine. I have a 1994 F150 XL with this monster of an engine in there and it runs great now after I redid the head, put all new gaskets on it, new manifolds, vacuum lines, and spark plugs. I also gave her a little color. I'll have pictures of my truck when I get a camera. The stupid cell phone isn't gonna cut it. Anyway, I just wana get some information on how I should go about getting performance out of this strong engine. I'd like to put a Thumper camshaft inner, get rid of the AC compressor, remove the smog pump, and the whole emission system. I know getting rid of all of that junk will take soo much strain off of that engine and give it a lot more power. I'd like to know some more about this engine! I have many questions and would appreciate if everyone reading this that knows a little about it can help me out. You can email me at Thrasher.Garrett@GMail.com. Thank you!

Given that the emissions system is functioning correctly, it will actually net MORE mpg's.....

-Wes

I don't think you will see all that much getting rid of emissions and and AC. I pulled the smog pump off of my 95 and noticed no change, just that it kept throwing the belt after that. In my opinion, removing the AC compressor will net some, but not really that much.

What type of exhaust manifold do you have, is it the one that has two sets of 3 that y together? If not, pick that up. Also, get copper plugs, and all new ignition parts, set the gap to .055" and advance the timing a few degrees.

I have two, three exhaust port manifolds. I would like to run true duels down this sucker one day. The two pipes come down about two feet and meet into a collecter. From there they come out as one and into the cat and then into the Cherrybomb I put on there. I am getting a whole new firing system today and thanks for the advice. I'm gonna take you up on the plugs and timing. How much more power is that gonna give me and will it give me a more meaty sound?

If you want to dump all the emission stuff which cause the ECU to have issues and go in to limp mode and hurt performance and MPGs.

The best thing to do is go back to the Duraspark 2 ignition and carb setup(pre 83). Get a Offenhouser or Clifford carb intake and go with a 4BB carb. Use the EFI exhaust manifolds as they are just as good as headers but with out the problems of headers.
With using a aggressive cam, the ECU will not adapt with it and will cause driveablity problems.
Once you have it tuned up(most important!) The 300 I6 will be a good preformer.

Here's a site for building up the Ford Big Block Six
FORDSIX PERFORMANCE • View forum - 240-300 "Big Block" Six Performance

Sounds like you have the better manifold already, which is good news.

The ignition changes wont make much of a change in sound, or at least they didn't for me, but the power difference was noticeable.I don't know what the HP difference would be for this change, but it's been tried by many truck and bronco guys and works quite well.

I found most of the power gain was in the low end, helping the truck pull through when I was lugging the engine. I didn't notice much when I had the pedal to the floor and had the motor revved up.

To convert to a carb, wouldn't I have to replace the fuel pumps and fuel lines? I've heard they use too much pressure for a carb.

I just put the manifolds on too. Me and my friend Mike are gonna replace the cap, rotor, coil, plugs, and wires today. We are gonna play with the timing too. I wana put high performance fuel injectors and a Thumper cam in there. How would that work out?

I don't know if the injecters will net you any gains, but I'm not an expert in that subject. Just to be clear, the ONLY plugs to run are motorcraft or autolite copper plugs. do not run platinum. Also, if you are going to gap the plugs out to .055", make sure you get high quality plug wires.

Bigger injectors won't really help at all on a near stock engine. I'm not familiar with the 300 cams available, but your best bet would be to go carb'd if you do a cam swap. I love fuel injection, but tunability just isn't there for this case, unless you can find someone out there that can do it. The biggest issue with any modification is tuning. If it's not tuned right, it'll probably run WORSE.

Getting rid of the emissions system and a/c alone won't really do anything either. The a/c compressor just acts as an idler pulley when they a/c is off. Most people get rid of this stuff for weight...which in a full size truck is not going to net much performance.

I'd start with the ignition system and go from there. For me, if I really wanted a well performing 300, I'd look at a turbo, or NO2 setup with carburation, but at that point you're looking at some $$$

91chevywt makes many good points here. When your car weighs 2000lb, loosing all of the ac components can make a big difference, but on a 5000lb truck, the only thing you will notice is how hot is today.

I don't know if they exist, but if you want to put in a hotter cam, it might be worth finding out if they ever made MAF 300's. the V8 guys do it all the time. late model 95 and 96 351 & 302 motors had this type of computer, which can handle engine mods much much better. If they ever used this in a 300, it would be great to put this system into your truck, then your fuel injection system can keep up with all sorts of mods.

I 2nd the turbo idea, that is a great way to wake up a 300.

A 300 I-6 is just that...A 300 I-6....You want tuneability and top end power; Go to a 4.6l.....You want low end reliability, and torque; Stay with the 300....

If you wanna keep the Speed Density, you'll have watch the lift on the cams....Too much lift, the factory computer will **** bricks.....You'll need either a QuarterHorse or Moates sysytem...($$$)....Or you can just swap it to MAF....You'll have your tuneability then....

But simply enough, a smidge lumpier cam, a ported head, and squaring the cylinder bores are good ways to get some extra oomph....

Here's a question: I talked to a former Ford Stealership mechanic, and he said simply advancing the dizzy will not do crap (His words were a bit more colorful), however, he said retarding the timing at the crank 4* will make more torque.....Kinda sounds legit, as ADVANCING the dizzy is actually turning the spark advance farther AWAY from the actual spark time.....Just from what little I know....But the 4* retarding is actually making everything run closer to the spark....Am I correct/Far off?

-Wes

Typically retarding the cam will boost high rpm power, while advancing the cam will give you more on the bottom end. My 2 cents.

My bad....Again, I am only human...Therefore prone to countless mistakes...lol

-Wes

Factory base timing is usually 10° BTDC. These trucks generally work their best at around 12° - 13° BTDC. These trucks are very unique because they are old enough to have a distributor but new enough to be computer controlled. These trucks, unlike chevy trucks, wont compensate for the base advance, because the computer has no way to tell if that you made a change. Just make sure you pull the SpOut connecter before adjusting timing.

For more info on how ingition timing effects power, check out this page: Fuel saving - a professional engineer's view

If you're lazy and don't want to read the whole thing, skip down to paragraph 5 where it starts out "The main driver for knock is..."