I don't have any specific experience with changing a cam on this engine. Generally speaking though, as long as you're not going with too radical of a cam, you'll be fine with the factory MAF setup.

 

No that's totally wrong actually, that particular EFI system is one of the most adaptable available, there's virtually no limit to what can be done to the engine with it.

Quote:

Originally Posted by Yaga1973

I understand the difference between Speed Density systems and Mass Air Flow systems. What I don’t understand and what I can’t find is this: Why is MAF regarded as the best system to have on these engine.

It's the most adaptable because it measures the air the engine is consuming in real time and does not depend on pre programmed volumetric tables to calculate fuel requirements.

 

MAF doesn't depend upon engine vacuum so cam choices are more open, you can even use non EFI grinds as long as it is compatable with your particular powertrain combo.

That's a new one on me and I'd have to say no don't do it.

Quote:

Originally Posted by Yaga1973

Should the cam be installed straight up instead of how the factory installs it 4° retarded?

Factory installs in straight up as far as I know and that's what I'd suggest you do.

 

On a low compression low rpm motor like the 4.9 I don't see cast pistons being a liability, and those fancy pistons coatings typically don't last very long so all of this is money wasted on a build like this IMO.

 

Timing gears have no effect on the knock sensor and billet steel is the most durable so that's what I'd suggest for this motor, I would never use aluminum or vinyl timing parts on an engine like this, steel double roller only.

 

A better cylinder head. The stock head is the main reason this motor doesn't make any horsepower and also why it falls well short of making as much torque as it should. A bigger cam will help fill the cylinders better but overall I don't see this motor making more than 200hp with the stock head on it, and that's pathetic for 300 cubic inches. Exhaust is another area all of these trucks suffer, get a header on there and lose the stock cats at your earliest convenience.

 

Here's my two cents, I just did a performance rebuild on my '96 F150 4.9 4x4.

1. Agree with previous posts, MAF is better. Direct metering of the airflow allows for more accurate fueling. I have no experience with speed density. If you have a programmable chip on the EEC, you can use any size MAF, any injectors, any cam, slap a turbo on it, whatever, with a tune you're good to go. The problem is that there's only a few people who have bothered to put a chip on this truck, so you're kind of on your own in figuring it out. The chip I used to tune and datalog is the Tweecer RT.

2. I used a Comp 268H. It's lopey, wants to idle at 900 RPM, needed a lot of tuning to smooth it out, and it's still kinda choppy. On the other hand, with my other mods, it pulls hard to 4800 rpm. You can get away with a 256 or 260 without a tune, but you won't make the power you could be making.

RE running more zinc on break-in, I used Quaker Defy, which comes with extra zinc. Might save you a few bucks. Grooves in the lifter bores, never heard of that, but a machinist would know. Finally, my Comp instruction sheet specified zero degrees for the 268H, and using other than new Comp lifters voids the warranty.

3. Cast pistons are not an issue with factory-ish power levels and rpm limit.
I used Keith Black hyper-eutectic pistons, moly rings, ARP rod bolts and head studs, and raised my rev limit to 5000 RPM to take advantage of the cam's powerband. I don't know about those coatings, seems like the construction of the pistons is more important IMHO. No experience with Speed-Pro, but the KBs are holding together nicely.

4. I used the steel timing gear, and my EEC hasn't pulled timing for knock that I'm aware of. Also, my truck already had a steel timing gear on it, FWIW.

5. All of that sounds good, should stay nice and quiet/stock sounding.

If you're handy with power/air tools you can P&P your own head. Information can be found on the FORDSIX forums about this. Major port reshaping was not recommended, all I did was smooth and polish the combustion chambers, remove sharp edges and casting flash, reduce the valve guide humps, blend the bowl-to-port transitions, and made sure the openings on my headers were bigger than the exhaust ports/intake ports bigger than the intake runner outlets. I used Comp heavy duty valve springs to go with my 268H - you don't need them with a 260H. Took me 12 hours in the shop total.

Agree with previous comment about adding up to 4 degrees of initial timing, either twist the dizzy/timing light, or if you have a chip, just change a 0 to a 4 under global spark adder and you're good to go.

I installed Hedman long tube headers, which means my smog stuff doesn't fit anymore other than some high flow cats. These were a bit of a headache for the minor performance gain they provide. They sound wicked, though. I used a Flowmaster 40 muffler, sounds OK, but not great - a little raspy.

Your stock injectors are going to be kinda close to being maxed out with the new cam - you might want to consider swapping in 19 lb mustang 302 or explorer injectors, and dropping the fuel pressure; google "Eddie's injector swap" about this one. With a chip, you can run stock fuel pressure and dial in the injectors perfectly.

3.55s are a good choice with the stock tire size. I also put a Detroit True-trac in my rear diff and lifted the front end 2 inches on springs to help with carrying a winch.

Other things that go well with a cam upgrade are raising compression/possibly running premium fuel, and a high-stall torque converter. Totally unnecessary with a mild cam, though, and you've got a manual. Seems like your main concern is about the 256/260 being compatible with the stock tune in the computer - I'm 99% sure you won't have any problems. You can always buy a chip or pay someone to tune it later, if you want to get the maximum performance out of it.

Overall, in my truck it's nice to blast to 75 mph in second gear on the uphill onramp near my house, and towing snowmobiles uphill is much easier in 3rd.
Fuel economy, well it wasn't great to begin with on 33 inch tires, I went from 16 to 14 - partly because if I have more power, I use more of it. No regrets, though, it's not my DD, have an efficient little BMW for that.

 

268H is too much cam for this motor with a stock head IMO, a 250 something degree would be more suitable for what's gonna be an airflow limited 0-4000prm powerband.

And 75mph in 2nd gear? Sounds like you need a gear change.

 

Agreed, I wouldn't have put the 268H in without the P&P head, longtube headers, high flow cats and such. The 268 does shift the powerband upwards due to the valve timing - I don't understand the details of how that works, though. Just trying to give Yaga some ideas about what else can be done for more N/A power.

I thought about putting in shorter gears with the 33s, but I usually swap on another set of wheels with smaller tires in the summer. My truck has the 4 speed automatic, so it's probably taller in 2nd than a 5 speed manual. I'll probably go back to 31" winter tires to save some gas after these tires are done for.

 

Hey guys, I've been off the grid for the weekend. Thank you for all of the replies.

So, I agree that the 268H cam would be a little aggressive for my build. Do any of you have any experience with the Crane 503901 grind (besides the 503901 thread https://www.ford-trucks.com/forums/5...installed.html)? Since you all mention the stock limitations regarding the flow characteristics of the head in stock form, I would think that a dual pattern grind would help out and the 112° LSA would be idle and comp friendly. Even so, I would probably want to advance the cam 4° to bring the power band down just a bit. (I could go with the Crane 500511 grind, but it costs about $100 more than the 503901.) In all honesty, I can’t afford to have a good P&P job done on the head and I’ve never done that type of work myself. Unfortunately, I don’t have any of the tools to do the job myself. The only thing I have is a Dremel tool and I’m sure it wouldn’t like performing a clean-up job on a head.

Cloyes 2764S – This all steel gear set is only listed up to 1983 applications on the Cloyes website. If I search for year specific on my engine, the fiber set comes up, which is not a surprise. Searching on Summit’s website yields a Cloyes 8-1014 gear set that has an aluminum cam gear and a steel crankshaft gear with three keyways on it for plus/minus 4° of cam timing. The Cloyes 8-1014 gear set can only be found in their Performance Application PDF Catalog and they only have a steel crank gear and aluminum cam gear set available – there is no choice between all steel and the steel/aluminum setup UNLESS you search for 1983 and earlier stock application. Summit does list a gear set from Comp Cams that is all steel (3224), but I haven’t heard anything regarding the quality of Comp Cam timing gear sets. Obviously, I really don’t want the stock fiber gear set, but I am unsure if I should order the Cloyes 8-1014 set on Summit’s website ($92.95), the Cloyes 2764S set from another supplier ($46.99 from O’ Reilly’s), or the Comp Cam 3224 set from Summit ($59.95).

However, if I did decide to run the adjustable Cloyes 8-1014 gear set, I would be able to install my cam 4° advanced to lower the power band just a bit (leaning heavily towards the Crane 503901). I will have 3.55s in the rear end when all is said and done, and with 31” tires and my M5R2 in OD, I’ll have a cruise RPM of 1907 at 65 MPH and 2200 at 75 MPH. The Crane 503901 has an advertised 2200-2600 cruise RPM and that is obviously a little high for my application and if I advance the cam 4°, the power band should move down 200 RPM (if I remember correctly), and that will still be good for towing in 4th at 65 MPH as I should be hovering around 2542 RPM, according to the calculator on Calculators (ringpinion.com).

Because of the horror stories of stock cast pistons losing their skirts (usually a good thing but not in this application), I have no problem using hypereutectic pistons as they really don't cost much more than cast anymore. I'm undecided on the Duroshield coating, but I'm leaning towards putting my money to good use somewhere else as the difference between coated and non-coated piston set is about $40.

 

Sounds like you've done your homework. I used the Comp steel timing gears, no issues with quality, but no adjustments to cam timing are possible. Some people say the metal gear sets are noisier than the fiber ones, but I'd much rather have a louder, reliable engine than a quiet, unreliable one. Cloyes has a good reputation, you'll probably be fine either way.

There's a weak cast metal thrust plate (and maybe a spacer too?) that fits on the cam under the gear and bolts to the block - If I recall you have to pull the old cam gear off to retrieve it, and I broke it trying to get the gear off. Since you're putting a new gear on a new cam, I'd order a new thrust plate for $10 beforehand, and not even mess with pulling the old gear off. Here's where I got mine:

Ford 240 300 4.9 liter 6 cylinder engines Cylinder head bolts / fasteners

 

You're correct on both counts. When I built the 300 for my 1983, I simply replaced the thrust plate and spacer and didn't even bother with trying to remove it from behind the cam gear. Like others experienced, the fiber gear assembly simply broke apart when I tried to remove it with a puller. To make things even better, I had to finish the job (breaking off the cam gear from the steel hub) so I could gain access to the cam retainer bolts as I wasn't able to quite get to them through the holes in the cam gear. That was frustrating!

 

Ah, I didn't realize you'd already built a 300 once before. Must be nice to know beforehand what you're getting into. Good luck with your build!

-Coder

 

I just went back to stock fan clutch on my 94 F-150. Electric fans didn't produce any tangible improvements. Well, no fan noise at startup....but the mpg didn't really improve and the fans crapped out after about 10K+ miles. If you look at a Contour sites posting, that was an issue with them. Cooling issues. D'uh!

My brother has Taurus electric fans on his 79. It's bigger, but no issues for him.

Small sample, but something to consider and/or be prepared for if you do swap out your fans.

 

Thank you for that info, Jonas.