Since poking around my engine in the following threads:

https://www.ford-trucks.com/forums/1207258-head-case-air-injection-or-no.html

https://www.ford-trucks.com/forums/1213894-factory-hypereutectic-pistons-in-4-9-a.html

I’ve decided to yank the rest of my engine out of my truck and do a proper rebuild. I want to make a few improvements to the engine to make my big six even more reliable and to develop a little more power while I am at it. So, before I start ordering from my wish list, I’ve got a couple of questions for all of you regarding some of my selections. I’m going to make a couple of initial posts to make this thread a little more readable and easier to answer questions, which have been italicized.

To begin with, I have a 1996 F-150 4.9L SWB 5-speed 2WD with OBDII and MAF. I am planning on converting my truck over to a 4WD and will probably do so at the same time I'm rebuilding the engine. I will be running a 3.55LS rear and a 3.50 front when all is said and done. (I’ve only been able to find a 3.50 front in my area and I know these ratios should be fine with each other. If anyone in OK has a 3.54 front they would like to swap, I’m all ears!) I don’t tow a whole lot (but when I do it is usually a vehicle on a trailer), I don’t plan on playing Stomper with my truck while out and about in 4WD, and I’m not one to drive a truck like a car and I hate lugging my engines.


I have five areas that I have questions in:

1. MAF: The "Gold Standard"
2. Cam Selection
3. Piston Selection
4. Timing Gears
5. Other Modification Recommendations

Thank you all for reading and your inputs!

 

First of all, I understand I am rather limited to what modifications I can do to the engine because it is EFI and OBDII. 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 engines?

I've read over and over again on the limitations of SD on older EFI 4.9’s, but I haven’t found anywhere on FTE a list of the positive differences of why MAF is so much better AND a list of MAF friendly modifications. If MAF is the way to go, what are the best modifications for a MAF engine?

 

I’ve been reading about “computer friendly” cams on FTE. So far, I’ve found a really big thread on the Crane H-260-2 (503901) and a lot of people like it. Since doing a little homework on LSA’s and the like, it also seems that an Isky 256 Supercam or a Comp 260H High Energy would be good cam choices. I did read Isky’s article about split profile cams and I can honestly say my mostly stock application doesn’t really apply so a split profile isn’t out of the question. I do know that I’ll have to run a zinc additive and I’ve even read about machining groves in the lifter bores to aid in lubrication of the cam lobes. Does anyone have any experience with these cams and MAF? If so, what do you have, do you like it, and would you have picked something different? Should I have grooves machined in the lifter bores to help with cam life? Should the cam be installed straight up instead of how the factory installs it 4° retarded?

 

Since it is readily apparent that standard cast pistons should be avoided and hypereutectic pistons used in their place, I’ve easily made up my mind on that. I’ve been looking at Speed-Pro pistons as they have a good price compared to the equivalent Keith Black choices. The question I do have is about piston coatings. Is it worth the extra price to pay for the pistons with DurOshield coated skirts? In real world applications, does this coating hold up for 100k miles or more?

 

I know that steel timing gears are typically the way to go. However, considering I have an OBDII engine that has a knock sensor, this brings up a question. Am I able to run a steel/aluminum timing gear set? Will the steel/aluminum gears transmit undesirable vibrations and pulses that will affect the knock sensor and the computer?

 

For the rest of my build I’ve planned on using moly rings, a good set of lifters from whatever cam manufacture I finally decide on the standard Melling M74 oil pump, stock replacement rocker arms and push rods, stock injectors (cleaned and rebuilt, of course), new O2 sensors, and the stock exhaust for now. I’m retaining the EGR system and all of it is working properly. Down the road I will replace my cats and muffler for something a little freer flowing. I just picked up a remanufactured EFI head without air injection ports with a 3-angle valve job. Unfortunately, I wasn’t able to afford any P&P work. I’m going to retain my stock fan, fan clutch, and shroud for now – I’ve got the large 2 core radiator and I’m just not keen on switching over to an electric fan setup until my new engine has broken in.

What other modifications and/or performance parts should I consider while building my engine?

 

Because with a Mass Air Flow Sensor, it can ADAPT...

Simple as that..

It's actually metering airflow and making small, minut changes to the engines' running on an "As needed" basis...


Versus

Speed Density follows a given scalar of A/F Ratio's etc and will follow those until the engine dies out; Instead of adapting to keep the engine running, like MAF..

 

Thank you, Wesley.

Anyone else care to take a stab at my other questions?

 

I retimed my engine...

Found the Distributor Hold Down Clamp had loosened, allowing the Dizzy to retard back to 8* of timing, instead of 10*..

Retimed it to 12*, and could tell it had a lil extra "OOMPH" on the hills, etc...

Not saying it made it a racing engine....Just a good solid bump in power...

Timing is a BIG thing with the I6's...

 

Good tip; thank you.

 

Agreed, but you're over-stating the importance of that. A SD computer can adapt as well, just not to changes in VE like a MAF computer can. As such, there really isn't a significant value to swapping in a MAF setup for SD unless you are making a hardware change which will effect the VE. Indeed a cam change will do this, so in your case, a change-over may be warranted, but perhaps not if the cam is only a minor change from stock and is "computer friendly" as you've suggested.

 

I'm not seeing any validity here as it relates to breaking your engine in before switching to an electric fan. Now, while everything is out, is the optimal time to ditch the stock fan. That's what I did and have no regrets - I went with the 2 fan w/ shroud setup from a V6 Contour/Cougar. Bring your sawzall with you to the junkyard - it will make extraction much quicker.

 

I actually have the dual electric fan setup from the V6 Contour on hand in my garage and the higher output 130amp 3G alternator to go along with it. (I purchased these things to put on the 1983 F-150 that now belongs to my stepfather - see my signature.) My thoughts on not switching over at this time until the engine is broken in are for a margin of safety, which may or may not be imagined depending on one's view of mechanical vs. electric reliability. The PO overheated this engine I don't know how many times, hence the 5 cracks in the head, aftermarket temp gauge, and obvious head gasket replacement, and I just want to mitigate some risk. However, I'm not against making things easier while everything is already out of the truck.

Since I have A/C, I want to wire in a trigger from the A/C compressor to engage the fan assembly when the A/C is turned on, so that adds a bit of complexity to the whole set up. Do you have A/C, and if so, what did you do for wiring up your electric fan setup?

 

Do you see this changing the selection of cams that I've identified? Do you have any experience with any of them in a MAF situation or know someone who does?

 

No A/C on my truck but I figure you could hook it up one of two ways - simple manual switch that you activate from the cab or triggered from the clutch-engagement circuit.

For the coolant switch, I currently have one from a Jeep Grand Cherokee 5.9, but I need something with a higher strike temperature. The problem is that it comes on but never shuts off - as a result, I actually have it disconnected - figured I could stop and re-connect if I got into a situation where I needed it. Haven't yet, despite getting stuck in traffic while hauling a trailer - a new AL rad really keeps temps in check.

Plans are to install this switch (pulled from Explorer Forum)....

ok after some testing the switch that kicks on at 200-210 and off at 173 will work but runs all the time.the kick off is way to low.i went with a fan switch from a 84 tempo diesel,its 1/2 thread and said to kick on at 217 and or off at 192.i found it kicks on at 212 and off at 195.it works perfect and doesnt run the fan all the time.217 is a little higher than i would like but is a perfect temp for a dd.i also have an override switch in the cab so i can manually turn it on if i want to keep it cooler.i also used a relay for a 92 explorer blower motor,50 amp with 8 gauge wire and a 30 amp circuit breaker.

84 tempo deisel
advance:
tfs13p

autozone:
sw 532

napa:
fs 102