91 F250 5.8 EFI

[plowboy34]

I bought a 91 F250 truck, really didn't want to since it only had a 5.8. I like the BIG BLOCKS in my work trucks but this thing only had 86,000 miles, rides and drives quieter than any work truck I've ever had. Now to the question, this thing is just a little to doggy for me and I am about ready to yank the injection off, put the 69 heads I have on with a good low end cam and carb this bad boy. Then I wondered if Ford ever put mass air on any of it's 5.8 F250 trucks. I was hoping maybe someone here would know, cause if they did I believe I would rather go that route but I have to do something to up the power in this thing. The way it is now is never gonna get'er done here on the farm.

[cgrey8]

The 5.8Ls suffered from a very crappy cam and a mild tune. The intake is OK, nothing to brag about, and the head as you know are E7s so they are probably better than the 69s so many people are fond of. Those 69 heads had their place in history and in history they were far better on 289s than larger CIDs. Since you have experience with porting E7s, I'd say port what's on them OR get some GT40/GT40p heads.

And if it is a roller block, there are a number of good torque cams out there FAR FAR better than what Ford put into any of their trucks including the Lightnings.

Now that being said, the answer to your question is yes Ford had 2 5.8L MAF setups that I'm aware of (could've been more). The 5.8L Lightnings and the 5.8L Cobra Rs are the most notable. The Lightnings early on were SD, but eventually went MAF and are the source of the infamous 90mm Lightning MAFs that people find so nice because of their low airflow resistance and affordable price. I believe it is the same 90mm MAF used on some Cobras.

So while your engine can be converted to MAF, I don't know that it is worth the effort. I have no clue what all goes into doing a MAF conversion on an SD setup. It could be just as simple as running the MAF lines to the EEC and connecting everything else up like it currently is. Or it could be a fair amount of repinning of the 60pin EEC connector which would require wiring diagrams of both your existing EEC and the new replacement. If it were me, I'd be doing that. But I'm very fond of injection and I know the Ford 89-93 Mustang EEC very well...and I'd be tuning it using a datalogger. For those that aren't that interested in EFI and DIY tuning, and rather prefer carbs, I have to admit it is simpler.

Although if you want to keep the SD system, RM Competition makes a cam specifically designed for SD Trucks and boosts their output considerably.
RM Competition Custom Grind Cams

These cams have been honed to work with SD systems while boosting power with only minor changes to the fuel pressure required to get them dialed in and possibly a twist of the dizzy for good measure. They have a high lift, but they are within the limits of stock hardware. Although the high lift does "beg" that you replace the rockers with rollers if that is in the budget. Although as a truck engine, you likely won't be reving this thing to valve float so stock equipment might be just fine.

Even if you don't keep the EFI, this cam of his is still quite a performer with carbs and with SD out of the mix, you can get more gains by advancing the cam 4-6°.

[plowboy34]

Hey Chris, Thanks for the heads up on RM competition, I never knew you could do anything with the speed density system. I contacted him and he thinks he can help me quite a bit. I was impressed with what he had to say. I can't believe I forgot about the Lightnings, talk about a "Duh Huh" moment. I wouldn't mind doing a mass air and start learning this stuff a little better but with what the RM comp guy said I believe I might just go that way on the work truck and save the learning curve for a real Hot Rod. Again thanks on that.

As for the 69 heads and the E7's I'll take the 69 heads. Much better intake runners and I believe bigger valves, not 100% on that but if memory(although that has been drug fried from the young and dumb day's) serves me correctly I believe so. I actually like the 289 heads in the day. You did have to do quite a bit of port work but the combustion chamber was much smaller to help keep compression up. I had a set that would flow and run like a raped ape but I ruined like four heads getting them to that point. I would port into water passages trying to get as much as possible. We started cutting these things in half both way's to figure how much we could shave. It was insane but we had a lot of fun.

[cgrey8]

Let Randy know it was me that sent you to him. He spent a LOT of time with me when I was talking about doing a 331 back a few years ago. He finally gave up on me and as it turns out, I had so much time to research the build, that I found buying a kit over the Interent would possibly cause me more issues than working closely with a good machinist. So I'll most likely buy my kit from the machinist. I had full intentions of buying one of those cams of his, but Adam McLaughlin wound up giving me a Crane Powermax 2020 which is a VERY close derivative to his cams so I couldn't justify buying it. But I do feel better knowing I could send him some business even if I wasn't his business.

As for those heads of yours, I have never looked at the 69 heads so I can't say anything other than what I've heard about them. But if they have larger valves than the E7s, then they have more HP potential particularly when ported. But for a high torque engine, not a high HP engine, the standard things you need to look for in a head are not the same as if you were building a 289 high RPM screamer. High torque isn't gotten from huge chambers and large valves. Those things support big flow at high RPMs. At low RPMs, the cam, intake, and displacement are the prime movers...and bigger ports can hurt torque more than help it. What also has some influence on torque performance is quench, swirl, and tumble. Tight quench will let you run higher compression to get more torque while running lower grade gas. Swirl and tumble are things that the combustion chamber design can help with to help further atomize the fuel into the air before the spark ignites it. Quench, swirl, and tumble are the things that E7s and the various GT40 heads do pretty well when everything else is setup right (deck height, compression ratio, quench, etc). My guess though is you aren't looking to get a Ph.D. trying to do what should be bolt-on upgrades. So I won't bore you further. But if you want to discuss it further, I'd need more details about the 69 heads like chamber shape and chamber volume. Overall though, I think the biggest upgrade is going to be getting Randy's cam. Regardless, I'd like to see some pics of those infamous heads...specifically the combustion chambers.

[cgrey8]

Are these the 69 heads?


If so, I see why they are so famed. They are very similar in design to the E7 and GT40 head chambers. Although the valves could really benefit from being unshrouded on the edges.

[plowboy34]

Chris, Chris, Chris, you want me to send pics on the puter. My kids moved to NC dude.....lol. I'll see what I can do, I did it once a while back but didn't know what I did. Also though I was on phone lined then and now have broadband so that may help.

[cgrey8]

Also the forum lets you upload pics directly to the forum now as opposed to the way it used to be years ago.

Worst case scenario, email them to me and I'll get them posted...or find some websites on the Internet that already show the chambers and facts about them.

BTW, you did see I had a post above the big-huge pic that posted in right?

[plowboy34]

Yes I seen the post above the pic, that's how I knew you wanted to see a pic of the heads.

So to post a pic do I click the Img button then insert pic.

[cgrey8]

You don't mess with the IMG buttons anymore. Just browse to the pic on your PC using the browse button below where you type a response. Then click the Add the File button to actually upload the pic.