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kee 10-05-2006 12:48 AM

1988 5.0 non HO to HO conversion
I have a 1988 F150 5.0 non HO engine and I want to convert it to HO. Did anybody know what exactly I need to make this conversion,


is it possible just add mass air and change computer and injectors from Mustang?


SweetStang 10-05-2006 01:06 PM

1988 5.0 non HO to HO conversion
You have to add mass air. HO engines are roller cam. So you need a roller cam,roller lifters,injestors shouldn't matter but you will need the computer

vinnietbird 10-05-2006 03:19 PM

1988 5.0 non HO to HO conversion
You can find a Mark VII Linconl for super cheap.They have the H.O in it,and you could probably get the whole car for less than it would take you to buy the parts you'll need to convert your engine.I bought a Mark VII for $400.00.Sold everything in pieces on E-bay,made about $300.00 profit,kept the H.O.,stuck it in my T-Bird,all is well.I just found an '88 T-Bird Sport for $350.00.I'mm all over it.

kee 10-05-2006 11:35 PM

1988 5.0 non HO to HO conversion
Thanks. Yes, I already thought I will buy a vehicle, but there is a small problem with buy a vehicle for me - I live in Europe and I have here lot of BMW, VW, Audi, etc, but no old USA vehicles For me it's easyest way to buy all this parts on eBay, it's pretty cheap.

Basicaly, I will be glad if I could split this project in two parts. I have just engine and chasis (it's an offroad project) so I need to simplify wire harness as much as I can. I found wire harness from Painless (it's pretty expensive) but it's for mass air engines. So, if I could in first part of this project just add mass air and change ECU and add second O2 sensor and use new wire harness for mass air engines and the engine will work it would be great. Then, in second part of this project I will make all other changes to fully convert to HO as you said guys.

Do you think I could do it this way? Will it work just with mass air, new ecu and wire harness properly?


wayne64 10-06-2006 06:41 PM

1988 5.0 non HO to HO conversion
I'm far from being an expert but as far as I know an 88 non HO is still a roller engine, just with a different profile cam, cast pistons and lower performance heads. Mass air would be my first change along with a MAF EEC-IV computer. Don't fall into the A9L computer trap as others will also work fine. If this site lets me I'll give you a good link for parts and great info, I can't post my forum as it gets blocked but check here

If you buy a used Ford harness off eBay make sure it's a MAF one, otherwise your'll be buying the converision harness to run the mass air. just my couple of pennys.

kee 10-20-2006 03:27 AM

1988 5.0 non HO to HO conversion
Hi again, thanks for reply. I bought this two things on eBay:,1,1

The guy from who I bought it don't know anything about conversions, so I have my last questions, hope so
When I buy a A9P computer I'm ready to do this conversion. Am I right? Or do I need anything else? I need to arange shipping to Europe so I want to be sure a I will not miss antyhing.
Anyway, what from vacuum harness must be connected?

vinnietbird 10-20-2006 04:14 AM

1988 5.0 non HO to HO conversion
You still need the H.O cam,and a Mass Air wiring harness.Otherwisw,get a Speed Density H.O computer and you won't have to worry about Mass Air until later.

kee 10-20-2006 05:47 AM

1988 5.0 non HO to HO conversion
Are you sure about the HO cam shaft? I read (at coolcats, guess so) that I don't need to change cam. They wrote it's better to change it, but I will just have lower HP, everything will work. But I don't understand this stuff. How complicated is to change the cam? Do I need some special tools?

That guy from who I bought the manifold sold it with wiring harness and this harness is from 1991, so it should have the Mass Air wiring, hope so.

vinnietbird 10-20-2006 04:39 PM

1988 5.0 non HO to HO conversion
When you go to the new computer,it will tell your engine to firse like an H.O.,which fires like a 351W.The cam will help a ton with your horsepower.Without the cam,it's really pointless in my own opinion.To change the cam,you'll need to pull the balancer,timing cover and timing chain.If you've never done it,have a knowledgable friend or shop help out.While you're swapping intakes and all,that is the time to do it.

kee 10-21-2006 12:21 AM

1988 5.0 non HO to HO conversion
Ok, I will try to go thrue cam change. Do you know if on the engine are some marks to correctly set the timing chain when I put there a new cam?
Do you know if there is any difference between A9P and A9L wire harness? The intake manifold and wire harness I boguht comes from manual (A9L) Mustang. In my truck si AOD transmission, so I'm not sure if I will have the right wire harness. Thanks.

sevenlitrestang 10-21-2006 05:27 AM

1988 5.0 non HO to HO conversion
the marks for the timing are on the the gears themself, and it's really a no brainer, just line them up dot to dot, but i would recommend replacing the timing set with a new one while you're there, it's cheap insurance. there are no differences in the harness for the a9l or a9p, if we're just talking about the engine harness.

sevenlitrestang 10-21-2006 05:38 AM

1988 5.0 non HO to HO conversion
by the way, i just thought of something, i have a cam that you may want, it came from a 97 explorer that was rolled over in an accident. i got the whole engine from it and put a high performance cam in the motor. the explorer only had 23, 000 on it when it was wrecked. just to help you out (if this actually will), i'll sell it to you for 20 bucks, plus whatever shipping it will be to get it to ya, but you may be able to get a part such as a cam cheaper across the big water versus getting mine, and paying the shipping. just thought i'd throw it out there.

kee 10-21-2006 05:46 AM

1988 5.0 non HO to HO conversion
If that fits in my engine I will buy it. I'm just not sure if it fits. My engine is 88 non H.O. 302. The 97 Explorer has the same cam as Ford Mustang from 86 - 93? If yes and if fits there from your Explorer the timing set you told about I will definitely buy both (cam and the timing set). I'm not able to buy it here, or yes I'm but it's real expensive.
About the wire harness, how I will connect the AOD transmission to the ECU?

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