I have been asking about converting my '87 EFI 302 van to 351w.

I have been told this is easy if you have a mass airflow (MAP)setup. The Chilton/Haynes EFI schematics show a manifold absolute pressure sensor (MAP) and a temp sensor, not a MAF sensor.

Do I conclude correctly this is not a MAP system I have heard about?

Can I upgrate this to a MAP system? Would this benefit the 302 even if I did not upgrade to a 351w? How complicated would it be and what would the costs be like?

 

As a side question- I had a mechanic note that my intake manifold has some leakage between the upper and lower intake. Now on a MAF system, the computer would clearly underestimate the amount of air entering the system due to this effect. But is this even going to affect a MAP? The computer only looks at pressure and temp.

The leakage shouldn't affect the pressure, the pressure inside the intake will be basically the same whether it took air in through the normal intake or a leak. I guess the temp could be off a bit since I think the temp sensor is located close to the intake's top so the air from the leak won't physically flow past it. But it doesn't seem too significant to me.
Is it even worth fixing? Removing that manifold in a van isn't easy.

 

It isn't necessary to convert to MAF just to swap in a stock 351. If you were planning on building it up for high horsepower, then MAF might be a good idea. The 351 is a relatively easy swap - all the wiring from your 302 will work on the 351, as well as the accessory brackets. The 302 computer can run a 351 in a pinch, but it would be best to find a 351 computer if you decide to swap the motor - the 351 computer will plug right into the 302 wiring harness. You are right on about the leak and the MAF not being able to detect it. The MAP system only sees vacuum and throttle position, so it doesn't matter where the air is coming from, to an extent - a large vacuum leak would still throw things off. The stock system on your van is a MAP system, the other one is a MAF. The dominant sensor in a MAP system is the MAP sensor, and the MAF sensor in a MAF system.

 

Would it help my stock 302 to try a MAF system, or is that only really helpful if other performance mods are being used?

Does it require a major harness change? There's no wiring for a MAF sensor on this engine, unless it plugs in in place of the MAP sensor? (Along with changing the computer I assume?)

 

go hear www.fordfuelinjection.com and read. will explain all in good detail

 

It involves a good bit of wiring. Do a search for "mass air conversion" and read what you can find. There is quite a bit of good info on explaining how each system works, as well as fordfuelinjection.com as mentioned above. It might help a little on the stock system, but the real reason for swapping is to allow for performance upgrades. The main things that must be wired in are 6 additional injector wires (8 if you don't use any of the stock system) and 4 wires for a MAF sensor. The MAP sensor remains, but with no vacuum line on it, so it becomes a BAP or barometric air pressure sensor. Upgrading to MAF would require a new engine computer. Again, search the forum, I know there are several threads that have all the answers you can ever think of about MAF conversions.