I have a 1990 F 250 supercab 4x4 with a 351 Windsor motor and 5 speed trans, not only does it get bad gas mileage it seams pretty gutless as well. I have done quite a bit of work on it lately, including new head gaskets, new injectors and fuel rails, new throttle body, new plugs and wires. The motor seams to run fine but I get about 10 MPG at best and is has no power on the hills. Towing my bass boat which is not real heavy it's down to 3rd gear on the steeper hills. I did a compression test and it was pretty much 140 psi on all cyl. give or take a few lbs. Is that a normal compression for this year motor? Would a rv cam help it out. Will the hi flow gt40 p heads I've heard about fit this? Would dual exhaust help? I could get rid of the cat as well as I live in a state with no emissions tests. What would give this thing some power? I also have a 1991 F 150 4x4 with a 302 auto and it pulls my boat better but its broke down right now with a burnt up trany.

 

Have you pulled codes and checked fuel pressure? If not do so and report back. Also check the timing, stock setting is 10deg btdc with the spout plug removed but many engines will tolerate 2-4 deg more. This vintage motor is well known as being badly smothered, if the cat is original it wouldn't hurt if it was replaced and exhaust upgrades in general produce positive results.
If everything checks out and the truck still doesn't have much power after exhaust work then a cam change is in order the Crane 444232 is my go to choice for these early flat tappet motors.

 

I had it at the shop last month and it had no real code issues and fuel pressures were good, most all the emissions crap has been removed except the cat which I checked by unbolting it and ran it with open exhaust and it didn't seam to help any. Even the check engine light with all the crap removed rarely comes on. Is 140 PSI compression about right for this motor? What would be the best way go get this old girl some power without braking the bank? I think he set the timing as well, but not 100% sure on that one. I know he checked the timing chain for slop and it was tight.

 

It's possible you have one of those early motors with a tiny cam, I have driven(and owned) a few that were unusually anemic but otherwise ran fine. In this case the Crane 444232 cam and lifter kit will really wake it up, be sure to follow the cam breakin procedure to the letter and always add ZDDP to the oil there after.

 

Can anyone tell me if 140 PSI compression on this 1990 351 W is good or poor? Would it be considered like new? good? just OK? or poor?
I just picked up a Crane Compucam 444232 for a great price $110 from a guy that didn't use it. I'm thinking of adding it with the Summit racing short headers and dual exhaust, reusing most of the stock right side and adding the same out the left. I plan to do a cold air box with high flow air cleaners in place of the stock stuff as well. I'd like to also find a set of GT 40 P heads to add to this, but not sure if they would work with the headers. Can anyone tell me if they would work. What kind of gains would I get with set up without the heads and with them?

 

You want the GT40 heads not the P version and then there will be no header fitment problems, but make sure you get truck specific headers. 140psi is good compression.

 

Ok i picked up a set of gt 40 heads tonite """"Dirt cheap"""" in great shape, so I will be putting this together soon. Is there any info I need to know to put the gt 40 heads on my windsor motor. Can I use the same pushrods and head bolts? I have not got any headers just yet. I think I'm going to put the heads and comp-cam in it and see how it runs. I do plan to put on better cast ex-manifolds then what it has also and run the stock exhaust for now. Then later figure out what headers to put on it.

 

GT40 heads were most often used on 5.0 motors which means the main bolt holes are 7/16" so you will have to drill these out to 1/2" to mount them on your 5.8. Otherwise it's a direct swap with no special parts required normally.

P.S. What is the casting number on those heads?

 

I have not found this 1/2 " over the 7/16" difference in the late model ford small blocks to hold true.
I have several sets of 302 and 351 heads , all have the same part and engineer numbers, with the exception of the 84Gt40 and the p series heads , tho the bolt holes are still of the 1/2" variety.
All of the heads have a poor exhaust flow , I personally would look for set of aftermarket aluminum heads e.g.: edelbrock with the 202 intake .
These can be had for a reasonable amount of cash , and result in a much better result even over the 84Gt40 heads.
When doing an exhaust upgrade , I would recommend a 1 into 2 muffler such as a magnaflow and run larger pipe , at least 2 1/2 " .
A larger single will actually flow better than duals.
I attribute this as the reason I get 14 mpg with my v10 and manual 5 speed over others that are struggling to see 10-12 .

 

F3ZE AA 71 6090 and it has GT in many places as well. They look to me like they are the 1/2" diam head bolts already.

 

It's entirely possible but can you eyeball a 1/16th if an inch difference? In any event if the heads do have the smaller holes drilling them out isn't a difficult or expensive job, I have even done it on a drill press.

F3ZE castings have a nominal 62cc chamber so you'll get a slight compression bump along with 25% better airflow over the stock E7TE heads.. a very nice upgrade just as they are. While you got this apart I'd suggest port matching the exists in the lower intake to the heads, you will find they narrow down quite a bit the last inch creating a bit of a choke point.

 

Yuuuuuppp LOL I dropped a 1/2" bolt in them with room to spare. I'm a good judge of that kinda stuff having been a ironworker and carpenter all my life.

 

Ok so I got my Crane Cams Compucam kit #444232 today and I have a question. I looked at all the parts in the box and fully understand them all except for 2 bags of small squarish metal washers. I have no clue why these are in the kit. Anyone know what these are. I got no instructions with it, but I didn't think I needed any.
I have also been busy working on porting my heads and intake, mainly the heads on the exhaust side and matching on the intake to heads. It should flow much better when I'm done.

 

The only thing I can think of is shims for the pedistal rockers but beats me why they would include those in cam kit.

 

Ok so I'm currently in in the middle of my 351W upgrade. I have the F3ZE AA 71 6090 GT heads ported, and put in the 444232 comp cam. I still have the stock exhaust manifolds, but I ported them as well as I couldn't find a set of shorty headers that fit for a reasonable price. I keep the stock fuel injecton and ignition systems.
My main question is, What spark plug does this set of heads take? I didnt know my old plugs wouldn't fit till I tried to put them in.

I bought a set of Autolite Ap104's as thats the only plug we could find at the auto parts store that looked like it would work. Is that the correct plug for this set of heads?

My other question is should I up grade the spark of fuel injection as well?

What kind of HP gains should i get with what I've done so far? I hope to end out with something around 300 hp and at least that much torque or more.