Long time, no post. Glad to be back!

I'm finally getting around to pulling my (fully stock) 352/NP435 from my '66 F250.

I am going to rebuild it, and want to do the rebuild (but not the machining/boring) myself. The engine is about bare, with driveshaft, mounts and clutch linkage remaining prior to removal. I am currently soaking my upper manifold bolts this week, and will remove those uppers prior to taking the engine as well.

I'm having trouble deciding on what to do for the rebuild. This truck will be a 3 season truck, may see some towing down the road (boat). It isn't going to race, but I would like it to be capable of 70-75 w/ acceptable gas milage. Can I do this w/ my current NP435 and 4.10 rear setup?

So far, my plan is to get a used 390 crank, have her bored 4.050" and rebuild the lower as a "stock" 390 with new pistons etc. NOT sure what to do about the camshaft, and confused as to what sorts of lifters and what length of pushrods I will ultimately need. There is a TON of info here (and elsewhere) and mostly I'm just trying to get all my ducks in a row before opening up the wallet (or the block!)

For the top end, I plan to find an edelbrock performer rpm intake, and will use a new HEI type dizzy. I have a set of Hooker Headers that are new and came w/ original purchase, so I'll use those, too. Not sure what to do about the heads? Are the stock 352 heads acceptable for what I'm doing, if so, is the cost of rebuilding them worth is compared to buying new ones? If I don't want to use them, which ones should I use?

What am I not thinking about? (Lots, I imagine)

Thanks!

 

Define acceptable gas mileage.

Your plan sounds solid.

The stock heads will probably be fine but a rebuild is not a bad idea to put new valves, springs and hardened seat in them.

Find a mild grind cam that will improve your top end power somewhat.

A 650cfm carb will be plenty.

4:10 gears in the rear will not get you any kind of gas mileage. Im assuming its a Dana60, so 3.54 gearing at best.

 

Sammy, I think I would leave it a 352. Add headers, an rv cam and a 500 cfm carb, and it will pull anything that you want to hang on the rear.

Until you drop to a 3.00/3.25 rear ratio you will hold your single digit mpgs, and that aint likely to happen with your Dana.

You could buy a 73-76 donor F100 for power disc brakes/steering upgrade and make your truck a half ton. getting the lower ratio will be much easier.

just a thought.


John

 

How long have you been driving your truck in its present configuration? Did you drive it 70 -75 as is with the 4.10s? Did the gas mileage suit you? Ordinarily, I wouldn't think "70 - 75", "4.10s", and "good mileage" could be found in the same sentence, but I think Jetcopter Pilot says he can do some of that with his rebuilt 352. Look up some of his posts. Before you look for your 390 crank, have your block evaluated for its bore potential by a competent machine shop/engine builder. Some 352s can successfully be bored to 4.05, some not. Number Dummy could, Jetcopter Pilot couldn't. According to an Edelbrock tech rep I talked to on the phone, the Performer RPM manifold is NOT recommended with stock heads. I don't remember why. They want you to use their aluminum heads with that. The Performer (non-RPM) manifold will work with OE heads. Check with Edelbrock and see if you get the same story. For the amount of money my engine builder wanted to really do up my stock heads, I forked over a bit more and got the aluminum ones. Depending on how much you want to spend, you can put a retrofit hydraulic roller cam and lifters in it, as well as roller rocker arms to free up some horsepower and lower heat and friction. My in town gas mileage increased by 20% (which certainly sounds better than 2 mpg, which is what it was). Bill W and I both had 390s built at the same time. He put in a stock grind Comp Cam. I put in a custom grind Comp Cam emphasizing low end torque. I think his came out better, but I am comparing apples to oranges as his is a C6 auto and mine is a manual. I kept my small 600 cfm carb I was already using on my previous 352. Bill is using a 750 double pumper. Either seems satisfactory unless you want more high rpm horses, in which case Bill's would be better. Choose your pushrods last after everything else has been assembled - getting the right length is critical. Buy a heat shield mit to put over your starter to protect it from header heat. A starter change with that set up is a royal PITA. Also consider a 1 inch phenolic spacer between your intake manifold and carb to soak up some of the heat and lower chances for vapor lock. If you do that, you may have to build a spacer to raise your throttle linkage bracket which bolts on the rear of your intake manifold. Speaking of your manifold, be careful when installing. The design is prone to leaking if you get it wrong. Is that more than you wanted to hear? Have fun with it!

 

Well, let's be honest... NO, the mileage has never suited me, but I suppose that's just the way it is. I go back and forth between the idea of just rebuilding it as cheaply/effectively as possible (as a 352) and going "all-in" on a stroker setup, with the thought that rather than being unhappy and incrementally upgrading, I might as well go big right away.

I had thought that the 4.05 bore was a gimmie for the 352, but that beyond that was iffy. Lots of conflicting information on that subject! I will be sure to get the block checked for suitability.

I do plan on shielding the starter... is there a product available? Or do I need to fabricate one?

I am familiar with the PITA-ness of the intake installation... I replaced the lifters a couple of winters ago and between me (6'3" 205) and my Uncle (6'3" 255) it was about all that we could do to wrangle that cast intake down smoothly... and I STILL wound up with a leak. I expect that I'll be staring down a heavy schmear of rtv on the backside of that intake when I get the engine pulled!

This will be a little-by-each build, y'know, as swmbo disburses the fundage... so while I may be in a hurry... reality isn't!

 

I got my starter heat shield from CJ Pony Parts. It's sort of a generic piece, 22 x 7 inches, that you modify to fit and then strap it on. At the time it cost $31.95, but CJ's have a lot of sales so maybe you can do better. Good luck!

 

I'm with John. The 390 conversion will not help fuel mileage. An "RV" cam that brings torque in low is what you want for pulling; this is not a race car, and FE's are not rev happy unless you build them in that direction at great cost. Build for torque, not horsepower.

One nice thing is the Edelbrock intake will be MUCH easier to install than the cast iron door stop!

For fuel mileage you have got to change the axle gearing. You can compensate somewhat with a much taller tire, but a different gearset/axle is the only really effective way to move in that direction. Other than dual exhaust and electronic ignition, mine is stock with a 3:54 (I think) rear. 70-75 is happy cruising speed, even towing. 15 mpg empty, 12 mpg towing a car on a steel trailer with the bed full (highway).

 

The 390 change will not really hurt his mileage either. Depending on the application, the extra displacement can actually help mileage as you are not working the motor as hard. Its all in how you look at it. My '06 Trailblazer is exactly like this. I have an I6 in mine, a guy at work has a V8. I get about 18mpg, he consistently sees 21mpg. He has 69ci on me. Everything other than the engine is the same with 2 vehicles other than the color. The I6 is a great engine, I pull my '65 on a big trailer with no issues. The V8 would do the same, and get better mileage in the process.

"The is no replacement for displacement!" <- sorry I had to

 

That, to me, is acceptable. That's about what I'm getting in my current daily driver, my father-in-law's 2000 V8 3/4 ton truck of other brand origin.

SO...

I currently have 31x10.50s all the way around, your (and JoWilker's) rec is to get taller on my diff gear and rebuild as 352 w/ an rv cam, aluminum intake, new or rebuilt heads, headers.

Hmmm.

 

If I go w/ a 390 Crank, can I reuse my 352 balancer, or do I need one specific to a 390?

 

Get the compression up. That will help in the power AND economy areas.
I don't know about 352s, but the compression claims for many engines are optimistic because the pistons are in the hole, that is the top of the piston is below the surface of the deck at tdc. You might find a point of compression right there and it may not even require a higher grade of gasoline.
Maybe some 352 savvy guys can confirm this.

More power does not have to equal less economy. My higher performance, higher compression, stroked, ported, 292 with headers and aftermarket aluminum 4v intake got 1mpg better than the lower performance, lower compression, stock stroke, unported, dual exhaust manifold and iron 4v intake version before. I owned both engines from day one so it is not that the lower performance engine was worn out. The combination of parts on the higher performance version just worked out better all around.

 

BTDT. Then built a mildly warmed 460. Much better. More power, cheaper parts, and literally a bolt in deal. Pick a Part stores are full of these engines. Currently I have a 460/C6 in my red truck that runs perfect and only cost 100 bucks for the engine, transmission and a heavy duty drive shaft. FE's are great but for simple cheap and powerful the 460/C6 combo is better. Check out 460forddotcom. IMHO.

 

OK. But I'd rather keep the stick. Have done some quick searching and it sounds like a MFer to mate the NP435 with the 460. Intriguing, but unless I can find a mated manual tranny and a decent 460... not so sure...

 

"Fuel economy" and "460" are not terms you will ever see together. Have not spoken to a single owner of a 460 who doesn't complain about the fuel mileage.

 

Sammy, I just went back and read post #1to try to make sense of this thread, that is all over the place, with numbers just as far out.

To get mpgs up you have got to get rpms down, no other way while using 1950s designed iron when gas was $.22 a gallon. I have read some numbers in this thread that are very hard to chew. All of you guys have smart phones, download a couple different apps that are gps related with speedo options. I bet you will find your truck speedo off from what the cell phone reads. Go to the new car lot and look at the mpgs listed on the windows of new trucks all with OD trannys. Most of them that I see 40 years later aren't getting 20 mpg.

Sammy it is your money bro, spend it like you want. When I re-read post #1, I got that really you want to freshen up your engine that you are not unhappy with it in terms of power, nor don't think you need a lot more. You are hung with a stump puller that I am going to guess gets 6 or 7 mpgs now & improving that would make you happy. That is the reason I posted what I did.

My truck engine was built for torque and will do some pulling, because it has a lower rear ratio will run the numbers off the clock. I haven't tried it, but believe I can pull the C6 down to 2nd and reach 100mps like it will in 3rd.

Let's look at this, what is your budget? What are you wanting to spend?



John