390 build advice
 

I'm looking for a little advice on a 390 that I'm putting together for a friend. He recently bought a very nice '76 F250 with 70,000 miles and very little rust (hard to find here in PA). He bought it from the original owner who is a farmer, but even for being a farm truck its entire life it was very well cared for.

The truck currently has a 360 that runs pretty bad. He decided rather than put any money into the 360, he would rather swap to a 390 for some extra cubes. I found a freshly rebuilt 390 for it, but would like some advice on building it since I am done when it comes to FEs. I know 460s inside and out, but this is the first time I've touched an FE.

His goal for this motor is just to make a nice driver with good torque. He doesn't want a race motor with a lopey idle. The motor that I found is from a 75 truck, and was freshly rebuilt. It has an Edelbrock Streetmaster intake and an unknown Comp Cam installed. The PO couldn't remember the specs on the cam, but he said it "ran really good". Unless I can determine what it is, I'm planning to swap it for something that I know will make good torque. I've ran a Lunati Voodoo cam in my 460 for a few years and it makes for a very torquey responsive engine that is very fun to drive on the street, and makes a big, heavy truck feel very light.

So, to put it short, here is the proposed engine:

Stock '75 390 long block, fresh rebuild
Edelbrock Streetmaster intake
Hedman long tube full length chassis exit headers/2.5" dual exhaust
Lunati Voodoo 62000

• Advertised Duration (Int/Exh): 250/256
• Duration @ .050 (Int/Exh): 207/213
• Gross Valve Lift (Int/Exh): .503/.524
• LSA/ICL: 112/108
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: 800-5000

I don't have carb yet, but was considering a 750 CFM Summit vacuum secondary carb. Is this too much carb for this motor? Is the cam too small? I figured with the stock compression and heads this motor isn't going to rev good, so this cam should work well. Thoughts? Suggestions?

Oh, and since everyone likes photos, here is the motor as received (don't mind the green paint, that will be getting stripped and painted Ford blue).


http://i278.photobucket.com/albums/k...y/IMG_2000.jpg

http://i278.photobucket.com/albums/k...y/IMG_2002.jpg

Welcome to the world of FEs!

That thing sure is BRIGHT!! Look at my aluminum heads...not! lol

Here's my advice..

The Streetmaster intake while a very good intake is still a single plane that makes its power at higher rpms. I would get a dual plane intake. The factory CJ intake is one of the best but is still a Heavy (80lbs) cast iron sucker. If you're looking for an aluminum intake then I'd go with either the Edel. Performer or Performer RPM. The RPM makes about 20hp more peak hp. They make the SAME peak tq and avg. hp and tq. The Performer just makes it at a lower rpm. Under 3k Perf>RPM, over 3k RPM>Perf. I'll let you decide which you prefer.
I like the Lunati voodoo cams as well, but I would go to the next size, the 62001.

The factory intake, cam, and exhaust is what limited the rpm not the heads.

You need to check what pistons you have when you tear down, specifically the compression height. There are 2 options it could have been, 1.676 "truck pistons" or 1.776 "car pistons" (well theres a tiny bit of range but they'll be pretty close to one of these). What you want is the 1.776 pistons as this will give you a 9.5:1 static CR with standard .041 fel-pro gaskets. You'll have to check to see if it is still at standard bore. If it is the pistons in the 360 will fit and "should" be the ones you want. Ford recycled alot of parts and many 360s got leftover 390 4v pistons. If it's overbored and it has the "truck" pistons, new ones are usually $1-200 for a set of the cheaper ones, and upwards to $4-500 for a set of the perty nice ones.

There are oiling mods that I do to any FE. They can be found here oil
That is all the info you'll need and more on the mods. It'll keep it oiling smoothly for the life of the motor.

I think a 750cfm carb will be too much for this application. I'd go with a 650-670cfm carb. A lot of people are brand loyal but I've run Holley and Edel and both have worked fine. If you plan on doing some offroading then I would suggest the Edel 650cfm Thunder off road, or the Holley 670cfm truck avenger. If you're going to keep it pretty level then the standard versions of these will be fine.

I think that's everything, I probably forgot something I'm sure. lol

Cool, thanks a ton for the info. Good read on the oiling mods, I'll definitely be doing those since I want (and he expects) this motor to last a long time.

After a second look at the cam specs, I think you are right on the cam choice. The 62001 should work well without any negative tradeoffs on this motor.

When I first picked up the motor and saw the old single plane Streetmaster on it, I instantly thought "that's gotta kill torque, I better throw that in the trash". But I did some reading on it, and it sounds like they work very well above 2000rpms, and are much preferred over the Performer dual plane. They still lack compared to the RPM intake however. Thought? Did I find bad info? If so, I can probably sell it for enough to pay for a Performer RPM (I saw one sold recently on Ebay for $250 freakin dollars!)

I thought the 750 carb might have been too big (I'm used to 460s, which need 750s even in stock form). I'll look for something in the 650-670 range (rules out the Summit, they only make it in 600 or 750).

My next step is to teardown and see what it looks like. The PO said he had the block honed and installed new rings, so I have reason to believe it is standard bore. I have a low-mileage 360 in a parts truck that I can use for a piston donor, also the original 360 from the highboy. While my friend is not hurting for money (he owns a very successful excavation business), I still try to keep cost down when I can.

just some random thoughts:
1. rear end gearing?
2. Why not measure the current cam and figure out what it is? (save a lil cash to be put somewhere else.
3. Search the local craigslist for parts.... I recently bought a nearly perfect F427 intake for $75. I like them on a truck, I probably would have gone with something else, but what can a guy get for $75? You can probably sell the StreetMaster for $150+ so thats helpful too. Also got a 1.75inch primary 3inch collector headers for $50 brand new.
4. anyone that paints an engine block green and heads a fake aluminum..... well crap, I dunno what to say about that.

I'd be salvaging as much from donor engines as well. No need in spending money if you don't have to.

That $250 RPM is a great deal. You don't find used ones for sale very often and you can't find them for less than $350 new.

The Performer is a much better truck intake than the Streetmaster (makes 30ft/lbs more tq on something of this power level). The Streetmaster is a better car intake making 20hp more than the Perf.
The RPM is about the same as the Streetmaster for hp. The dual planes just make more tq and at a lower rpm. But you're getting Jays book so I'll let you read all about it and compare the numbers yourself. You can decide from that what you should look for at the swap meets. Good luck with it! Keep us posted.

only problem I had with Jay's book (and really moreso a problem with dyno's) is that the low rpm range is not able to be measured.
sure would have been more helpful in this case.

1. I'm not sure on the gearing yet, since I don't have the truck at my place yet, but I'm assuming it has 4.10s like 90% of the highboys in this area have.
2. I am going to investigate the cam further to see if I can determine what it is, but if I can't figure it out or if it isn't what I want, I'm going with the Voodoo. Like I said, the customer is not hurting for money...
3. I have been scouring Craigslist already. In fact, I found this motor on Craiglist. I paid $250 for it as it sits. It came with all of the components to finish it except a carb. I also got a 4 speed bellhousing, flywheel, and a new clutch/pressure plate with it. I paid the guy an extra $50 for the Hedman Headers for the highboy with very low hours on them (look brand new, still have paint on them). So, $300 total for a fresh motor, clutch, and headers.
4. Just a note on that- the guy must have had a thing for green. His current project truck is a lifted '79 F150 painted almost the same shade of green with a ton of metal flake in it. Talk about BRIGHT! Really nice guy, though, and very passionate about his dentside Fords (someone I can easily relate too).

Sleepy, just to clarify, it was a Streetmaster intake that I saw on Ebay for $250, not an RPM. Sorry for the confusion. And thanks for the clarification on how the Streetmaster stacks up against the Performers. Sounds like dual-plane is the way to go with this motor. I really need to pick up Jay's book... I'm going to keep my eyes peeled at Parts-A-Rama this Friday. - On that note - if I was to come across a used factory intake for an FE, what should I look for? How would I recognize a F427 intake?

dang. Nice price for that engine. If it's standard bore especially. The block alone would be worth somewhere around there.... good job!
http://i68.photobucket.com/albums/i6...h_IMG_0498.jpg

Thats my F427, nice lil unit.
The reason I asked about gearing was 4.10's sure can make a softer motor feel ballsy. I had a truck with 2.73 gears and it was interesting :P
On another note, if the guy isn't hurting for money, why not stroke the 390 to 445? (it'd be under $2000) I'm pretty sure that would get his low end torque fix without any problems.

The only thing I have to add is stick with a 650CFM carb if you're looking for low-end-torque and throttle response.

Anything else was already covered ;)

I'd keep an eye out for the CJ, PI, and Medium Riser, then the 390HP and C4 intakes. The first 3 compare pretty well to some of the aftermarket intakes. The last 2 are good but not the best.

@DeepRoots I know what you mean. I wish there was a dyno that'd read from idle to infinity! All we can look at for low rpm performance is the little 500rpm window from 2500-3k.
The F427 has very similar results as the Streetmaster in the book. A little less peak hp.

Sounds like you've already scored some pretty good deals!

Art has the right idea about the carburetor, but for your application, I would use a 600 cfm. One of the biggest mistakes most people make is to go to large a carburetor. You want throttle response.

A little update on the 390. I got the heads pulled off last week, and discovered that while the previous owner did hone the cylinders and install new rings, the real reason it was smoking is because the bores are completely wore out. There are deep scratches in a few of the bores, and a noticeable ridge at the top and bottom of the cylinders where the rings stopped. I also found new main and rod bearings like he said, but the crank is scored and should have been turned before installing the bearings. I got the OK from my friend to proceed with a full rebuild. The block will most likely get a 0.030 overbore and the crank will get cut 0.010. I need to start a list of parts to get this thing back together.

I also got the part number on the cam that is in it currently, it has a Comp High Energy 268H in it right now, which isn't what I want to run. The 268H has a noticeably rough idle, where I would rather run the Voodoo 62001 for a little more low-end.

Here is the list of parts that I need to purchase:
-Flat top pistons for 9.5:1 compression, .030" overbore
-.010" under rod and main bearings
-Edelbrock Performer RPM intake
-Voodoo 62001 cam and lifters
-New oil pump (high volume???)

I'm planning to sell the Streetmaster intake and put the money towards the RPM intake. I'm also going to try to sell the Comp cam, but that's a stretch. It is barely broken it, maybe 100 miles on it or so.

I'll get some pics of the bores on here soon. Not horrible, but definitely need bored.

I just installed a Edelbrock 600cfm and Performer intake on my otherwise stock 390. Really woke it up and fixed the vacuum issues it was having it would seem. Even with the 2000lb camper in the bed, it's got great pickup. I'm eager to pull the camper out so I can see how the truck really feels.

Only because you didn't mention it but, don't forget new lifters with that cam and the 20 minute 2,000 rpm cam break in rule. Add some ZDDP to the oil if running flat tappets.

That's a given, but thanks for mentioning it anyway. I've done 5 or 6 motors so far, never lost a cam yet.