Hi, from the Rockies! I would like to build an HO390 with some good low end grunt (towing etc). Help me out.

I have an old 390/428 4V (it has smog, late 70's early 80's).
I also have an excellent running 360 2V. (1976F250).
Help me combine the parts to make a reliable HO390 with
grunt.

From what i've read in the FE forum, i can use the 360 pistons with the 390 crank and rods. Is the crane 914 cam the best choice for breathing (low end/tow) ? I will need to have the crank balenced for the 360 pistons ? (yes). I will use the 4v intake from the old engine, carb recommenations ? I will port the 360 heads myself (good condition/no smoke). Headers vs stock, no duals (Yet).

Thx for any input, Rog.

 

I'll try and answer questions in the order they were asked.

The cam you're thinking of is probably the Crane 343901. If you were to use standard 360 pistons (the ones that came from Ford) your dynamic compression ratio would be too high and your motor would probably ping.

Any time you change any bottom end component you should have it balanced.

Using the 4V intake from the old motor is a good idea if it's in good shape. Personally, I'd use a Holley 600cfm vacuum secondary, with a manual choke. But that's just my personal preference.

Porting the heads is a good idea, as FE heads really respond to being ported. Headers and dual exhaust are a must on any over-stock-performance FE.

That said, here's how I, personally, would build the engine:

1. Use the 360 block, bored .030" oversize, 390 crank and rods, ported 360 heads
2. Use the 4V iron intake
3. KB150 pistons, 20cc offset dish, with large quench pad
4. Crane 343901 camshaft
5. Holley 600cfm vacuum secondary
6. Mr. Gasket steel shim .020" thick head gaskets, verify deck and cylinder head straightness before use
7. Check hydraulic lifter preload before running motor with aftermarket cam. Conversion to adjustable rocker arms may be necessary.

Any questions, feel free...

 

sure, whats quench? you got a sister? a credit card number?

JK, I would go with a rpm or blue thunder intake, the stock intake will choke your porting efforts. If you are sold on the the 4v intake, i personally would only smooth the short side, and get a 3 angle valve job. Anything else would be of no use.

 

Questions answered, in order:

Quench = flat area between piston and cylinder head. When distance between piston and cylinder head is less than .050", this promotes combustion chamber turbulence, which speeds up the burn, lowering the amount of ignition timing needed, lowering the octane requirement, and allowing more compression.

No, plenty of brothers though.

Yes.

Now that that's out of the way, it may surprise you to know that the stock iron 4 barrel flows somewhere between the Edelbrock Performer and the Performer RPM. It's not really a bad intake, aside from the weight. Where these FE's were choked was in the exhaust manifold. Not to say a good intake like the BT wont help though; it's just become my opinion from what I've read on this board that the sealing issues with aluminum intakes outweigh the advantages on engines where low rpm torque is the main goal.

 

just messing with you on the questions, feel like a broken record on quench? I actually read the articles in the links back in day and understand the concept.

As for the intake, i don't know for sure but i would be surprised if the stock "T" version is flowing more than 200 cfm, while ported heads should be flowing that at about .300- .350 valve lift, so from then up you not gaining anything more out of the heads, imo. I also feel the rpm has good lowend, and that intake max's at about 215- 229cfm, at what lift i do not know. The blue thunder cj is in the 245-255cfm max flow, and thats what I want for my current heads. That way I would get the most out of my heads, other than a bigger camshaft.

Btw, whats sealing issue is there, that people have problems with?

 

Quite the broken record. I need to just bite the bullet, write up a huge FE tech article, get a mod to stickey it, and be done with it.

You may be on to something with the intakes. I saw a comparison a while back, but hadn't made the connection between that and actual head flow numbers. It does look like that may be restricting the heads somewhat. But I think the way they flow, you cant directly compare the flow numbers. For instance, in the head you've got a valve that is opening and closing, causing pressure waves, where the intake will be more of a continous flow, letting it catch up while the intake valve is closed. I think a look at the actual port dimensions would tell the tale.

Edit: Almost forgot about the question on sealing! First, read this thread:
https://www.ford-trucks.com/forums/s...d.php?t=451559
I know he wasn't the first one with problems. Many years ago, IIRC, Ratsmoker was having a problem with his sealing. There have been many others since then with problems.

 

your right about the tech article.

Its not completey fair to judge intakes based on flow, but I am a bench racer i guess. The stock and performer intakes are going to have a lot of velocity, but thats only goes so far. Its takes a balance of port volume and velocity. The ideal goal being max velocity from the port or runner volume. The old ford way, was volume, ex. the high riser heads and cleveland heads, etc. While they can flow great amounts of air but the velocity sucks, and that hurts bottomend performance.

i have seen some of scott J 385 work. From what I recall, a intake bolted to head seemed to help low lift flow a little but hurt mid and top. Even the best flowing intake/head combo lost some flow compared to the heads by themselves.

Its, my very honest opinion Greg, is hurting himself by running the rpm intake. They say for an optmised setup, one cfm on intake is worth about 2-2.2hp. Heck if we lower it to 1.5 for Greg, A blue thunder cj should be about 40+ more horsepower. A victor would be even more, but its probaly not "boat friendly".

 

i feel kinda lazy, thats a long thread. I don't use oil because of my intake, the only thing that i have noticed is that i seem to leak coolant or something on drivers side. I use rtv on the intake gasket for the water jacket but coolant always seems to seep through. I have had the with the iron intake as well. I just accept it as an FE deal.

I seem to have a minority view on everything engine related, including manifold end gaskets. I DO NOT use those cork mf's, I use rtv and have had no problems.

 

A victor would definately not be "boat friendly." The dual plane sets up a resonance which crams more through the intake valve at lower rpms. Single plane's dont do this, which is why you lose low rpm torque. The smaller intake ports also increase velocity which will increase low rpm torque for this guy's towing motor.

On the ported heads, it's kind of silly not to. They pick up so much flow, disproportionate to other heads, that it really is time well spent. Even on a toque motor like this they will help for the time he has to downshift and pass someone. I'm not talking about "hogging them out," rather, just smoothing them up to increase flow without losing velocity.

 

Yeah, the velocity from the stock intake will help the idle to 1500-2000rpm range, but on the other hand the rpm will deliver more horsepower to move the weight down the road and up the hills and broaden out the powerband some more. A 112-114 lobe seperation should be selected for this towing rig as well. It so happens the 901 has a 112.

I have been working with some 351c 4bbl heads on the bench and have learned a few things. The more flow at low lifts also translates into torque. Opening the pocket will hurt the low lift flow. From first hand experience, the two most critical aspects are the short side and the valve job. A good 3 angle job helps low lift and torque. A smooth shortside might be as critical as the shape imo. Heck you have to be careful with the transition from the grinded area to the cast finish, it can leave a small lip that will cause turbulence at higher valve lifts.

it all depends what the intended towing defintion is, the above is for stump pulling.

Do not get me wrong, more work on the heads will help greatly when the proper induction and exhaust is used. It will just sacrfice some "bottomend" power but the mid and top are awesome. I worked on everypart of my heads except for the chamber. I did not gasket my intake ports to the cj gasket, because i wanted some velocity for my HEAVY truck. They are 2.20ish vs 2.34 inches tall.

 

Good build sheet Rusty, thx, good information from fordeverpower
also.

I read the Hottrodder article about Dynamic and static compression.
It also talks about quench.

Raising the cam lift offsets the increased static compression ratio
to provide a lower dynamic compression ratio ?, would like use my 360 pistons.

also the stock cam circle may be different than an
aftermarket cam ?, thus requiring an adjustable valvetrain.

Can i do anything to help the stock exhaust manifolds breathe ?
(junkum for headers)

I'm tryin to do this build "on the cheap", but lets make it worth
the effort.

 

Yep. Find the neares trash can and put 'em in. Then get headers.

It's the intake valve closing angle that determines dynamic compression ratio. If you used the 360 pistons, you would wind up with a very high dynamic compression ratio with the 343901 cam. One user on here has a dynamic compression ratio above 9:1 in a 428 and he says it doesn't ping on 87 octane. If you're going this way, be sure to use the thin head gaskets for good quench. Also, you'd need to find a block with a clean 4.050" bore for those 360 pistons. The reason is, there is a ridge built up on the cylinder wall. So I think you'll be getting pistons anyway. You might as well get some pistons that will let you run a cam appropriate for towing.

I honestly dont know if the base circle of the 343901 cam is any different than the stock cam or not. I have heard of people using the 343901 with a stock non-adjustable valvetrain without one problem. Then again, I've heard plenty of people bending pushrods. I think the problem arises from not checking lifter preload. Basically, if the pushrod pushes the plunger down too far in the hydraulic lifter, the lifter can pump up at high rpms, leaving the valve slightly open when it should be closed. If you have the proper lifter preload, it doesn't matter if you use the adjustable or non-adjustable setup. It's just that it's a lot easier to get the proper preload with the adjustable setup.

 

If you can afford it I'd definitely change to the adjustable valve train. Kurt, I noticed you referenced that super long thread on my crazy engine. I probably should post another update. I have just been driving the truck in hopes that maybe it's the rings and they will eventually seat. Haven't had much luck in that department. I had noticed though that it would almost always send out a big puff when I first start it but that it would clear up some....yet still smoke all the time. Because of the puff at startup, I decided that maybe the top was filling up with oil. I had tried running 20w50 but the smoking was no better and the oil pressure was about 80 psi. Yesterday I changed to 5w30 just for grins. I was wanting to get the oil pressure down and I thought maybe thinner oil will put less up top and it will run down easier too. I don't know if the thinner oil just burns cleaner or if the problem is really better yet....but it does seem to be a whole lot better. I really should have cut my old valve covers and installed so I can see what is going on on top of the heads. I probably still need to do that. After all the issues posted with DSC stuff I'm wondering if the adjustable valve train I purchased from them just let's way too much oil out. I do think I had issues with the intake and I don't know if the intake is still a problem or not.

Tracy

 

Could i get away with a reamer and hone on my
m105 block ? Its a 360 with ~30k mi good running/
no smoke. I could then run the 390 crank and rods after
balancing ?

BTW, the donor engine is a 3904V out of a wrecked/rolled
4x4 from the junk yard. It has smog pieces on the intake,
must be a California engine ?

 

Also an appropriate Cam for this setup, (question again).
Dynamic vs static ratio, (again ).
I will get a triple angle job on the heads, port/smooth myself.
I will get headers, (low heat ceramic, good choice ?).

Thx,Rog.

ps. the Dana 61 with 3.31 ratio behind the 4spd, any
suggestions/likes/dislikes. Perhaps an overdrive/different
transmission ?