Any difference between HO and non-HO shortblocks?

redterror302 · Dec 30, 2003

Is there any difference between a non-HO and an HO shortblock? Reason I ask is because I have a 5.0 HO shortblock sitting in my garage right now. I don't really have any plans for it right now, because I am strapped for cash. My stepdad has a nice bronco with a non-HO 5.0 in it that is getting tired. I said he could have the block to do a rebuild if he wanted, but then I got to thinking about whether the block would work or not.

Right now as it sits, it has the crank, stock HO cam, timing chain, cover, connecting rods, and pistons in it. I know the cam would have to be changed to his non-HO cam, so basically my question is whether the cranks are the same or not. I know they have different firing orders, so I wasn't sure whether the cranks strokes the pistons the same way between the two motors or not.

Any help you could give me would be appreciated.

Chris

ps-I tried to persuade him into changing it over to an HO, because I could give him my stock heads and intake, but he did not want to have to swap out the wiring harness to have it fire correctly. Oh well....

MustangPunk302 · Dec 30, 2003

No no difference...

Edit: All 1979-93 5.0 where fitted with cast iron cranks, though earlier cranks used two piece rear mains.

tomst9 · Dec 30, 2003

the cranks are the same and as far as i know the blocks are the same.

P.s. I might be getting a tranny and belhousing, centerforce clutch, tranny mount, flywheel and shifter for $500. I have to find out how many miles are on the tranny. Did you talk to jimmy? You could always give that block to me, you know

eric88gt · Dec 30, 2003

I don't believe that you would have to change over the harness if you keep the HO cam in there. You would just have to change the firing order to the HO firing order. I'm going to be swapping in a HO into my 1990 f150 pretty soon, I've talked to a couple people who have done it and they loved the change.

MustangPunk302 · Dec 30, 2003

No you shouldn't have to swap harness for it to fire correctly, though for it to run correctly maybe, depending what year bronco he has and if it's MAF and such. Shouldn't be diffcult at all if it's already MAF, just put on the H.O. heads and cam make sure it's got the H.O. firing order and you'll be set.

65ShelbyClone · Dec 31, 2003

I thought you had to change some wiring to get the injectors to fire in the right order.

eric88gt · Dec 31, 2003

I believe that all regular f150's/bronco's were speed density until somewhere around 1995-96, except for the lightning, which was mass-air. The truck should run just fine however, even with speed density. All you should have to do is hook up the factory wiring to the new motor and change the firing order. The stock bronco would also have the same heads as your HO, they both had e7's on them.

I would say to leave the stock HO cam in there, put on your heads (assuming they are fresher than the stock heads) and use the truck's original intake. The stock truck intake would probably be better for the low-end torque needed in a truck, it would also be easier to hook everything up as it was from the factory.

TwoToneTerror · Dec 31, 2003

Ok, might be dumb questions but bear with me please....
so the no-HO and HO engines are identical? if so why is the fireing order different? and if they have the same crank, how's that work? Might be something that i'm completely missing here but to me it's not makin sense...

Thanks
-Bart

TwoToneTerror · Dec 31, 2003

eric88gt said:
I believe that all regular f150's/bronco's were speed density until somewhere around 1995-96, except for the lightning, which was mass-air. The truck should run just fine however, even with speed density. All you should have to do is hook up the factory wiring to the new motor and change the firing order. The stock bronco would also have the same heads as your HO, they both had e7's on them.

I would say to leave the stock HO cam in there, put on your heads (assuming they are fresher than the stock heads) and use the truck's original intake. The stock truck intake would probably be better for the low-end torque needed in a truck, it would also be easier to hook everything up as it was from the factory.

I auctually read that the 5.0's in the trucks auctually had worse low end than in the Mustangs, for no apparent reason, so swapping out the intakes might auctually help the low end..... could be wrong but i'm pretty sure, anybody who can confirm if it's right or wrong?

-Bart

FoxChasis · Dec 31, 2003

Shortblocks are different, depending on the model-year...

1. H.O. had forged pistons ('85 4V and '86-'92 in the Mustang) and standard output had cast pistons.

2. H.O. had a unique (351W) camshaft (hence the different firing order).

3. '85 (4V) and '86+ H.O. blocks had taller lifter bores to accomodate roller lifters and standard output blocks had shorter lifter bores until later years.

The rear main seal changed from two-piece to one-piece in late '82.

jrichker · Dec 31, 2003

HO cam needs a HO computer. The injectors need to squirt when the valves open. The non-HO computer won't do that without some changes. You can either move all the injector plugs around, or change the injector wiring at the 10 pin connector, or at the computer connector (UGH! ).

Or you can convert to Mass Air and use the HO computer, or use a speed density computer from an 87-88 stang.

redterror302 · Dec 31, 2003

Thanks for all the replies. I knew the firing order was different, meaning I would have to change the way the injectors fire. I will talk to him and see what he wants to do with it. And YES you do need to change out some things such as the computer or at least change the wiring of the injectors. I knew that, just wasn't sure as to whether the blocks and crank were the same. The block came out of an 87 5.0. Would it just be better to put his cam into it and keep it the way it is, just a rebuild?

Thanks again,
Chris

p.s. Tom, I didnt have a chance to talk to Jimmy. He saw me at the shop, but just drove by, probably thinking that I would laugh at him for crashing his car(probably would have). Anyway, I would look somewhere else for the tranny, because he was horrible at driving stick. If you can get a good deal on that stuff, I would go for it. I want Jimmy's alum. driveshaft anyway.....

ironmedic · Dec 31, 2003

is there something different about an H.O. cam too? or is it the same? i forgot what type of cam is in there! flat tappet or hydro?

jrichker · Dec 31, 2003

IronMedic said:
is there something different about an H.O. cam too? or is it the same? i forgot what type of cam is in there! flat tappet or hydro?

HO=Hydraulic roller, steel camshaft, requires steel distributor gear.

MustangPunk302 · Dec 31, 2003

TwoToneTerror said:
Ok, might be dumb questions but bear with me please....
so the no-HO and HO engines are identical? if so why is the fireing order different? and if they have the same crank, how's that work? Might be something that i'm completely missing here but to me it's not makin sense...

Thanks
-Bart

Look at Chevies they can use up to 8 different firing orders on some v8's...

It has to do with the cam and it's timing of cousre...

TwoToneTerror · Dec 31, 2003

Ok, thanks, still a little confused, but now i at least understand that timing has to do with the cam (like someone noted, valves don't open and you don't get a boom). What i still dont really get is if the pistions come up in an order of 1-2-3-4-5-6-7-8 (hypothetically (sp?)) then how can you have different fireing orders? Do you then just make the cylinders fire at different points in their travel or what? Thanks for bearing with me guys...

thanks!
-Bart

ashford · Dec 31, 2003

TwoToneTerror said:
Ok, thanks, still a little confused, but now i at least understand that timing has to do with the cam (like someone noted, valves don't open and you don't get a boom). What i still dont really get is if the pistions come up in an order of 1-2-3-4-5-6-7-8 (hypothetically (sp?)) then how can you have different fireing orders? Do you then just make the cylinders fire at different points in their travel or what? Thanks for bearing with me guys...

thanks!
-Bart

in a 4 stroke engine the piston goes up and down twice between each fire, so the crank makes 2 turns between each fire. anoter factor is that every engine that i know of with 4 or more cylinders has a companion cylinder setup. that means that every piston has another that shares the same physical position-so if ine piston is at tdc then another is just at different valve timing. eg #1 is on its power stroke, so #5 is on its intake stroke.
a v8 fires every 90 degrees or 1/4 turn not 45 degrees not 1/8 turn.

TwoToneTerror · Dec 31, 2003

Ohhh, now i see the light! Ok, thanks, that's what i wasn't getting, makes sense, haha, imagine that! I was thinking that it was fireing every 45, not the 90 degrees.

Thanks guys!
-Bart

eric88gt · Jan 1, 2004

5.0GT said:
Thanks for all the replies. I knew the firing order was different, meaning I would have to change the way the injectors fire. I will talk to him and see what he wants to do with it. And YES you do need to change out some things such as the computer or at least change the wiring of the injectors. I knew that, just wasn't sure as to whether the blocks and crank were the same. The block came out of an 87 5.0. Would it just be better to put his cam into it and keep it the way it is, just a rebuild?

I know a guy who put a 5.0 HO out of an 87 mustang into his 89 f150 and used the factory computer and injectors (from the truck) and it runs just fine. I believe the f150 uses batch injection, where all injectors on one bank fire at once then the other and so on. Anyway, his truck runs just fine with the original computer, and he says that it has quite a bit more power than it had. And also, the truck made peak torque at 2400, the mustang at 3000.

Any difference between HO and non-HO shortblocks?

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