Poor mans 4.5 inch stroke?

[Joey120373]

I'm in the process of gathering parts to build a large cubic inch FE motor based on a BBM block.
This is not going to be a drag race motor by any measure, it's going into a 72 2 wheel drive F250
and the motor will never see much more than ~5500rpm.

Right now the motor is still in the planning stages, I have a block and I've made contact with Blair Patric about a set of his pro port heads. Outside of that nothing else has been nailed down.

My Father and I are enjoying putting this engine together on paper, while both of us agree that the only substitute for cubic inches is more cubic inches, he likes to get a little more adventurous than I do, he's not the one buying all the parts after all .

My initial plan is to just order a 4.375 rotating assembly from Barry R. And call it a day. With a ~4.42 bore ( leave a little room for a rebuild or 2 ) I will have a 537ci motor.

My father would like me to take that crank and offset grind it to the Honda sized rod journals to get as much stroke as can be had before rods start hitting the cam.

Several warning flags pop out at me thinking about this.

First, I know Jay has used a 4.5 inch stroke in his HR motor with a little grinding on the rods, and the smaller overall rod end should help. But outside of bottling it together and measuring it, anything past  what Jay has already done (4.5 inches) scares me a bit.

Secondly, and more importantly, offset grinding the crank that far with such a small journal is not going to leave much in the way of overlap( I calculate ~.180ish ), and it might well hit an oil passage or lightening hole.
I tried to debunk it strictly on overlap, so I looked up long stroke cranks offered for other motors.
Scat offers a BBC 4340 steal forging at 4.75 inches of stroke, given the 2.75 man and 2.2 rod journals this crank would seem to have less than .1 inch of overlap. I think this is not an apples to apples comparison, .1 inches of overlap on a 2.2 inch journal is not the same overall overlap area as a .1 inch overlap on a 1.88 inch journal. But since the proposed 4.5 stroke combo has .080 more overlap it still seems plausible.

Thirdly, even if all this is do-able, the cost of the rods becomes an issue.

Still scares me though, and I'm not sure I'm willing to take a gamble on destroying a $3600 block by trying to get another 15 cubes out of a cheep forged crank.

I decided to offer up a compromise combination, as my father keeps pushing the idea.
If I could offset grind the crank to a 2.086 journal
And use off the shelf 5.4L ford rods, I could get close to or attain a 4.5 stroke for relatively cheap.

While I think it would be great to get all the cubes I can, I'm just not sure it's worth the risk.
So I thought I would offer it up here and get some opinions from the experts.

I know the rod stroke ratio is not going to be great on such a combo, but this  is a whole different debate. My father thinks the shorter the rod the better for this application, I'm not sure that's the case.

Thanks, Joe

[blykins]

RPM says the 4.375" crank is made for a 6.800" rod, but the 6.700" rods will still let the pistons clear the counterweights.  If you used an even shorter rod, it's possible you'll get into a situation where the counterweights will need to be turned down.  Not sure. 

Custom pistons will be necessary for either scenario, so you have any more expense there. 

However, it's a  lot of work for what you'll get back at this power level.  You'll always learn a little bit from going the road less traveled, but you'll have to decide if the extra expense and effort is worth it.

[Joey120373]

Ahh, the old counterweight smacking the piston trick....

Thanks for the info on the RPM crank Brent, I was not aware of the 6.8 rod requirement.
I have seen a few builds that used the 6.7 rod so I was assuming it wasn't a big deal.

I had thought of counterweight interfearance, ran into it years ago when we ( a machinist I worked with at the time and I ) played around with some Chrysler Pistons in s ford 400M.
Ended up having to mill a bit off the Pistons but it worked. But in all the back and forth I've been doing on this project I kinda forgot about that. My other concern was how far out of the bottom of the bore will the piston extend....

Anyway, if the counterweights on that crank are close with a 6.7 rod, then I really don't want to toy around with an even longer stroke and a shorter rod.
 Thanks

[CaptCobrajet]

I use rods shorter than 6.700 on those cranks regularly.  If you offset it, you'll need to re-heat treat it.  It is doable.  I think for longevity, a 2" SBC is as small as I would go.  The rod would need to be custom to get the side clearance to jive with the 2" width of the BBC.  You can't keep a head gasket on a 4.42 bore.  Should stop at 4.350 to have a future service capability.  520 cubes is safe and healthy.

[Joey120373]

Thanks Blair.
Not sure what a good offset grind would cost, let alone the heat treating. But I'm guessing the cost of custom rods alone will be more than I want to spend for the few extra cubes. Think I would rather put the extra money in a good set of heads and bullet proof valve train .

What you say about the head gasket makes sense, I had not really thought about it but there is not a lot of metal there and no head bolts near by.
Not sure if a copper gasket and o-rings would hold up, but I don't really want to go down that road. I'll gladly give up some cubes for long term reliability.

[turbohunter]

Thanks Blair.
Not sure what a good offset grind would cost, let alone the heat treating.

Had it done recently. $600 in SoCal dollars.

[Joey120373]

Had it done recently. $600 in SoCal dollars.

With the heat treating?

So $700(?)for the crank, $600 for the machine work
And .... Still don't know..$1500 for custom rods?

Hmm, those last few cubes start getting expensive. They always do I suppose .

[jayb]

I've done the Honda rod journal thing, and won't go back there; that setup did not last.

I think that if you went to the 2.0 SBC rod and offset ground to fit that, it may be your best bet.  I had my high  riser all set to go with the 4.5" stroke, but when I got to some of the higher lift cams (0.750"+) the grinding required to make the rods clear got to be excessive.  If I'd had a 0.650"-0.700" lift cam the 4.5" stroke and BBC rods would have been fine.  Seems like the same general idea would probably apply to the SBC rods.

[Drew Pojedinec]

I know I know, this is an FE forum.  I love Fe's.
That said, this isn't a race motor, this is just a big cube engine to go into a 3/4 ton truck.

Why not look in the 460 direction if you need big cubic inches?  521ci 545ci etc are all very common, easily done with a stock block and have proven to be very reliable.

Just tossing that out.
If you stay FE, take lotsa pictures and post them, not a lot of folks going that big with an FE.

Good luck

[garyv]

I'm with Drew on this one.
Can't beat a 460 based engine for cheap TQ for a truck.
I have one in my 78 F 150 and it's great.
Also have a 511 cube tunnel port 
460 is WAY cheaper.
my 2 cents
garyv

[turbohunter]

That was the offset grind and nitriding price. Induction hardening may be cheaper.
I mention SoCal dollars because the price may vary where you are. But at least you have a reference point.

[Joey120373]

I know I know, this is an FE forum.  I love Fe's.
That said, this isn't a race motor, this is just a big cube engine to go into a 3/4 ton truck.

Why not look in the 460 direction if you need big cubic inches?  521ci 545ci etc are all very common, easily done with a stock block and have proven to be very reliable.

Just tossing that out.
If you stay FE, take lotsa pictures and post them, not a lot of folks going that big with an FE.

Good luck

Gotta laugh! You are absolutely 110% correct, and I do apreciate your willingness to bring it up on this forum. My father, who is ever the tinkerer, would love me to put a stroked 540 caddy motor in the truck. It also offers a substantial torque curve for much, much less money. I told him that if I wanted the cheepest motor, I would go with a 557 385 motor.
That set off a week long discussion where I was finally able to prove that, bang for buck, a 557 385 with the new AFR heads was undoubtebly king of the hill, both in ease of making gobs of power and price. I even managed to talk myself into it for a couple of days.

But I came to my senses, cost be dambed I love the FE, I have since high school . And have always thought the 385 was a great motor.... For someone else to put in their car.

So I couldn't agree and yet disagree with you more! 

Jay, if a 4.5 stroke and 2.2 rods will clear with some grinding.
Would it hold true that a 4.6 inch stroke with 2.0 inch rods would also clear?  I would think that the 2.0 rod would gain ~ .100 more clearance because the big end is that much smaller. So adding another .100 stroke would soak up .050 of that. But still should have roughly .050 more clearance that your high riser. Or do I have my wires crossed.....

Can anyone give me a ballpark figure on custom rods?

[Joey120373]

Correction, offset grinding to a 4.6 inch stroke is really pushing it, unless my wires are still crossed, max theoreticle stroke would be 4.375+0.200. So maybe shoot for a 4.55 stroke.....

[Joey120373]

I'm with Drew on this one.
Can't beat a 460 based engine for cheap TQ for a truck.
I have one in my 78 F 150 and it's great.
Also have a 511 cube tunnel port 
460 is WAY cheaper.
my 2 cents
garyv

Well.... Yea... The 460 is great stroked 460 even better, but a 511 tunnel port, now that's just cool.
To me, even a Boss headed 385 motor takes a back seat to a tunnel port or cammer.

I even contemplated doing a Kasse headed 557 boss9 motor, I think in the end the cost would have been comprable. A bit scary to think what kind of power that would make.

But like I said before, I've been dreaming since high school about building a hopped up FE, that was a long time ago. Back then my ultimate build was going to be a cross bolted 427 block with a 428 crank and a set of tunnel port heads. That was the early 90s though, and by then finding good FE parts was impossible, especially for a 19 year old kid with no money.

[Drew Pojedinec]

But I came to my senses, cost be dambed I love the FE

Well, your logic is sound.  Just felt I needed to add those two cents.  (and remember, post lots of pictures)

[Joey120373]

I'll do my best to post picks, this is going to be a long process. I'm in no hurry, want to get it right.

[cjshaker]

Can I ask why you feel the need for such a large cubic inch engine in the first place? You're not drag racing, or pulling a sled, right?  Just a 4.25 stroke and bored block will get you plenty of inches, and power, and there are plenty of readily available parts for it. Why double the cost and triple the effort for just a few cubic inches that won't make any real difference?

[WConley]

+1 on what Doug says.  With that cam in the tunnel you're fighting yourself for those few extra inches.  You'll have to keep the cam lift below a certain value, which will hurt the big engine's ability to breathe.

I also can't imagine a Modular 5.4L rod working in an FE.  Have you seen how narrow those things are?  You'll have to run 140 wt gear oil to get any pressure with those side clearances 

[Joey120373]

Very valid points. It's a lot of trouble and expence to go through for what will ammout to an extra 20-25 cubes.

This is all very achademic, I would prefer to keep it simple, 4.35 bore ( thanks Blair) and 4.375 stroke.
But my father wants to go as big as possible, he is dead set on it.

 That's mainly the reason i started this thread :

A, to find out if it was possible, and

B, if so, how much can be gained and what is the cost for those extra cubes.

As it sits now it looks like it is possible, but those 20 extra cubes are going to cost  about $100 each, minimum. Putting  it in those terms, it's just not worth it, to me anyway. And I think, with the info I now have, I might finally be able to get him to come around.

If I thought I could get an extra 1/8th inch of stroke or so for $5-$600 I would probably conceder it. But it looks like the machining alone is going to be that much or more. but once the custom rods enter the mix it's just not worth it.

At the end of the day, I'm the one footing the bill for the motor, so it's my call. My dad and I have always bonded over hot rods, so half the fun for me is including him in the build. Honestly I think  he is more excited about it than I am.

Thanks.

[fastback 427]

If your not in a hurry you should get on the list for one of Jay's raised cam spread bore fe blocks. Any update on those?

[Joey120373]

If your not in a hurry you should get on the list for one of Jay's raised cam spread bore fe blocks. Any update on those?

Man that would be cool, but I'm guessing a billet crank is pretty much a must on one of those...

[jayb]

If your not in a hurry you should get on the list for one of Jay's raised cam spread bore fe blocks. Any update on those?

Just to clarify, they are not my blocks, I am waiting on the block manufacturer.  I have not had an update in several weeks, so as far as I know the design is still in process - Jay

[KMcCullah]

Welcome Joey, I enjoyed reading this thread. I did a big inch FE with my dad last year. He's raced a bunch of FE's in his day. So the whole project was sort of a homecoming thing for him. Wish I could afford to do one every year with him. Below is a link to the build.

http://fepower.net/simplemachinesforum/index.php?topic=2481.0

One thing I can tell you.......With a 4.375 stroke, 2.2 Scat I-beam rods and .660 lift cam I could barely fit a .025 feeler gauge between the hip of the rod and #7 exhaust lobe of the cam. Didn't have to grind on anything but it all was damn close.

Again welcome Joey and please keep us posted. Shit tons of pics too...... 

[Pentroof]

Get in touch with Robotnik at Survival. He's got a set of custom 4.350 pistons for sale that he got stuck with. Couple other variations as well.

I don't know why you're stretching to get the cubes either...it's not like you'll ever feel the difference in a 2WD pickup. The tires will never hook well enough, especially on the street. At this point it's about conversation utility because it's not like you'll SEE the difference either.

A sexy exotic intake is worth way more when bench racin' 

[Drew Pojedinec]

*cough*
http://www.network54.com/Forum/74182/thread/1337989141/Recipe+for+630+lb-ft+of+torque...

[plovett]

You're killing yourself for nothing.  this is coming from a guy who likes "different combos".  This isn't the place for one, in my opinion.  You're going to gain a few cubes which is a bit useful for a truck combination.  If you're going to stick with the FE then use a "normal" 4.25 or 4.375 inch crank and rod combo.   Cubic inches are not magic, especially when increased in relatively small increments.

It's much cheaper and more effective to just lower the gearing by about the same percent as you were going to increase the displacement.  Use a 3.91 gear instead of a 3.70 gear and you have the same result, except for cruise rpm, for waaaaaaay less money and engineering. 

People get psychologically stuck on numbers, though, especially cubic inches.  In your case, it doesn't make sense, IMO.  Unless you just WANT to do it to prove you can.  Nothing wrong with that.

Logically, a stroked (or even a stock stroke) 385 series makes much more sense.  If you want to stay FE, I'd say a "cookie cutter" 4.25 inch rotating assembly is the way to go.

JMO,

paulie

[Joey120373]

People get psychologically stuck on numbers, though, especially cubic inches.

I belive you very accurately described my father.

After reading the responses on this thread, and way to many emails back and forth with the old man, I think we have moved past the issue.
I'm going to do what I wanted to do in the first place, which is to call Barry and order the kit.
I apriciate all the advice, and it is fun to play around with engines, on paper anyway, much cheeper that way.

Thanks

[plovett]

People get psychologically stuck on numbers, though, especially cubic inches.

I belive you very accurately described my father.

After reading the responses on this thread, and way to many emails back and forth with the old man, I think we have moved past the issue.
I'm going to do what I wanted to do in the first place, which is to call Barry and order the kit.
I apriciate all the advice, and it is fun to play around with engines, on paper anyway, much cheeper that way.

Thanks

It happens to the best of us.  That is, the infatuation with numbers.  I think you are on the right track with regards to cost/effectiveness. 

I will repeat that gearing, as unsexy as it is, compared to cubic inches, cylinder head flow, exotic intakes, multiple carbs, etc., etc. is vastly important and hugely ignored.

JMO,

paulie

[Drew Pojedinec]

All that money you were going to spend getting an extra 20 cubic inches could be put toward a Gear Vendors which make Plovett's gearing suggestion even better.