My lot is cast, decision is made. I bit the bullet...Feuling

journeyman

I was waffling before, but now it is all but in my hands. I take delivery today on a pair of Feuling centerfire heads. This confirms my commitment to the BBC (I was considering an LX style replacement).

Now, I am faced with a myriad of questions about what I am going to do with them. Bolt them onto my Gen 5 block? rebuild my Gen 5 block with a longer (4.375? 4.500? I heard that Gen 5/Gen 6 allowed for longer strokes than the mark IV) stroke?
Buy a new(er) block (gen 6?) and build it? Not sure what.

Is the stroke clearance in the crankcase of the Gen 5 and the Gen 6 the same? How much more stroke will these allow compared to the Mark IV? I know that generally it is held that the Mark IV will accommodate up to a 4.25" stroke crankshaft. What will the 5/6 accommodate?

af2 · Posted: Fri Mar 11, 2011 9:38 pm Post subject:

So, you are saying you got a set of Fueling heads?

journeyman · Posted: Sat Mar 12, 2011 12:18 am Post subject:

clay · Posted: Sat Mar 12, 2011 12:34 pm Post subject:

Cool on having a set of those heads. I can't wait for the results and I hope you keep us posted. Not really a BBC guy but it seems like most people shy away from the Gen V because I believe there is something different with the water passage configuration on the deck surface. I think you can run a Gev IV head on them but it takes a special gasket that doesn't have a lot of sealing area. The Gen VI's are evidently a pretty good block. When my buddy was gathering parts for his 540 build, I think he said one option is to use a Gev VI factory block. He ended up finding a Merlin block but the fact that a factory block can accomodate a 100" increase is impressive to me. Clay

journeyman · Posted: Sat Mar 12, 2011 1:06 pm Post subject:

So how much clearance IS there in a Gen 6 block?

I asked about the Gen 5 because I already have one. Cost wise, that is an advantage (I think?).

The Feuling heads are especially attractive to me, and one of the main reasons I bought them is that I live in California. The heads are C.A.R.B. certified.
I just wish The ACCEL Stealth intake manifold was!!!

My thinking on the bottom end is: If I am going to buy a stroker rotating assembly, I want to get by the longest stroke possible. I figure, the cost between a 4.250, a 4.375 or even a 4.500 stroke rotating assy will not be significantly different price.

I want to keep the bore at 4.250 - 4.280

journeyman · Posted: Wed Mar 16, 2011 6:11 am Post subject:

After a bit of research, here is what I have found. Please tell me if my findings seem incorrect:

1) Mark IV blocks can be stroked to 4.25 with little/no clearance issues. Beyond that, you run into the risk of hitting an oil or water passage.

2) Gen 5/6 blocks can handle up to 4.375" stroke with little or no clearancing. 4.500 is unknown. There have been claims, but...

3) Bowtie blocks can handle up to 4.500" strokes and possibly up to 4.6"

I am still wondering what to do. I would like to build the motor with another block so that the vehicle stays running during the build. The only extra blocks I have are Mark 4.

It seems like a Gen 6 block would be the most practical and afford 4.25 or 4.375" stroke. It also comes with roller cam/lifters. That is nice because of modern oil formulation.

Bowtie is cool. Cool is expensive.

SMOKEmUP · Posted: Wed Mar 16, 2011 9:40 am Post subject:

I'd say Gen 5/6 block is the way to go.

Big Dave · Posted: Fri Mar 18, 2011 10:29 pm Post subject:

Gen V and Gen VI blocks are suposed to be able to accept a 4.5 inch stroke crank (clearance to the cam tunnel), but I have not found one that fits yet. Biggest I can get in the block (standard deck height ) is a 4.375 inch stroke crank. May be if you turned the counter weights down and added heavy metal it will fit. But not out of the box it won't.

Big Dave

Knarley Darley · Member Joined: 22 Apr 2004 Posts: 1247 540238.26 points

As far as I have seen, the bow tie blocks will not handle any more stroke than any of the others you mention, they are basically the same in that department. I think what you meant is the bow tie can be bored to 4.5 to 4.6 which is correct. I am currently running one at 4.615 on the bore. The limiting factor is on the bore is spacing. At 4.630 the sealing surface between the cylinders is thin enough that it will barely accept the sealing rings of the head gasket. If the bores were spaced farther apart to begin with, the block is thick enough to bore even more. I am talking about 4.840 bore spacing which is what all gen 4 blocks are, even the bow tie.

Knarley Darley · Member Joined: 22 Apr 2004 Posts: 1247 540238.26 points

Actually I correct myself. The gen 4 is limited by the fact that it oils through the length of the left pan rail, and not much clearancing can be done without breaking through. The later gen 5 and 6 blocks I believe have priority oiling through the center of the blocks and can handle more stroke.

Big Dave · Posted: Sat Mar 19, 2011 4:26 pm Post subject:

journeyman · Posted: Tue Mar 22, 2011 6:47 am Post subject:

I have been researching....
But, as always, the more I learn, the more questions I have.

Is there any DISadvantages to a longer stroke in a low RPM application?

clay · Posted: Tue Mar 22, 2011 11:17 pm Post subject:

I would say in the stroke range you are talking about no. If you look at a 0.500" change on a 4" stroke, it is actually a smaller percentage change than a 0.500" stroke change in a 350 SBC with a 3.48" stroke and I have never seen any negatives as far as power production goes - only with trying to make it fit. Now if you go really extreme like the IHRA Pro Stock vs. NHRA Pro Stock you would think the IHRA stuff would be a lot faster since I think they have something like a 300 cubic inch advantage. They are faster, but not a LOT faster (at least several years back - I really haven't kept up with them lately). I think parasitic losses starts to come into play at some point but these guys are running way over 5" stroke and still spinning them pretty hard - just not something even remotely related to what you are trying to accomplish but interesting none the less. Clay

Scooting · Posted: Fri Jul 20, 2012 1:19 am Post subject:

New to the site, ran across a 454 with these heads today. Am curious if you ever got yours to run and have impressions of how they work on the street. What was your final selection for a build?

journeyman · Posted: Mon Feb 17, 2014 5:39 pm Post subject:

OK, this is WAY overdue (couple years?) but the heads do work and I did see significant efficiency gains with them.

Unfortunately, there was a whole saga with the install and delays, but the heads ran well and I went from about 5.5 - 5.8 mpgs (towing heavy, GCW over 28,000) average on a 100 mile trip over 4 passes to just shy of 7 mpg.

Power seemed to be improved, but it was not something immediately noticeable. Overall, I am pleased with this.

I also added a snow water injection unit that pumps pretty much constantly while towing. Fortunately, since it is a motorhome, there is a 60 gallon water tank (which the water injection is plumbed directly into).

Right now the motorhome is undergoing a rear end conversion (heavier rating and two-speed) so I will have to wait a while before taking it out more. I really want to test this solo.