390 Stroker for FE Power Cylinder Heads

[jayb]

Seems like that wouldn't be that tough to correct.  One big advantage of machining the pan rail is that you can use a big cutter, maybe a 3" diameter facing mill, and it wouldn't matter if the block was perfectly square in X and Y on the machine. That would save a bunch of setup time.  You would set the block on the table, resting on the china walls, and then measure Z dimension at the cap mating surfaces, shim the block to make them the same height in Z, and then take a cut off the pan rail to square it up with the cap mating surfaces. 

Of course I haven't done it, but it seems like this would be much, much easier than what I had to go through to install the crossbolt caps.

[Gaugster]

Thanks for the topic Jay. As I am doing the 390 stroker also this data will be super helpful. I'm leaning towards the girdle as the "Everyman" solution since the crossbolt cost is extensive. I've heard of pinning the caps also and wondered how effective it could be. What crank stroke are you planning? 4.25"? or 4.375"?

[jayb]

I'm going to make the block .020" over, and use the 4.25" crank that I have here, for 442".  Looking at about 10.3:1, with a small cam.  I actually plan to try at least 3 cams.  I'm going to pick some of them myself, and then have Lykins pick at least one for me also.  Probably solid roller, since I'm not a big fan of hydraulics...

[WConley]

The rails and cap saddles won't necessarily be parallel, because they are done in different operations on the line.  The saddles are finished with a giant broach that goes through all of them.  Impressive machine!  Generally the block casting will have been "cubed" with earlier big face milling operations. 

You rarely see square deck faces or pan rails on older factory blocks.  The locating features on the machinery were crude, got dirty, and got beaten up / worn.  Newer engines are machined in a much cleaner environment, with nicer equipment.

Jay I hear ya about not wanting to install crossbolt caps for a living!  That is a TON of fussy work.

[cjshaker]

I've heard of pinning the caps also and wondered how effective it could be. What crank stroke are you planning? 4.25"? or 4.375"?

It's very effective at eliminating "fretting", or cap walk under high RPM/stress cycles. The same reason for using dowels for locating rod caps, to eliminate any movement. It's just not really a necessity for the vast majority of builds.

[Gaugster]

I've heard of pinning the caps also and wondered how effective it could be. What crank stroke are you planning? 4.25"? or 4.375"?

It's very effective at eliminating "fretting", or cap walk under high RPM/stress cycles. The same reason for using dowels for locating rod caps, to eliminate any movement. It's just not really a necessity for the vast majority of builds.

Okay. What is the exact definition of pinning main caps? I vaguely remember it as basically a dowel/sleeve around the studs. Or are we talking about a separate solid pin?

[jayb]

Yes, normally there is a pin in the block and a matching hole in the cap.

[frnkeore]

I've done both SBF and FE on my Bridgeport type milling machine, a Lagun, with a 8" riser. You won't have a enough vertical space, for a FE, under the quill (Z axis), to do much, if you don't have at least a 4" riser on a Bridgeport type machine.

Here are some of the things I did to work on the FE.

The hoist is a HF, pickup type mount. I bolted a 3/4 thick steel plate, D&T for the hoist, to my turrets one, lifting eye hole (7/8x9, most BP's are 3/4x10) then, mounted the hoist. I don't plan on lifting more than 300lb, off that bolt and I won't recommend lifting more than 200lb, off a 3/4x10 bolt.

To secure the block, I used a piece of 1" sq alum, in the WP bolts on the front and in the bellhousing bolts, in the rear. I drilled a additional hole, in the front mount, to fit the timing cover holes, when it sets on the pan rails.

The alum mounts, sit a little above the table, so all the pressure is on the block and not part of it on the table.

I'm considering using a girdle on my industrial block, with six, 3/8 dowel pins, into the pan rails and pinning the mains, both to the block and at the top, into the girdle but, that's a ways away.

[cjshaker]

Okay. What is the exact definition of pinning main caps? I vaguely remember it as basically a dowel/sleeve around the studs. Or are we talking about a separate solid pin?

Here's a couple links to pictures of the BBM blocks main cap pins. These are very robust.

The block:
https://bearblockmotors.com/wp-content/uploads/2013/10/3-e1402336829139.jpg

The caps:
https://bearblockmotors.com/wp-content/uploads/2013/10/5.jpg

[frnkeore]

That's the first I've seen of the BBM blocks and is VERY substantial!

The pinning I have in mind is long, hollow pins, similar to the head bolts but, solid. Thin wall, pressed into the cap, going threw it, into the block and girdle.

[Gaugster]

Thanks for the replies on the pins. I found the article I was referring to. I'm an Electrical Engineer by trade so way out of my wheelhouse and would like to know if something like these dowels have been tried on a regular 2 bolt main?

https://www.dragzine.com/news/building-blocks-getting-the-most-strength-out-of-your-main-caps/

[Barry_R]

So, what's the issue?  Are they not flat, or are they not parallel to the cap registers, or?

All of the above.

Plus the bolt spot faces on the caps are not all at the same height relative to the block surface.

Installing a girdle properly is a PITA

If you wanted to install pins you can put a 1/8 drill hole through both the cap and into the block main face as assembled.  Remove the cap and use that hole to center up for a 1/4 dowel hole - light press sizing in block and a hair larger for a slip fit into the cap.  If it was easy...

[Royce]

I faced a fretting problem on one of my race Y blocks..  Instead of using spacers between the caps and girdle I had some new caps machined that are flush with the pan rails, then tie it all together with main studs that clamp the girdle to the cap.. Add a couple 3/8 bolts through the girdle asd cap to help prevent caps twisting, or you could pin them and it makes for a very rigid bottom end.. I think I have some pictures . If I can find them I will post

[67xr7cat]

Given how tight those caps fit to the block and the cross bolts I don't think is a need for pins.  Considering the main webbing is weak to begin with drilling more holes in it would not help strength.  I remember years ago a discussion on the 400 SBC as to if better to rn a 2 bolt block vs stock 4 bolt because of all the extra holes in the important part  of the webbing. 

[jayb]

Just a quick update, I got the block back from the machine shop today after align boring and align honing for the new caps.  Cost was $525.  Now waiting for pistons...