Crankshaft Crossroads - Now 2027 Build

[Rob Combs]

Good morning all,

Been out of town a few weeks so just getting back into this.

On one of my other threads I asked about cylinder head differences between the panchito and another 044 variant. Brian suggested to not overlook the AA 502s.

Since I had nearly 7 hours sitting at the airport on Sunday, I was able to do a lot of reading and concluded the AA 502s would get me real close to where I need to be. Ordering them as we speak. Will be ready to ship on or near this coming Friday.

I recognize I will need a valve job done after the bowls are cleaned up but at least if I nick the seat it will not be an issue since they have to be recut anyway. Total cost after the valve job will be about the same as with the Panchitos.

Thanks to all for all the suggestions and guidance!

[Brian_e]

[Rob Combs]

Thank you for this Brian!

I will definitely lap the valves to get a baseline for whoever I take these to. Time to start searching for machine shops to do the valve job. I'm sure there are dozens in my area...

[chrisflstf]

[Rob Combs]

[Rob Combs]

Got my cylinder heads in yesterday afternoon.

Worked on match porting my intake manifolds and got a little wild with the first one. The scribe line is where I blew out the manifold a little beyond the head port.

This is only about ~ 035", maybe .040", but that seems to be a little bit too much of a step into the airflow. I don't trust epoxy to stay put so would rather not build up the inside of the manfold and re-port. If the epoxy comes out it would be disastrous.

So, should I just run it as-is or should I relieve the port out to the manifold and blend a tight radius back into the port? It could be either cylinder #2 or cylinder #3, depending on how I assemble it. I plan on making it cylinder #2 because it has slightly higher compression and, splitting hairs here, would be better suited to compensating for any velocity loss from relieving the port a little.

The other manifold came out just about perfect.

Thanks for any suggestions!

[Brian_e]

Best thing to do is make the other 3 holes all match that one.

That spot is about the best spot you could be removing material. Just make it a smooth radius between the two.

That port shape is a little tough to make proper manifolds for. Spend your time extending the shape up higher up into the manifold. Try to keep the cross section consistent.

Brian
_________________
So more or less the lazier and stupider you want to be, the nicer quality parts you need to buy.
-Modok

Narrowed beams, Drop adjustable spring plates, Bus disk brake and IRS kits.
www.type-emotorsports.com

Type E Engine Parts and Supplies
https://type-emotorsports.com/collections/engine-parts

[Wreck]

What he said ^^^^^^^

[Rob Combs]

Sounds good fellas thanks for the input!

[Rob Combs]

Ok working on a template to port the intakes - filled the voids in an FI end casting spacer with epoxy and am waiting on it to dry out so I can match it up to the ports and transfer the shapes to the heads and manifolds. Should have done that in the first place rather than depending on prussian blue markups and a not so steady hand...

Now on to the heads - I have one of them broken down to look through the ports, and as far as I can tell AA must have been listening to Brian because there's no step under the guides and you can see where the port shelves were cut off flush with the valve seats:

I can maybe see doing a minor cleanup to those sprial cuts with a cartridge roll but not much else, as far as I can tell.

The pics with the flashlight show how the seat fits up to the port. The long turn into the exhaust looks completely unobstructed. I don't think any material needs to be removed here. The short turn into the exhaust port is a pretty sharp "corner" but not sure that needs to be touched at all. Should I radius it a bit or just leave it the hell alone?

There is a bit of a step between the tops of the valve seats and the combustion chambers, should that be flattened off/blended in?

Seat cuts are single angle ~ 45*

And we knew the valve job kinda sucks out of the box; valve seat right down the middle and a little wide:

Those dual valve springs are no laughing matter to compress! First time I've had dual springs.

Should those intakes be back cut when it goes out for a valve job, or does that transition look ok?

Overall I'm rather impressed by the ports under the seats as delivered. Am I close to seeing this right?

Again any input is welcome!!

[Rob Combs]

Manifolds and ports are matched up (at least as good as I can get them without letting my OCD tendencies run wild and cause me to ruin the heads and the manifolds), got the bowls cleaned up - very little grinding was actually needed - and now ready to go to the machine shop for a valve job on Monday. I'm told it will be a few weeks because they're a little backed up on work right now.

So I thought while I wait for Monday, I'd get a head start working out valvetrain geometry. Side play is set up on Berg bolt together shafts and rocker to valve tip placement looks pretty decent. Valves are held in with checking springs, so easy to start estimating what I'll need.

Yes, I have watched Brian's video. And think I have a pretty good handle on what to do but still have a quick question for those who have been here before -

"Theoretical" valve lift with 1.25:1 rockers should be .490". I'm starting off with stock-style, adjuster-over-the-valve 1.25s and TP elephant feet. Arcing the valve through its travel, the retainer hits the top of the guide at .580" lift. So, I figure ~ 5/6 of the way to impacting the retainer is about what the actual valve lift will look like. I have 1 thread of the adjuster sticking out the bottom of the rocker arms, which have been back cut ~ .080-.100" and look evenly cut to the naked eye. Much more back cut and we'd get into the oiler holes so gotta stop where we are.

With this initial setup, the valve adjuster angle "sweep range" is biased toward the pushrod side by quite a bit. This is clearly visible to the naked eye so no need to bust out the angle finder just yet. So the shafts need to be shimmed up. Just for giggles, I stacked up two .030" shims under one rocker shaft (that's all the shims I have on hand at the moment), and things got a lot better but the angle sweep is still biased to the pushrod side a little bit.

I estimate I'll need somewhere between .090-.0100" of shims to get it to sweep in the middle. Does that sound about right with stock style 1.25s and elephant feet? Or am I off by a country mile and does something seem wrong?

Thanks as always!

[chrisflstf]

Are you using an adjustable pushrod to set up the rocker geometry?

[Rob Combs]

I will be once i get it mocked back up. The initial trials were just with the heads on my desktop. Checking springs in place and actuating the valves by hand.

Zero lash with closed valve is still exactly the same starting place regardless of whether the head is bolted to the engine or not, though. I do expect my actual valve lift to decrease a bit due to the consensus that these type rockers measure out to 1.18 vs 1.25. I also expect the valve to sink just a touch when the valve job is done. This shouldn’t affect my ability to get it in the ballpark. Just looking to approximate what shim stack I need to buy while I’m waiting on the machine work. And if my projected .090-.100” is about normal for these rockers or if I’m hopelessly out of normal range.

That said, IIRC the final pushrod length is determined after the geometry is set up.

Of course, I’ll go watch the video again.

Maybe I’ll just buy a shitload of shims so I’m ready for whatever and however it works out is how it works out.

[Brian_e]

On your heads, the smooth transition from the seat insert into the material just below the seat is a standard bowl hog cutter. It’s the material right at the end of the bowl hog cut that needs to be worked on. That ridge from the cast port to the machined ridge from the bowl cutter needs to be smoothed out.

The port just below the insert needs to carry the ID of the seat insert down into the port. Both intake and exhaust. If you have a snap gauge you can set it at the smallest diameter the ridge and compare it to the ID of the seat insert. That is usually a good indicator. It should be nice and smooth, and the same ID from the seat cuts to about 3/4” down into the port.

These are pics for the 502’s I did. These are the ones I listed the flow numbers from.

I would have the shop do a 30deg back cut on the intake valves for sure.
This is what my lapped valve with a back cut looks like after my seat cut.

Brian
_________________
So more or less the lazier and stupider you want to be, the nicer quality parts you need to buy.
-Modok

Narrowed beams, Drop adjustable spring plates, Bus disk brake and IRS kits.
www.type-emotorsports.com

Type E Engine Parts and Supplies
https://type-emotorsports.com/collections/engine-parts

[Rob Combs]

Thanks as always for the informative feedback Brian!

Copy on the back cut. I'll definitely have that done.

The above pics of the ports are as-boxed. The lighting has the contrast between the bowl cutter marks and the casting itself grotesquely overexaggerated. Sticking a finger down there, one can barely feel the transition. I've since cleaned that up a bit and gotten the transition even more smooth. In all honesty I was expecting a lot more cutting and cleanup to be needed based on some of the pics I've seen of other people's panchitos they've posted up.

Based on your postings on other threads, I also relieved the sharp corners in the exhasut ports on the short side. Not too much material removed, just enough to break the sharp corners.

That said, I'll pop the valves back out, have another peek in there, and double-check before I take the heads over. I'll use your posted pics for comparison. And a snap gauge to measure the diameter. If it stlll needs some more cleanup I'll get it done.

Once this is done we'll be getting close. CSP super comp exhaust should be here in a couple days. Not too many more parts to buy - the list is getting shorter and shorter!

[Brian_e]

The side walls in the exhaust ports are what usually need the most work. The bowl just under the seat is too big on most heads, so it opens up quick. This is the same spot on panchitos that is really tight.

The sharp inside corner on the short side of the exhaust has a very minimal effect on flow. I leave it as big as possible to support the valve seat. I only knock the sharp corner off a bit. Lots of people go WAY over board on that sharp corner.. The air just blows right past that corner and mostly flows the side walls. There is no amount of radiusing that could get the air to stick to that turn.

Brian
_________________
So more or less the lazier and stupider you want to be, the nicer quality parts you need to buy.
-Modok

Narrowed beams, Drop adjustable spring plates, Bus disk brake and IRS kits.
www.type-emotorsports.com

Type E Engine Parts and Supplies
https://type-emotorsports.com/collections/engine-parts

[Rob Combs]

I think I got it.

Couldn't find my snap gauge set right off hand so I used this to check the valve seat and bowl diameter on all 8 valves:

I did need to remove a bit more material. Now the diameter holds down the valve seat, into the bowl, and into the turns without getting tight and without loosening up either, except in one small place where the casting was always a tiny bit little wide. I don't want to take any more material out from anywhere.

While not perfectly consistent in texture like in your pictures, there are no ridges left from tooling, no shelves protruding out from under the valve seats, and some of the more intrusive casting flash was ground flush to the port walls even if that doesn't actually do anything productive. Probably all I can do without a flow bench, more tooling that I may not ever use again, and a lot of experience that I simply don't have. I think any more and I might start going backward.

I really appreciate your coaching on this. I'm pretty happy with where it is. Off to get the valves ground tomorrow!

When I get the heads back I'll cc them for final CR measurement, and jump back into that valvetrain geometry and pushrod length determination. In the meantime I'll pick up a rocker stand shim kit so I should have everything I need to get pushrod length locked down.

Thanks again!!

[Rob Combs]

Sorry if this double-posts - I got a posting error first time I posted this question.

With the TP lifters, can I expect upper end oiling similar to lifters that have been grooved/Hoover modded, or will they oil closer to stock? Comparison below:

Block has been drilled to join cam tower to lifter galley oilways and center cam tower oil groove has been widened.

Thanks to all who can opine!

[Rob Combs]

As I wait for my heads to get finished up (heads are at the machine shop with checking springs and a spare set of keepers, awaiting a valve job and some other work), thought I'd share clearancing valve keeper end gaps for those who:

1) don't have access to lots of professional engine building tools or the space to put them

2) don't wish to commit a lot extra money to what might end up being a one-time-use tool

and,

3) believe there should be an end gap between valve keepers

Here's a hand crank piston ring end gapper that I found on Amazon for just under 30 bucks:

Clamped to the table with a piece of scrap aluminum bar used as a fence to keep the keeper from tilting into the gap between the cutting wheel and the tool frame.

With the crank handle removed, I was able to insert an 8mm allen socket into the end of the cutting wheel axle and spin it up with my drill, holding the keeper flush and square against the cutting wheel until it got too hot to hold down. About three friction-induced heat cycles on each keeper was enough to go from < 0 gap to enough to lock the retainer to the keepers, enough for a light to shine through and show there's no contact:

The only extra part you'll need is a spare new valve to check your progress.

Hopefully this helps someone looking for a keeper grinding solution but, similar to myself, has no room for a complete workshop.

(Word of caution: For those who don't have a lot of experience gapping rings, I strongly recommend against using a power drill to spin up the grinding wheel when gapping rings. That goes pretty fast just hand cranking it...easy to overdo it!)