Max valve size for 4.0/4.6 heads?

[BlownMGB-V8]

Based on those photos I wouldn't have any issue with going an extra .050" deep. Makes the offset retainers easier to find too.

Jim

[MGBV8]

Or deeper if needed.

[turbodave]

Ok, I have some updates.

Reel Steel in the UK and TA performance have both confirmed that there is no valve keeper / lock (aka collets in the UK) that are the Rover v8 valve profile and have a 10 degree angle.

TA never got back to me on a group purchase, but ReelSteel did allude to them purchasing these in 100 engines worth at a time.

So, if anyone is really wanting to run the beehives (using the Rover valves), then I'd recommend a 10-degree chevy cap, and machined out to 11 degrees. I have a very retired good machinist friend who still has his own shop and would be interested in helping with this if anyone wants to be the first.

I was actually spending a lot of time myself in the last 2 days with my heads since getting them back from the shop who skimmed them and re-cut the seats for the larger DW500/DW501 1.4/1.63" valves.

I have both the standard Rover pre 1980 (single spring) machined valve caps/retainers, and the Comp 712. I measured the heights of these relative to the top of a valve, and the Rover ones are .234" and the Comp 712 are a little shorter at .225.

I then measured my current spring pocket heights to the top of the valve, and have 1.802" pretty much across the board, no more than 3 thou variation anywhere! This is nice work from the shop that did the seats....

So, 1.8 minus 0.225 = 1.575" installed spring height. Clearly that's not going to work as all the springs in our range are 1.700 installed height.
So, I had already purchased Manley 41824 spring seat cutter, and trialed it on a scrap head. Works very nicely.

I have already purchase Comp 980 springs and these look to be a good general fit for the application.

How deep can we go on the pockets? Well I've cut up heads previously, and .332" is the min material thickness across any of the heads from the factory spring pocket to the water jacket. This is on the exhaust; the inlet is definitely thicker. You'll note these are a mix of the earlier heads and the later 10-bolt. The easiest way to tell is in the height of the "yump" of the bottom of the port; the 10 bolts are a lot lower than the 14 bolt heads; while this gives more initial flow, it becomes less of an advantage as you start seeking higher flow figures. I suspect this change was to put more tumble than swirl into the mix, presumably for emissions.

As I'm using the Crower 50233 that has 0.488 inlet and .501 exhaust lift, and the comp 980 springs are rated to .490 max lift, I'm actually going to run an installed height of 1.700 for the inlet, and relax it to 1.72 for the exhaust. Hence the inlet will meet the comp figures of 243lb at 0.49" and 92lb seat pressure, but the exahust will be 243lb at 0.51" and 85.8lb seat pressure. I don't think the loss of a little seat pressure will be an issue, especially as the valve is lighter than the inlet.

My seat pressures are a lot lower than others quoted here, but I just don't think I need that much pressure for the waisted stem valves at a 6200RPM redline. If i was going for 7000rpm, sure - but that's not what I'm planning for.

So, I will need to machine the inlet spring pockets to increase the depth by 0.125" and the exhaust by 0.145". This should still leave just under 3/16" material above the water jacket. Its not as much as I'd like, but that thinnest part of the casting is only around 90 degrees and it gets a lot thicker in the other 270 degrees.

Really, the best solution here is to use valves that are anything from 0.10 to 0.20" longer than the Rover valves (and it gets you into common valve locks/keepers/collets. I now fully understand why longer valves are often listed. Of course longer valves also means spacing out rocker gear, and then longer pushrods, so it all suddenly gets very pricey!!!!

[turbodave]

10 bolt head exhaust section.

[mgb260]

Dave, Great work! Did you see the Dodge Viper V10 springs I mentioned above. They are for 1.75 installed height. These are also 1.7 height:

https://www.summitracing.com/parts/CCA-26981-16

[turbodave]

Those and a few other springs would be highly suitable...
But the pressures still seem a little on the high side unless you are going to be turning some big RPMs or using heavier valves???

I'm just flat running out of time right now unfortunately, otherwise I would be purchasing a 11° Carbide mill and Setting up to machine some retainers to 11 degrees.

Maybe on my next set of heads!

[turbodave]

Well, here is a potential issue...

I drew it up in CAD to better visualise it (click on the image below and it'll open in a new window).
While Beehives are great, there is only so much that can be done using the stock rover valve stem dia and the matching 11 degree locks / keepers / collets. These 11 degree jobbies sure take up a lot of room :-(

Two retainers shown, the left is the comp 712 (incorrectly listed as 980), the right is the pre 1980 single-spring non-sintered Rover item.

The beehive spring shown is the Comp 26981 with the .650 ID / .825 OD at the top of the spring, and the 1.24" OD at the botttom.

I have positioned the spring to line up with the standard spring surface.

As can be seen, lots of interference. While we could move the spring lower, this would lose installed height, and no way to get this much back

Maybe we  should be looking instead at the next dia larger for the springs (1.375 ish? to get a larger ID at the top?

[mgb260]

Dave, Could you do an image of these retainers if reamed to 11 degrees?

https://www.summitracing.com/parts/cca-795-16

[mgb260]

Dave, Is this the reamer we would need?

https://conicalendmills.com/cutting-tools/special-application-end-mills/tapered-end-mill-carbide/11-degree-carbide-tapered-end-mill/

[turbodave]

Hey Jim,
It is indeed a 11-degree (22 deg included) but you need one with a major dia of at least .590" dia (and a minor dia of .400), so none of those will suffice; it'd be a custom piece.

There isn't enough info on the comp site to make a drawing unfortunately.

I can purchase a set on amazon and measure them up to see how they would work (and return if its a no-go), but if you assume that you would use a reamer and set it up to just clean up at the bottom of the existing 10 degree, you are radially increasing the diameter by approx 8 thou at the height that the top of the spring would be sitting (or 16 thou on diameter)!

I think though, there still isn't enough installed height - you're still going to be digging material out of the seat pocket in the head.
I have seen offset retainers in the past; not sure if they were for 10 degree though; obviously the further up the top of the spring, the wider the keeper/lock/collet so you start losing diameter...

[BlownMGB-V8]

I just confirmed with Tim that the 10 degree keepers that TA sells have in fact the Chevy type groove. Dave was right, no help there.

Still no luck I suppose on the tapered carbide reamer? Might be easier to find in the reamer category as opposed to the end mill category.

Creating a carbide tapered reamer is not a minor undertaking, but not impossible either. For this job I would start with about a 3/4" round stock in mild steel, cut the taper, make relief cuts to locate the carbide, and then braze pieces of carbide in position. Then back to the lathe to grind the taper with a tool post grinder, followed by grinding the relief angles. Using 3 edges would give a self-centering action although it could also contribute to chatter.

Finding the pieces of carbide is as much a challenge as anything, however here is one source:

https://www.carbideanddiamondtooling.com/search?query=stb26a

They would need to be roughly about 3/32" thick, .200 wide, and 5/8" long but the above ones should work.

Jim

[BlownMGB-V8]

I ordered some of the carbide pieces, after they come in I'll see about making up the body of the tool. I have everything else here that I need to make it.

Jim

[turbodave]

Hey Jim,

II just ordered some of the retainers and will draw them up and verify there is enough meat in them to make this happen.

Cheers

[BlownMGB-V8]

OK Dave, if it looks like it'll work I'll cut your retainers if you'll send me a second set for my own use. Does that sound fair?

Jim

[roverman]

Anyone have cut-up pic's of the 300 alum. head ? I have such a head.
                                                                                                                  Art.

[turbodave]

Jim, That sounds fair.

Here is the latest CAD..
The beehive Comp 26981 spring is shown on all (height is adjusted to suit.

The one on the right is the stock pre-1980 cap / retainer - note the beehive spring is overlapping as its designed for a 1.25 spring.

The Comp 712 (I just realised I still have identified as 980) is pretty much the same as the stock one; it just sits a little higher (see previous pics).

Both the right two would need (for a 1,70" seat height) the spring pocket lowering by approx  .142"


Middle pic is a proposal I had to modify the Comp 712 (again, wrongly identified as 980) to take the beehive spring. I have a friend with a CNC lathe that could be set up to have a mandrel chucked up, and machined with a 11-degree taper, and threaded, such that it can repeatedly machine these to suit. This would need 0.105" machined out of the stock pocket.

The second from left pic is just a reference, of the comp 795 retainer - obviously wouldn't work as the angles are not matched,

The left pic is the Comp 795 modified to 11 degree. As this would raise the height a little more, so needs only .072 removed from the spring pocket.

The next post will have all these pics (except for the stock retainer as this is pretty much the same as the 980) in better detail.

[turbodave]

Close-up pics for reference.

The last one is the modified 795. The real question, is what are the thoughts on so much of the keeper being outside of the retainer?
See the following post for a more detailed image with dimensions (only four images per post permitted)...

[turbodave]

As can be seen here, the top 10 thou and bottom 20 thou of the stock rover valve locks / collets have a slight chamfer, so you already lose contact surface area. But still with the modifuied 795, you would have just under 70 thou sticking out the bottom in fresh air. Is this bad? I just don't know....

As always, click on the image and it'll become a lot larger...

[mgb260]

Dave, I like the 980 modified the best. On the 795, what bothers me is the valve tip is so close to the retainer. If it was milled flat on top it would be better. The keepers are a lot longer than most and the part below the retainer won't hurt anything.

[turbodave]

Hey Jim,
Well maybe here is something a lot simpler.

If we chucked up the comp 795 in a CNC lathe on the 0.639" dia, and located up to the spring face, it can be used to bore the angle to 11 degrees and face the top, and it'd be quick and easy to do all of these.

It will still need some material digging out of the heads, but that's not a surprise....

[BlownMGB-V8]

I don't really see any problem with the 795. As long as the valve tip sticks out any above the retainer nothing is going to hit. The part of the keepers that stick out below won't hurt either as long as they don't hit the seals.

Jim

[turbodave]

Well, I guess I'll speak with my local shop and see what they want to machine these on their Haas lathe. After initial set up we're talking less than 2 minutes each, so can't be all bad.

[BlownMGB-V8]

Yep, let us know.

Jim

[minorv8]

What is the diameter of the valve stem at lock ? The stem is 11/32" but it is thinner at lock position. I was just thinking if it would be possible to modify the smaller 7 degree 5/16 locks by removing the tang. In other words make it look like Buick/Rover lock ?

[turbodave]

Jukka,

This is the dimensions of the valve and locks of the stock rover setup.