Max valve size for 4.0/4.6 heads?

[turbodave]

Jim,
Well the shop I spoke with suggested it would be a better idea if they did the setup, and I stood by the machine and ran the parts. Basically, for the price of a case of beer to them, I can get the 795 modified to the 11 degree angle. I'll obviously extend the offer to mod a set for you as well...

They also have a diamond wheel and spin fixture, so are happy to modify my manley 41824 seat pocket cutter to a slightly smaller diameter (it currently cuts 1.265 dia which is a hair too large for my liking) ... If you don't have a pocket cutter, you are likely to need one.....

So, I'm going to do a little more gathering of the other parts (like confirming and purchasing the springs I'll be using) but it sounds like we have a plan.

The ONLY thing I would want to add, is that based on the drawings, modifying the 795 to 11 degrees does reduce the cross-sectional area at the narrowest part from 43 to 37 thou. This then becomes 87% of the cross-sectional area it was previously.

[mgb260]

Jukka  has a good idea! Here is a pic of a 7mm 10 degree you could use 7 degree also. You could use a retainer as a fixture and drill to remove the ridge. I think it should work fine.

[turbodave]

interesting. Now I understand the thinking.
0.277 inch is 7.06mm so yep,

For a fixture, you'd need to stop them spinning, and maybe also add something to space them apart as they aren't meant to touch, and I'm sure unless using an end mill, they will drag up and out as soon as you drill them.

I feel that something more like this  would be better, where you cut up half a retainer, machine it just a little past half way so the lock sits flush, and put it against a block (yellow) that has a notch in t for clearance (maybe tack them together at this point?) and use a clamp (purple) to hold them and use a 2-flute end mill to remove the offending lump?

What's the p/n for the 10-degree 7mm???

[mgb260]

Dave, here you go:

https://www.racingsprings.com/index.php/valve-spring-retainer-lock-5090.html

[mgb260]

Dave, I was thinking of just clamping the retainer in the drill press vice. Dressing a 9/32" Cobalt bit down to .278". I think the taper will stop any spinning. You just want to take the ridge off and hone it out a little. Once drilled, shut off drill, lift up and remove locks.

[turbodave]

I am sure if drilling as a pair you'll want to put a known thickness shim or gauge wire between the two (on the flats) to space them apart, and press down to seat them and prevent spinning.  Rethinking it, that would probably be pretty easy to achieve, just a little fiddly with the shim, but totally do-able. Doing as a pair would stop the drill walking and be a LOT quicker of course!

McMaster has metric colbalt drills I'm sure. I do have a few metric R8 collets so will probably just use my mill.

How great is this that the .277 is right there at 7mm?
Nice idea Jukka !

[mgb260]

That is what I hoped the TA locks were! Actually, if you use a 7mm bit and they are touching, they won't be when on the valve stem because it is slightly larger diameter.

[BlownMGB-V8]

Good idea but it will be fiddly and tricky to do. That spacer between the two halves will have to be an accurate thickness so you don't cut into the rest of the bore and your clamping device will have to press the halves into the taper pretty firmly. You might make your spacer as a long tab that extends out the bottom and just drill away the center of it on the first set, then deburr and continue with the rest. That way the bottom part would make it way easier to insert as a single shim rather than two individual ones. Might want to make the shim out of aluminum.

But how to clamp it? Maybe something like a big nut that the retainer will fit into? Then a hollow bolt in the top that will press only against the keepers? Drill through the open center of the bolt. Has to be a step in the nut for the retainer to sit on. Draw something up Dave and I'll throw out some more ideas.

Jim

[turbodave]

I'll throw something together in 3D to make it easier to visualise.

Based on my playing with locks in the past few weeks, I'd have thought we're only talking about 4-8 thou a side. That'd be not too difficult to cut into 1/16" wide strips. If cut to 3" lengths it'd be pretty easy to slide in there.

[mgb260]

Jim or Dave, You guys can check the gap on the stock Rover pieces.  For a shim, a pop or beer can is around EDIT.004 thick so a piece doubled would be about .008.

[turbodave]

Yep, I'll check out the gap this evening, but the reality is the valve locks that we will end up using / modifying for use need to be put around thee appropriate diameter valve / pin gauge and their gap measured.



I'm about to order one each of the PAC-1231X and a few pairs of the 10-degree locks that I can do some experimenting with.


I had seen this mentioned earlier, but hadn't t appreciated the 1231x as being a 1.575" installed height, and having up to .550 lift, and 291lb rate, which makes it about perfect for me with a 50233 cam and hydraulic lifters.
EDIT - the 1233 spring is 7 degree only as it has a smaller ID so I'm not bothering with that...

I'm also going to order a pair of PAC-R310 to see how they compare in the installed height to the Comp 795 as they appear to be almost identical to each other.

I do like that PAC lets you order onsie/twosies of everything very easily.

Finally, I wanted to add this pic as a reference of where my measurements are at. The important things to note, is the 1.80" dimension is larger than it typically would be as there was a little pitting on one of my head seats, so i told him to just cut them a little deeper (rather than replace the seat) as it'd be beneficial for me to have a taller installed height anyway.  The other thing to consider is the yellow dimension - I am running shortened guides and these were pressed further into the head, to keep the seal off the keepers.  
It is generally regarded the later 10-bolt heads (as I'm using) are only good to .450 or so of lift, but I found even that puts the top of the seal into the reduced diameter of the stem, so I went a little deeper to compensate....

Finally the 1231X springs are 1.083/.720 at the base, so the head will need modifying (of the 0.832" diameter) to allow these to sit where they need. The manley seat cutter i had mentioned previously only cuts to .742" ID, so I'll need to find another option for that...

[mgb260]

Dave, Sounds like fun!

[BlownMGB-V8]

I believe the gap between the two keepers is going to turn out to be bigger than you think but I haven't tried to measure it yet. I would expect to see something closer to .010 - .015" per side and maybe even a bit more. It's not a place where a close tolerance is needed. The overall length of the keeper is also somewhat important and it would be a good idea to look at the top and bottom edges of the bore to see how closely they match the original keepers. The top corner in particular needs to have a larger radius than the inside corner at the top of the valve groove.

Jim

[turbodave]

interestingly there is no chamfer on the top of the rover keepers...  It doesn't seem right, but that's how it is, and how I've shown it as a gap in my CAD models. Try it on a few heads yourself - theoretically, there should be no gap atop the keeper, but you can probably slide a feeler gauge in there a little ways.

Again, my experience is all on the 10-bolt heads.

[turbodave]

8 thou per side is approximately where the rover keepers are sitting at.

Pac Springs online store has been down for a few days, so i finally called up today and ordered over the phone.
I got very confused as the guy on the phone told me the 310 retainers wouldn't work with the 1231X springs, and I should instead use the 311 retainers.
I got confused, so said I'd call them back, and after checking my notes, I'm still a little unclear. The 311 has the same 0.640 diameter as the 310, but the 311 is 7 degree, compared to the 10 degree of the 310.
Now, the ID of the top of the spring is .0.636, which means its unlikely to fit the retainer, but I'm not sure what's going on there?  I'm not adverse to taking a small stone in a die-grinder and relieving the ID of the top spring coils a few thou radially to get it to fit over a .640 diameter.

Anyways, I just called back and ordered what I wanted. End of the day, I like the 1.575 installed height of the spring, as itt'll reduce the need to dig lots of material out of the head.

[mgb260]

Dave, I think he thought you were using the stock valves for that spring which is for 7 degree keepers.

[BlownMGB-V8]

Dave, you're right about the square corners on the keepers. Or such a small radius you'd have to measure it under a microscope. Should be fine.

The retainers will press into the top coil of the spring. The spring will expand slightly to accept it and then grip. No worries there.

Jim

[turbodave]

Thanks Jim and Jim! That all makes sense.

I must say, I really appreciate all the good grounded conversation in here  :-)
Makes a refreshing change from the FB pages that seem to have killed a lot of the forums.

[mgb260]

Dave, I'm having trouble finding a small spring seat cutter for that spring. That spring is meant for a DOHC Ford Mod motor. You would think that there would be one. Comp Cams has a 1.1 OD inside valve locator for a .510 valve guide. What is the OD of the Rover guide? We may have to go back to the Comp 26981 spring

[mgb260]

The Dodge Viper springs set at 1.66 will give the higher pressure Jim B needs for the solid cam. Meant for 1.75 installed height and .600 lift at 1.66 it is good to .550 with .030 until coil bind.

https://www.racingsprings.com/index.php/valve-spring-11196.html

[turbodave]

The manley 41824 (that I've mentioned a few times) is a .742" internal on the spec sheet.

I need to do another trial cut on a scrap head to figure out what it actually cuts to, but its likely close.

Should have the springs in my mailbox on Friday or Saturday, so I'll report back more on the weekend.

Here are dims that should help you make a decision....

[MGBV8]

Just to clarify, Dave, the dimensions in your last drawing are for a stock Rover 4.0/4.6 head.  Correct?

[turbodave]

That is measurement for my refreshed 10-bolt heads (1994 on). If i was to guess, you can probably reduce the 1.80 and 1.566 by 20 thou or therabouts.
I do have a 1980 SD1 head, and a 10-bolt head in my shop; I'll measure both over the weekend and make a drawing as a reference.

[MGBV8]

I have a set of both the 4.0/4.6 heads & a set of 3.9 heads (& 300 heads).

[mgb260]

Dave, could you do the diameter of the valve guide under the seal too. Thanks!