Engine and Transmission Tech

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...





Edited 4 time(s). Last edit at 01/23/2023 04:11PM by turbodave.

Dave, Sounds like fun!

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

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.



Edited 1 time(s). Last edit at 01/24/2023 10:30AM by 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.

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

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

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.



Edited 1 time(s). Last edit at 01/25/2023 12:22PM by turbodave.

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



Edited 1 time(s). Last edit at 01/25/2023 01:36PM by 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.

[www.racingsprings.com]



Edited 5 time(s). Last edit at 01/29/2023 11:18AM by mgb260.

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....





Edited 2 time(s). Last edit at 01/25/2023 05:04PM by turbodave.

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

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.

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

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

Just a FYI ,
The Engine Masters series has an excellent entry level episode on valve springs.
If you find yourself lost on this message. It will clear off some of the fog.
I get the program locally on the Discovert Channel.

Live like you mean it.
Fred

Fred, could you post a link perhaps?

Jim

This video is pretty good:

[duckduckgo.com]

It's on the CTV network, Discovery Velocity channel, Engine Masters, season six episode 26.
Not sure if this link works, but give it a shot.

[account.bellmedia.ca]

Appreciate that, it should help anyone following the thread.
Here is the spring I'm considering:

[www.lsxceleration.com]

If it is installed at about 1.6" seated pressure will be just under 200 lbs and it will allow .550 lift with a little over 400 lbs open. That should work well with the (relatively) smaller valves in the 4.6 head and the solid lifters I think. The pockets will have to be opened up a bit.

I believe I'm ready to order springs and retainers.

Jim