Engine and Transmission Tech

I am pretty sure last time I called and spoke with TA about the keepers, they said they weren't compatible with the Rover Valves. Now, I may be mistaken, but I was putting an order in with them at the time, and I would surely have purchased them if they were compatible.

Now, here is a suggestion though; A group (bulk) purchase. Personally, I'd purchase at least two engines-worth of keepers, maybe even three. I'm sure a lot more folks would be interested as well. If enough folks got together and requested it, I'm sure they'd make whatever....

Finally, for the springs, the Rover heads have a diameter of 1.23" in the heads for the springs. There is a lot of thickness under the seats, so it's possible to dig this out more. The Manley 41824 is a well made piece of kit. I have one, but haven't tried it on a head yet.

[www.summitracing.com]
[www.vividracing.com]

Finally, let me add that if there was enough interest, I could get a 11 degree (22 degree included angle) tapered milling cutter custom made, and make a fixture to hold a (10 degree) retainer, then come down and dress out the 10 degree to 11 degree pretty easily.

Lot of options, but I feel like we need to home in on a beehive spring that'll really do the job. Something that'll offer up to .520 lift, but I'm not convinced that a sping much over 300# rate is really needed - especially for a reasonable redline of 6250rpm or therabouts.

The spring pockets will have to be machined for the smaller diameter springs. There were no shims under the stock springs. The pockets could be cut a bit deeper to use shims.

Jim that link is for the keepers, I think this is the one for the V8 application:
[www.taperformance.com]

This seems to be the link for the retainers:
[www.taperformance.com]

And the link for the springs:
[www.racingsprings.com]

At 120/280Lbs@.550" Dave this sounds like what you are interested in. I could see maybe going a bit higher on the open pressure myself but there's room to shim it to get more pressure if needed. $16 each for the springs seems like a lot to me though, that's $256 for the set. Maybe we could find something a bit less expensive, the costs are starting to add up. This one is for the GT500 and Cobra Jet, I'd expect there are other options.

Jim

Jim the TA retainers are for standard springs not beehives. There are Coyote beehives that are similar, but I don't know if you can get 10 degree retainers that small of ID on top of spring. Coyote retainers are 7 degrees for 3 groove valves and are for a 6mm stem.

[www.racingsprings.com]



Edited 4 time(s). Last edit at 12/17/2022 01:58PM by mgb260.

Ah, so you were suggesting those for the dual springs then. That makes sense.

How about this:
[www.amazon.com]
[www.summitracing.com]

At .004" larger than the small ID of the spring they will certainly fit.

Jim

Yep, those are the ones. If the Buick keepers fit the Rover valves the TA 10 degree for Buick V8 should work too.

Maybe we have a good combination then. Have to check with TA on the keepers. If that's a go I think we may have something here. We should recap the links once that is confirmed.

Jim

Let's clarify one last aspect. The spring pressure. The load required for a flat tappet cam is less than for a roller cam. This seems weird but the roller cams have a more aggressive ramp angle so they need more spring to follow the lobe and can tolerate it because of the roller.

So while 280lbs of open load is fairly high for a flat tappet, something like 350 might be equivalent for for a roller cam. I'm no authority on this, being kinda new to roller cams and would welcome some concrete data from you other guys. I know it's something of a moving target but...

Has anyone seen performance figures for something like redline vs spring pressures for a roller cam? I'm sure lift also plays a part.

Jim

[www.motortrend.com]



Edited 1 time(s). Last edit at 12/18/2022 11:43AM by mgb260.

Springs used on aluminum heads should run at least a hardened shim to prevent brinelling the softer aluminum material. If you need to reduce installed height, don't stack shims more than 0.090 inch-use a spring locator instead. Also use a locator if the spring diameter is smaller than the pocket.

Beehive vs. Conventional
Even on a relatively mild 406ci small-block Chevy with a hydraulic roller cam, a spring incorporating the latest technology can make a big difference. Westech Performance tested a traditional Comp Cams dual spring with damper (PN 954) against one of Comp's new single beehive springs (PN 26918). The 954 developed 210 pounds on the seat and 523 pounds open, compared with the 26918's 130/318-pound specs. Both springs were installed with titanium retainers and locks, yet the beehive combination was still 52 grams lighter. If the engine's steel valves had been replaced with titanium valves instead, the weight savings would have been just 40 grams.

Overall peak output was virtually the same: 418.4 lb-ft for the 954 versus 416.9 lb-ft for the 26918, both at 4,800 rpm; and 418.2 hp versus 419.3 hp for the 954 and 26918, respectively, at 5,800 rpm. Average output throughout the 2,500- to 7,000-rpm test range varied by only about two numbers. But above 6,500 rpm, the difference was huge: The new-tech 26918 effectively extended the engine's rpm range, proving to be worth 15 to 36 hp and 12 to 28 lb-ft on top. The stiffer 954 did produce more low-end torque because its higher loads were actually bending the other components, effectively decreasing duration at the valve.

If using the longer 75-76 Oddfire 1.62 IN and 1.42 Ex valves you could use the cheap LS beehives. Cut the valve seat a little bigger. You would need 1.75 installed height and would have to shim the rocker stands up.

[www.ebay.com]



Edited 3 time(s). Last edit at 12/18/2022 12:42PM by mgb260.

That engine seemed to have really high spring loads. But then it is a BBC and has big valves and everything. Rover valves are considerably smaller. I'm also using solid roller lifters which are cut down and are significantly lighter than the hydraulics.

On those Blackhorse springs, by the time you bought the valves and machined the seats to match I suspect it would be a wash.

Jim



Edited 1 time(s). Last edit at 12/18/2022 01:30PM by BlownMGB-V8.

What does the cam manufacturer recommend?

Solid roller for a street engine?

[www.motortrend.com]

They didn't make a recommendation. It's basically a GM grind done through TA on a blank by one of the major cam companies like Crane or Isky. It was that "Hot" grind suggested by Jim N., I'm having trouble coming up with the name at the moment.

Jim

LT4 "Hot"" cam. Spec for Jim B's cam. Should be perfect in a 350 motor.

[www.gmperformancemotor.com]



Edited 1 time(s). Last edit at 12/18/2022 02:27PM by mgb260.

Dave, I'll be using Rover heads, so definitely interested in participating in a bulk purchase.

Eric, I think you want to go the other way and machine the 11 degree Buick to 10 degree so you can use aftermarket retaners. Which is what TA sells in the link above. If you use Dave's idea, you are limited to the stock Rover or Buick retainers which may or may not work with aftermarket springs.



Edited 1 time(s). Last edit at 12/18/2022 06:28PM by mgb260.

Milder cam than I was expecting, especially when the valve lash is factored in.

Thanks Jim, the whole spring thing is a mystery to me--thanks for letting me know.

Well, TA Performance are closed till the third of Jan

So I guess we will have to wait a little longer to verify 100% if these are compatible with the Rover Valves.


[www.taperformance.com]

Cheers,