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Old 09-08-2020, 02:03 PM   #1
142 guy
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Default Yellaterra roller rockers

Does anybody have any direct experience or anecdotal experience with this Australian supplier?

http://store.yellaterra.com.au/categ...?sort=priceasc

I stumbled across them quite by accident. I don't need rockers right now. But, my B20 rockers have been reground and profiled once to remove the inevitable grove so it might be a useful product for the future. A true 1.65 lift as opposed to the variable number that comes with the OEM rockers might also be a nice feature.

Just curious, what is the limit on valve lift before you run into coil bind issues with the stock B20 springs?
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Old 09-08-2020, 02:42 PM   #2
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Not those, but I do run a set of the KgTrimning roller rockers on my PV's B20. I was curious, doesn't look like they list them any more.

When I first put them on, I drove around a bit with the stock rockers in, swapped the rollers on, and took it for another drive with the first stiff fresh in mind. And it's not a large difference, but it's a nice little dash of added pep sprinkled all over the RPM range. A little more noticeable at higher RPM's.

Not sure about coil bind on the stock springs, I have dual springs on my head (R-Sport stg 3).
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Old 09-09-2020, 12:46 AM   #3
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What was the rocker ratio on the KG rockers? I think the Yellaterra rockers are 1.65:1.

I admit to having a bit of a problem wrapping my head around their name. Sounds like a Yogurt brand.
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Old 09-09-2020, 08:55 AM   #4
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1.6 IIRC. I think they were some slightly modified Kenne Bell rockers for some Buick engine. Presumably with the pivot slightly enlarge and rebushed to fit the Volvo rocker shaft.
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Old 09-10-2020, 08:20 AM   #5
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I tried to communicate with Yellaterra via email, last winter and did get one reply, but gave up after that because of no further replies. It may have been a temporary thing?

I've also communicated with an Aussie who told me about a set of Harland Sharp roller rockers he uses on his 142 track car.

The actual width (front to back when installed) of the rockers the Company manufactures looks smallish when compared to those manufactured and used for racing here in the US.

Andrew White who has run pavement rallies in the AU for years put a set of Yellaterra rockers on a B20 in his 122 he uses for road racing now and told me that after a couple of events they were working out OK earlier in the year.

If you are interested in pre-1975 racing and rally cars and speed equipment check out the Historic Volvo Racing Rally and Speed Society on Facebook. With the help of some friends I started it in the spring and its been fairly active and has grown to 1.6K members: https://www.facebook.com/groups/232999844689051
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Old 09-10-2020, 12:34 PM   #6
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Reading the Yellaterra product information, I got the impression that the Yellaterra rockers were based on rockers sourced from the US. However, their product information on their website is lean (I was not able to figure out exactly what the differences are between the various rocker versions for the B 20 was because the product descriptions all appeared the same).

Harland Sharp does not list an application for the B20. Do you know which rocker was being used on the B20 and how much modification if any was required to fit. I had heard that people had been using one of the Kenne Bell roller rockers on the B20 (some suggested that is what VPD was using); but, Kenne Bell appears to be out of production.
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Old 09-10-2020, 12:47 PM   #7
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I got my set of KG Trimning rockers used (from a guy racing a Marcos in England), not sure what mods were done to them. I've just heard second or third hand that they were or at least appeared to be modified versions of Kenne Belle rockers.

Here's my setup - the more supportive 'briged' that replaces the rocker stands and repositions the rocker shaft slightly (to better work with higher lift cams), and the roller rockers.


These ride on bronze bushings pressed into the aluminum bodies - I'm just assuming that the original rockers (which have left and right hand versions to reach over form he pushrod plane to the valve stem) had smaller bores - they were enlarged and had different bushings installed to suit the Volvo rocker shaft diameter. I think the shaft was modified as well, but I've never looked to see. Maybe some different drillings for lubircation points?
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Old 09-10-2020, 12:55 PM   #8
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I don't recall seeing any numbers or markings on the lifters themselves.
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Old 09-10-2020, 01:08 PM   #9
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There's certainly some similiarity with KB Buick rockers:
https://www.turbobuicks.com/forums/b...-assembly.html
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Old 09-10-2020, 01:21 PM   #10
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The rockers I bought from Topi were modified Kenne Bells. The KG Trimning rockers have offset rollers while the KB's have offset adjusters. I suspect KG had rockers custom made for their kit.

Topi ground the name off the rockers but a local rebuilder identified them as Kenne Bell and I was able to source replacements when needed. Topi made kits with standard width slots and narrowed roller rockers so that stock rockers could be used as well as ones with wide slots so unmodified rollers could be used.



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Old 09-10-2020, 01:52 PM   #11
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Doesn't show up well in my pic, but the adjusters are off center as well on the KG rockers.
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Old 09-10-2020, 07:21 PM   #12
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They are roller tip rockers not full roller bearing rocker arms. you MUST check that they ride on the valve stem properly, On one of the race cars that I built we used full roller bearing rocker arms, they have a time life, I have one that failed as a key fob, also they weigh more than stock rockers. I have a MG Midget/1275cc engine stock push rods and rockers that makes 100 HP/Litre will rev to 8,500 RPM [limit on the crank shaft] They are nice, cool to tell your friends about, but unless you are build a full out race motor you won't see any differance.
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Old 09-11-2020, 12:24 PM   #13
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I assume your reference to 'not full roller bearing rocker arms' is to the fact that some of the rockers use bronze bushings on the rocker shaft as opposed to the needle bearings that some use?

My primary interest was not light weight / high RPM. It was about a possible replacement in the future for rockers that have already been 'de-grooved' at least once and perhaps getting some rockers that I actually know the ratio. My understanding is that with a nominal rocker ratio of 1.5:1 the valve lift on my D cam (which is new) is supposed to be 4.2" I measured lifts on the valves with a dial gauge and my de-grooved rockers and the lifts varied from 0.397" to 0.413" with an average of 0.404". Assuming that the D cam was manufactured correctly, the 0.404" valve lift corresponds to an average rocker ratio of 1.44:1. I have seen conflicting internet references that the stock rockers are supposed to be 1.45 or 1.5. If its 1.45 my rockers are probably sort of in spec. If its 1.5 then they are quite a bit out of spec.

After re profiling it appears that some of my rockers might be as low as 1.42:1. Getting a set of rockers that ae consistent would be nice. A modest increase in rocker ratio might also be nice. However, I would have to be mindful of the potential for coil bind with the original B20 valve springs.
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Old 09-11-2020, 01:02 PM   #14
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Originally Posted by 142 guy View Post
I assume your reference to 'not full roller bearing rocker arms' is to the fact that some of the rockers use bronze bushings on the rocker shaft as opposed to the needle bearings that some use?

My primary interest was not light weight / high RPM. It was about a possible replacement in the future for rockers that have already been 'de-grooved' at least once and perhaps getting some rockers that I actually know the ratio. My understanding is that with a nominal rocker ratio of 1.5:1 the valve lift on my D cam (which is new) is supposed to be 4.2" I measured lifts on the valves with a dial gauge and my de-grooved rockers and the lifts varied from 0.397" to 0.413" with an average of 0.404". Assuming that the D cam was manufactured correctly, the 0.404" valve lift corresponds to an average rocker ratio of 1.44:1. I have seen conflicting internet references that the stock rockers are supposed to be 1.45 or 1.5. If its 1.45 my rockers are probably sort of in spec. If its 1.5 then they are quite a bit out of spec.

After re profiling it appears that some of my rockers might be as low as 1.42:1. Getting a set of rockers that ae consistent would be nice. A modest increase in rocker ratio might also be nice. However, I would have to be mindful of the potential for coil bind with the original B20 valve springs.
Any thing that gets rid of parasitic friction=HP. Full bearing roller rockers will do that, bushed rockers that still have bushings that have friction. Friction is the enemy. Teflon coatings Titanium parts, any thing with less mass that you have to move = more power that the engine can send to the rear wheels use. Aluminum fly wheels, small diameter clutch disc/pressure plates,etc. How far do you want to go and yet not have an engine that needs a lot of maintenance.
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Old 09-11-2020, 01:27 PM   #15
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Yeah, I'm not sure how much yo'd notice the reduction in friction by the rocker tip rolling against the valve stem vs. sliding, but you can (at least I do) notice the difference created by the higher ratio leading to more lift.

Like I said earlier - it's a pretty quick swap. I drove my PV around a bit, came back swapped the roller rocker setup on pretty quickly, then drove it around again, as close to back-to-back as possible, and I could tell a difference. Not much down low (possibly none, or a bit less), but certainly a bit more pep up higher in the PRM's. This is an engine with plenty of supporting mods.
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Old 09-11-2020, 02:57 PM   #16
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Here is the image of rockers that an Aussie sent me which he told me were made by Harland Sharp (although they don't have Sharps trademark orange anodizing.) No they don't list them in the catalog, but they will make a set for most any engine. This set up isn't as good as the KG Triming rockers or the ones that Topi made because both of them have support for the shaft on both sides of the rockers. Another issue with this set is not enough surface contact under the rocker arm supports to equalize the stress caused to the top surface of the head by 300psi and higher racing valve spring pressure. This leads to cracks forming on the top surface of the head.

I've been meaning to contact Sharp and did this afternoon, although they close early on Fridays so I missed them, I'll try again on Monday.

142 Guy: The main benifit to roller rockers for racing with high valve spring pressures, even if they don't have full needle bearings on the tip or the rocker shaft, as you probably know is less sideways force on the valve stem. That cuts down on the bending of the valve stem and or friction between it and the valve guide while using radical racing cams. The upside is less valve stem breakage and friction which results in a little more power at high RPM'S.

Cost wise a good set of roller rockers is quite expensive. You would be better off to just buy another set of stock rockers and have them resurfaced. I've equilized and increased the ratio on a stock set of rockers by installing thicker bushings and offset boring them in the milling machine and then finishing the ID surface with a Sunnen honing machine. I'm fortunate to have the rocker arm grinding attachment for our Souix valve grinding machine so I can do my own. Any good machinest can do the rocker arm bushings for you as well.

Last edited by vintagewrench; 09-11-2020 at 03:19 PM..
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Old 09-11-2020, 04:03 PM   #17
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Quote:
Cost wise a good set of roller rockers is quite expensive. You would be better off to just buy another set of stock rockers and have them resurfaced. I've equilized and increased the ratio on a stock set of rockers by installing thicker bushings and offset boring them in the milling machine and then finishing the ID surface with a Sunnen honing machine. I'm fortunate to have the rocker arm grinding attachment for our Souix valve grinding machine so I can do my own. Any good machinest can do the rocker arm bushings for you as well.
Competent machinists here are not inexpensive. I have heard of increasing the ratio by removing the 5/16" adjuster and offset drilling for a new 3/8" adjuster. Struck me as a little dodgy. I understand the install new shaft bushing and offset bore to get the desired ratio. However, by the time I source spare rockers on which to experiment and pay for the machine work, I don't know how much more expensive the roller rockers will actually be.

I understand the potential benefits associated with the stands made by KG and Topi; but, I am not looking for higher RPM or dealing with high rate springs or pushing the rocker ratio really high to get a lot of lift. If I was going to do this I was thinking more along the line of retaining the original stand and just replacing the rockers, a bit like the idea VPD claims to offer; but, who I refuse to deal with.
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Old 09-11-2020, 10:00 PM   #18
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Originally Posted by 142 guy I understand the potential benefits associated with the stands made by KG and Topi; but, I am not looking for higher RPM or dealing with high rate springs or pushing the rocker ratio really high to get a lot of lift. If I was going to do this I was thinking more along the line of retaining the original stand and just replacing the rockers, a bit like the idea VPD claims to offer; but, who I refuse to deal with.[/QUOTE]

Well then the Yellatera set up might be the best way to get what you'd like to have and the price isn't all that bad. If you do contact them I like to know how you make out.
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Old 09-13-2020, 07:20 AM   #19
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This video shows a set of Volvo B20 Roller Rockers that Tom Kirk from Illinois machined and has been using for several years on his 122s.

https://www.youtube.com/watch?v=Hpl-gz3E5Lc
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Old 09-13-2020, 07:36 PM   #20
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That looks like the hot ticket!

Now, I just have to figure out the original source for those rockers or at least the originally intended application that would allow me to source something with the same geometry. Is there any other information on Tom Kirk's application floating around? I did a brief search and the only thing I came up with was a brief reference to him on the HVRC Facebook page.
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Old 09-14-2020, 07:06 AM   #21
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Quote:
Originally Posted by 142 guy View Post
That looks like the hot ticket!

Now, I just have to figure out the original source for those rockers or at least the originally intended application that would allow me to source something with the same geometry. Is there any other information on Tom Kirk's application floating around? I did a brief search and the only thing I came up with was a brief reference to him on the HVRC Facebook page.
Tom Kirk is active on the Amazon and Historic Volvo Racing Rally and Speed Society pages on Facebook. Maybe he will share some details about the rocker arms if you contact him?

I have thought about machining a support and a set of my own rockers but don't have the time to do so now. Not knowing what aluminum alloy and heat treatment is used by manufacturers I thought that checking out the properties of forged aluminum stock which is available, and talking with a heat treater might be a good starting point?

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Old 09-14-2020, 12:47 PM   #22
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Here's a photo of the other side of Aussie's set up. Also found many of the details of his turboed 142 @ https://ozvolvo.org/discussion/5044/b20-turbo-in-142
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