1.95 ratio roller rockers

92bird

Registered User
So I recently purchased a set of Yella Terra 1.95 ratio full roller rockers for my Grand Prix GTP. These are custom made rockers specifically for the Series II and III 3800 GM engines. They are made in a 1.61, 1.7, 1.8, 1.9, and 1.95 ratio.

They seem to fit amazingly well on on an SC head. The pedastals are a perfect fit, and roller tip placement appears to be good.. I need to head over to a buddys house and test fit them on his spare engine, and roll them through a few cycles and see how everything lines up.

If these work, they would give us .502 lift intake and .515 lift exhaust on a stock 89-93 cam. Possibly a nice bolt-on? Althought, it would require valve spring upgrades.

Anyway, take a look at the pics of one of these rockers bolted down.. Thoughts?

Jeramie
 

Attachments

  • IMG_0092.JPG
    IMG_0092.JPG
    89.2 KB · Views: 432
  • IMG_0093.JPG
    IMG_0093.JPG
    77 KB · Views: 473
  • IMG_0094.JPG
    IMG_0094.JPG
    75 KB · Views: 409
  • IMG_0095.JPG
    IMG_0095.JPG
    106.5 KB · Views: 440
  • IMG_0096.JPG
    IMG_0096.JPG
    89.1 KB · Views: 439
more pics.... :)
 

Attachments

  • IMG_0097.JPG
    IMG_0097.JPG
    112.9 KB · Views: 418
  • IMG_0098.JPG
    IMG_0098.JPG
    87.1 KB · Views: 417
  • IMG_0099.JPG
    IMG_0099.JPG
    88.3 KB · Views: 419
  • IMG_0100.JPG
    IMG_0100.JPG
    94.2 KB · Views: 417
Last edited:
The big questions are:

What happens to the tip as you move through travel. You'd have to remove a valve spring and see how much tip travel there is. I suspect it will be ok, but that's one thing you'd want to check.

Another thing you need to check is how it affects pushrod clearance. Typical 1.8's caused the pushrod to contact the clearance hole in the head. If the pushrod cup is moved even further in then I suspect that it may bind significantly.

I notice that the pedestal does not sit down properly in the pocket. It looks like it would require clearancing of either the pedestal or the cylinder head.

Nice find though, might be a cool upgrade for some folks.
 
I was wondering the samething. Where did you find a set with the 8mm bolt mount? My GTP set was a size larger. :rolleyes:

Let me kwow how it turns out. :)
 
I notice that the pedestal does not sit down properly in the pocket.

Correct.. The part that sticks out would need to be grinded/machined down, which will lower the rocker a hair, but could be brought back up with a shim or two. The part that goes down actually is a perfect snug fit.. it almost snaps when you push it down.

I was wondering the samething. Where did you find a set with the 8mm bolt mount? My GTP set was a size larger.

Let me kwow how it turns out.

Correct also, I just happened to have a metric bolt laying around that fit!

A side note, these rockers are super, super light weight. A fraction of the weight of a stock rocker, or scorpion rocker. I'll have to dig out the scale and weigh em..

Jeramie
 
Last edited:
A side note, these rockers are super, super light weight. A fraction of the weight of a stock rocker, or scorpion rocker. I'll have to dig out the scale and weigh em..

Jeramie

Yes, they are very lightweight. I've seen the 1.7 versions on LS motors. Unfortunately they are a little on the too light side when running high spring pressures and are known to break. I'm talking 200psi seat pressures/500psi open though so it's not like it would be a problem on someone with a typical SC motor.

There are benefits to running a low lift cam and high ratio rocker.
 
Another concern is what does that make the ramp rate look like, and is it still acceptable for the hydraulic lifters and available valve spring's for stock valves?

Also, any adverse effects on the stock timing chain/damper?

Jeramie
 
Probably not since the valve spring upgrade will not have to be that much seat pressure. Should run really well.

SWS
 
Keep us up to date on this I am about to order the 1.9 yella terras for my GTX I am on grandprixforums as well
 
Another concern is what does that make the ramp rate look like, and is it still acceptable for the hydraulic lifters and available valve spring's for stock valves?

Also, any adverse effects on the stock timing chain/damper?

Jeramie

No, would not be worried about any of that.
 
Did you ever get to test these on the roller motor? What did the valve tip wear pattern look like? Early trickflow heads 4 5.0s ate valve guides because of valve side loading. Did you check for valve to piston clearance (clay check)? If there is clearanc issue with push rod holes, how much material is there to poss. grind clearance?
Keep us up on this it looks a cool mod.
 
PTV clearance is typically due to when the valves open not how much they open, i highly doubt PTV clearance would be of any concern

i'd have a really close look at the pushrod placement, may need to open up the pushrod through hole to give it more clearance
 
i know its all too soon but...

92bird... any progress?

I'll be putting a crate engine I scored recently into my black 90 5spd possibly this weekend, the 1.95s would give it some extra pep and are ideal for what im doing with it.

I'm almost tempted to purchase a set and try it out, I already did a 5 angle valve job with 130lbs OTS so I don't forsee any problems there

where do you gtp folks order the yella terras? pricing?
 
The 1.95's were exclusively made for ZZP so you'd have to contact them to purchase. I can get the 1.90's which would still be a big improvement if they work out. I'll have to order some and then do a mock up. Waiting on confirmation of pricing and availability (I have access to Yella Terra).
 
What kind of performance increase would increasing the rocker ratio to 1.9 have? Is it the same effect of increasing cam specs without actually doing so?
 
That's what it does to the grand prix. It increases the lift and duration gives you more performance in the higher rpm range. It simulates camming the car without actually going into the motor.
 
i know its all too soon but...

92bird... any progress?

I'll be putting a crate engine I scored recently into my black 90 5spd possibly this weekend, the 1.95s would give it some extra pep and are ideal for what im doing with it.

I'm almost tempted to purchase a set and try it out, I already did a 5 angle valve job with 130lbs OTS so I don't forsee any problems there

where do you gtp folks order the yella terras? pricing?

Look on intense racings website they have a number listed and can get any yella terra product you want. I do NOT recommend dealing with ZZP they have the worst customer service of any business I know of however you can reach john at intense with ease and he is very knowledgeable and knows a bit about our platform as well.
 
Still waiting to get these mocked up..

These are not cheap, but if they work for the SC, we would not need their whole kit, which includes pushrods, pedestal rail, the wrong bolts, etc..

Dave, now that crane is back in business, can you get the correct springs for stock valves again? I haven't checked. If so, that would make it a nice package if it all fits.

If the mockup works, i'm going to test them out on my bone stock '94 SC.. With that pathetic excuse of a cam it came with, it might actually make a noticeable difference.

One other thought, what about a split ratio? Like 1.95:1 on exhaust and 1.9:1 on intake, or vica versa?

Jeramie
 
I can get the valve springs, but at over $400 just for a set of rocker arms that don't fit without modifications, this isn't starting to look like such a wonderful idea.
 
cam VS these rockers

Both listed web sites list 1.9 as highest ratio ava. $399 with pushrods and wrong size hardware. How much did u pay for the 1.95s? In the above pic from the end of the head it looks like the tip is well to the inside of the valve tip, and rocker is at furthest point of arc of travel (flat or level). When valve is opened the tip looks like it will move further in. Is the geometery totally fubar there? Summit lists a supercoupe cam at $369, how much would one expect to pay for a custom cam? Is a cam with the cleveland type rocker (1.73 stock ratio, under $200) worth the slightly higher cost and add. work?
 
Back
Top