See discussion here
Although we cannot vouch for the accuracy of the discussion (in fact considering the source i would call it rumor at this point), it implies that the solid lifter conversion is necessary with the GMR cams because they are regrinds; the base circle is smaller, and hence there is too much lash leading to failure. So i'm wondering, if these are regrinds, is it higher lifts that causes the failure, or is it excess lash, and would a cam profile with high lift and a standard base circle really require the solid lash adjuster upgrade?
Does anyone have an idea of the tolerance in our valvetrain for regrinds? I mean going from stock to 0.500" lift is drastic, but there has to be a value that is tolerable in terms of a smaller base ciricle. The thing is with a smaller base circle, you are not inducing more absolute squeeze on the spring. I hope this makes sense, but because you are starting with less preload, the spring has the more delta (net lift), but it is not getting any closer to coil bind than a stock camshaft profile.
It's kind of an interesting discussion point, although anyone installing cams, regrinds or otherwise, would probably benefit from upgraded valvesprings anyway, so that utility is kind of negated.
Thoughts?
I'd be hesitant to believe them to be completely honest with you, like mentioned GM ran these cams in the LSJ build book build on stock lash adjusters. I would think that if anyone knew what was up, it would be the guys at GMR that built the motor.
The Cobalt guys seem to have alot of crazy theories...I've gotten into countless arguements with those guys over some pretty rediculous things.
I've read through posts on there that also claimed that the Comp Cams where regrinds as well.
Easiest solution is to just measure the base circle, why none of those guys have done that yet is beyond me...its quite simple.
I'm going to measure my Comp cams when I swap them to my new head just out of curiousity.
That being said, I had a lash adjuster fail on me when I was still on the stock valvetrain and cams, I believe a few other people have as well.
Its hard to say what the stock ones can handle as there are very few that take cam profiles that high. Best person to ask tho would be Voocky (sp?) he is running those GM Europe cams now which I believe are more aggressive than the GMR ones are....he is also quite knowledgeable when it comes to anything ecotec. Its to bad hes not on here much anymore.
I do think you might have got your theory wrong tho about the coil bind tho based on the base circle. While reducing the base circle reduces the pre-load on the spring it doesn't change the amount of lift it can take.
The cam doesn't compress the spring, it pushes the valve down, which in turn compresses the spring.
If you where to compress the valve and inturn the spring, while not being acted upon by the lobe, then the valve would no longer be seated and would be open.
You can preload a spring but not more than the seat pressure, anything more than that and it would cause the spring to start to compress which would cause the valve to open.
So buy reducing the base circle it does reduce preload on the spring but it doesn't allow you to run more lift, you are still constrained to the amount of lift avalible based on your installed height.
Hopefully that makes sense, but I'm pretty sure thats right.
Hmmm, i think that makes sense. I actually don't know what i was thinking before - a closed valve is a closed valve no matter what cam and/or base circle is installed. It makes sense now why regrinds are rather risky too - I still wonder how much tolerance is there for a smaller base circle, but honestly i can't see it being much at all.
Yes, I remember when I was instaling my cams it didn't seem like there was much holding the rocker arm down.
I guess it also depends how much the lash the lash adjuster can take up.
Very interesting subject tho...I wish there were more very knowledgable people here to help answer some of these questions.
Where is Voocky when you need him?? lol
talk to to ben wenzel about this, guys.... i know he used those 'europe' cams...
If it takes forever.... I will die trying. Underdog Racing
Look at your source Ryan. JBO has a greater ecotec knowledge base.
With that said I do still have my blower cams and a few sets of stockers laying around.
its an old concept. time for something new to take the reigns. - Z yaaaa
On another note, i contacted deltacams in washington state about their experience with L61 cams...apparently they have some programs in place. They recommended a "264 grind" for my upcoming s/c set up. The email response seemed quick and vague, but i intend to follow up by phone when the time comes. BTW, they quoted ~$200 for the set + shipping and cores. This is a lot of speculation at this point, but if it all pans out you could have custom ground cams for about 250-300 out the door.
oldskool (eco meatcake) wrote:On another note, i contacted deltacams in washington state about their experience with L61 cams...apparently they have some programs in place. They recommended a "264 grind" for my upcoming s/c set up. The email response seemed quick and vague, but i intend to follow up by phone when the time comes. BTW, they quoted ~$200 for the set + shipping and cores. This is a lot of speculation at this point, but if it all pans out you could have custom ground cams for about 250-300 out the door.
I had an intake cam reground through them last summer. It was only 75 dollars a cam then. mine was for a 2.3 HO cam i wanted to get more out of and they were very limited on the specs they could give me. Maybe they have more options for the L61.
i have heard of a lot of honda guys, sohc d-series, running a deltacam regrind. no issues that i have heard of
Zs Z wrote:oldskool (eco meatcake) wrote:On another note, i contacted deltacams in washington state about their experience with L61 cams...apparently they have some programs in place. They recommended a "264 grind" for my upcoming s/c set up. The email response seemed quick and vague, but i intend to follow up by phone when the time comes. BTW, they quoted ~$200 for the set + shipping and cores. This is a lot of speculation at this point, but if it all pans out you could have custom ground cams for about 250-300 out the door.
I had an intake cam reground through them last summer. It was only 75 dollars a cam then. mine was for a 2.3 HO cam i wanted to get more out of and they were very limited on the specs they could give me. Maybe they have more options for the L61.
Hmm i wonder if they just did not want to share the specs, or didn't have them. Either way, i want to know at least some specifics if i'm buying them right?
I just measured the base circle of a set of stock L61 cams and my Comp Blower cams.
Stock L61 cams have a base circle diameter of 30mm.
Comp Blower cams(Stage 1 intake & Stage 2 exhaust) have a base circle diameter of 30mm.
Sooo, Comp Cams are NOT regrinds.
its an old concept. time for something new to take the reigns. - Z yaaaa
Ah thanks for looking into that!
At least we know 100% for sure now.
