Experiment: Cam Motion Low Lash Solid Roller with stock rocker arms
12-07-2015, 09:29 PM
#81
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Congratulations!
Great results and Outstanding Documentation!
You have provided a great benefit to any one else considering
LLSR, the shim process you have described does not seem
That much more complex then some of the shimming I have
Seen described on high end HR set ups.
Looking forward to Dyno and track comparisons.
Great results and Outstanding Documentation!
You have provided a great benefit to any one else considering
LLSR, the shim process you have described does not seem
That much more complex then some of the shimming I have
Seen described on high end HR set ups.
Looking forward to Dyno and track comparisons.
12-08-2015, 08:08 AM
#83
Once I have some dyno and track results and track how this works over the long term I wouldn't mind picking up some nice adjustable rocker arms and valve covers down the road.
But I'm pretty sure they will remain with the stock 1.7 ratio. Would still be interesting to see if there are gains with a full roller rocker versus the stock fixed tip rockers.
I'll be getting the car on the dyno in the near future. First I just need to finish polishing the tune.
Currently battling an idle surge issue when warm and in park/neutral (thread in the tuning section). I made some changes to the top end as well after my last log run which showed AFR was in the low to mid 12 range so I pulled a little more fuel to get it in the 12.4 range around peak torque and leaned out to 12.8 up top which the car has liked in the past.
But I'm pretty sure they will remain with the stock 1.7 ratio. Would still be interesting to see if there are gains with a full roller rocker versus the stock fixed tip rockers.
I'll be getting the car on the dyno in the near future. First I just need to finish polishing the tune.
Currently battling an idle surge issue when warm and in park/neutral (thread in the tuning section). I made some changes to the top end as well after my last log run which showed AFR was in the low to mid 12 range so I pulled a little more fuel to get it in the 12.4 range around peak torque and leaned out to 12.8 up top which the car has liked in the past.
12-08-2015, 01:17 PM
#84
An important question which came up on YellowBullet in regards to this project: "In hindsight, do you think this could be done without grinding the valve tips?"
Yes, in hindsight I don't think that grinding the valve tips was as critical as I was afraid it was going to be. It was really more for peace of mind since I knew in advance mine were likely to have a variance. But they turned out to be much closer than I expected them to be.
I was also originally very concerned about if shimming one rocker would begin to affect the neighboring rocker.
But as you can see on my sheet I was able to get at least .011" difference without even beginning to affect the neighbor. In the future out of curiosity I may try to shim one up .020" or more and see if it begins to have adverse effects on lash of the neighboring rocker.
The critical change if the valve tips are not close would be what that would do for your pushrod length. Since mine were close it was not a requirement to measure for pushrod length on all 16.
At the end of the day I think cutting the rocker pedestals into smaller sections played a large role in minimizing issues with the entire shimming process. During the process of shimming my roommate who was helping me and I discussed that the project would be almost maddening trying to do a whole bank at once. I would think that would ramp up the difficulty 10 fold...especially in regards to keeping the shims in place while reassembling.
I'm not familiar with ls3/l92/ls7 heads at all. So if it would not be possible to section the rocker pedestal I would take that added difficulty into consideration.
Yes, in hindsight I don't think that grinding the valve tips was as critical as I was afraid it was going to be. It was really more for peace of mind since I knew in advance mine were likely to have a variance. But they turned out to be much closer than I expected them to be.
I was also originally very concerned about if shimming one rocker would begin to affect the neighboring rocker.
But as you can see on my sheet I was able to get at least .011" difference without even beginning to affect the neighbor. In the future out of curiosity I may try to shim one up .020" or more and see if it begins to have adverse effects on lash of the neighboring rocker.
The critical change if the valve tips are not close would be what that would do for your pushrod length. Since mine were close it was not a requirement to measure for pushrod length on all 16.
At the end of the day I think cutting the rocker pedestals into smaller sections played a large role in minimizing issues with the entire shimming process. During the process of shimming my roommate who was helping me and I discussed that the project would be almost maddening trying to do a whole bank at once. I would think that would ramp up the difficulty 10 fold...especially in regards to keeping the shims in place while reassembling.
I'm not familiar with ls3/l92/ls7 heads at all. So if it would not be possible to section the rocker pedestal I would take that added difficulty into consideration.
Last edited by thunderstruck507; 12-08-2015 at 01:25 PM.
12-08-2015, 04:19 PM
#85
Here's an interesting idea for LLSR / aluminum block guys: aluminum pushrods link. They use them in VWs for the same reason - to keep lash from growing when the engine gets hot.
12-08-2015, 04:33 PM
#86
Those do look interesting. Just not sure how feasible they would be to have made and if they could be made strong enough. Some people already seem to think the standard ls pushrods could stand to be larger diameter to prevent deflection. Not sure aluminum pushrods in the standard diameter would be up to the task.
12-08-2015, 05:09 PM
#87
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Not even close to the same stiffness. Chrome-Moly steel is WAY stiffer than aluminum
12-08-2015, 05:37 PM
#88
3/8 aluminum pushrods are available from Smith Bros. They're custom built so I assume they would change the wall thickness to handle the open spring pressure you have. I don't think they are a sponsor so I won't post a link but you can Google Smith Bros. and find them.
12-09-2015, 09:07 AM
#91
There is so much low end and the suspension is so stiff it takes a Hoosier drag radial in 275/50 to get it to hook at my track. With a MT ET Street in the same size it blew the tires off more than it ever hooked.
I'm afraid to add more gear or converter and make launching more difficult.
I'm afraid to add more gear or converter and make launching more difficult.
12-09-2015, 09:56 AM
#93
First gear is useless at WOT, I can try and manage to get 50-60% throttle ok. I run a 285/40r17 Nitto 555 (not a drag radial).
Other than that it's manageable.
Our track (at least on the fun drag days) is slick. I can hook better on the street than the track unless everyone else is lining up in the groove and I can line up outside where there is rubber and VHT noone else is using. Doing that I've cut a 1.8 60ft on my street tires and a 1.61 on Hoosiers.
On the street I could hook an ET Street radial fine. It was only a problem at the track.
I don't notice any major difference from a dig as far as old cam versus LLSR. Just pulls like a mad dog up top.
Other than that it's manageable.
Our track (at least on the fun drag days) is slick. I can hook better on the street than the track unless everyone else is lining up in the groove and I can line up outside where there is rubber and VHT noone else is using. Doing that I've cut a 1.8 60ft on my street tires and a 1.61 on Hoosiers.
On the street I could hook an ET Street radial fine. It was only a problem at the track.
I don't notice any major difference from a dig as far as old cam versus LLSR. Just pulls like a mad dog up top.
12-12-2015, 12:03 PM
#94
Getting the bugs out of the tune. Warm idle was unstable due to long term fuel trims dumping gas because the O2 sensors read lean. Tried everything with air and timing to fix it before just commanding it to hold Open Loop at idle and commanding 16:1 afr. Now its rock solid and doesn't make my eyes burn to sit in the thing.
Also the rpms drop back after throttle stabs much better than they ever did in closed loop idle
Next step is to finish fine tuning the VE and then maybe try a different timing map to bump up peak torque a little and it's dyno time.
Oh the only real problem left with the tune is a dead cold start...she really hates that without throttle input. But as soon as it starts if you let off the pedal slow its fine. Should be able to tune that out, just slow going as I can really only get 1 or 2 shots at it a day.
Also the rpms drop back after throttle stabs much better than they ever did in closed loop idle
Next step is to finish fine tuning the VE and then maybe try a different timing map to bump up peak torque a little and it's dyno time.
Oh the only real problem left with the tune is a dead cold start...she really hates that without throttle input. But as soon as it starts if you let off the pedal slow its fine. Should be able to tune that out, just slow going as I can really only get 1 or 2 shots at it a day.
12-12-2015, 05:37 PM
#95
Have you done the base idle reset on it where you disconnect the IAC and get it barely idle on it's own(warm) . After that adjust the throttle stop screw so your IAC counts are around 50.
After that you can use the Russ K config file to determine your RAF.
Russ actually recommends doing the RAF last after you calibrate the VE and MAF.
After that you can use the Russ K config file to determine your RAF.
Russ actually recommends doing the RAF last after you calibrate the VE and MAF.
12-12-2015, 05:44 PM
#96
Also to adjust fueling for cold start leave the VE table alone and use the OLFA table to adjust the fuel.
Good call on keeping it open loop at idle. Due to the overlap on some cams and reversion it contaminates the intake charge.
I'm sure you probably already knew those things, I thought I'd throw it out there for anyone reading.
Good call on keeping it open loop at idle. Due to the overlap on some cams and reversion it contaminates the intake charge.
I'm sure you probably already knew those things, I thought I'd throw it out there for anyone reading.
12-13-2015, 10:26 AM
#97
Have you done the base idle reset on it where you disconnect the IAC and get it barely idle on it's own(warm) . After that adjust the throttle stop screw so your IAC counts are around 50.
After that you can use the Russ K config file to determine your RAF.
Russ actually recommends doing the RAF last after you calibrate the VE and MAF.
After that you can use the Russ K config file to determine your RAF.
Russ actually recommends doing the RAF last after you calibrate the VE and MAF.
12-13-2015, 11:05 AM
#98
I'm wondering if you might have a vacuum leak. I re read your post and you said in CL it was that it was lean and adding fuel. From what I've seen(which isn't much)that normally with a bigger cam and overlap you will see -STFT at idle due to the contaminated intake charge.
12-14-2015, 11:06 AM
#100
TECH Addict
Do a smoke test through your intake. That is the easiest way to find a vacuum leak. I had an intake gasket leak that i couldn't find by spraying. I made up a homemade smoke machine and blew it through the intake and found the leak in a second.