I was just wanting to know, what pushrod did you go with using these lifters? I have the Jesel 1.7 rocker shaft mount non-adjustable and these lifters and for some reason I get to the 2nd gear at 6000 rpms and it will go no higher as it seems like its hitting the rev limiter but there is not one until 8000 as this is what the computer was set at. I had Jason @ MTI tune it but there was this problem with the valvetrain geometry. What do you guys think????


<img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

<small>[ April 20, 2003, 09:18 AM: Message edited by: BADZ ]</small>

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">
I was just wanting to know, what pushrod did you go with using these lifters? I have the Jesel 1.7 rocker shaft mount non-adjustable and these lifters and for some reason I get to the 2nd gear at 6000 rpms and it will go no higher as it seems like its hitting the rev limiter but there is not one until 8000 as this is what the computer was set at. I had Jason @ MTI tune it but there was this problem with the valvetrain geometry. What do you guys think????
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">A local guy had the same problem, those lifters are crap. I think he went to compRs.

 

Might not be crap but you need an adjustable valvetrain or alot of time to shim them correctly (PITA) All they are is a regular lifter with less hydraulic play correct? Probably binding up. You run the motor over and check pushrod length with the lifter pumped up?

 

Boy, that Terry is sure quick to judge when he doesn't know the whole story... <img border="0" title="" alt="[Razz]" src="gr_images/icons/tongue.gif" />

Anyhoo, as Granny mentioned, a set of adjustable rockers is almost a necessity with these lifters... they are hydraulics, but not by much. They are simply modified GM pieces that, after modification @ Schubeck, only have ~.010-.012 of hydraulic "plunge" left in them. After speaking with Joe the other day, my understanding is that that ~.010 or so of hydraulic action is just like the first ~.010 of plunge on a non-modified lifter. After that, they may as well be solids. Think of them as a solid lifter that has a slight bit of hydraulic action in it so that it can be run in classes that require a non-solid lifter.

They require more work during install for sure, but as long as you understand what's going on, it shouldn't be a big deal.

I have been doing some more thinking on BADZ's problem, and I have a question- with the current pushrods, how much lash/preload is on the lifters?? If the pushrods set the rocker height/adjustment such that there is pre-load into the hydraulic range of the lifter, I have to wonder if what you're seeing is the result of good ol' lifter pump-up resulting in hanging the valves open a bit.

Oh, and the information that resulted in me going to an adjustable valvetrain: over time, the valves will beat in the seats a little, resulting in a taller effective installed height of the valve spring/retainer/valve stem tip. Since we're talking about such tight tolerances with these lifters, even a change of .005 could make a difference in the way that the car runs.

BADZ- good luck; let us know what happens.

 

When you say that it feels like it's hitting a rev limiter, are you saying that it's doing the "popping and banging" thing, or will it simply not rev any higher??

I will have a set of Schubecks in my car fairly soon, and I spoke w/ Joe (Schubeck) on Friday regarding proper set up of the valvetrain. His recommendation is that there be .002-.003 positive lash (read: slip a .002 or .003 feeler guage between the tips of the rockers and the tops of the valve stems and set the rockers to 0 lash).

I have to admit, though, that I forgot to ask him if this is a hot or cold measurement. The point is, to quote Joe, "...just enough to make sure that you're not getting into a pre-load situation. Pre-load is the enemy."

This is the reason that I decided to go with adjustable rockers instead of trying to stick with non-adjustables and dialing in the pushrod length down to the thousandths of an inch. Unfortunately, all of this was pointed out to me after I had already bought the Jesel SS non-adjustables. <img border="0" title="" alt="[Frown]" src="gr_sad.gif" /> I should've asked the questions sooner, so it's my own fault, though.

In any event, on why your car is acting the way it is, I'd say that you need to locate someone with a GM Tech2. Strap her down on a dyno (or just a set of rollers... any load-simulating device) and run 'er through the gears to see what the Tech2 picks up.

Sorry I can't be more help.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by BurnOut:
<strong> I have been doing some more thinking on BADZ's problem,.......... I have to wonder if what you're seeing is the result of good ol' lifter pump-up resulting in hanging the valves open a bit. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yep that's what I was thinking too. Man back in the day Pontiacs has this as the rev limiter. 5200rpm and they go no further because of the pump up. Does it do this at part throttle too? or does it just do this at WOT? Take it out and run it up to 6K in 2nd with as little throttle as possible and see what happens.

The Schubecks are a tricky puppy to work with. I thought about building some of these but the fact that they need to be adjusted is a PITA. I do recomend the Comp R's if you can find them.

Bret

 

Well all I can say is that I will be using the cranes and a 7.350 lenth pushrod until this is figured out and gone through. I tried to use a 7.350 pushrod on the schubeck lifters and it was too much pushrod and there was no compression (valves were held open) went to a 7.300 pushrod and the car as it is today started and ran o.k. but going down the track in 2nd gear @ 6000 rpms, I had to shift because there were no more rpms to go. Took it to MTI and Jason said that it was a problem geometrically in the valvetrain as I thought it could be a computer problem but it seemed to be in either the lifters or pushods. I dont really know what to do with these lifters but I want to run a good 10 sec pass and this seems to be holding me back from doing it....Sould I try the 7.250 pushrods? Try shimming the rockers shafts? What does Joe recommend with the 1.7 rocker set?

 

Jeff.... Sorry to hear that you're having issues with your car. To be quite honest (and I know nobody on this thread wants to hear this), but ALL of you are wrong.

Quite honestly, what length pushrod you run has absolutely nothing to do with what type of lifter you run, or what kind of rocker arms you have. It has EVERYTHING to do with how tall your valves are, the install height of the spring, and the overall geometry of the spring/valve.

If you run too long/short of a pushrod.... yeah, the car will run because it's not running the valvetrain real hard. But, if you run the car hard then the rocker arm will actually slip off of the spring.

To make a long story short.... you need to have someone set up your valvetrain that knows what they're doing and don't go based off of what you read on here and what should work in a stock configuration. What you're trying to do is far different than what would work on a stock setup.

Get your valvetrain geometry checked out, that'll fix all of your problems.

 

MastaAce you mean to tell me that all these guys on the board don't know what the hell they are talking about??? Man, I have been misguided all this time.... <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">
Boy, that Terry is sure quick to judge when he doesn't know the whole story...
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">This guy had adjustable rockers and adjusted them 10 ways to Sunday trying to get them to work. IMHO, they are crap. Just one trolls opinion. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

BADZ- I didn't ask Joe for a pushrod recommendation, so I'm not sure what he'd say to that. If you do speak with him to get a recommendation, please let us know... Thanks...

 

Jeff, If you reacall, Patrick G had this same problem. The Retainers on the back of the springs were hitting the bottom of the rocker. Look at the bottom of a rockerarm, and tell us what you see.

Whats your Valve/spring/retainer setup consist of?

 

Steve has and easy fix to this madness and it will be fixed tomorrow, the way these lifter work are very very similiar to a solid roller setup. Joe stated that you have to come close to .004 preload as all this grows when she heats up and I think and am not positive but from what I get from all this is that I will just shim the rockers about .010 to .015 and then it should be fine but I will not know 100% until its gone through tomorrow but Steve say's 99.9% that it has too much preload and holding the valves open at 6000 rpms, on a good note, the car put down a wopping 558 ft/lbs of tq N/A....I will add to this when the covers are off!!! Steve, chime in when you get a chance!!!!! <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

If you run too long of pushrod you can have too much lifter preload and you can end up having valves open.

But if you need a 7.250 keep in mind that stock is 7400, that's quite a change.

You could be floating valves maybe you need more spring pressure.

 

"BurnOut: If the pushrods set the rocker height/adjustment such that there is pre-load into the hydraulic range of the lifter, I have to wonder if what you're seeing is the result of good ol' lifter pump-up resulting in hanging the valves open a bit."

"SStrokeAce: Man back in the day Pontiacs has this as the rev limiter. 5200rpm and they go no further because of the pump up."

"BADZ: Joe stated that you have to come close to .004 preload as all this grows when she heats up and I think and am not positive but from what I get from all this is that I will just shim the rockers about .010 to .015 and then it should be fine."

Hmmm, I'd have to say there are alot of people on this board that know what they're talking about and from what I've read in this thread their help and advise should help you resolve this issue. I'm sure you'll be rid of the 'Pontiac rev limiter' soon. Good luck!

 

One thing that most people overlook is the pushrod length. Milling the heads, block, using a thicker or thinner gasket, new valves or even just a valve job can change the required length. Aftermarket heads with longer valves will also change the required length. Any time any part of the valvetrain is changed, the geometry should be checked. Changing the pushrod length is the easiest way to change the rocker to valve tip contact point, in most cases the pushrod length can be adjusted to compensate for best power and reliability. Is some rare cases, the rocker stud might have to be relocated, like when 1.7 big-block rockers are used on a small-block Chevy or when a longer valve is used in a stock head (this is usually only a problem when the valve is +.200" or more).

Checking Pushrod Length

A rockers pivot point is lower than the pushrod cup and the valve contact points for a good reason, so the wiping action across the valve tip is the greatest at the lowest spring pressures, this helps reduce guide wear. When higher than stock lifts or any of the modifications listed above are done, the pushrod might be too long. This would cause more side loads at peak lift, which is where spring forces are the greatest. Imagine a line from the center of the pivot point to the valve tip contact point. As that line passes 90° of the valve stem, the wiping action across the valve tip is minimal. So it makes sense to put that point where the spring forces are highest. For best valve guide life that point should be at about 2/3 of peak lift. If the rocker pivot point is in the correct place, the tip should be in the center of that valve at that point also. To figure the best length, you must use an adjustable pushrod and adjust it until you get what you need, you can then order a set of pushrods the same size as you adjustable one, you should do this with a solid lifter to avoid any leak down and remember add any hydraulic pre load to the length. Manley offers an inexpensive pushrod length checkers for most popular engines, these work fine if you know how to use them, and most people don't. For an example, the tool to check length on a small-block Chevy is set to check correct length with 0.600" lift at the valve. If your valve lift is not 0.600" you will need to do some math, or you can just use it as a starting point to adjust your adjustable pushrod. Manley will provide you with the information needed for your application. On a small-block Chevy, any lift more than 0.600" gets multiplied times 0.22 and that is subtracted from the pushrod length. So if the valve is lifted 0.650", you will need to multiply 0.22 with 0.050 and the pushrod will need to be 0.011" shorter than measured. If the valve is lifted less than 0.600", you take a different approach. Subtract your lift from 0.600 and divide it by 3. Then take a feeler gauge of that thickness and put on the valve tip when checking length. If your valve lift is 0.500" the difference would be 0.100", divide it by three to get 0.033", now insert a feeler gauge of that size between the checker and the valve, and the measured length will be correct. Once you adjust the pushrod to the right length, you can then measure it and order the correct length pushrods.

<img src="http://www.grapeaperacing.com/GrapeApeRacing/tech/pics/pushrodchecker.jpg" alt=" - " />

The pictures shows the Manley pushrod length checker for small-block Chevy engines. The engine here has a cam with 0.510" lift. In order to get the proper length, I need to subtract 0.510 from 0.600 to get 0.090". 0.090 divided by 3 is 0.030. One last thing to consider on a hydraulic cam is that when you pre load the lifters, the plunger will change the pushrod position. A 3/8" rocker stud has 24 threads per inch. You generally pre load the lifters about 1/2 turn, which will put the pushrod about 0.021" lower. This needs to be considered as well. So I need a 0.021" as well as a 0.030" shim on the valve tip to make my measurement. I simply put 0.051" feeler gauge on the tip of the valve between under the checker. Now I just need to adjust the checker pushrod to just touch the checker, lock it, and pull it out to measure it. In my case, with the hydraulic roller, the length cam out to 7.345" long. It so happens that 7.350" is a popular size, and that's pretty darn close, so that's what's going in. Pushrods generally come in 0.050" increments. It's better to go a bit long that short, so it's better to round up unless you are less than 0.015" short.

Geometry For Best Power

Setting the correct pushrod length will get the most mileage out of the valve guides, but when radical cams are used they might not be the best for power output. What many engine builders don't realize is that the rocker ratio is not constant. The rocker ratio changes through the lift cycle due to the geometry, this gives a chance to change the lift curve slightly. On most engines, the peak piston velocity will fall in between 73 and 78° after TDC, so the higher you can get the intake valve lifted at that point the easier it will be to fill the cylinder. Once you get the pushrod length correct, try adjusting the rod a little longer and shorter. See where the point is that you get maximum lift at 75° ATDC. On most engines this should be pretty close to the correct length. You will also find that when geometry is optimized for performance, the point of maximum rocker ratio will be close to TDC. After you find the best lift at 75° ATDC go back and recheck your rocker to valve contact point. The geometry for best power will usually be close to what was measured. Small details like this could mean 10 hp on a 500hp race engine, so it pays to check. I have heard a more than once that the proper length pushrod will give the highest peak lift, this is simply not true. You want as much lift as you can get at peak piston speed, which is the hight airflow demand. With todays technology, we just can't get the valves open fast enough. The point of peak airflow demand comes somewhere between 73 and 78° after TDC, but we can't get peak valve lift until more than 100° after TDC. What I'm getting at is that if the piston speed peaks at 75° ATDC and peak valve lift is at 108° ATDC, extra lift will help more at 75° ATDC than it will at 108° ATDC.

 

Very well put JROD...

Philip

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by BADZ:
<strong> on a good note, the car put down a wopping 558 ft/lbs of tq N/A....</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">TTT

Damn those are some crazy numbers for a 346. Hope you fix the problem. Where you having problems at the sbso?

 

Yeah, I showed Steve the Dyno run and he nearly **** on himself as he quoted that's big block territory...I also told Craig @ GTP and he was tripping over himself and just said get the other deal worked out and then let him know the final numbers which we both know it will be even better!!!! Will see as I have to pick the car up tomorrow night completed is the shimming deal works..... <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> I will post are results when its done and the fix method...

<small>[ April 23, 2003, 04:43 PM: Message edited by: BADZ ]</small>