[Joey Soul]

So I'm more of a over head cam guy, first time putting together a pushrod engine. I recently rebuilt my engine with forged pistons and a BTR 225, Caddie race lifters and btr valve train. Non-decked head and stock head gasket I assumed to stay with the 7.850 rods. On start up engine ran like crap, I went back into it and noticed it was hanging the valve open a bit. Talked to btr and they recommended going 7.80s with ls7 style lifters in the lt1. I went ahead and measured the valvetrain at 7.750 and zero lash and the race lifters call for .05-.1 preload which lands me back at 7.80s. So here is the problem, I run the rockers down by hand until they stop with the 7.80s, then Torque them to 22lb which is abot 3\4 turns and its still pushing the valve down by just a bit which is hanging it open even on the heel of the cam. So the question is what am I doing wrong? The lifters don't seem to take any of the preload.

[Katech_Zach]

Originally Posted by Joey Soul

So I'm more of a over head cam guy, first time putting together a pushrod engine. I recently rebuilt my engine with forged pistons and a BTR 225, Caddie race lifters and btr valve train. Non-decked head and stock head gasket I assumed to stay with the 7.850 rods. On start up engine ran like crap, I went back into it and noticed it was hanging the valve open a bit. Talked to btr and they recommended going 7.80s with ls7 style lifters in the lt1. I went ahead and measured the valvetrain at 7.750 and zero lash and the race lifters call for .05-.1 preload which lands me back at 7.80s. So here is the problem, I run the rockers down by hand until they stop with the 7.80s, then Torque them to 22lb which is abot 3\4t turns and its still pushing the valve down by just a bit which is hanging it open even on the heel of the cam. So the question is what am I doing wrong? The lifters don't seem to take any of the preload.

If your camshaft/lifter is not on base circle (when the roller is not on the cam lobe), then it will open the valve based on where its at. You need to check on a cylinder that is set to base circle to accurately measure pushrod length.

Once you verify you are at base circle, take your pushrod measurement at 0 lash (rocker should be stocked down by hand, with the ability to move the rocker side to side, but not up and down. Add .075 to that number and round to the nearest size.

If you are at base circle already, and it is still hanging a valve open, you are unfortunately not measuring correctly, or there is something fluky going on.

[KingLT1]

Get on the base circle of the cam, use an adjustable pushrod to find zero lash, measure the adjustable pushrod end to end with a caliper. Now add the desired preload on top of the previous measurement and order the correct length pushrod.

[Joey Soul]

Originally Posted by Katech_Zach

If your camshaft/lifter is not on base circle (when the roller is not on the cam lobe), then it will open the valve based on where its at. You need to check on a cylinder that is set to base circle to accurately measure pushrod length.

Once you verify you are at base circle, take your pushrod measurement at 0 lash (rocker should be stocked down by hand, with the ability to move the rocker side to side, but not up and down. Add .075 to that number and round to the nearest size.

If you are at base circle already, and it is still hanging a valve open, you are unfortunately not measuring correctly, or there is something fluky going on.

Im sure im on base, I've checked at tdc and even when one of the intake or exhaust valves are open to check the opposite one. Are the lifters suppose to compress easier then the valve spring even after being pumped up with oil?

Originally Posted by KingLT1

Get on the base circle of the cam, use an adjustable pushrod to find zero lash, measure the adjustable pushrod end to end with a caliper. Now add the desired preload on top of the previous measurement and order the correct length pushrod.

I did use an adjustable pushrod and got an 8inch caliper. My btr 7.80s are coming in at 7.807 tip to tip and at zero lash im at ~7.758. Im not sure if there is something im missing with the GM race lifters that have a unique quality to them.

[easttxss]

How long did you let it run after startup?

I have had some pumped up flat tappet lifters take a full minute or two to level out after pumping the lifter up by hand. 40 years ago they would tell you to do that, then a few years later they changed the procedure to just soak them in oil.

[Kerry]

I crank mine with no fuel a good 2 to 3 minutes to let oil and pressure get everywhere. Then its quite when u start it up. Otherwise it sounds like its gonna break on start up.

[Baddawg53]

I found getting the right length pushrod kinda difficult on this engine. The adjustable pushrod isn't really adjustable once it's in place. I found I had to pre-set it and then install it, check the clearance and then pull it out and reset it, try again ... ended up being a lot of trial and error, and I used Johnson lifters which have a tighter window of preload than the LS7 lifters do. I finally felt confident after I would set it and then tighten the rocker arm down to a certain amount of rotation before it bottomed out. I can't remember exactly what that was, but I did it multiple way before I felt confident.

[Joey Soul]

So I pulled the heads off to check the lifters and I found they are all stuck fully extended and would not compress at all. I disassembled one to relive the pressure and clean it, it then seemed to function normally on the bench. Im under the impression that soaking these race lifters may have caused them to overfill and they are unable to bleed out in order to self adjust. The pistons all had light intake valve marks but no bent valves.

[Joey Soul]

Originally Posted by easttxss

How long did you let it run after startup?

I have had some pumped up flat tappet lifters take a full minute or two to level out after pumping the lifter up by hand. 40 years ago they would tell you to do that, then a few years later they changed the procedure to just soak them in oil.

It was run for 15 min and a couple times after trying different pushrods. I read thru some older car forums and it seems a few engine builders didnt recommend soaking them and just lubed them and let them pump up under the installed height. But most users did say they soak them, im unsure if the gm race lifter is more resistant to bleed down then a regular ls7. I may post some phots of the internals compared to a regular lt1 lifter.

[Baddawg53]

Interesting ... Are you planning on using different lifters?

[Joey Soul]

Originally Posted by Baddawg53

Interesting ... Are you planning on using different lifters?

Not yet, Ive dissembled all of them and inspected and compared them to the non dod stock lifter. Im not sure if they where just locked up from sitting on shelves for years or what but they're moving freely now. I've oiled the internals and I will reinstall without soaking.

[oldman]

I run the regular Johnson lifter which has a much more pump room vs their race, still probably less than a LS7. I had to buy like 20 different pushrods, after 1000 miles or so I had to check them and swap all of them, there is no easy way out. I would NEVER run a race lifter on the street, they are too sensitive IMO and at a very minimum you really need adjustable rocker arms at that point.

It has been many years now and the Cam Motion cam and Johnson lifters for me have been an ideal setup. Yes I fought the LS1 valvetrain wars, skip the LS3- LS7 vavletrain wars (had a Challenger), and broke a LS7 lifter / Texas Speed cam setup, and now live with say 15 less HP but a long term still going mild ramp profile Cam Motion cam and Johnson lifter (non race) setup. I'll check preload in the next few weeks (lazy).

[6spdhyperblue]

Did you get to work this out?

[Joey Soul]

Originally Posted by oldman

I run the regular Johnson lifter which has a much more pump room vs their race, still probably less than a LS7. I had to buy like 20 different pushrods, after 1000 miles or so I had to check them and swap all of them, there is no easy way out. I would NEVER run a race lifter on the street, they are too sensitive IMO and at a very minimum you really need adjustable rocker arms at that point.

It has been many years now and the Cam Motion cam and Johnson lifters for me have been an ideal setup. Yes I fought the LS1 valvetrain wars, skip the LS3- LS7 vavletrain wars (had a Challenger), and broke a LS7 lifter / Texas Speed cam setup, and now live with say 15 less HP but a long term still going mild ramp profile Cam Motion cam and Johnson lifter (non race) setup. I'll check preload in the next few weeks (lazy).

Which lifters from Johnson are you running? 2116,2126, 2110? I didn't think the gm race lifters was unstreetable since it seems nearly the same as an ls lifter in every dimension. But I did find a new issue that has been causing the issue.

Originally Posted by 6spdhyperblue

Did you get to work this out?

I have the pan off and front cover, found out I missed the pin on the cam gear over advancing the cam causing all this bs. I assume that was knocking the lifters out of proper preload