valvetrain geometry check - do I need shorter pushrods?
 

Well crap - I did a quick mockup on the new engine to check valvetrain geometry. Installed one head and intake/exhaust lifters in #1. Spun engine over a few times with magic marker on the valve tips. Looks to me like I need a shorter pushrod. I am running stock length pushrods in it right now. Block had maybe .006 taken off to square things up - pistons ended up .008 in the hole. Heads were milled around .025 to help bring up compression. Head gasket compressed thickness should be .039 - this is actually an old gasket that I put on temporarily for the mockup. I was hoping things would even out because cam was reground for more lift and had about .050 taken off the base circle. I actually thought I might end up needing slightly LONGER pushrods, not shorter.

Someone who has been down this road a few times take a look at these pictures and let me know if I am OK, or if I need to dump another $300 on custom pushrods. :mad:

http://i1224.photobucket.com/albums/.../rckr-tip1.jpg

http://i1224.photobucket.com/albums/.../rckr-tip2.jpg

http://i1224.photobucket.com/albums/...shrod-chk2.jpg

http://i1224.photobucket.com/albums/...shrod-chk1.jpg

http://i1224.photobucket.com/albums/...shrod-chk3.jpg

Fixx
 

yep! with shorter make sure the underside of the rocker dont scuff on the spring retainer..you may be able to get away with lash caps but you will have to change the valva keepers..lash caps will raise the valve tip some to center the rocker..

OK, so just for grins I went back out there and tried it again, this time I mocked the intake side up with an EXHAUST pushrod I had from a flat tappet motor. This pushrod is actually about .25 shorter than the stock pushrod.

http://i1224.photobucket.com/albums/...short-int2.jpg

The marks it left on the valve look pretty good to me!

http://i1224.photobucket.com/albums/...short-int1.jpg

I am doing these tests with the stock hydraulic lifters. They were pretty much pumped up all the way for the first few rotations. Now they have bled down, so tomorrow it's off to the hardware store to find a bunch of washers I can stack up inside a couple of lifters. Even if the plunger is going down a little bit, it further emphasizes my first test showing that the pushrod might be too long.

Stay tuned...

I worked with Bob Madara (Marine Kinetics) over the winter on this very issue. You can really hurt valve lift (full and mid) by not having correct valve train geometry and you will not take full advantage of the mods you have made to make hp. Bob has some articles that are very informative that he would be glad to share with you if you call him. His number is posted on here a million times. You need better geometry from the pics.

I'll give him a call and ask him. What do you think about the geometry shown in the last picture?

You might as well order in the test valve springs right NOW he is going to make you. then get a bottle of Crown reserve because he is going to shoot you about 10 pages of reading you will need to do. And it's all the right thing to do!

When your valves are closed the roller will not be centered over the valve. Assuming your lifter is pumped up all the way your marks are very close to the center of the valve stem so I'd let it fly. However, if it's a hydrualic roller you should use test springs. If you milled the block and did a valve job theoretically your pushrod would need to be shorter but it looks as close as can be, again assuming the lifter was pumped up. You milled the block down but milled the cam down so you're probably netting close to the same installed heights.

Another thing to check is geometry from the top. Check to make sure the roller is centered over top of the valve. You can move the guide plates around a little bit and sometimes this can get everything close but if you can't get it close you have to modify the guide plate or buy the new Dart guide plates that have an adjustment in the center.

oh yeah. I can't tell from the pictures. Do you have sealant on the rocker arm studs?

Check this site out www.mid-lift.com

Panther, it's just a mock up, so I don't have any sealer on anything yet. Going to check it again with a lifter that was made into a solid with some shims. Also have adjustible PR's to use.

I would be more concerned with Mid-lift than where the roller is riding on the valve stem. The theory that the roller has to be centered on the stem is BS. It's nice to keep it near the center, but not being there has almost no effect on Guide or stem wear like first thought.

Have you checked valve lift with the cam specs? You need to have a solid lifter to do it correctly. This is the only way to determine if VT geometry is really correct.

Was this a Merc motor originally? Are these stock length valves?

Going to run a dial indicator on it tonight to measure lift at the retainer.

It was not a marine engine originally, but not sure why that would matter. Stock valve lenghts were used, set at 1.90 installed height. Isky 8005 SP springs.

I have seen a little bit about the Jim Miller touted "mid-lift theory", and it makes sense. I'm going to take a look at it from that perspective tonight.

If I had to choose, would I be better off with the longer push rod shown in picture 1, or the shorter one shown in the last picture? I guess it will depend on what my measurements show tonight.

I'm probably bashing my head against the wall for little to nothing!

It looks like you will end up closer to Mid lift with the shorter pushrods. But like I said, check for correct valve lift @ retainer. Changing the geometry can have a huge effect on actual lift at the valve. I assumed I needed longer pushrods with mine because I used longer valves. I assumed wrong. Valve lift was .025 short. With the stock length pushrods, it put the rocker closer to Mid Lift (not perfect but close) and the valve lift was only .004 off.

I've n ever gotten any of my engines perfect. Got them pretty close and let em fly with no issues.

Converted a hyd roller to solid, installed the Scorpions, and ran through it again with the stock push rods. Geometry looks much better with these rockers...

http://i1224.photobucket.com/albums/...9/IMG_0543.jpg

Mid lift...

http://i1224.photobucket.com/albums/...9/IMG_0544.jpg

Full lift...

http://i1224.photobucket.com/albums/...9/IMG_0546.jpg

Patterns look pretty good - close to center and looks like maybe .060 travel...

http://i1224.photobucket.com/albums/...9/IMG_0541.jpg

http://i1224.photobucket.com/albums/...9/IMG_0540.jpg

I measured gross valve lift at the retainer. Oddly enough, I got about .580 lift on the intake, although cam is supposed to have .575. Probably lack of accuracy on my borrowed gauge...

http://i1224.photobucket.com/albums/...9/IMG_0545.jpg

What do you all think now? I have a set of adjustable push rods to try, but at this point I don't really see the need.

Man don't think it will make any difference trying to get it better than that. That looks good. Just curious what brand were the other rockers you were using at first?

The others were Comp Cams - from my old engine. They had about 450 hours on them.

The Scorpions work well on there, but the problem is, they are so big that I am going to have trouble with valve cover clearance. :rolleyes:

My only concern is what you did to convert the lifter to solid configuration. You should use some test springs to check everything, that is the only way to truely check your set-up. Your results look good if they are accurate reflections, since you converted to the solid configuration.

Boat1, since I had the intake off, it was easy to watch the plunger on the lifter to ensure that it was not moving. I stacked a bunch of washers inside the lifter in place of the spring. Believe me, it had nowhere to go - it was a real pain getting that retainer back on.

That was indeed a tough job, sounds like you have done everything correct to verify your measurements.

I would say your good to go..

Well, MAYBE NOT!

I was torquing the head bolts last night, following the procedure to step up the ft-lbs by 20, 40, 60, etc. When I got up to 70 for the long bolts, one of them did not want to "click" on the wrench, and seemed to be turning a lot further than the others. I stopped short, concerned that I might pull the threads out of the block. I am going to get a different wrench just to verify it is not an issue with this wrench I have. At this point I am very worried that I have some bad threads. I used high pressure lube under the washers like the gasket instructions specified.

Damn! :mad:

are you using NEW bolts...i had same problem an it was because they were not new,had corrosion from being thru the water jackets,ended up with lotsa helicoils,,,,NEVER AGAIN

No, not new, but I carefully cleaned the threads. The only corrosion at all was on the first couple of threads. Glass beaded that part, and they easily threaded in. There was no corrosion at all further up the threads. From what I understand, with engines like the 454 that do not have blind threads, the damage occurs when the bolts are REMOVED, because the corroded threads are pulled through the head. All the threads were carefully chased out with a tap.

Might be time to look at a set of studs.

That sucks.. Sounds like Helicoil time.

It gets better - decided to pull that bolt out this morning, and the damn thing broke right at the threads! I'm beginning to seriously doubt the accuracy of my torque wrench! Time to pull the head back off, extract the broken bolt, and beg/borrow/buy a good torque wrench from somewhere/someone. I wish there was an easy way to calibrate these things. I borrowed an older Craftsman beam wrench, but not sure if that is any more accurate.

Anybody got a line on a decent, affordable wrench? Yeah, I know Snap On probably makes the best one, but I'm not in the business where this is an everyday use item.