Engine Carnage

[bobcowan]

Just a little update. I got the engine apart, and did some looking. Not as bad as I thought it might be. Obviously, it needs a new piston. I had planned on replacing the pistons this year, as I wanted more compression. It needs one rod. The #4 cylinder needs a sleeve.

The heads are Dart Pro-1, ported by Gordon. I'll have a new head drop shipped to him so he can port it for me. That will take 2-3 weeks - I'm hoping less. Both heads get all new gear. I think the only thing I'm going to re-use is the guide plates.

The crank doesn't look bad at all. I'll have it mic'ed at the machine shoip and we'll see what we can do. Oil pressure never dropped below 50psi. Although, there was a lot of coolant in there. The bearings looked pretty bad.

I need the car to run by Sep 9th. I wonder if I'll make it?

[bobcowan]

Another damage note. I was inspecting the valve tips very carefully. They look pretty good. Based on the damage I see in that area, it looks like a failure of the retainer or lock was the main problem. I'll be switching to 10* locks this time.

[Snakebit]

Who recomended the 7* locks when the springs were installed? They are normaly stamped steel and used for stock rebuilds or mild street applications.
I have the 10* locks and noticed one was cracked when I adjusted my valvea after 2000 miles!

If you need to use lash caps, you need to install the valve locke that are recessed to accept the caps.

[TButtrick]

You might also check the spring seat pressure at installed valve and max lift height. Any good engine builder will have the ability to measure the pressure with a force gauge at installed and max lift height for your valve geometry. When they test for max seat pressure, they should also check for bind (min space between coil turns at max compressed spring height)

[67FEfastback]

I'd certainly take the time to figure out all the contributing factors, to your failure.

There are two parts, the cause, and the subsequent damage.

My engine failures, typically were
1. bad advise,
2. Not being honest about how the engine is going to be used

There often are recommended sets of parts, that are prescribed by manufacturers. Then the engine builder tells you we've always used part C with cam A, I don't think you really need to spend an extra $200 on part B.

Hope you guys get it right this time ;-)

[Paul F]

Originally Posted by Jerry Clayton

Expert????? do you want referances??? or can't you guys really see that the use of fitted lash caps that fit the tip of the valve/retainer/keepers will take the valve spring pressure load off the valve stem???if the lash cap doesn't push on the keepers, you are transmitting all the forces of the valve spring compression pressure waves to the groove of the valve/keeper and you will shear them creating havoc---also , on a road race car---more engine damage comes from downshifting than anything else than a poorly designed oil system---one of the main things I enjoyed about karting with my boys was no lub system, no valve train

We never did settle this point about lash caps as to whether or not they are to ride on the keeper. The Comp Cams and Crower web sites only say that the lash caps protect the valve stem. They make no statement about clearance away from keepers nor do they say the ride on the keepers. I emailed Comp Cams and got no response after 2 days. Crane Cam says:

Valve Lash Caps

Precision machined from 8620 steel alloy, heat treated and black oxided. Provides a better wear surface and lengthens valve for correct geometry. (Maintain .030" clearance from bottom of lash cap to top of the valve locks)

This indicates that they are there to protect the end of the valve stem and not to ride on the keepers. Any other documented instructions for the use of lash caps is appreciated.

[Jerry Clayton]

We??? as in you and me?? or are you looking for a vote????

You can build your engines any way you want----

But, please consider the fact that I have never had a valve push thru or shear the keeper grooves----I use lash caps that are either combined with the keepers or that have the valve tip shortened til the clearance is taken up between the lash cap and keepers. this way, there is no valve spring pressure adding hundreds of lbs of force to the valve stem, except during the lash part of the cam rotation!

[Paul F]

We as a group Jerry. I understand your application. I'm just trying to understand what manufacturers had in mind when the came up with lash caps. They are poorly documented at their web sites.

[Jerry Clayton]

Now we agree on something----They are poorly documented at their WEB SITES.

[Jerry Clayton]

Paul

check page 4, loc cap system

www.manleyperformance.com/dl/2010/cylinder head components

This will pretty much give you an idea of what manley developed in 1990s that is sort of what I was doing in the 1970s

the cutaway profile drawing shows visually how the lash cap cap be set up to rest on the keepers so that the spring pressure is directly against the rocker tipand the valve stem is in tension at off the seat duration of the cam lobe

[Paul F]

Thanks Jerry. That is significantly different than what the other vendors are describing. It looks like a well thought-out system whereas the other caps and descriptions leave me wondering.

[Jerry Clayton]

Jamie Mac Murry's father used to work for Manley---trivia test later

And I'm ready for the vote!!!!

[bobcowan]

Originally Posted by Jerry Clayton

Paul

check page 4, loc cap system

http://www.manleyperformance.com/dl/...headcomponents

This will pretty much give you an idea of what manley developed in 1990s that is sort of what I was doing in the 1970s

the cutaway profile drawing shows visually how the lash cap cap be set up to rest on the keepers so that the spring pressure is directly against the rocker tipand the valve stem is in tension at off the seat duration of the cam lobe

Pretty interesting stuff. I'v never seen anything like that - but my experiances is pretty limted.

Two statements in the catalog cought my attention: "Clearance in the system allows linear valve lock movement independant of LocCap". That (to me) means that the bead lock is for retention only, and doesn't transfer the force to the locks. I can also see where it could do both. IDK.

Also, "100% contact between the underside of LocCap and valve tip." If it's in 100% contact, how does it not transfer pressure from the rocker tip to the valve tip? Again, IDK.

As I read the catalog page, it appears to be a lash cap with a positive retention system. When I look at lash caps, I see the thinnest ones are 0.040" How thick are the LocCaps? Do you need to lengthen the push rods to compensate? I wouldn't think .040" would make that much of a differance in my application.

The more I learn about Lash Caps, the more I think I like the idea.

[Gaz64]

Originally Posted by Paul F

Thanks Jerry. That is significantly different than what the other vendors are describing. It looks like a well thought-out system whereas the other caps and descriptions leave me wondering.

Yes, agree there.

Can I assume that one can only use "cap to keeper contact" with machined keepers?

I intend to use a "wear cap" of one design or another in a future engine, sceptical about using just a "lash cap" now.

[Paul F]

Jerry,

Your application seems to be unique. As I understand it, you trim the valve stem to assure that the LocCap presses down on the valve lock rather than the end of the valve stem.

As Bob points out, the catalog indicates that the LocCap should ride on the valve stem and there is clearance between the LocCap and the valve lock. I contacted Manley and they said "As you can see in the diagram we design the LocCap system to have 100% contact between the underside of the LocCap and the valve tip without any contact with the valve lock"

It's interesting success your having with this. You may have a unique advantage. I'm wondering if it is it time for a patent or is it a bad idea? I don't know enough to have an opinion, but you may be on to something.