Lash Caps....Seven Came Off

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Jay Anderson

Jay Anderson

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First time with an engine with lash caps. 360/408 hydraulic roller. This is an engine that was built by Mike at at MRL Performance. He broke the engine in and tuned it on his dyno. The engine sat on my stand for maybe less than a year. I occasionally primed it, turning it 90 degrees at a time. After putting it in, it was primed thoroughly. It started right up, missing and rattling bad from the top end. Pulled valve covers and found some. Pulled intake and found the rest. This is going in a street/strip car, shifting about 6500. It makes 543 hp and close to the same tq. What happened here, and now i'm paranoid about this engine now. Any advice appreciated!
 
lash caps ? aren't those things like mini grenades ready to explode at random? I wouldn't have expected that from MRL , I'm assuming there was a good reason , but if it were mine , I would definitely eliminate them and rectify the reason for them being there in the first place
 
73AbodEE said:
lash caps ? aren't those things like mini grenades ready to explode at random? I wouldn't have expected that from MRL , I'm assuming there was a good reason , but if it were mine , I would definitely eliminate them and rectify the reason for them being there in the first place
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I've built several small and big block chevy engines, with never a problem. I had Mike build it for me, due to never putting together a Mopar engine, and getting the valve train geometry right was a big priority for me. Can you tell me a little about what it would take to rectify? I just finished the car build that took several years. Startup and checking for odds and ends was all I lack.
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If lash caps were used and it's an LA and not a magnum, you need to fix the geometry. Go to b3racingengines.com and read his tech pages and then call him.

I never use lash caps unless I absolutely have to. They are just something else to fail.
 
yellow rose said:
If lash caps were used and it's an LA and not a magnum, you need to fix the geometry. Go to b3racingengines.com and read his tech pages and then call him.

I never use lash caps unless I absolutely have to. They are just something else to fail.
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I read the info at B3 again. I know it takes a lot of expertise to get the geometry right. That’s why I had a Mopar engine builder do my engine. It was not a budget build. I’m hoping someone can give me some scenarios of what I’m facing here.
 
I had a old Mopar racer named Dan Dvorak build a 440 race engine for me some 28 years ago and he recommended lash caps. While I studied them for a long while I finally decided not to use them. They touched the keepers when installed and I was worried about them kicking the keepers out at high RPM. I had a ton of passes on that engine and never had a problem with them NOT installed. I still have all of them in a little bag in my tool box.
 
SGBARRACUDA said:
I had a old Mopar racer named Dan Dvorak build a 440 race engine for me some 28 years ago and he recommended lash caps. While I studied them for a long while I finally decided not to use them. They touched the keepers when installed and I was worried about them kicking the keepers out at high RPM. I had a ton of passes on that engine and never had a problem with them NOT installed. I still have all of them in a little bag in my tool box.
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Was there a pushrod length change to make it work?
 
Only way I see them coming off is if there was clearance between rocker and valve stem. Maybe the valves were sticking a little in the guides creating slack?
 
SGBARRACUDA said:
Only way I see them coming off is if there was clearance between rocker and valve stem. Maybe the valves were sticking a little in the guides creating slack?
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The engine sat on the stand for some time. I turned it over and primed. I guess anything is possible. Crap.
 
I don't like using them but that is just me. Check to see if the PR's are long enough without them.
 
Hate to admit it, but what is a lash cap? I thought I knew just about every engine part name.
 
I have never found a reason to use lash caps, I think the guy that invented them needs kicked in the balls.
 
Jay Anderson said:
First time with an engine with lash caps. 360/408 hydraulic roller. This is an engine that was built by Mike at at MRL Performance. He broke the engine in and tuned it on his dyno. The engine sat on my stand for maybe less than a year. I occasionally primed it, turning it 90 degrees at a time. After putting it in, it was primed thoroughly. It started right up, missing and rattling bad from the top end. Pulled valve covers and found some. Pulled intake and found the rest. This is going in a street/strip car, shifting about 6500. It makes 543 hp and close to the same tq. What happened here, and now i'm paranoid about this engine now. Any advice appreciated!
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Being hyd. roller, if the engine was revved up past it's happy point, where the lifters pump up, this will allow the caps to come off.
 
Isn’t it possible that the lifters were collapsed on start up after sitting so long, and I’d bet that if you put them all back in and run it again that motor will be fine.
 
It’s just because the motor sat with hyd lifters. Put it back together and run it.
Very nice car by the way.
 
Jay Anderson said:
So is it possible I could take a look at the roller swipe and if needed, go to a shorter pushrod?
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If you have shafts you can change the pushrod length all you want and it won't matter. You have to change the position of the shaft.

The only time I use lash caps is if the stem height is too short (which is very rare) or using 5/16 or smaller diameter stems.

Get rid of the lash caps if you can.

If you have magnum heads than yes, you adjust pushrod length to correct geometry, within reason. Then you have to move the stud.
 
I don't see how they could have came off just by sitting unless the valves are tight, pushrod length is short or rocker ratio? im no expert but all the advice above is spot on . if you are having issues now you don't want it coming unglued at high RPM
 
604b1duster had the answer. Lifters collapsed from you turning motor over without oil being pumped into them. So on your initial start too much clearance with lifters due to collapse and giving the caps the room to come off. So in a sense you created a problem by eliminating the problem of pistons seizing by turning motor over. lifters may have collapsed any way just sitting there.
 
brian6pac said:
I have never found a reason to use lash caps, I think the guy that invented them needs kicked in the balls.
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----------------------JFYI---Chrysler used to suggest lash caps on race hemi type engines , back in the day. We ran them on a hemi w/ a 785 cam dynamics roller in it for years and years, and did not have a problem at all! I am going to try installing them on my exhaust valves "if I ever have my heads off on my currant engine.
 
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