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Collapsed lifters and broken valve springs on SBC 383

8K views 51 replies 17 participants last post by  pannetron 
#1 ·
Well, I have posted some things about this issue before.

It has happened again.

Im at a lose as to what is going on here.

First, let me say this car is driven by my father. He never abuses the car, Never takes the rpms over 5000. I believe the car to make about 475 horse.

Its a very basic 383 built. Eagle rotating assemble, 10 to 1 compression, Dart heads ported by Eric Weingardner with a 2.08 valve in there, at his request. Has a Luanti Harold Brookshire hyd. roller cam. Its 280/288 and 226/234@.050 for .530/.530 lift installed at a 109 ICL on a 112 LSA. Very mild build. Cranking compression is right at 195 psi. Comp 1.52 roller tip rockers for .536/.536 lift. Intake is a Edelbrock RPM with a Holley 3310 on it. Modified GM HEI that has 18* initial and a curve of 16* curve in it. It has 34* of total timing. I have the can modified as well and it provides like 14* of timing for a total of 48* at cruise. With the can added at idle its like 32*. Exhaust is a set of ! 3/4" headers with 2 1/2" exhaust.

I dont know why the professional engine builder installed the cam at 109 ICL. The cam card calls for 104 ICL.

Car is a little sluggish down low to me for such a small cam but with the 109 ICL seems like it wants to rev to 6500 maybe 6800.

Car has a M20 4 speed and 3:55 gears. Its a cruiser and not a racer. Street tires all the time.

We had 4 lifters collapsed when the rockers would not hold a adjustment. Replaced them. We now have broken 4 valve springs on the car. I live in Florida, so cold starts are not really an issue.

The valves were originally adjusted by a the builder and I have adjusted a few here and there when I had to replace some springs.

The cam was bought from Luanti directly with THEIR kit. Matching lifters, springs, retainers, locks and etc.

I finally called them today to see what they would say about these problems. The guy got pissed off at me and said he needed to know the spring pocket diameter and installed height of the spring. Told me the part numbers I gave him told him nothing. I was like, REALLY? You cant tell me the springs that your recommend cant work? I realize not all heads may have the same pocket and etc, but come on. Its your spring. Tell me something else. The spring pockets are just stock.

I called a local machinist that does work at his home and builds engines for a living.

My builder has since become a track promoter and is not building anymore.

He said run by the extra Luanti springs by and we will check them out.

Anyway....I wanted to post this to see what you guys have to say about these issues.
 
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#4 ·
I hired a well known dirt track builder with a machine shop at his house. Surely he checked all this. I was not at his shop during assembly, but who knows.
 
#5 ·
The block is zero decked. The pistons are -12 dished pistons with a 66 chambered head. Lift is .536 with a 106 ICL.

Yes, the rods where clearanced. Cam lobes looked fine when we replaced the lifters.

I hired a well known dirt track builder with a machine shop at his house. Surely he checked all this. I was not at his shop during assembly, but who knows.
 
#8 ·
Did the engine have a P to V contact sound when it was running warmed up? now thinking about the valve spring to retainer contact issue I had that sounded like the valve tapping the piston didn't break springs, coil bind ?
 
#9 ·
sounds like a coil bind type issue. That's a pretty well thought out engine with all good stuff. There got to be a clearance issue somewhere. has it bent/broken any pushrods?
 
#16 ·
Comp 1.5 roller tip rockers.

This has been discussed before and some people get lucky and have no issues but others do have issues.

Grooved pivot balls and issues with them.
Sometimes the grooved balls do not allow oil to poop up in the rocker and flow over and out and onto the valve springs.
The oil just runs out of the rocker through the groove in the pivot ball.

Springs get hot and fail to do what they are intended to do and many times other problems arise like busted studs and burned up rockers.

I trust no one except myself when it comes to checking everything for clearance.

Well except for a few guys on here.

I have had friends get engines built at some friends shops and well known "great shops" and get screwed in the process.

It happens.
Slapping springs on a head without measuring things as you know is not correct.
Just because they are stock heads means nothing either as there are variances and your larger vlave was the seat cut deeper or is it not.
You must measure all this.

Good luck Aaron I hope all turns out well.
 
#17 ·
Thanks Jeff. I appreciate you chiming in.

Well, I havent heard about the Comp roller tip issue, but that is whats on it.

Im going to be real upset if this turns out to be a assemble issue. Dad spent real good money on the build and this builder is highly regarded in the dirt track world on the circuit her in Florida, at one time he was building also all Late Model engines for several series.

Interesting assessment of the intake valve.
 
#18 · (Edited)
Are all the broken valve spring intake springs or a combination of both? I think the guys comment above about the piston contact is that sometimes when you go with a bigger intake valve the piston needs to be adjusted/cut for it. Most of the SBC pistons out of the box are cut for a 2.02 valve. With a larger valve though there is a valve pocket for a valve the larger valve maybe be nicking the side of the piston/valve under load. Sounds like you feel comfortable about heads assembled correctly so this is maybe the next step after you have checked the heads (I think this is where issue is - but you never know). There is a way to do PTV clearance with heads on car. One thing you could do it get the piston to TDC #1. Take the valve spring off and see how far down the valve drops (at TDC the valve will get stopped by the piston before too far down). You should have like .300 of a drop at least this will account for the clearance needed when the opposite cylinder in the cycle number 6 is active. When the motor is at TDC#1 the cam is active on the number 6 cylinder with both valves open and this is where the piston to valve clearance issues occur as both valves are like .100-.200 off their seat. The cam people should have the lift numbers at this measurement (comp cams has it in there cam catalog) they range from like .050 to like .200 for the big cams. You take this number and multiply by the 1.5 rocker arm ratio to get the lift at the overlap and the ICL is important as you noted in your post and this can move the valve a lot as far as lift in the cycle (like .030-.040). Anyway say you find out it .100 then you multiply that by 1.5 so the valve is at .150 lift at the overlap point. You could also measure how far the pushrods move up on number 6 (needs to be done with no rocker on number 6). Given there is some dwell time and the cam is moving while piston is not you probably want to see .300 of total clearance (assumes .100 pushrod movement) when you drop the valve which includes the .100 safety margin plus a little more. I know seems like a lot but if it is hitting piston on side as you drop the valve you might feel some resistance a like .100-.150 drop in the valve as the valve is going into the valve pocket but is catching on the sides. It still may be hitting the piston under load even with this test but at least you can check it. Good luck.
 
#22 ·
Lew, thanks for taking the time to type that out. Good stuff there. I will need to look over and use it need be.
 
#19 ·
When I typed my question I had worded it wrong, my problem was my cam lift (.533) was causing the valve spring retainer to have contact with the valve guides & seals and it sounded like P to V tap ( had that problem on my 454 too and had that on a couple Harley engines :frown2:) Like said is the piston valve notch wide enough for the bigger valves and deep enough for cam lift?
 
#20 ·
AAron,

I did not look at all of the responses but the fact that you bought a matched set of parts from Lunati does not mean squat :( Like the guy at Lunati told you, without the correct installed hgt, spring pocket sizes etc etc you cannot tell anything.

I am working on a set of World Product heads at the shop right now that were set up by another shop with the "matching" springs etc for an Isky cam. The inner springs will not go down over the boss of the valve guide and were stacking up solid :( The tore up a few other things along the way. All the other shop had to do was machine the guide bosses so the spring would fit and they probably would have been fine. Now they are a mess and need to be redone.

Also, dont assume that the guy who built the engine checked anything :( Everyone can make a mistake no matter how good you are.

Has the engine builder checked the remaining springs yet ? Look at the remaining springs and see if there are any marks or scratches etc on them.
 
#24 ·
I understand Bill. I guess all the more to do all your own work I guess.

Lets hope its a easy fix.

Bill, I think we are kind of mixed up here. The spring was just broken yesterday. Its on number #7 cylinder. The original engine builder is not in business anymore. I think he may do some stuff on the side, but he a full time track promoter now. I ran a spare spring over to another machinist friend who builds too and he checked out the new Luanti spring I have and said it was a good spring and goes beyond the need expectations. He offered to check things over if I had to pull the heads.

I will check the remaining springs for marks and post some pics tonight.

Thanks for the chime in.
 
#21 ·
About how many miles when first break happened , and how many miles since then til this second problem.?? I'm leaning towards clearance or binding issues with springs or rocker slots.

I agree with BILLK and SWISHER...I had bad experience many(45) years ago with a highly recommended "BB guru"...built a 396 that smoked a qt every 100 miles til it dropped a valve. Disassembly found some UGLY stuff.

Good luck on the fix; we all know how frustrating this can be when everyone's pointing finger at the "other" guy.
 
#25 ·
540Olds, I would say around 20,000 maybe when the first break happened. Probably another 15,000 or so since the second breakage.

Im not pointing the finger at anyone. I realize things happened like this. Professional or not. I would never second guess someone who puts food on their table by doing this.
 
#26 ·
the trouble with racing engine builders is they can sometimes fall into thinking "it's only a street engine, it'll be OK". On valvetrain stuff nothing but nothing beats seeing with your own eyes. of course, this leaves the typical guy in a pickle.

How much clearance between the valvespring coils at full lift? Hard to check on the car as the springs will compress or collapse the hydraulic lifters after the engine is shut off. If you can get one spring off you can compress it in a vise to see visually.

Old dad might be enjoying the power a little too much. Got a telltale tach? Does sound a little like over-reving.
 
#28 ·
Tom, I will post some pics.

I pressed Dad on that. I told him when I installed it to never run it over 6000 before shifting.

I just made my comments on it wanting to rev to maybe 6700 based on how it felt to me when I drove it from time to time and shifted it around 6000.
 
#29 ·
If not, I have a 430 horse 350 on a stand that was in the car previously. Been seating in my climate controlled house. YES, my house!
 
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#30 ·
Here are some pics of the engine. If you scroll your mouse over the pics, it will tell you what your looking at. I rolled the pushrod on a glass table and to the naked eye I could not tell if it was bent. Appeared to be straight to me.
 

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#34 ·
I think if I remember right the pushrods are 7.2 maybe?

Not sure what you mean by spread...can you explain?
 
#37 ·
My machinist friend thinks the spring is not getting enough oil.

In those pics without a rocker....I did wipe that stem clean with a paper towel and brake cleaner.
 
#39 ·
Aaron,
I have to agree with Jeff that the rockers look like they have been hot at the pivot point. I have some new ones at the shop to compare them to. When Comp first came out with the roller tip rockers we had a problem with them on a couple of marine engines. Seemed that the oil hole was not in the correct position to allow enough oil up from the pushrod. Burnt up a couple of sets of them till we figured it out. But that really would not explain the broken spring. Hard to tell from your picture but what kind of spring seat is that under the spring ?
 
#41 ·
I have read about some issues with the Comp roller tips.

With what your calling the pivot point. Is that from a lack of oil as well to the spring?

I have no idea on the seat. I bought these out of yard sale and Eric Weingartner set them up.

Going to find out next week when I take the spring out.
 
#42 ·
Aaron,

I suggest getting or making the lightest checking spring you can find, and install on a set of valves for a cylinder. Reassemble the rocker/pushrod, zero lash, and turn the engine over and at peak lift make sure you have enough piston/valve, retainer to seal, retainer to rocker, rocker slot clearances etc. The checking spring should not collapse the lifter as the lifter should be full of oil.

Its a quick and dirty test.
 
#45 ·
Good ideas except the p/v part,,,,max lift has nothing to do with the p/v clearance
At peak lift the piston & valve are no where near each other
Check intake every few degrees between 10 & 20° ATC overlap, exhaust BTC overlap this is where you will find them closest.

That said unless something is very wrong like too small a valve pocket radially for the valve which is a possibility with the 2.08 valve,,, or the cam is installed wrong which would be pretty obvious by the way it runs.....
There is not a chance the valve & piston are anywhere near each other with that cam ;)
 
#47 ·
Correct Lew540. The photo is the intake for #7 intake spring.

None of the issues happened all at once. They are happened independent of each other. Im pretty sure all the springs breaks are only on the intake side, but dont recall exactly.

All the lifters have link bars, so Im not sure if both went south, but there were 3 or 4 sets that did. I would have to go back and look.

Im switching the Comp roller tip rockers out for a set of Crane energizers....have some that have like 30,000 miles on them.
 
#44 ·
Aaron Home Depot or Lowes sells springs for bifold closet doors for a couple bucks that work great IMO for light checking springs, might have to open up the ends of the springs by twisting them with pliers, didn't have to do that on my 063 heads but did on my Brodix heads
 
#52 ·
If the pushrods aren't stiff enough, they can bow and snap back and introduce some really nasty harmonics into the rocker arms and springs. Regardless of their length, they need to be STIFF. I use Manton Series 5 push rods, as large a diameter as will fit in the head. There are also tapered pushrods that allow more diameter between the lifter and opening in the head. A valve spring can look like a slinky if the harmonics are bad. Lots of builders use stock pushrods which may or not even be the optimum length and which aren't stiff enough for stiffer valve springs.
 
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