Terrible news when I pulled valve cover

[arkracing]

I cant remember if this is a problem on BBC or just on the SBC's - but some of the intake bolt holes in the head go right into the lifter valley and some of them are extrememly close to the push rods. If you use a Bolt that is even 1/4" longer than the one that is supposed to be in there you might bend the push rod just putting the intake on. (especially if you adjusted the rockers without the intake on the motor)

ask me how i know (it only happened once and that was enough)

if a valve is hitting a piston it will tick all of the time most likely. I would suspect that you are ok in that department since you are running a resonable cam lift. and since it hasn't been revved over 2500RPM since you put it together I would doubt you floated a lifter and caused the piston to hit the valve - that would require alot more RPM's in most cases.

get a set of good aftermarkt pushrods Comp or Crane or whatever put them in re-adjust and see what happens.

[Mudder]

man your luck sounds about like mine.........

[Yukon Jack]

Tried to get the bent pushrod out and must have put to much pressure cause the rod broke. I think I was not pulling up straight enough.

Then I notice some of the metal bands from the teflon valve seals. Looks like two broke. There are three pieces, with two metal pieces being missing so I guess my engine is persuading me to pull the intake.

Is it unusual to have a couple of the teflon valve seals bands break in connection with whatever caused the bent push rod?

[68C15]

uh-oh!, did you swap in a cam with more lift & now the spring retainers are bottoming out on the valve guides?!

[GSFMECH]

Looks like the adjustment was too tight and the retainer bottomed out against the valve guide/ seal and this is what bent the pushrod. You need to get a compresion tester fitting and screw into your spark plug hole and connect an air line to it. Be sure both valves are backed off and put air into the cylinder. Be sure you are out of the way of the fan etc. as the engine may turn over until the piston gets to the bottom of the stroke. Now listen for air leaking out of the intake or exhaust. If you have no leaks you are good, but if you have air leaking you are going to have to pull the head to replace bent valves. If there are no leaks you can replace the seal on the engine without pulling the head.You can pick up a spring compressor that you can use to remove the valve spring and replace that broken seal by using the compressed air in the cylinder to hold the valve closed. They have lever type in most parts stores but Moroso makes a real good lever type compressor that screws onto the rocker arm stud. I have even threaded small rope into the cylinder before and rolled the engine over until the valve is held closed before but the air in the cylider works best. Good luck and don't lose hope this is fixable.
Mike

[LUV2XCLR8]

Damn that does sux, hope I don't have the same issue, just got my exhaust done yesterday

[Yukon Jack]

68C15 - a cam and lifters were installed along with matching springs, retainers. Also installed the new magnum tip rockers of the correct ratio.

GSFMECH - my buddy who helped install the cam has the spring compressor and that air fitting so we are good to go. Now just have to find time to get it all ready and talk him into giving me a hand.

[3 on the tree]

Did you check installed height of the valvesprings, and compare it to the cam manu's numbers? Still sounds to me like too much lift, might require maching down valvespring seat, or offset retainers to get the required height on the valvesprings. Did you go with a higher ratio on the rockers?

[iluvmy72]

This isn't such a bad thing......now yuou hvae a chance to upgrade to some roller rockers.

[Yukon Jack]

The rockers were standard ratio. The valve spring height was not measured, better check that as I don't want this to happen again.

[rage'nrat638]

make sure the holes the push rods go down thru are not worn out....on the heads......


this will cause the rocker to turn sideways......

[cochran63]

This does suck, if it is any help I have a new set of comp 3/8 pushrods ill let go for 40 shipped.

[Yukon Jack]

I checked the pushrods last night and I was wrong, these stock units are 5/16 rather than 3/8". cochran63, I'm pm'ing you. Looks like I need to step up the pushrods and will have to change out the guideplates also.

[chevyfarmer]

I am going on some new information here because I am in the process of building my first BBC but others please feel free to chime in on this.

I am building a 76 (i think) 454, and last week I was @ my machinist and he told me something that GM had placed under the valve springs (like a washer of some type) to cause the valve to rotate in the valve seat as the motor was running. He said that it is uncommon to use these for preformance applications these days and that he was ordering for me the proper valve springs to accomodate for the height difference once the washers were removed. I do not tknow if GM was still using them in your newer motor but I just wanted to help out if I could. Best of luck, please keep us posted!

[Yukon Jack]

Thanks for the info. I don't think there was anything like that on mine but will make sure when I pull a spring.

[VetteVet]

Originally Posted by Sillyoldman

Be sure to buy new crushed nuts for your rocker arms!

I.

Ouch!! man that just sounds too painful------Sorry, Silly I just couldn't resist. LOL

[Yukon Jack]

Just a little update - have had no free time so little has happened since the initial post. I got the driver side valve cover pulled and there was a valve seal that broke on that side also. Haven't pulled any of the springs yet to see if more valve seals broke.

From what I can see of the cam, I don't see any visible damage.

Here is a pic of the pushrod that bent - pretty substantial bend I would say.



Here is a pic of the engine. I was concerned that it looks like the cam would be better positioned in relation to the lifters if it was positioned a bit more towards the front of the engine. I showed a person at a local speed shop a pic of it and he said it was fine.



Any of you engine gurus think the cam position looks incorrect?

I hope to be able to get the installed valve height checked tonight to start figuring out what the problem is.

Got the pushrods from cochran63 and the 3/8" are way beefier than the stock 5/16" rods.

[smokekiki]

It sure looks like a couple of those lifters are trying to ride on two cam lobes!Might be an illusion,but..

[Yukon Jack]

I sure think it looks too close. I didn't get a very good pic of the back of the engine, but here is the slot 2nd from the back of the engine.

[cduster]

I'm not positive, but I think that it is designed like that so the lifters rotate. Looks fine to me.

Dan

[Yukon Jack]

That is what the speed shop person said after looking at the pics. Just looks awfully close to me.

[Fred T]

That's the way they are designed. There is a slight cant to the cam lobe, which causes the lifter to rotate when the engine is running.

Did you check the piston to valve clearance when you assembled the engine?

[Yukon Jack]

We only did a cam, lifters, springs and rocker arms - did not pull the heads and did not check the piston to valve clearance. Engine had about 120,000 miles on it.

[jhow66]

Hey Yukon how much lift does the new cam have? Sounds like your spring retainer is hitting the telfon seals at full lift. Most of the time when you install this kind of valve seal the valve guides must be machined. Just used a cam in my son's (orangeuavol) BB 408 that had .538 lift on exhaust side that cleared with regular seals and stock springs. When you are replacing the seals that are broke here is a way to check to see if you have enough clearance:
1--install valve retainer and keepers (valve spring off).
2--hold valve on seat and measure from under lowest part of retainer to top of valve guide with seal installed.
3--Take this figure (as an example say .505) and subtract the cam lift (say .498 as an example). This shows that you only have .007 clearance (not enough).
4-- Someone will know what the clearance should be, so chime in.
5--Don't put it back together until you check this clearance as this is what is breaking your seals (and probably bending your push rods.
Hope this helps.

[crazy4chevs]

for some reason 60 thousanths comes to mind.