How much preload was on the lifters? If too much and the lifters pump up?

Yes, that's the best way for sure. I didn't do it that way because it was all stock parts except for the timing set. I should have. What I measured was purely PTV clearance. Top dead center of the piston stroke, how much clearance did I have to the piston.

I'm not disagreeing with you...
Also, fwiw, I spun the engine over probably 40 times degreeing the cam. It was nice and smooth. Nothing was touching until the valves pumped up probably.

That cam is so small in terms of lift that the only way it could have made contact was with it being grossly advanced. When you get it back together, put the stock GM timing chain and gear on there and install straight up. The GM timing set is less than $100 and comes with the retaining plate and screws. I’ve used these without any issues in a number of MK-IV and Gen V-VI builds. They just plain work. I wouldn’t even worry about degreeing it (it’s stock as stock can be and came out of my running 502 MPI). And throw that Summit pos in the garbage.

Also, noticed that you mentioned having cleaned up rods and pistons and reinstalled. You really should have them resized especially now that you had a major failure. I’d also check all the intake valves for straightness. I’m sure they all got tweaked.

I'll be pulling it apart completely, so I'll check all the valves rods etc for straightness. I've only pulled a head and one rod and piston so far. My guess is that the parts from that cylinder are the only ones damaged. If it was a solid lifter motor I'd be more worried.
Before I pull it apart I'm going to know what happened. I want to know for sure what went wrong so I don't let it happen again. I won't be able to get back to it until next week though.

There are not several ways to check PTV clearance. There is only ONE way, although you do have several choices as to which compressible media you use.

The ONLY way to check PTV clearance is to mock up the motor with at least ONE piston and rod installed, the cam and timing set installed (at whatever position you plan to run it), something COMPRESSIBLE on top of the piston (I make a "snake" out of clay and run it across the center of each valve relief), the head and gasket (old head gasket is fine if it is the same compressed thickness as what you're reassembling with) torqued down, the lifters and pushrods installed, rockers installed - light springs or single springs are fine, especially if your hydraulic lifters are not bled.

Turn the engine over slowly for at least 2 full rotations.
Pull the head.
Use the depth probe on your dial/vernier calipers to find the thinnest clay for each valve. Also examine the clay around the notches to make sure the valve reliefs on the piston are giving enough clearance radially as well.

There is no such thing as measuring PTV clearance at TDC. I mean, you can measure that, but it is a totally meaningless number. Minimum PTV events will NEVER occur at TDC. Never ever.
So, learn 3 things from this..
1) before the motor goes into a vehicle, and really, before the intake and valve covers go on, prime the oiling system with a drill operated priming tool where the distributor goes. Make sure a gauge is hooked up so you can see the oil pressure. Prime until you see oil oozing everywhere its supposed to ooze, and make sure it isn't oozing anywhere it isn't supposed to ooze. Have a buddy turn the motor over with a breaker bar slowly while you prime - must do on any motor that has timed oiling..
2) always - always - always degree your cam. Pay somebody to let you watch how it's done, and never button up a domestic US engine without checking the ICL. Just don't do it.
3) plastigage is better than inaccurate measuring with precision equipment. I've honestly never heard a guy tell me he checked his bearing clearances with bore gages and micrometers who couldn't tell me off the top of his head exactly what his max and min clearances were, as well as how far out of round his main caps were. It doesn't appear that bearing clearances were the cause of any if this tragedy, but since you're back into the bottom end now, you need to check for any scuffing of the mains and rod bearings. Obviously, one rod journal will at least need polished.

Any time you need guidance on how to perform a necessary measurement or procedure, let us step you thru it.

Should have stopped right there and figured out why :(

Is it one of the three keyway timing sets ? I have seen way too many of them installed incorrectly over the years. Almost always cause the intake valves to hit. Post a picture of the crank sprocket on the crank when you get it back.

Personally I have never used anything but the single roller "motorcycle" chain and simply have not had a problem even with cams up in the .625 lift range.

Welp... That answers that. Thanks for all the suggestions. In the end it was just a bonehead that installed the bottom sprocket wrong. I just got back to it last night and figured it out. Too many cervezas while installing it I guess.

https://cimg7.ibsrv.net/gimg/www.off...3de62b7a40.jpg
https://cimg1.ibsrv.net/gimg/www.off...bc64687605.jpg

Glad you figured it out :( At least you know what happened. Right keyway but wrong dot. Personally I wish they would stop making those things. Yours is probably at least the tenth time I have seen it happen over the years.

Hang on. Are you saying you lined up 0/keyway with the dot on the cam sprocket? The keyway should always point to approximately the 1 o’clock position.

Don’t assemble engines while drinking. ;)

**edit: keyway at 1 o’clock if installing straight up.

Absolutely dumb mistake. Alcohol is my only excuse lol Led me to drag two long block L29 gen 6 454s back from ME to VA on the cheap at least. Found them on market place while we were in NH.

Glad you got it figured out. I guess go through everything, make sure crank is happy after the oiling incident, and get her back together. Still some season left.

If you dont my asking how much did you pay for the L29's ?? I have a real nice complete one here I want to sell but not sure how much to ask for it. It is complete from fuel injection to oil pan.

Those timing sets are a little confusing for the first timer me included, put one on my 427 Vette engine, sorry man. lay off the hooch .........:ernaehrung004:

Thanks bud. Head already has new valves and seat. I'll pull the crank etc and give everything a good once over.
$400 each. One of the blocks will need to be bored, but otherwise in excellent condition. They came with an extra 297 head also, but I'll need to do some work to get the exhaust bolts out. Only the bolts were rotted and broke off when he pulled the manifolds. Both set ups were fresh water only from Sebago Lake ME. One block is Mercruiser and the other is Volvo Penta.
If I was a first timer I'd have a better excuse lol All good. Not sweating it. I don't do it every day.

Haven't done any engines in many, many years, please explain what's off since the "0" in on the key?

yhx

He used the keyway to align the bottom sprocket with the top instead of using the "Zero" "dot" on the sprocket. The keyway should be pointed to about 1:30 oclock.

The 0/keyway is lining up with the alignment dot on the cam gear. There should be a corresponding dot on the crank gear that lines up with the dot on the timing gear for 0/straight up.

They way was installed, the cam was very advanced leading to intake valves smacking pistons.

Could have been a lot worse.

Dave, make sure to get the intake valves checked. It was pretty noise when running and pictures make it look like they were all touching.

**Edit - I saw you mentioned above that you had new valves.

Cloyes version instructions
https://www.cloyes.com/3-keyway-crank-sprockets/

The Zero at the keyway means the cam is neutral. The A2 and R2 is that the cam is physically Advanced 2° or Retarded 2°.
There are dots on the timing gears that need to be aligned, not the Zero at the keyway.

Almost. I'm not looking at the instructions right now, but not quite. That's what I thought and is what got me into trouble here. When the number 1 piston is at tdc the woodruff key should be pointing at about 2 o'clock. The zero mark or neutral on the lower cam gear should should be lined up with the dot on the upper cam gear. That's for the Summit set anyway.
Edit: rookie, you're right, but here is how I set it up on my 69 which is the correct way. What's missing is the printed zero that lines up with the upper dot on my boat 454.
So it's my fault in that I didn't notice the marks were missing and I lined it up with the wrong 0.
https://cimg9.ibsrv.net/gimg/www.off...9b3c047432.jpg
https://cimg5.ibsrv.net/gimg/www.off...4677e95b7c.jpg

That looks correct :)

After 10k miles rowing through the 4 SPD pretty hard I'd say I'm safe there... :ernaehrung004:
Sad part in all this is that I obviously knew better.

You still going to degree it ?

Yep. If not just to prove that I still can lol Just a stock mag cam, but I want to see the numbers come out right before it goes back in the boat this time. Never should have put it back in with not having the numbers jive last time.

Get the factory timing set that comes with the retainer plate and be done with it. No need to degree it.

I'm surprised it ran and made power?

It ran beautiful (exhaust sounded great) up to 2k rpms, but didn't make enough power to even get on plane.
In the interest of being honest and not bashing a vendor who doesn't deserve it... The markings got covered with assembly lube. The timing set was perfect. I pulled the cover last night and just shook my head.
New piston and rings are in. Bearings all look good. Now to decide what to do about the oil pickup. I ordered a Moroso that gets bolted on, but it's 1/2" shorter than the one I had in there. Worse comes to worse I'll weld a tab on the old new one. I could braze it's but I'd rather have it bolted in.
One last thing, before I took the 1,3,5,7 head off, I turned the motor over to line up the timing and what a surprise, contact. I didn't have contact when I first built it because the lifters weren't pumped up. When I pulled the head it was smooth again.

https://cimg8.ibsrv.net/gimg/www.off...bd5c98e7ed.jpg
https://cimg1.ibsrv.net/gimg/www.off...22345a9408.jpg

why not just run a mellings pump and pickup ? M-77 ?

Glad you're getting it back together quick!

I am, but you really should braze the pick up on. The pickup is just a press fit unless you're talking about something else I'm not picturing.

Thanks. Hopefully the humidity stays reasonable for a while like it is right now. Makes working on the boat so much nicer not having to bathe the parts in sweat.
I need to throw a new lower shift cable in before I drop the motor back in. Other than that this won't be bad to finish up.

I miss read you stating you ordered a moroso ? yes tig or braze all the way around the pickup tube

The Moroso was just a replacement pickup. I wanted to replace the factory round press fit with one that bolts in. Just so I don't have to braze it. I don't Tig and my brazing skills between dissimilar metals leaves alot to be desired.

See any need to braze the tube after I mig weld this tab on? It's pretty decent gauge so nothing is moving. I don't understand why they can't just come with a tab...
https://cimg6.ibsrv.net/gimg/www.off...4ba2cd5e3b.jpg

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I finished with the short block, but unfortunately my machinist ended up in the hospital before I could get my head back. I might clean up one of the heads I just picked up depending on how long he's going to be. If I had the head, I could have been on the water this coming weekend without a problem.

https://cimg8.ibsrv.net/gimg/www.off...0b219b0bb3.jpg


https://cimg8.ibsrv.net/gimg/www.off...8b1440846f.jpg
https://cimg3.ibsrv.net/gimg/www.off...3dd2bee5f9.jpg
https://cimg8.ibsrv.net/gimg/www.off...56005924ec.jpg
https://cimg3.ibsrv.net/gimg/www.off...2aa0e44ce9.jpg

I like to braze the tube in place so there's no chance of it sucking air

Did you end up replacing all of the intake valves (both heads)? Because contact was made across all of them, and with one severely damaged, I would assume they're all compromised.

I'm not replacing all of them. Most of them were barely touching by the looks of the pistons. I checked them all and they seem ok. I know you can't see micro cracks etc., but with it being a hydraulic valve train I'm not as worried about it. If anything, I'm worried more about the pistons.

Hyd lifters don’t quite work like that.

Like what? Have any give? I know, but it's still not a solid lifter at least. False sense of security. I get it.

Edit: I gave a bad example/visual in this post, lol