Disassembly of a 69 Z/28 DZ Three Oh Blew Engine

[SuperNovaSS]

I realize I have not been sharing here as much as I used to and am going to try to start posting more often.

I buy complete muscle car engines that have been sitting dormant for long periods of time pretty often. Sometimes they are engines that were pulled out of running cars or boats, others were pulled from non running cars, and the gambles were pulled to to sudden death. Sudden death is the case with the engine I am sharing with you today.

This is a 69 Camaro Z/28 "DZ 302" engine that was pulled from a 69 Z/28 after some enthusiastic tuning sessions. As you can see by the oil pan, the high revving mouse engine was likely pushed a bit further than designed. This was the cause of death for many early Z/28 engines. Like a kid eating cake, the engine keeps asking for more but eventually it is going to have to puke!

This engine was in a true 69 Z/28 but was not the VIN matching engine for the car. After "tuning" this engine, the owner decided to build a new engine for the car from scratch, taking items off this engine like the pulleys, etc. This engine was put on a dolly and put in the corner of the garage without ever being opened up to evaluate the damage. The owner decided to sell the engine recently and I could not resist seeing what was inside.






















Looking at the numbers, the engine began life as a true DZ 302 and had likely been tinkered with in the past. I say this because the block has a March 69 casting date and assembly code but the heads are dated August 1968. I imagine the top end was original to the Z/28 the engine was installed in and the shortblock was replaced at some point. That is just an assumption though, the heads on the engine could be off of anything and could even have the smaller 1.94/1.50 valves. It is reasonable to assume if the engine has been apart than it has likely been bored and possibly had other work done. Other evidence that this engine has been apart include a later model timing cover and later model valve covers with drippers(69 were non dripper).

The only way to find out is to dig in and get dirty........

[SuperNovaSS]

Here is the oil pan, one side has multiple dents from something trying to escape and there is only one spot on the other side:










While the little oil that is the pan is draining, let's check out the top end:












Hmmmmm, where did those pushrods disappear to? Let's check under the intake:




No, I did not remove that lifter. If that is not strange enough, where are the 2 missing lifters????

Oh, there is one. I wonder how that got down there?






The oil is still draining. We might as well pull the heads. I want to see if they are 2.02/1.60 valves anyway.






Looks dirty but not bad at first glance. I don't see any stampings on the pistons. Could this possibly be standard bore?

One piston looks to be sitting a bit high and has a nick in it.



Let's check the head on that cylinder:




The good news is the heads are factory high performance units with 2.02/1.60 valves and no modifications like porting or screw in studs. The bad new is one intake valve is bent from that piston. Not a big deal.

OK, the oil has stopped draining out of the pan. We know there is carnage down there. Want to check it out? I do.









Hey, there is the missing pushrod! Amazingly, it is still straight!

I don't think we can straighten the windage tray. But we did find the other lifter. Notice anything missing from the crankshaft?

[SuperNovaSS]

Yep, we seem to have misplaced a rod.




Oh, there is part of it in the next bank:







GM part number on the bottom of the TRW pistons. This block is standard bore. The question is, can it be saved?




Look what I found, that explains the magic disappearing lifters:





Time to dig deeper, let's get the rods and pistons out:




.001 under rod bearings. Uncut rod journals. Unfortunately that was that was rodless needs some attention:








Hmmm, to much tuning:





Let's get that crank out so we can see how this block looks:

[SuperNovaSS]

Well, there is damage to the bottom of the cylinders but nothing I see in the ring areas:






Oh wait, is that a........ damn it:




And another in the next cylinder:



It may still be repairable with 2 sleeves. It will have to go to the machine shop to be cleaned and checked for other unseen cracks.


Lets get that cam out:




It looks like the last time the engine was messed with was the early 90's bases on the cam sprocket:



Alright, we got the cam out!





OK, we did it! No exactly what we were hoping for but that's the way the cards fall. If you guys are interested in the outcome, I will let you know when I hear from the machine shop.


Thanks for looking,

Jason

[ss427copo]

Two words: Boat Anchor.

[Salvatore]

Good job Jason!

[300deluxeL79]

love this engine stuff, keep it comin! [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

[earntaz]

Took me a few minutes to check all the battle damage which I might add occurred in a heart beat ... good pictures Jason!!

[ds1]

Looks like the one Crack goes to the head bolt. But not a big deal. Two sleeves and a Threadsert and it's back in play. Comes down to how bad someone wants an OE engine. But then you already know that. The rod broke and hit the cam.

[green crv]

Wow, that was good suspends, bad ending thought. Gives new meaning to big cam sound lol. [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]