Question for the Canucks, or anyone running a ZZ4

[Foggerjet]

I have a customer w/ 21' Baja sterndrive, last year I replaced his 350 mercruser with a stock out-of-the-crate ZZ4. it has Lightning TT exhaust and a 750 vac. Holley. It ran great until last week, he took it out one last time before putting it up. he was cruising at about 4k rpm and it developed a miss and started pumping oil smoke out the left bank. he got it to the ramp and loaded and brought it in. Upon a compression check the #3 cyl. registered "0". Al 7 others were 165-170. I pulled the valve cover, nothing wrong here. The plug was oily and the other plugs had a nice tan color. Pulled the head. "holy shit", the # 3 crown was competely separated from the skirt/pin boss. Pulled the motor. Upon inspection, this thing has virtually no wear measurable. I see no evidence of foreign objects or water entering the cyl. There is no out-of-round or taper. The crown is intact with all the rings still on it. It didn't so much as scratch the cyl. wall. The skirt retains the pin boss and small end. The plug shows no alum. speckling or otherwise. He (customer) says the temp was 170 deg. OP was 55 psi. He is a good customer and want to take care of him. He wants to get a replacement piston from GM and fix it, this goes against my better judgement I recommended a full set of forged flattops and freshen up the bottom end, even though the bearings don't look like this thing's ever been run. Has anyone ever seen this? What happened? It looks like someone took the piston out and cut it staight across between the oil ring and the pin boss. I know they use Hyper pistons, is this the problem, maybe? BTW the boat swung a 23p wheel at 5300 rpm at about 63 mph. :(
thanks
fog

[spectras only]

Did he use 92 octane ? Sounds like detonation to me ,what caused the disaster. The hypereutectic piston is fine with the 10:1 cr ,until some bad gas picked up at marinas :jawdrop: . I try to fill up at land gas stations where the gas is replenished more often.Did you install the old merc distributor or used the dist that came with the ZZ4 ? My friend sold many of these engines with no issues. You can call Dave at 604-278 1880 for suggestions.

[canuck1]

Hyper-junk pistons, most guys have had great luck with the ZZ4 right out of the crate but me being the exception bought the ZZ383 and had a bitch of a time with it. Don't let him replace just one piston replace them all with a GOOD forged set

[Foggerjet]

Thanks guys, I'll ask him about the fuel. He usually fills up on the trailer on the way to the lake, but he could have filled up at the docks. They have had Issues before.
fog

[AMC-Nut]

I would suggest this motor..Best Small Block Available! (http://www.theengineshop.com/113_0307_454_pg1.shtml)

[canuck1]

I would suggest this motor..Best Small Block Available! (http://www.theengineshop.com/113_0307_454_pg1.shtml)
Good choice but Infomaniac is a better choice for the similar package

[Turbo666]

Did he use 92 octane ? Sounds like detonation to me ,what caused the disaster. The hypereutectic piston is fine with the 10:1 cr ,until some bad gas picked up at marinas :jawdrop: . I try to fill up at land gas stations where the gas is replenished more often.Did you install the old merc distributor or used the dist that came with the ZZ4 ? My friend sold many of these engines with no issues. You can call Dave at 604-278 1880 for suggestions.
Hey Spectras, is that a Mirage in your pic there?

[spectras only]

257 with new 6.2 MPI's . :cool: What part of canada you from ?

[Foggerjet]

OK, Ive about got this thing done, 8 new forged pistons, new rings and bearings, heads goin' right back on it. Now, while I've got it apart should I change the cam? Is the ZZ4 roller cam the best choice? BTW it still looks brand new, and he (customer) never bitched about power. The ZZ4 cam is .474-.510 and 208-221@.050. Seems kinda wimpy but it ran pretty good. I know that a high idle is hard on sterndrives, should I leave it? The customer will go for it if I recommend it, but I don't want to make a costly mistake.
fog

[Turbo666]

257 with new 6.2 MPI's . :cool: What part of canada you from ?
Im from N. Delta. Im trying to sell my Mirage. Whippled 502 with Imco Extreme, and big stereo!

[spectras only]

Nice boat Turbo. Keep it in mind .What are you asking for ?

[Stab-n-Steer]

OK, Ive about got this thing done, 8 new forged pistons, new rings and bearings, heads goin' right back on it. Now, while I've got it apart should I change the cam? Is the ZZ4 roller cam the best choice? BTW it still looks brand new, and he (customer) never bitched about power. The ZZ4 cam is .474-.510 and 208-221@.050. Seems kinda wimpy but it ran pretty good. I know that a high idle is hard on sterndrives, should I leave it? The customer will go for it if I recommend it, but I don't want to make a costly mistake.
fog
I'd leave the cam alone. I had a ZZ4 in my '37 Ford Street Rod and it ran great, had good low and mid range torque. If you are only spinning it 5300 I doubt you need more cam. I put a set of 1.6 rockers on mine and I got a little more top end out of it. Still idled ok and it didn't seem to hurt the low-mid range performance... They are great motors for the price, the pistons being the weak link as you found out.
S&S

[canuck1]

OK, Ive about got this thing done, 8 new forged pistons, new rings and bearings, heads goin' right back on it. Now, while I've got it apart should I change the cam? Is the ZZ4 roller cam the best choice? BTW it still looks brand new, and he (customer) never bitched about power. The ZZ4 cam is .474-.510 and 208-221@.050. Seems kinda wimpy but it ran pretty good. I know that a high idle is hard on sterndrives, should I leave it? The customer will go for it if I recommend it, but I don't want to make a costly mistake.
fog
the best bang for the buck is to do a little head work and as someone else mentioned the 1.6 rockers

[Foggerjet]

Thanks guys, I'll leave it alone.
fog

[Turbo666]

Nice boat Turbo. Keep it in mind .What are you asking for ?
I'd like to get 80 for it, I havent even listed it anywhere...