My 2nd or 3rd post, unfortunately, it's bad news.

[Scarface]

Gentlemen,

My 1980 SC engine, newly rebuilt with JE pistons, DC40 cams, Jerry Woods valve springs and retainers, crankfire ignition, headers, M&K exhaust and 40 PMOs suffered catastrophic damage on a drive.

Was only doing about 120km/h and careful not to over-rev the engine when I heard a BOOM!, lots of smoke and subsequently a loud drone from the driver's side (expletives from me)

Question is, what could have possibly caused this?

Ever since the car was picked up from the shop, the engine didn't feel like it made a minimum of 210bhp (I specced the engine according to Wayne and Bruce Anderson's book) It wouldn't pull and somehow, I felt that the power band was very, very flat.

Mechanic mentioned that the carbs weren't jetted properly hence the lowish power.
My guess is that the cams weren't timed properly, hence the collision of the valve and piston. Or that maybe, the valve seat dislodged and caused the valve to jam.

Needless to say, the valve and rocker is broken. A liner is scored. The head is museli and the JE piston is now a desk accessory for pencils. Pictures attached.

The other 5 cylinders, heads and pistons are in great shape. The engine had over 1000km on it since the rebuild.

BTW, are my heads the desirable early large port ones that I keep hearing about?

Would you gentlemen be kind enough to offer some enlightenment to my plight?

[Scarface]

Here are the other pictures.

[cgarr]

Looks like the seat fell out and was bouncing around. did you have seats put in it?

[equality72521]

I don't have advice to offer but DAMN, that's messed up. Hope you get it sorted out.

[James Brown]

Ka-blam, dropped a valve. At least you only need one piston/cylinder/head but the whole engine needs rebuilding, hole in the piston no doubt contaminated the inside with tons of fine metal. Could be a manufacture defect, hard to tell from the pics if the seat is in the head. The outcome will be the same-rebuild. Any warranty with the engine? You have good parts on the engine, just a minor setback. The 79 heads are the bigger ones.

[petevb]

Sorry to hear that.

What were you doing at the time- wide open throttle in 3rd gear? Not cruising down the freeway I assume. How long since the work was done?

[Scarface]

Gents,

The engine had just done over 1000km, gently broken in. I've been driving the car for about 4 months already.

The engine is opened and yes, there are bits of piston every where.

PeteVB, I wasn't going banzai with the revs, just a gradual increase in speed to 120km/h in 5th gear on the freeway.

Cgarr and James Brown, the seats weren't touched as the mechanic said they didn't need doing at the time of the rebuild. The valve seat is missing in the picture and I assume in a gazillion pieces.

I'm not sure if I'll go back to the mechanic for the warranty claim...though, to his credit, he gave me a liner, head and conrod.

Should I change the oil pump because of the contamination or is it alright to open and clean?


My rides...the engine belongs to the black IROC replica.

[johnsjmc]

I agree it looks like a valve seat came loose. A complete teardown and cleaning will be needed. The oil cooler/s will also need to be flushed carefully. There is no filter on the scavenge side so trash can get everywhere.

[ivangene]

only question is who is paying for the re-rebuild... if not you, now worries...

sorry to see this.

[911FASCINATION]

Hi Scarface, So sorry to see the carnage-but at least your other 5 cylinders are salvageable! Did the mechanic have prior p-car rebuilding experience?

[johnsjmc]

I would expect the expense will be all yours. Unless the seats were changed it,s just bad luck. Any help the shop offers should be accepted with thanks.

[cgarr]

What cylinder was this? The only thing I could think would make a seat drop like that without beating the crap out of the engine would be a lot of heat. Was it running cool? someone leave a rag inside the shroud?

Tight valve adjust on that cylinder would also cause that seat to heat up but you should have heard it thru the exhaust too?

[Walter_Middie]

Scarface,

Sorry to hear about your engine, sounds like it had issues from the start.

Just had to mention - I love those Alfa coupes. Very cool car.

[nixtfy]

I don't think anyone could have seen this coming; might just chalk it up to being the beauty and the beast of a hand built motor. GL

[Scarface]

johnsjmc, i'd assume that the oil pump will need to be opened and cleaned too. any thoughts on perhaps an update of oil pump? 964 or 930?

ivangene, looks like i'm paying for the rebuild AGAIN!

911fascination, the mech is an experienced bloke...but my engine didn't make the power it should have when it was working and now this...so my confidence is shaken.

From the posts i've read, PMO usually gets their jettings right first time round?
So I'd eliminate the low power problem due to the carbs.

Cam timing would be crucial no? cld it also be a cause of this damage?

cgarr, the cylinder is from a 911SC manufactured 10/79 chassis no 91A0140586, engine no (star) 6400620 (star).

i've installed a front mocal oil cooler in series with the brass cooler in the right fender, so cooling wasn't an issue. if anything, it was a touch too cool.

there were no rags under the shroud. iirc, it had a valve adjustment and an oil change just before my trip...hmmm...

the rocker arm was broken, so i'm getting all changed. any suggestions cgarr?

walter, haha, not personally a fan of alfas, it's not mine btw. the white 964 is.

thanks for your replies, thoughts and time. i feel a little better today

[cgarr]

DC 40 cams is what we run our 2.7 and require a lot of overlap 4.5mm and some run up to 5mm if you go lower or set them to original 3.0L spec you are going to get a piston hit.....

Do you know what they were set at?

[Scarface]

oh, btw anyone with a single JE piston that you'd want to sell?

i contacted JE but no replies as yet.

[Scarface]

cgarr, i did supply the cam timing to the mech when i gave them the new GE40 cams.
perhaps they were set at stock then...

any reco on which rockers to use - stock or otherwise?

[cgarr]

Nothing wrong with stock rockers!

We played around with our cams and at certain overlaps (less overlap) the engine was a dog so that could have been why the poor performance you indicated?

[Scarface]

"DC 40 cams is what we run our 2.7 and require a lot of overlap 4.5mm and some run up to 5mm if you go lower or set them to original 3.0L spec you are going to get a piston hit....."

cgarr - so overlap setting for a slightly warmed up 3.0SC motor should be somewhere 4.5mm to 5mm?

i've got Jerry Woods valve springs and retainers, 3.0L 95mm bore 9.5:1 com JE pistons, the DC 40 cams, 40 PMOs and headers.

At a minimum this engine should be making 210 right?