Solved - bad engine noise!!

[Arde]

Well, my lost wedding ring theory was not that far fetched then .
When a door closes another one opens. Others can contribute cheesy metaphors about what good happens when a piston blows up...My nickname is spleen, so it will not come from me.

 

[Frederick]

There is certainly a great deal of comfort in knowing what exactly caused it, and that you weren’t hearing things and going crazy! Best of luck with the rebuild. nice to hear the pistons are available.

 

[Markos]

Wow! Little bastard made colossal mess of things!

 

[sfdon]

can contribute cheesy metaphors about what good happens when a piston blows up...My nickname is spleen, so it will not come from me.


Senor Bazo.."..

 

[wkohler]

Wow what in the heck did that used to be?

 

[Fritzie]

TRIGGER WARNING: What you see may cause emotional distress!

So the good news is it wasn't an m6 nut from me leaving it on a carb and falling in the throat, but a piece of metal did get in while driving sans air box. So I feel stupid but not THAT stupid. All you bareback trumpet sidedrafters take note. Here's the culprit:

View attachment 161313


Piston:

View attachment 161314


and the head. Toast.

View attachment 161316


Fortunately I am in the trustworthy hands of the Man From San Fran. I will acquire a fresh head, and the block comes out next to rebuild the bottom and install new pistons. This concludes this thread, next up, the rebuild thread

First impression: general surface damage. Valves and cilinder undamaged(?)

Also interesting; is the answer to the question “where the piece of metal lefts it roots? Is it a square bar? Something missing from the airbox or .. (air-valve)

Thanks for sharing your story.

Fritzie

 

[Stevehose]

Wow what in the heck did that used to be?

“where the piece of metal lefts it roots? Is it a square bar?

Good questions, it does appear to have been a square bar before "reshaping" inside the cylinder, sort of like a rectanglar woodruff key that fits into a shaft slot. It is magnetic so it's not aluminum. I don't have anything like that on my intake system so it must have come from something external unless I find a clue during engine disassembly.

 

[TodB]

At last, you can see the end via a rebuild and you know the source of the noise. I'm curious to hear how you settled on a 284 cam and not something a bit more aggressive to go with the higher compression.

 

[Stevehose]

At last, you can see the end via a rebuild and you know the source of the noise. I'm curious to hear how you settled on a 284 cam and not something a bit more aggressive to go with the higher compression.

I have that cam in my head now and like the mix of smooth idle and better higher rpm performance. It's not a racer and I still want it to be civilized and not loping along as I cruise in to Starbucks

 

[sfdon]

A good description of the 282 cam is that it is a mild street cam.
Not a track cam. Not an aggressive street cam. It gives good power and torque at lower rpm levels. Meaning you don’t have to drive like an asshole through your neighborhood on the way to a nice dinner with your wife.
just sayin…..

 

[Oldbmwcoupes]

All my builds have used the Schrick 282. I think it works best with a bit more compression and some basic clean up on the head porting

 

[JFENG]

Steve,
Sorry to see the bad news. Your head could be saved if it were important enough to you.

I just had a DHC alloy head that had significant damage everywhere (Water passage corrosion, totally buggered up valve seat recesses, tacked casting around the valve guides, piston interference eg hitting the head, etc). It required a lot of of careful welding and machining. In my case it was a full number matching car so I felt the extra $$ was justified even if I keep running on my spare motor and put the original motor in a bag.

The machinist was an old school guy who has 5 decades of experience building some tremendously weird/rare motors that required significant amounts non-standard machining and fabrication.

I’m sure there are a couple guys in your area like this.

I agree w your plan to build up a new motor, but if this is the original head, it’s worth saving in the barn, and possibly even restoring.

John

 

[Stevehose]

Steve,
Sorry to see the bad news. Your head could be saved if it were important enough to you.

I just had a DHC alloy head that had significant damage everywhere (Water passage corrosion, totally buggered up valve seat recesses, tacked casting around the valve guides, piston interference eg hitting the head, etc). It required a lot of of careful welding and machining. In my case it was a full number matching car so I felt the extra $$ was justified even if I keep running on my spare motor and put the original motor in a bag.

The machinist was an old school guy who has 5 decades of experience building some tremendously weird/rare motors that required significant amounts non-standard machining and fabrication.

I’m sure there are a couple guys in your area like this.

I agree w your plan to build up a new motor, but if this is the original head, it’s worth saving in the barn, and possibly even restoring.

John

Thanks for the info, if it was the original head I would make the effort to save it. In this case the head I trashed was a BMW warranty head from 1987 that Don put the Schrick in before sending it my way. I have the original (cracked?) head plus an intact 72 head that someday I will look into seeing if the original can be repaired or the other 72 built up. Meanwhile I will run another later model head with better cooling passages and the Schrick for the hot climate here.

 

[sfdon]

On a Csl - a matching year, fuel injected head is important.
There are no matching serial numbers on coupe heads- just date and casting.
I have shelves full of early carbed heads. Very little demand.
Todays special - BOGO. Buy one and get two.
500 bucks you get TWO! early carbed heads.
I’m waiting…..

 

[TodB]

I have that cam in my head now and like the mix of smooth idle and better higher rpm performance. It's not a racer and I still want it to be civilized and not loping along as I cruise in to Starbucks

I've got the Schrick 284 in my (low comp) B34 in my coupe. The idle is lumpy. My old hi comp B34 in my E28 had a Dinan (welded) stroker crank in it with a Paul Burke built head and cam. Very smooth idle and torque all day long. Miss that car. I thought I read somewhere that M30 stroker cranks were now available but require custom pistons, rods, etc. The ultimate project scope creep!

 

[Stevehose]

I've got the Schrick 284 in my (low comp) B34 in my coupe.

I found that with the triples if you keep the idle at 1000rpm it's acceptably smooth.

 

[TodB]

I found that with the triples if you keep the idle at 1000rpm it's acceptably smooth.

Agreed, I don't mind it and it gets better as the engine warms up.