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Engine Block Detective Required

andyleonard

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In attempting to determine what - exactly - the compression ratio is in the replacement motor in the 73 CSA, I have the following data: Former owner states "My first wife ran the motor with no oil and I got a new motor in Pengrove, CA in 1985/6."

The head is dated 4.84 and has a hole for the fuel pump. Part number 1-277-358.
Block casting is dated 12.17.77 (17L77) and is stamped 530J/US. There's fuel injection stuff on the front pulley/balancer and it doesn't use a CS oil filter.

Any guesses as to compression ratio? Sounds like a Brand X factory replacement short block and a replacement head from the dealer in 1984. I'm trying to see if it's worth bolting carbs/headers etc. on this motor or use one of the other ones. I'm hoping for 9-1 or better if it's a 530 block/pistons.
 

sfdon

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no VIN number above starter motor hole?
No 3.0 on drivers side of block?
Got a pic for us of drivers side of block?
Water pipe by cylinder 6 on block?
Water jacket on drivers side?
Compression test?
What kind of "Stuff" ? "fuel injection stuff on the front pulley/balancer "

Sounds like a 530 or a 630 but not likely to be 730
 

andyleonard

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no VIN number above starter motor hole?
No 3.0 on drivers side of block?
Got a pic for us of drivers side of block?
Water pipe by cylinder 6 on block?
Water jacket on drivers side?
Compression test?
What kind of "Stuff" ? "fuel injection stuff on the front pulley/balancer "

Sounds like a 530 or a 630 but not likely to be 730
Block above starter is stamped 530J/US No chassis number.
Compression 170x6
3.0/3.3 cast on block
Maybe just FI front cover? I didn't recognize the little post in the OD of the front pulley, but hey.
Not sure about water jacket/pipe on block.

1595715874514.png


1595715915231.png
 

sfdon

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The bracket at front is for TDC sensor (diagnostics only)
jetronic or motronic (early)
the bolt plugging the hole in block at #6 cylinder marked 3 in red is for jetronic throttlebody and AAV heating.
the intake port Marked 2 does NOT match e9 carb or injected ports
the value of that head is dependent on the depth of the dimple located in my second pic - dimples are circled in red

HBChris has given you good info.
 

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sfdon

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Well that didn't take long at all, now you know what you've got! Curious though, is that some creative copper pipe plumbing solution running between starter and brake booster?
that pipe is on sale at walloth!
good timing!
 

andyleonard

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Curious though, is that some creative copper pipe plumbing solution running between starter and brake booster?
LOL Yes the pipe was a 15 minute proof of concept to solve the "2 Hose Problem" without disconnecting the heater. I didn't cut it to length in case the carb/manifold package wants something different.
 

andyleonard

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the intake port Marked 2 does NOT match e9 carb or injected ports

the value of that head is dependent on the depth of the dimple located in my second pic - dimples are circled in red


Are you referring to the protrusion into the intake opening from the "shadow" of the valve guide?

I'm guessing that head came over the parts counter in 1985 as a replacement, based on the date and the drilled fuel pump hole, and has never been off. Maybe we'll see the dimples if it gets pulled when we go after some compression. It might be easier to start with a bigger/newer motor, which I have a couple of but have never inspected. They came with a load of 745i stuff I bought and I just stashed them.Now I have to go figure out what they are. Isn't 170 compression pretty good for 8-1?
 

sfdon

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You can feel the dimple with your finger tip.
170 compression is 9:1 stuff.
something strange there.
use a boroscope

here’s what e9 ports look like...
7EE3DB27-8298-469C-8B57-221988901151.jpeg
 

andyleonard

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You can feel the dimple with your finger tip.
170 compression is 9:1 stuff.
something strange there.
use a boroscope
Yup. Strange.
Dimples are present on head. Pretty sure this was an over-the-counter replacement head in 1985.
Borescope shows flat pistons with minimal carbon.
Is it possible BMW decked the block enough to raise compression when they remanufactured this 530J/US engine? Or was it a bare new block from 1977 sold in 1984? WTF?
 

HB Chris

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Yup. Strange.
Dimples are present on head. Pretty sure this was an over-the-counter replacement head in 1985.
Borescope shows flat pistons with minimal carbon.
Is it possible BMW decked the block enough to raise compression when they remanufactured this 530J/US engine? Or was it a bare new block from 1977 sold in 1984? WTF?
The early casting blocks were still being made in 84 so 84 doesn’t mean much. US got flat top pistons and 8.0:1 in the e9, they would sell you the same motor not an upgrade. Don’t know what compression the 530i had but at 176hp US vs 200 ROW, and the e9 at 170hp I say they are the same. You still have the dimples so it wasn’t decked much if at all. My 73 had this same block from BMW when I bought it
 
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