haha this is weird ? timing tab ?

starsnstripers

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ok i'll do my best here to explain. 1968 auto block gm 250 out of a lobster boat putting into my boat. On the timing tab there's a 0 at TDC right? Now looking at the harmonic balancer the engine turns clockwise.Looking at the timing tab there is an "A" to the left of or before TDC, doesnt the "A" mean after TDC ? whats wrong with this picture?
 

ziggy

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Re: haha this is weird ? timing tab ?

just looked at my 72 timing marks. the word before is above the numbers and to the left , the word after is to the right and above the numbers. the hash marks are in 2* incriments, the numbers stamped on it are in 4* incriments. ie. 0, 4, 8.

just a guess. but a 4 could look like an A maybe?

the numbers are above the hashmarks, the words are above the numbers....
 

starsnstripers

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Re: haha this is weird ? timing tab ?

I'll look again but all thats on my tab is a 0 to the right end and an "A" at the left end with little incrament marks in between. i'll check again though thanks Zig
 

flabum

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Re: haha this is weird ? timing tab ?

"A" is for "aneurysm".
 

starsnstripers

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Re: haha this is weird ? timing tab ?

That was helpful Flatbum thanks alot "A" for _ _ _ _ _ _ _ !
 

Don S

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Re: haha this is weird ? timing tab ?

1968 auto block gm 250 out of a lobster boat putting into my boat

What engine is this? Please describe it other than saying it a gm 250. Is that cu. in.? hp? automotive out of a lobster boat????
Confused.
 

starsnstripers

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Re: haha this is weird ? timing tab ?

It's a 1968 250cid l6, It came from and was rebuilt for the same year 1968 lobster boat however the boat died i guess anyway i ended up with the motor in my boat needing to be installed. My boat origionally had a mercruiser 165 hp 250cid so should go right in right? wrong the front mounting ear is not on the block for the front mount sooo my previous posts have pics and discussion on it. So yea im goint to fabricate a mount i think and go with it for this season comingand find a 292 for next season. this post was for the timing tab there;s an "A" that should be the "before" on the tab it just confused me so i was qurious why that would be thanks
 

starsnstripers

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Re: haha this is weird ? timing tab ?

dont know if its an old marine engine or auto or if its just an old truck motor? thanks again any info would be appreciated
 

JustJason

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Re: haha this is weird ? timing tab ?

if my memory serves me right "0" is 0 degrees TDC. "A" means advance. Every hash mark is 2 degrees.
 

starsnstripers

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Re: haha this is weird ? timing tab ?

I was thinking that, but why would the "A" be before TDC the way the engine rotates the "A" is before TDC ? just curious about it. The timing is to be set at 4* BTC and yes the marks are 2* per mark. Thanks Capt.
 

ziggy

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Re: haha this is weird ? timing tab ?

a pic of a 72 mercruiser 165 (250 cid) L6 timeing cover marks....
my 75 is exactly the same.... does this help?

IMG_2705.jpg
 

Don S

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Re: haha this is weird ? timing tab ?

I was thinking that, but why would the "A" be before TDC the way the engine rotates the "A" is before TDC ? just curious about it. The timing is to be set at 4* BTC and yes the marks are 2* per mark. Thanks Capt.

Why don't you post a picture of your timing marks like ziggy did, then we can see what you are seeing.
 

JustJason

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Re: haha this is weird ? timing tab ?

i don't believe you have the same as the pic ziggy posted.

biggame64 said:
I was thinking that, but why would the "A" be before TDC the way the engine rotates the "A" is before TDC ?

Because your ADVANCING the timing... its going to fire BEFORE TDC. I think your getting confused coz you think the "A" means "after" and not "advance"

If your going to set the timing to 4? then its going to be 2 hash marks before the "0". The mark on the balancer would be moving to the left of the "0" towards the "A". Then at full advance, It should be very close to the "A" mark. But make sure you count your lines because to much advance at WOT will smoke the motor.

Cheers!
 

ziggy

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Re: haha this is weird ? timing tab ?

i think capt jason has it right. my pic is not the same as yours.....

ya need a service manaul it seems. capt jasons idea can be confirmed in sevice manual #1...

"http://www-alt.mercurymarine.com/mnetdata/sisdata/srvcovr.pdf"
 

starsnstripers

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Re: haha this is weird ? timing tab ?

Thanks don, zig and you got it capt.J when i read the timing problem forum don answered on checking the timing advance on a recent post and When Capt. J said the "A" is for advance and it is on the BTC side of TDC it made sense. Thanks for the pic Zig yours is a marine engine most likely and i believe mine is a 1968 auto block. I looked in some old auto manuals and it showed my block same timing tab and missing front mounting tab for mercruiser block engine mount.:)
 

JustJason

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Re: haha this is weird ? timing tab ?

I think the whole A O thing confused alot of people.... and it's probably why they don't do it any more.
 

starsnstripers

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Re: haha this is weird ? timing tab ?

oh yaa ! it confused me an "A" before the "0" TDC had me scratching my head lol ! thanks Capt.
 

ziggy

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Re: haha this is weird ? timing tab ?

I looked in some old auto manuals and it showed my block same timing tab
there's a pic of your timeing mark tab in mercruiser service manual #1. page 1B-6.....
 
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starsnstripers

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Re: haha this is weird ? timing tab ?

Yep i see that, I guess they had that on the marine engines too. My block is still missing the mounting ear though. It's an auto block, oh well gonna try it thanks Zig.
 
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