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  #16  
Old 12-22-2006, 08:36 PM
t walgamuth's Avatar
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unless you can verify the cams are the same, i would use the cam that came on your engine with the towers that you get. there may be a way to measure the towers to be sure they arent too worn as well.

if you can tell us the engine type and year i can look in my old reference books to see about the compression.

tom w

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..I also have a 427 Cobra replica with an aluminum chassis.
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  #17  
Old 12-22-2006, 09:56 PM
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It's a 1972 M130 engine (manufacture date 7/71) - engine number 130.923-12-012837.

ryan
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1984 300D
1972 250
1986 560SL
1991 300CE
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  #18  
Old 12-22-2006, 10:53 PM
t walgamuth's Avatar
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and the new head is from?

tom w
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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  #19  
Old 12-22-2006, 11:04 PM
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ok, i looked at my books. my old chiltons ends with 1971. in 71 it shows two 130 engines, one with 9 to one comp. the other with 9.5. in my Motor starting in 72 it shows only one 130 motor with an 8.7 to one compression ratio.

i was alive and kicking back then. iirc 71 may have had no emission requirements at all, so everything would have been based on optimal performance and economy. so perhaps in 72 the dreaded emission controls may have begun with the response of lowering compression and perhaps fiddling with the ignition timing and so forth.

from your description i suspect you have the older head, perhaps the 9.5 compression one. i dont know how they changed the compression ratio but i would have thought that the two different ones offered in 71 would have been accomplished with different shapes on the top of the pistons. one flat, one domed or dished.

the head with the bigger combustion chamber is no doubt the lower compression one possibly prompted by emission requirements.

so if you use the new higher compression head, you will need premium probably and may have to run less ignition advance since modern fuels have no lead and will have much less knock resisitance than what was still available in 1971.

others with more specific model knowledge will kick in here and fill in the blanks i suspect.

i have a head in my garage off a 66 230 iirc but i have no idea what all it might work on.

good luck

tom w
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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  #20  
Old 12-23-2006, 12:14 AM
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Emission systems - in various forms - date back to at least 1970 (according to my supplemental 1972 manual - which I have been reading through). That manual lists 2 engines for the 250/8 - one with "normal compression" at a 9:1 compression ratio, and one with "low compression" at a 7.7:1 compression ratio.

The 'new' head, at least according to the seller, came off a 1971 250C (although it has 280 S/A stamped on it instead of 250A, which is what is stamped on mine).

I am assuming that my current compression ratio is the 7.7:1 and that the new head will result in a 9:1 compression ratio. Again, I talked about this with Mike at Metric Motors and he assured me the heads would be interchangeable. I didn't ask him about the changes, or the effect this increased compression ratio might have on the lower part of my engine?? I'm still not sure I don't have any problems with the pistons or rings, and until I pull the head I don't know about the shape of the pistons.

Ryan

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1984 300D
1972 250
1986 560SL
1991 300CE
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  #21  
Old 12-23-2006, 02:12 AM
t walgamuth's Avatar
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i wouldnt worry a bit about them. if they are sound you should experience no problems. the higher comp ratio may require either a retarded spark timing to avoid pinging or premium gas.

in this case then i would recommend using the cam that came with the head if it is in good condition. it could be slightly different to take advantage of the higher comp. ratio.

sounds like you are on the right track.

i would have the head pressure tested before using. a valve job is not a bad idea either.

tom w
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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  #22  
Old 12-23-2006, 11:11 AM
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emissions gear starts showing up in '68 actually. -cth
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  #23  
Old 12-23-2006, 01:58 PM
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Just checked the compression - cylinder 1 reads over 220 psi and cylinder 2 is a little low at 130 psi - all of the other cylinders are in the 140-150 psi range. I also noticed that when I pulled spark plug two, after letting the car run and warm up before the compression test - smoke rolled out of that spark plug hole???

Spark plug #2 hole wet test raised compression about 20-30 psi.

Any thoughts?

Ryan
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1986 560SL
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  #24  
Old 12-23-2006, 07:44 PM
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220 p.s.i. is waaayyyyyy too high for that engine! Pull all the plugs at the same time and double-check those readings. 130 p.s.i. is a little weak but not too bad. I cant imagine 220 p.s.i. on a worn engine. The only way you should get compression readings that high would be standing liquid in the compression area.
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  #25  
Old 12-23-2006, 09:01 PM
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That's what I thought - so I checked it 4 times and the readings were the same - with all of the plugs pulled. (BTW, plugs 3-6 are black and carbon fouled, #2 was a little brown and #1 was wet, dirty and oily looking). I have determined that the intake manifold is leaking right here - by the number 1 and 2 cylinders. I guess I could have fuel in the chamber???

I really don't know what is going on now.

I did a leakdown test and all cylinders showed a 30% - 60% leakage, except for cylinder 4 which was even higher at 70%. All of these numbers were in the yellow, moderate range on my leakdown tester. Using a hose to isolate leaks, all leaked at the dipstick tube - which is expected, but I also picked up on leakage between cylinders, especially when pressurizing cylinder 5 I could hear what sounded like the ocean in cylinder 4!

No leakage noted through the carbs, exhaust pipe, and no bubbles in the coolant.

I should note that I did this test with the engine COLD - I should have done it at operating temperature, so I'm not sure what difference that makes.

I have no idea about what kind of results I should expect here - the engine is 35 years old, but I have not noticed any problems with power. It still runs well at highway speeds, or at least it did prior to this excessive smoking problem.

Ryan
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1984 300D
1972 250
1986 560SL
1991 300CE
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  #26  
Old 12-24-2006, 01:36 PM
t walgamuth's Avatar
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the high reading also could be from carbon buildup.

this was common on carburated engines. with modern engines such problems are quite rare.

in reading back, i realize you never told us why you got the 'new' head to begin with. what problems are you chasing?

tom w
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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  #27  
Old 12-24-2006, 04:52 PM
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Tom,

Specifics are indicated in the thread below:

Clouds of white smoke (I mean clouds!)

Sorry about crosslisting things here : this thread was just supposed to be about my head and cam tower question...

Happy Holidays,
Ryan
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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE
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  #28  
Old 12-24-2006, 08:17 PM
t walgamuth's Avatar
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oh, ok.

i will read thru it all again later when i have more time.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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