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79 Head on a 72 Block ?

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PAUL161

PAUL161

Great Pumpkin
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I know there is a differance, but, will a 79 head replace a 72 head without many problems? Is the rear oil galley hole the same mating to the block? PJ /ubbthreads/images/graemlins/nopity.gif
 
A 79 head will work fine on a 72 block. You will have to block off the water choke outlet and use the later rocker arm assembly or at least the rear pedestal.

Alan T
 
Alan's advice is spot-on. make sure you pressure check any head for cracks, the late model cars are real bad to crack heads.
 
Thanks guys! That's all I wanted to know. PJ
 
I've got a question-- many years ago I put a Datsun "E16" or "J16" (don't remember which) on my '65 MGB and it fit perfectly and ran for a long time (until I sold it). Is this still a common practice? The story was back then that it was basically the same casting but far better steel.
Bill
 
The Datsun cylinder head was more of a copy of the MGA 1600 complete with the smaller valves. It was a direct fit but dropped the horsepower.

Alan T
 
[ QUOTE ]
Alan's advice is spot-on. make sure you pressure check any head for cracks, the late model cars are real bad to crack heads.

[/ QUOTE ]
Hap, are you saying that an early head fitted with hard seats would be a stronger head than a late model head? PJ
 
[ QUOTE ]
[ QUOTE ]
Alan's advice is spot-on. make sure you pressure check any head for cracks, the late model cars are real bad to crack heads.

[/ QUOTE ]
Hap, are you saying that an early head fitted with hard seats would be a stronger head than a late model head? PJ

[/ QUOTE ]

No, I'm just saying that finding a MGB head from the smog and converter years that is not cracked is becoming a real chore and I wouldn't dream of using a head from any MGB model year without pressure checking it for cracks first.
 
The higher combustion temps in the "later" heads tended to "point out" the weaknesses in the sand-casting head design... usually in the coolant passages around #3/#4 chambers. Pressure test indeed... and they're ~near~ impossible to repair, BTW.
 
Could this crack you speek of be the problem with my 75? It runs great on the driveway and will go to redline. When I get it on the road it has very little power and I cannot rev it past 3500 without it sputtering like poor fuel or timing. I stopped to do some adjusting the other day and while the engine was running it started pouring out white smoke. Once I cleared the engine of what ever was in it, by reving the engine it ran real nice, I even got it up to 4500 rpm with no problems. Then when I shifted to second I was back to the same problems, not being able to get it beyond 3500 rpm.
Steve
 
A possibility. Can you smell burnt coolant in the exhaust "cloud" when it happens? I have seen it occur as an "intermittant" since at low RPM the water pump isn't pushing coolant as fast, or system pressure/temp isn't up to "normal" yet due to short run time. But if it IS a cracked head it will only get worse. You can do a coolant system pressure test in lieu of a teardown to check.
 
Hap's right about the later smog heads - I take 6 to the machine shop & am lucky to get 2 that pass magnaflux & pressure test! I even had one repaired the other day...it magnafluxed with a small crack...we "pinned" it & pressure tested it to 40psi & it showed no leaks....but, you don't want to pay for a repair because its the same as a good, used head (plus magnaflux & pressure testing)!
 
So I guess I need to have my head checked?!? (lol) I do have another head I can send of to be checked, maybe I will. I also have another block I am thinking about building up, this might be a good excuse to build a nice little motor.
 
Jack "helped" me out the other day...he brought me an engine stand & said I needed a pretty engine on a stand in my garage...so, I've got to build an MGB engine just for display...thanks, Jack!
 
I have two engine stands, does anyone want to "help" me out with another engine for the second stand?? I do have a parts car with some decent metal on it.
 
Drive my way....
 
145 miles NW of you...in NE corner of AL....I've got lots & lots of parts!
 
TROLL!!! /ubbthreads/images/graemlins/devilgrin.gif
 
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