Cylinder Head compatibility [1979]

[beebopbogo]

I have owned my 1979 MGB for almost 10 years now, and my cylinder head finally cracked, irrepairably, in 2 places. Obviously I need a replacement. The problem is finding one that isn't cracked. Evidently, the 1975-1979 range of 'B cylinder heads have a tendancy to crack. So here's my question:

Is it possible to replace my 1979 cylinder head with a pre-1975 head? I know the pre-75 ones have no water port for the heater, but I took my heater out. My emmissions crap has also been removed (legal in Oregon). Are there any other things to worry about?

Thanks in advance,

--Beebop

 

[Guest]

Sure, any 18V head will do. Just be sure you get the right rocker pillar to match the head. Later ones use an offset oil feed opening. Get them wrong and your rockers will get no oil

 

[beebopbogo]

Cool! So since every MGB built from 1972 has an 18V engine, I could replace my cylinder head from any of those? But about the rocker/oil thing: what exactly is the "rocker pillar"? Is that the same as the "rocker bracket" as described in the Moss Motors catalogue? I still have my rocker assembly from the cracked head. Are you saying I should be careful about getting an older head because my rocker assembly wouldn't fit?

Let me describe my situation more completely:
1) My cylinder head cracked, so I removed it from the car. All parts are fine except the head and a couple of the valves.
2) I found a new cylinder head on eBay which I am considering bidding on. It's casting number is 12H2387 (see https://cgi.ebay.com/ebaymotors/ws/eBayIS...TRK%3AMEWA%3AIT for more details) and is advertised as a 1968-1974 head.
3) Is it possible to replace my head with this ebay head?

Ah, I think I see what the previous post was referring to. The bottom of one of the rocker brackets has a hole in it. You're saying that hole is aligned differently between the 1968-1974 heads and the 1975-1980 heads? Which means if I did buy the ebay head, I would have to find a rocker assembly somewhere to match it. Ugh, this is getting expensive.

Anyway, thanks for the help and if anyone wants to verify my ramblings, I would appreciate it.

--Beebop

 

[Guest]

I'd be leary of that head. Notice he says 1968-1974. The 18V engines started in 72, and the earlier heads used a larger combustion chamber snd would lower your compression ratio. Need to check the number to see what he really has. 12H2389 is a pre 18V (from 1968 thru 1971) head and not the head you want. His number may be a typo for this heat. And you are correct about the rocker pedistal oil hole. Get an earlier than 75 head and you have to use the matching rear rocker pedistal

 

[Guest]

his head would be a candidate because it has the rockers with it and it uses the same combustion chamber size.
https://cgi.ebay.com/ebaymotors/ws/eBayIS...;category=34202

 

[beebopbogo]

That's when I get leary. I don't want to pay $40 for shipping and handling for a cracked head. I already did that once, and after talking with a bunch of people it seems around 90% of these later MGB heads are cracked. I'd rather spend $500 on a head I know to be in good shape than fork over hundreds of dollars for cracked head after cracked head. Too bad the guy with the compatible head won't magnaflux it first...

 

[beebopbogo]

Alright, alright... I've talked myself into taking the risk and getting the cheaper, untested cylinder head on ebay. https://cgi.ebay.com/ebaymotors/ws/eBayIS...;category=34202 Anyone know how much a rebuild would cost (roughly)?

 

[beebopbogo]

Update: I bought the cylinder head from ebay for $109, had it checked for $30 (no cracks), then had it remanufatured for $275. The result is a beautiful sight ~sigh~ /ubbthreads/images/graemlins/rolleyes.gif It's bright blue, perfect and shiny, new hardened seats, and ready to plop into my 'B. All for a grand total of $414. Seems like a good deal.

Anyway, I was wondering if anyone has any tips as to refitting the cylinder head. Is there anything I should be aware of? My Haynes manual says to refit the pushrods in their original positions, but I never marked them before removing. Does it really matter all that much?

--Beebop

 

[Simon TR4a]

Since you have mixed up the pushrods now there is not much you can do about it, but do get a pane of glass and roll each pushrod to make sure it is straight (as you wouls a pool cue) before putting it back in. (If the engine has been over revved or the valve clearances set very tight by mistake the pushrods may not be straight.)
Simon.

 

[Bruce74B]

[ QUOTE ]
Update: I bought the cylinder head from ebay for $109, had it checked for $30 (no cracks), then had it remanufatured for $275. The result is a beautiful sight ~sigh~ /ubbthreads/images/graemlins/rolleyes.gif It's bright blue, perfect and shiny, new hardened seats, and ready to plop into my 'B. All for a grand total of $414. Seems like a good deal.

Anyway, I was wondering if anyone has any tips as to refitting the cylinder head. Is there anything I should be aware of? My Haynes manual says to refit the pushrods in their original positions, but I never marked them before removing. Does it really matter all that much?

--Beebop

[/ QUOTE ]

It seems to me that since you are putting them into a different head, the order should not matter. Just take your time adjusting them and you will be OK.

Sounds like a good deal to me too /ubbthreads/images/graemlins/iagree.gif

Bruce /ubbthreads/images/graemlins/cheers.gif