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MG MGB Technical - Head Case

I'm rebuilding my GF motor from my 70 B. I took it to the machine shop to have it evaluated today. .030 needed for the cyclinder bores and .010 needed for the crank. OK, now the bad news, the when magnafluxed the head revealed three cracks! Bummer!

I'm considering the following.

1. Buy a Peter Burgess Fast Road head. Estimate $610 US, +Shipping+ Customs. Does anyone know the cost to ship one to the US?

2. Aluminum head, either from Moss or Brown & Gammons. Estimated Cost $800.

3. Find a used head and rebuild at my machine shop. Cost? $350-$500

What do you suggest?
J Moore

J,

From my experience it can be tempting but a false economy to have your own head rebuilt. The cost of parts and work to do a proper job can push the cost up beyond what you might estimate (valves, seats, springs, guides, extra machining...) and most machine shops offer NO warrantee against future cracks. It is not uncommon for a head that tested with no-cracks to develop a crack or two after install but since it was your casting you are on your own and SOL.

Many "retail" heads offer at least a short warrantee period where they will replace a defective head (the longer the better) and you can be certain upfront of the total cost.


Cliff
Cliff Maddox

J,

I recently bought a good used head complete and ready to bolt on from Glenn Towery in Cheswold, Delaware. It was a little past the high side of your used estimate but it was for a very early car with no emmision controls (rare) so it went for a premium. I believe Glenn keeps an inventory of later heads. 302-734-1243

Paul
Paul Hanley

John. As I remember it, the shipping was about $100 when Peter shipped to me earlier this year. Customs was relatively small, about $20. The head Peter will be building for me next will be one he is supplying. My cost to ship the last head over was just under $200 for air shipment.

By the way, the GF engine was not correct for your car. The GF was used in 68. Yours should have been an 18GK engine. On my 68, which currently has an 18GF engine, I am going to be building up an early 18V engine using a Piper 270 cam and Peter's Fast Road head. The quality of the Econo Tune head he did for my daughter's car is outstanding. Almost a shame to put it on the block. It looks more like a work of art than a part of a machine. I recommend his work most highly. Les
Les Bengtson

Oh, so the prices Peter Burgess' list on his site are to rebuild and existing head? So I would have to find an uncraked head to send him? If that's the case, Alloy sounds better.

I can't say the engine is original. It had a GF tag. The head was eariler too, it didn't have air holes.
J Moore

Peter can sell you a new casting as well, so no need to search for an uncracked head. Cast iron holds heat better than alloy, so the CR must be bumped up to get equivalent power. Shoot Peter an Email and he can quote you current prices.
Paul K

John. Yes, the prices quoted by Peter are for the basic work to a cylinder head. Either you must supply a cylinder head or have him provide one at additional cost. Peter modifies cylinder heads for a number of different applications. While his "Fast Road" is commonly used by people who desire the maximum in "streetable performance", the people who have used his less expensive "Econo Tune" heads have raved about how well they work on relatively stock engines. Unless you are planning major performance upgrades, that is what I would recommend. Les
Les Bengtson

Les, I desire a reliable street engine with good HP. In addition to the bottom end rebuild, I was planning to add a Piper 270 cam and upgrading the ignition. I already have Peco exhaust on a stock header, my SU's are in good shape but I plan on adding K&N Filters. So, I feel a good head will pull it all together. I have an e-mail into Peter, but I have not heard back. If you do not mind me askeing, how much did Peter charge base head?
J Moore

John,

Being only 200 miles from Peter Burgess, I took my head to him for modification. Five minutes inspection by his expert Sean and there was the crack right across my head too. He supplied the replacement for an extra £50 I seem to remember (a few years ago now). There was a huge pile of discarded B-series heads in the corner. So yes, he can supply the replacement.

Mike
Mike Howlett

Thanks Mike, I'm still waiting to hear back from Peter about the cost. Which mod did you you get? Fast Road, Econotune, etc? Where you happy with the results?
J Moore

Hi J Moore
The engine that was originally in your car was a GH as used in 1969 and 1970. The GK was used in 1971. 18GV in 1972 and on. This is from Moss production data page in an old parts book. I had a 69 GH in my 1973 MGB - .I0 under crank and .40 over pistons. When I had the head cleaned up and the valves redone, there were a couple of small cracks that they welded for me. No problems - after 12-13 years. I would guess it all depends where the cracks are and how large/severe they are. I had the seats and guides redone 2 years ago and everything was OK at that point. I was running SU's / hotter cam / electronic ignition. I say was because I am in the process of converting to a Fuel injected V6 5 speed combination. FWIW Alan
Alan

My three cracks were as follows:

1. #3 Exhaust seat
2. #3 Valve Guide
3. Head stud hole.

From what I understand the valve guide and head stud cracks are all but fatal.

Are there any big differences in my GF and the later GH versions... I know I have the older "offset" rods. Which may be less desirable because they are heavier and use a circlip on the piston.
J Moore

Although cast iron heads are tough and take abuse they do tend to crack and not just in MGBs. My Datsun Roadster cast iron head had a hairline crack and started to overheat because of that and from what I was told cast iron isn't the easiest material to weld 'correctly.' Datsun also made aluminum heads for a majority of the Roadsters and I never had a problem running one. Of course if your engine overheats it can warp the head and I have seen, and owned, several aluminum heads from late 60s that were severely corroded from the crummy anti-freeze available back in the late 60s and 70s and of course indifferent POs who didn't change the A/F. Aluminum is also much lighter and it has better cooling qualities. It is also much easier to port and polish. I like aluminum heads :)
Mike MaGee

I agree with Mike. I like the aluminum head better as well, but you almost have to port it before its installed since the castings are not very good. But then again neither were the factory castings. I'm running 10:1 compression with mine, along with a Crane cam - the same power ballpark you'll be in with the piper 270. It is a huge improvement over stock, and if you shop around you'll find the head under $800 complete. Make sure you put in better valve springs though. The new springs that came on the head were of varying spring rates.

Jeff Schlemmer

This thread was discussed between 30/10/2003 and 31/10/2003

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