Leaded head

[James covey]

My 67 roadster has its original cylinder head still on it, although rebuilt about 20years ago. The head has got a hairline crack which has been liquid metal sealed.
Due to my lack of use the car hadn't been run for 12 -18 months and when I finally got it started and warmed up a valve stuck and bent a push rod.
Option 1
I could have the rod replaced, presumably quite a cheap fix?
Option 2
Replace cylinder head with new unleaded and push rods £7-800?
Option 3
Is it possible to keep original head but repair hairline crack and with new unleaded valve guides and push rods? £?

Maybe I'm being sentimental but If possible id like to keep as much original to the car as possible.

[Peter Cresswell]

Hi James
Welcome to the forum, and you have a very nice MGB judging by the picture in your other post. Not without a problem though, which unfortunately is fairly common. To take your options one at a time:
Option 1 - yes replacing a pushrod is fairly cheap: they are around £3 each depending on who you buy them from. Make sure you get the correct length push rod as there are two types and they must be used with the correct cam follower. These are interchangeable (the follower + the push rod) so could have been swapped in the past during an engine rebuild if the cam followers were worn, or a new cam fitted. Don't rely on the age of the car for this! Measure one and ask for one of that length.

Option 2 - A replacement cylinder head which has been converted to unleaded starts at around £200 plus a surcharge as your head will be scrap. This is for a used head that has been converted and you need to someone who specialises in B series engines and will have the head on the shelf. Two places come to mind - Peter Burgess in Alfreton near Derby (01773 520021) or Mechspec near Doncaster (01777 818283). I bought a head from Mechspec via ebay so they do have secondhand heads off the shelf. For their full engine rebuilds though Mechspec use Peter Burgess heads. Be wary of any 'big valve' heads as fitted to MGBs in the early 1970s and the Austin 1800S. The block needs to be modified to allow the exhaust valve to open.

Option 3
Try Slinden Services, Measham for repairing your existing head (see http://www.castironweldingrepairs.co.uk/). Getting successful repairs to a cylinder head is difficult and expensive as the process requires the head to be slowly heated for 3 days to a high temperature, then the welding done and followed by the head being allowed to cool for 2 days. Expect to pay about £250 for the repair alone, but the work is then guaranteed for 12 months. They can also fit unleaded seats at the same time. I had a Cooper S head repaired by them, but it is a process best left to very rare castings.
Personally with the MGB I would find another head which has the same casting number to preserve the originality (assuming it still has the head it came out of the factory with!). This web site (http://www.flowspeed.com/cylinder-ident.htm) tells you how to identify the cylinder heads by the casting numbers and the difference between them. The head doesn't carry a number unique to the car, but different heads were fitted at different periods of the MGB production. Note that all the new heads I have seen advertised are based on the late MGB/Marina TC castings, which have the strengthening lugs on the spark plug side, which were also used to fit the anti-pollution kit required by California.

All in all I think your best course of action is to get another head from a reputable engine builder, get them to convert it to unleaded and replace the bent push rod. This should cost around £350 - £400 with a new set of standard valves if you can fit it yourself.

[James covey]

Wow Pete, that's o proper reply to my situation.
The last work I had done on the car was by brown and Gammons, who did a great job on getting the car to the standard I wanted. There listing exchange heads for £495 inc vat plus fitting
If repairing the existing head is such a pain I'll probably go with a replacement head, then at least I don't need any fuel additive

[Peter Cresswell]

Take a look here for an alternative price!
http://www.peter-burgess.com/page12.html
but check you are getting an assembled head with valves and valve springs because I think that is what B&G offer. Peter burgess price is +vat and B&G include vat on their website. In both cases carriage is extra if needed

[Peter Cresswell]

I've just taken a look at the B&G website, and they list 2 heads for the MGB, part numbers 12H2708LF and 12H4736CRLF. The first one is based on a new casting and MAY have the large valves and the need the cutouts in the block, so check with them if you decide to go with B&G. The second one is reconditioned and is based on a late head, which I think will have the offset oil hole for the rear rocker post. The head you have should have the in-line oil hole, as will the 12H2708 head. To use the 12H4736 head you need to change the rear rocker post (and possibly all 3 of them). Talk it over with B&G - they know what they are doing!