Hi
I am currently having to change a blown head gasket/ doing a valve job on my 1950cc BGT.
Does anyone know why the engine block face has 3 brass blanking plugs between the cylinders ( on the distributor side) which prevent coolant flowing from the block up to that side of the cylinder head? As far as I can see from photos, most B engine blocks have these brass plugs inserted.
In fact my cylinder head only has the central one of these 3 holes and I was wondering if I drill out the central matching plug ( between cylinders 2 and 3 ) in the block this will improve coolant flow in the head and cooling.?
Since boring out to 1950cc the engine has suffered cooling and run on problems which it never had as a standard 1800 unit.
Any advice much appreciated!
Ken
Engine coolant blanking
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Ken johnson
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- Joined: Mon Jun 27, 2022 12:39 pm
- Forename: david
- Surname: Johnson
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Peter Cresswell
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- Forename: Pete
- Surname: Cresswell
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- Location: Stone, Staffordshire
Re: Engine coolant blanking
Hi Ken,
First off I would discuss your general engine problems with whoever supplied the engine. They may know why it is prone to overheating and running on.
Many engine preparation people don't recommend going to 1950cc as the bore walls become so thin from the machining, causing them to flex and leading to high oil consumption, overheating and head gasket failures. The factory only ever recommended going to a +040 overbore but this is mainly because early castings were very inconsistent. Later castings for the 5 bearing engines onwards were much better and up to +080 bores can be done with excellent reliability. Beyond this reliability suffers.
As far as the brass plugs go, if you have seen them on a lot of other cylinder blocks I would suggest you leave them. However No.4 cylinder is particularly prone to running hot on pre 18V engine blocks and a recommended mod is to increase the diameter rearmost waterway of the block and the head to 14mm so improving the coolant flow.
Hope this helps,
Pete
First off I would discuss your general engine problems with whoever supplied the engine. They may know why it is prone to overheating and running on.
Many engine preparation people don't recommend going to 1950cc as the bore walls become so thin from the machining, causing them to flex and leading to high oil consumption, overheating and head gasket failures. The factory only ever recommended going to a +040 overbore but this is mainly because early castings were very inconsistent. Later castings for the 5 bearing engines onwards were much better and up to +080 bores can be done with excellent reliability. Beyond this reliability suffers.
As far as the brass plugs go, if you have seen them on a lot of other cylinder blocks I would suggest you leave them. However No.4 cylinder is particularly prone to running hot on pre 18V engine blocks and a recommended mod is to increase the diameter rearmost waterway of the block and the head to 14mm so improving the coolant flow.
Hope this helps,
Pete
Pete
1969 MGB Roadster
2020 MG HS Exclusive
2007 Mercedes SLK
Plus 34 other cars since 1965
1969 MGB Roadster
2020 MG HS Exclusive
2007 Mercedes SLK
Plus 34 other cars since 1965
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Ken johnson
- Posts: 2
- Joined: Mon Jun 27, 2022 12:39 pm
- Forename: david
- Surname: Johnson
- MGCC Member: Yes
Re: Engine coolant blanking
Hi Pete
Many thanks for your very helpful and interesting reply-I was not aware of the possible overheating issues from boring out an 1800 to 1950 on my 74 BGT .
I have also been told that the blanking plugs in the block were a factory modification in an effort to improve the coolant flow to the rear of the head as on early engines cylinders 3/4 used to get hot-which ties in with your advice-so I have left the plugs alone. The head has been skimmed and stage 2 ported and I have treated it to a new copper head gasket.
Since rebuilding the engine to 1950 about 17,000 miles ago I have tried various tricks to assist the cooling including fitting a kenlow, wrapping the exhaust, fitting an alloy rad and using Evans pricey classic coolant in the system but none of these had much effect. I found the best improvement was from installing a 7 blade plastic fan alongside the kenlow which now keeps the temp gauge steady .
Thanks again
Ken
( Note you live in lovely Stone ,I am from North Staffs but now live in Somerset)
Many thanks for your very helpful and interesting reply-I was not aware of the possible overheating issues from boring out an 1800 to 1950 on my 74 BGT .
I have also been told that the blanking plugs in the block were a factory modification in an effort to improve the coolant flow to the rear of the head as on early engines cylinders 3/4 used to get hot-which ties in with your advice-so I have left the plugs alone. The head has been skimmed and stage 2 ported and I have treated it to a new copper head gasket.
Since rebuilding the engine to 1950 about 17,000 miles ago I have tried various tricks to assist the cooling including fitting a kenlow, wrapping the exhaust, fitting an alloy rad and using Evans pricey classic coolant in the system but none of these had much effect. I found the best improvement was from installing a 7 blade plastic fan alongside the kenlow which now keeps the temp gauge steady .
Thanks again
Ken
( Note you live in lovely Stone ,I am from North Staffs but now live in Somerset)