Early Engine Build - Printable Version

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Early Engine Build - RupertW - 23-10-2020

Hello all, 

I have a 1924 based Boulogne replica, currently running on standard engine internals. I'd like to run a more robust engine as I'm currently constantly worrying it'll do something terminal when being used in anger and write off the entire engine. 

My intention is to keep the current engine as a good spare and to build up a 'new' engine from scratch. I'm not looking for a full blown race engine, but more something along the lines of a fast road specification, and externally at least I'd like to keep the engine looking correct for its year. I already have all the 'bolt-on' bits fitted (Carb, inlet/exhaust manifold, wedge head).  

I have an early crankcase spare, albeit with some damage as per the pictures below, so my first question is views on how viable it would be to repair this crankcase?


The next key question is whether or not it is possible to fit a larger/later crank to an early crankcase (I have a splash fed phoenix in mind)? Would this require further machining to the crankcase? 

I'm also unsure about options for the block. I have a couple of spares kicking around, but they have the usual central stud cracking issue.
Are there any views on block sleeving, and does this exacerbate the central stud issue by reducing the surrounding material? 

Realistically I'll be looking to have at least the bottom end put together by someone who knows what they're doing, so any recommendations for engine builders welcome.

Apologies I know there's a lot of questions in there and some are probably quite basic!

RE: Early Engine Build - Chris KC - 23-10-2020

I'm sure that's repairable Rupert, it's more a question of whether it's cost effective to repair - it might serve you better simply to find another case. 1924 though might be a bit of a challenge. If repairing don't muck about, take it to someone who knows what they are doing and take steps to ensure correct geometry is maintained / recovered.

For fast road use a sleeved block is fine, I've had one in my Ulster for decades. The central cracks if anything are better with a sleeved bore as no risk they are going to extend into the bore; so long as the block survives lining in the first place. By all accounts many people are running with cracks around the centre stud with no great issues.

RE: Early Engine Build - Ray White - 23-10-2020

As you say a lot of questions. There are even more answers depending who replies. The crank case can be welded but I would want to know how the damage was caused as it may be just the tip of the iceberg. If it were me I would not start from there. I would source a good engine as a starting point.

Just my four penneth.


RE: Early Engine Build - mk1-mark - 23-10-2020

I have welded & re machined a lot of alloy engine parts & as has been said, that damage "could" be repaired. However, the amount of time & effort involved would almost certainly make it totally uneconomic to do so.

RE: Early Engine Build - Steve Jones - 23-10-2020

All depends how much you want to use that, particular, crankcase. Best plan would be to find a better one that was appropriate but if that's not possible or you have a particular affinity with the one you have suggest you get any repairs done by laser welding. Not cheap but no real possibility of distortion. I saw a cast aluminium sump that had been repaired by laser welding last week and it was an amazing job. £250 for the welding but significantly less than a new AC Weller engine sump.


RE: Early Engine Build - RupertW - 23-10-2020

As far as I can recall the number of the crankcase is four figure - 6XXX so presumably quite early which I think was the rationale for obtaining it in the first place. I'm certainly not set on using it if I can find another earlyish crankcase in reasonable condition.
To my untrained eye, I would guess that the damage is from it being dropped/having something dropped on it while out the car, rather than as a result of an engine failure, but I may well be wrong.

RE: Early Engine Build - mk1-mark - 23-10-2020

The biggest issue with that particular repair is that the face needs to be machine flat. If something has been dropped on it, and I agree, it does look like it has. The face will almost certainly not be anywhere near flat now. To build that up & re machine would be very expensive indeed.

I agree with Steve, Laser welding is a brilliant technique, but I fear that the actual welding isn't the most difficult part of that particular job.

RE: Early Engine Build - Chris Garner - 23-10-2020

+1 from me for Steve and Mark1-Mark's comments.

RE: Early Engine Build - Parazine - 25-10-2020

(23-10-2020, 09:39 AM)RupertW Wrote: The next key question is whether or not it is possible to fit a larger/later crank to an early crankcase (I have a splash fed phoenix in mind)? Would this require further machining to the crankcase? 

I covered fitting a splash feed 1 5/16" Phoenix to an early(ish) mag crankcase on page 10 of my "Restoring a Top Hat" thread. You'll need to do a bit of relieving....

RE: Early Engine Build - RupertW - 25-10-2020

Thank you for pointing me towards your thread - it confirms that it's rather more involved than I'd be willing to try and take on myself! If I were keeping things standard I'd be more inclined to give it a go, but I don't want to risk getting it wrong and ruining some brand new and expensive components, so any pointers towards engine builders would be appreciated!
There also seems to be a definite consensus on the crankcase, so I'll keep my eye out for a better one.