Building a hot vintage engine with Jonny69

[Jonny69]

About a month ago the engine in my old Pop expired. It was kind of expected because it had stood for about 15-20 years before I had it and I just put some petrol in it, cranked it over and it ran. Well it was getting slowly worse, lots of noise from the top end and it was weeping a bit of water. Then I took it on a long run on the motorway and the obviously very perished rear seal gave up and I was losing oil out the back.

The decision was taken to convert it to a later lump, out of a car called a 100E because it's a fairly easy swap onto the original gearbox and it's free extra horsepower for the same displacement, 1172cc. Plus I had one that was overbored, cammed, flowed and breathed on and it was going to liven the car up quite a lot. Given a bit of time I realised I really haven't got enough time to do it when my Anglia needs some time so a quick change of plan and I decided to work the original lump. It would all need a rebuild anyway so it's not much more to slip in a cam, do a bit of flow work and get the head ground down for some more compression.

So I'll be needing some vintage speed equipment. Aquaplane inlet manifold, check:



Aquaplane exhaust manifold, check:



Twin carbs, check:



A trolley full of junk parts, check:



And now I need to do much head scratching because everybody who knows anything about these engines is now dead so I'm pretty much on my own!

Saturday afternoon me and a mate hoiked the old engine out the car. Literally took the radiator out, took the grill shell off the front of the car and lugged it out with a tow rope and a chunky luggage strap. This is the offending item:



I have a spare engine I picked up for £30 that I'm using as a test bed. I was hoping it might be a runner but it has had water in it and the valve guides are shot but it's a good block to experiment on:



That's half a shopping trolley it's sat in, they make great engine trolleys. Please note: Sainsburys charge £1 for their trolleys but they are free at Waitrose. I stole mine from Sainsburys because I feel by not charging me Waitrose has trusted me not to steal their trolleys. I will honour that trust. Sainsburys on the other hand has made me feel like a petty theif so I honoured that too and nicked their trolley. And very nice it is too.

Here's my hot 100E engine. Head off and I'm going to be taking the cam out as it's the same fit for both engines. This one is a re-ground high lift item. Note how the valves are next to the bores, it's called a sidevalve engine and most vintage engines are this design:



First on the priorities is to increase the compression. These old engines have super low compression so they can run on ultra low grade petrol. The Pop engine is 6:1 and the later 100E engine is 7:1, both are too low really and it can be increased by machining the head down. With the extra lift of the cam I need to be sure that the valve isn't going to come into contact with the head if I start machining the face, because it's going to decrease the height of the chamber:



I've measured it in the 100E block and it comes to 9.5mm, direct lift from the cam so it will be the same in the other engine. Next because the inside of the chamber is rounded at the top I need to know I have enough clearance at the sides of the valves when they are open: