When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The 3.4 tube that goes from the block to the oil pump has a 2 bolt mount at the block. All of the tubes I've found are 3 bolt mounts.
Sorry, I was thinking of the pickup tube from the sump to the pump. The pipe from the pump to the block has a different flange on the block end as you say. The pump to block might be available from one of the usual suppliers. Otherwise, it's a case of making one using the flange from the 3.4.
I purchased both oil feed tubes today. The pump to the block feed line has a 2 bolt mount, most I found were a 3 bolt mount. Were there problems with the 2 bolt style mounts?
The engine is a 3.4 with a steel oil pan. The rear main seal assembly the "Cover", has an upper and lower where a rope seal would be installed. The two piece Cover on my engine does not have a channel for the rope seal (highlighted in red). The surface is totally smooth, what type of crank seal does the Cover use? The crank does have a scroll, is that the only seal for the rear main? Is the smooth style Cover like mine for the scroll type of crank?
I believe you have an early engine that didn't have a rear seal. I've never actually seen one in person before. You should be able to move over the 4,2 seal housing I think.
I believe you have an early engine that didn't have a rear seal. I've never actually seen one in person before. You should be able to move over the 4,2 seal housing I think.
Does the older design tend to leak a lot?
When did they change to the rope style?
I found some post on switching over and it's supposed to require machining the crankshaft.
I think the older style would leak if you parked on a hill. To be honest, the rope seal also leaks, so I expect the early one really leaked. However, I have no experience with them. As best I can tell, the seal was introduced with the Mark 2, so approximately 1960.
The talk of machining the crank is when people convert to a later one piece seal. The end of the crankshaft is too large to get a one piece over the flywheel mounting flange. The 4.2 style seal is a 2 piece rope seal, as long as the housing halves are the same bolt pattern it should bolt to the block.
I think the older style would leak if you parked on a hill. To be honest, the rope seal also leaks, so I expect the early one really leaked. However, I have no experience with them. As best I can tell, the seal was introduced with the Mark 2, so approximately 1960.
The talk of machining the crank is when people convert to a later one piece seal. The end of the crankshaft is too large to get a one piece over the flywheel mounting flange. The 4.2 style seal is a 2 piece rope seal, as long as the housing halves are the same bolt pattern it should bolt to the block.
The scroll is part of the crankshaft, it must be machined off to fit the seal diameter.
This is the crankshaft I have. There's a main bearing and the scroll, no surface area available for a rope seal without machining the scroll down to the diameter needed for a seal. The scroll is where the 2 piece cover is positioned.
It's not easy to judge from the photo, but I think yours is the early crank with the deep scroll that works without a seal. My opinion is that it's a satisfactory design. It will drip some oil especially if the car is parked with the nose high. What runs out is mainly oil that drains down the crankcase wall and is unlikely to have a major impact on oil consumption. If oil drips onto driveways worries you, add a catcher on the outside of the sump. Make the sides of the catcher low enough to empty the catcher in fast cornering.
Later crankshafts with the rope seal still have a scroll, but it looks more like a shallow groove. There are some upgrades to modern type seals. With these the crank is machined down to match a standard seal size. A load of hassle for a five bob seal.
As with many things, improvements and upgrades may claim some gains, but for most purposes the original is simple, efficient, and trouble free.
I generally agree with everything that Peter says. Much would be dependent on amount of use the vehicle gets.
My only concern is that our classics should not be polluting our roads & parking areas with oil. I fully accept that this engine is being fitted to a purpose made vehicle.
That is a very old scroll design. My Rope sealed rear crank has a very gentle scroll on it. It does not leak. It was fitted to the book with the correct Churchill tools & no trimming which is an absolute no-no.
Last edited by Glyn M Ruck; Apr 6, 2024 at 10:48 AM.
Purely from what I've read, the 1950s 3.4 engines with the simple scroll had similar oil consumption to those from the 1960s with a rope seal. As the consumption isn't low in either case and 'normal' is extremely variable from a half to one and a half litres per 1,000 miles it's hard to be precise about how much passes the rear crank seals. Still, it's difficult to imagine that it's much more than 100 ml per 1,000 miles. Now we have to decide if that's a tolerable amount to spill on tarmac or if we want to collect it. If we use a catcher below the old scroll seal, the oil could be collected in a small tank and emptied at the usual service intervals. I've heard of arrangements that drain the catcher back into the sump, but there are various arguments against that. A third possibility is to try to suck/pump the liquid up into the inlet manifold and burn it.
I sort of agree with Fraser, but, if the scroll and housing aren't worn and the scroll groove is clean, then scroll seals can work very well for a very long time. With clean oil and the right clearance, they work forever and the leakage can be minimal.
My 3.4 has an HD6 set of carbs with a Choke Operating Solenoid. There is a tube called a "Starting Pipe" that I found in a parts diagram. Where is this Starting Tube located? What is it's purpose?
