Diesel to petrol conversion - how much work

SantaHul

SantaHul

0
Hi all. Just wondering, how much work would it be to convert from Perkins 4108 to a Rootes 1725?

Engine and gearbox obviously. But how many ancillaries and are they readily available? I’d probably be getting somebody else to do the work but would source the components myself.

I’ve not bought anything yet, just feeling the ground.
 
Well hello there :)
I'm no expert on the oil burners but first off you will need an ignition system, coil, leads, dizzy etc and all the wiring which will probably include the ignition switch and starter button. Choke cable (not sure if the accelerator cable is the same) inlet and exhaust manifolds including the exhaust system and brackets so might as well go for an SU conversion straight off. Possibly engine mounts, fuel pump. The alternator may have a bigger pully on the diesel engine to account for lower revs.
I'm sure there's more and those who know better will hopefully ad their views. Ancillaries shouldn't be a problem (alternator, starter) as they are Lucas items used on plenty of cars in the period, you may be able to use your old ones (alternator brackets will be different though) but if not just make sure the starter teeth match the flywheel starter ring.
 
I guess I could try and get most of those bits with the engine though. I think the bit I’d be dreading is getting the damn thing out. I’ve also noticed the 1725 engines don’t seem to be as prevalent as they used to be.
 
Neil T said:
Why are you removing the diesel ??
Click to expand...
I'd ask the same question. A well sorted 4108 will give loads of smiles per mile, and about 35MPG. Mine's a diesel, and I'd never swap.

I have both types in my barn at present, so I'm able to compare...........

As to the differences I can think of, in no particular order.
  • Alternator on opposite side of engine, and opposite handed mounting. You can just about swap the hand of the mounting, but it's not that straightforward and pulleys may not line up. Diesel pulley will be SMALLER than petrol.
  • Fat wires in the harness are other side too, along with warning light wire.
  • Diesel starter is pre-engaged type. Not sure about petrol, but those I've seen aren't and will need starter solenoid.
  • Ignition switch and circuitry is different. Diesel has Thermostart wiring
  • Engine mounts are different type, but do fix to crossmember in the same holes.
  • Exhaust is different. You may be able to cut down a diesel down pipe to suit petrol.
  • You'll need wiring for ignition obviously.
  • Engine stop cable will be exchanged for choke cable, or may cut down for choke.
  • Fuel system on diesel is flow and return type. Petrol is flow only. Flexible hoses are different rubber.
  • Final throttle activator is lever on diesel, but Bowden cable on petrol.
  • Fairly obviously, coolant hoses are different.
  • Air intakes are on opposite sides, and different types. Petrol is paper type on left, diesel is oil bath on the right.
  • Oil pressure switch on different sides. Petrol on right, diesel on left.
As engine type conversions go, it wouldn't be the most difficult. My choice would be to sort the diesel. As it's an historic vehicle and LEZ exempt, the odd puff of diesel smoke won't matter too much, and diesels emit 40% less CO2 per mile. The difference in MPG shows up with much greater range for the diesel. Diesel is noisier:)
 
I'd be open to keeping the diesel if I liked it but I'd want the van to have a bit of speed. We'd be putting some miles on it, heading into Europe etc. I used to have a 1500 (I've actually been a member of this forum since 2008) and that was gutless so always dreamed of a 1725 that I could tune up a bit. Worst case scenario, maybe somebody on who really wants a diesel would be up for an engine swap.

For a bit of clarity, I'm going to view a van this weekend and it has a diesel engine so I'm considering my options.
 
In that case, and taking into consideration the costs involve with the swap, I would certainly hold out for a petrol van. Unless the diesel one is so good that it becomes financially viable - it would be a shame to convert it but I wouldn't slate anyone for doing what they want to their van, It's not the most radical swap we've seen after all.
 
Thanks Panky. I'll go and see it but that's kind of the way I'm leaning - will probably hold out for a petrol.

I'm also against modifying something that's original/rare but this one has already been butchered quite a lot.
 
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