504 conflict, opinions sought

Trent172

Trent172

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Fellow Frogger
Tadpole
Tadpole
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So my 1970 504 has a non original 2 litre engine in it with a bent inlet valve. It will also require a new water pump, clutch and carby. Do I fix this engine and continue as a 2 litre car or change it back to an 1800 which I may be able to obtain? I’ve been told it’s quite a rare car so I’m thinking originality might be the way to go but I’m a little concerned about the loss of performance going back to the 1800.
Any thoughts?
 
The performance difference between an 1800 and a 2L is noticeable so I would stick with the 2L. If you can do the work yourself the cost of a new valve (and new had gasket and water pump, etc) may not be that much. In the old days, a swap to a 2L engine was a common enough thing, for the extra performance.

I don't think anyone wanting to buy a 504 would be deterred by one with a 2L rather than the original 1800. 2L is a worthwhile improvement.
 
Don’t quote me on it I’m pretty sure Bob Nelson put a 1800 head with a 2litre bottom end back in the day, So maybe you can 1800 bottom end 2litre head. Least numbers match then! If that’s what you want. I’d compare head gaskets!
The
Doesn’t really matter these days matching numbers, unless it’s something they didn’t make a lot of. Example genuine ford XY GTHO or Monaro. They made plenty of 504 sedansbbut they mostly went overseas.

1800s go well in 404s 504s are heavier. I’d stick with the 2litre with a Weber 32/36 carby and a big bore exhaust or extractors and well flowing exhaust goes really well!
 
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Some good advice there BP, I take it a different inlet manifold will be required for a Weber?
 
You should be good to put on a Weber. One from a Renault Fuego is best, as others require mucking around re-jetting the darned things and still they're not right.
Even with the Fuego Weber, a small alteration is required. Can't remember exactly what.

The Solex is good though.
 
Peter C said:
The performance difference between an 1800 and a 2L is noticeable so I would stick with the 2L. If you can do the work yourself the cost of a new valve (and new had gasket and water pump, etc) may not be that much. In the old days, a swap to a 2L engine was a common enough thing, for the extra performance.

I don't think anyone wanting to buy a 504 would be deterred by one with a 2L rather than the original 1800. 2L is a worthwhile improvement.
Click to expand...
If you wanted to have the 1.8 and keep the performance of the 2L, there are ways of 'invisibly' improving performance. I attach an article that I've recently written for RCCQ's Rallye and the 4CV Register's Fourword.
 

Attachments

  • Oxenford ConversionsR0.pdf
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Thats an interesting read Phil, I think what I might do is port and polish a 2L square port head on a 2L engine, subject to any comments members with knowledge in this area may wish to share.
 
I’ve never had to rejet 32 36 Weber for cruising. I’ve got 4 cars with that setup and no problems

Fuego need water running threw them from memory and aren’t a nice Weber. And getting gaskets aren’t as common as the 32/36.

You play with the enrichment screw to compensate. Get one with a choke is the only mistake I’ve made.

The early solex work but performance and fuel economy Weber is the way to go.

Square port heads are better blowing as twice the size of a round port.
 
would really love to see anything at all on how peugeot inlets were developed after the 403 ( zero acquaintance ) but; these square-ports i keep seeing as The Go , the valves are presumably not square / is gas-flow twice as smooth, or ...?
 
Steven King said:
would really love to see anything at all on how peugeot inlets were developed after the 403 ( zero acquaintance ) but; these square-ports i keep seeing as The Go , the valves are presumably not square / is gas-flow twice as smooth, or ...?Some discretion neexds
Click to expand...
 
Steven King said:
would really love to see anything at all on how peugeot inlets were developed after the 403 ( zero acquaintance ) but; these square-ports i keep seeing as The Go , the valves are presumably not square / is gas-flow twice as smooth, or ...?
Click to expand...
Some discretion needs to be exercised with induction tract size in non-blown engines! Bigger isn't always better, particularly when looking for good 'driveability'. As a starting point for sizing, I do calculations based on 220fpm in the induction tract at my target maximum power revs. If you make the ports too big, you'll lose performance in the low and mid-range. My port gas speed calcs are based on mean piston speed. Of course, the most desirable sizes may not always be possible and compromises may need to be made to match manifold and port sizes and alignment.
 
harrisonati said:
Some discretion needs to be exercised with induction tract size in non-blown engines! Bigger isn't always better, particularly when looking for good 'driveability'. As a starting point for sizing, I do calculations based on 220fpm in the induction tract at my target maximum power revs. If you make the ports too big, you'll lose performance in the low and mid-range. My port gas speed calcs are based on mean piston speed. Of course, the most desirable sizes may not always be possible and compromises may need to be made to match manifold and port sizes and alignment.
Click to expand...
Correction! fpm should be fps (feet per second)!
 
harrisonati said:
Correction! fpm should be fps (feet per second)!
Click to expand...
Phil’s comment is interesting and on the money - knowledgeable tuning people ( i.e. not me ) do say that one problem of the injected 404 and the 504 heads is that the ports are too big. Subtle polishing and relief of turbulent bits is all that is recommended.

Interestingly, one current project chez nous is a 404 engine used in ARC in the 60’s. Was built by Repco racing for Regan’s at the time when they were doing the Repco Brabham engine. They created a four port head in the usual way ( grinding out and refilling plenum etc ).

THe ports on this head, into which went much thought from smart people are really relatively small.

Will be interesting to see how it goes. Head currently off being cleaned up and flow benched

Andrew
 
BP505v6Turbo said:
Fuego need water running threw them from memory
Click to expand...
a similar carb was used on some Fords, but with electric heating instead of water. Is there a 'standard' twin SU/Stromberg conversion ?
BP505v6Turbo said:
Bob Nelson put a 1800 head with a 2litre bottom end back in the day
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nice increase in CR with little work... :)

The 'Oxenford' thing was done by others as well in times of yore, one crowd even sold it as a set of instructions for DIY - it's here somewhere, at least the example combustion chamber drawings are. I used the 'system' on a Standard 10 way back when and the difference was certainly noticeable, but coupled with with a big overlap cam grind, larger valves, skirtless pistons etc etc noticeable became amazing... :)

Bob
 
I made an occupation of removing and binning fuego carburettas.

a webber pos
 
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