It is likely to be the brake shoes have become unbonded and now jammed inside the drum there is at least three or four different front brake assemblies and until you've got it in pieces you've got no chance of buying any parts in advance and then being correct
take some photos with the Drum off...
this is from pr 901the r4 relevant pages which tom scanned from my hard copy
https://drive.google.com/file/d/0ByjyTYVWAjtQaFQtNkpDa0
pPWVU/view?usp=drivesdk&resourcekey=0-8sc1Ra1ct_XZN4o-HtBxew
this is,pr1104 I found online...
I covered my solution to this on a Renault 4 recently on the Renault classic car club Facebook page
my solution was heat proof shielding on fuel lines
extra spacer under carb
and finally extending air filter intake down through inner wing to the gap below lhd master cylinder
Strictly speaking the distributor cap you have got fitted was designed for a Renault 5 mark 1 there is an equivalent upright version which is normally fitted to the Renault 4
the bit everyone is overlooking is modern petrol is designed for fuel injection and evaporation is at a much lower temperature
switch engine off the rising heat will evaporate it very quickly
fuel injection cars it is circulating to rail under pressure as soon as ignition switch turned on
not completed yet but some dashboard construction pics
originally brittle plastic and neither car had anything more than shattered remains to work with so this is my own diy effort
bit more progress painted wheels yellow figured out wiring loom using 5 Gordini speedo and extra wiring for RPM and temperature gauge rear fogs and reverse lamps etc
dashboard was plastic and shattered so next plan is make one from alloy sheet
Don't forget set if you're changing from 32mm to 28mm carburettors you will need a different manifold as the fixing spacings are different stick with 32mm as this was a easy power upgrades for people with 28 mm setup
normal 8mm fuel hose works fine as long as you are careful pushing it onto the plastic T piece as they go brittle make sure you remove the Old plastic restriction please and fit it in the new rubber tubing otherwise you'll be back to square one with the same running issues