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Anyone tried a Zenith 28if on an 850cc engine?

malcolm

malcolm

& Clementine the Cat
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My Rodeo is too slow. It has a 747cc engine and really bad aerodynamics and the maximum speed is under 80km/h. It has trouble holding 4th gear on the slightest incline.

The carburettor is a Solex 22-26 which I think means 22mm throat. That was only a 747cc option and it's going to be one of those things where they restrict the power to help sell the slightly bigger engine. I don't have any 845cc carburettors but I do have a Zenith 28if from an 1108cc engine and the mounting points are the same.

Has anyone tried fitting the 28if to a 747cc or 845cc engine? @angel maybe? Would it help with adjustments to jets or is the carb just too big for the Billancourt engines?

20230603_184426.jpg
 
Hi Malcolm

I temporarily fitted a Zenith from an 845cc to an 1108cc just to test it to see how it faired. It ticked over fine and pulled ok albeit with a loss of power compared to the Zenith 281f which came with the 1108cc engine. You are upgrading as opposed to downgrading carburettor. I have not tried it the other way round.
 
Turns out the manual says Zenith 28IF carbs were sometimes fitted to 680 engines and it lists the jet sizes. That somewhat answers my own question. :ashamed:

I'll give it a try. The Rodeo group on Facebook say their cars can go 10km/h faster than mine so some performance tuning is needed.
 
malcolm said:
My Rodeo is too slow. It has a 747cc engine and really bad aerodynamics and the maximum speed is under 80km/h. It has trouble holding 4th gear on the slightest incline.

The carburettor is a Solex 22-26 which I think means 22mm throat. That was only a 747cc option and it's going to be one of those things where they restrict the power to help sell the slightly bigger engine. I don't have any 845cc carburettors but I do have a Zenith 28if from an 1108cc engine and the mounting points are the same.

Has anyone tried fitting the 28if to a 747cc or 845cc engine? @angel maybe? Would it help with adjustments to jets or is the carb just too big for the Billancourt engines?
Click to expand...
Yes it can be done.
According to RTA no. 288 (1970) the Zenith 28IF and 28 IFE were also fitted on the R1122 (R4 Super) with 680-02 (747cc) engine and R1123 and R1124 with the 800 (845 cc) engines.
zenith on 680 and 800 engines.jpg
 
Most 845 cars I take care of, including both my 845 R4s, are equipped with the 28IF carburettor.
It performs well in general, its drawbacks are the main jet position which leads to clogging if the float chamber has collected sediment - common with modern fuel - and the tendency for the float chamber fuel to quickly evaporate after a brief stop when underbonnet temperatures are high. Again, a side effect of modern petrol.
Both Solex and Zenith 32mm carburettors will out-perform the 28IF on the 845 engine, but they need the appropriate manifold. I have seen some conversions to 32mm carbs bolted on the 28mm manifolds with adapter plates that never worked.
There are slight differences between 845 and 1108 28IFs, main one is the vacuum take-off which is only present on the 1108 carb, and can be capped or used to "drive" a later 845 distributor (sounds interesting but haven't tried it yet). Main and idle jets are larger on the 845 (94 vs 91 and 40 vs 35 respectively) but they can always be changed or drilled. There is no accurate information on air correction jets but since they are pressed in the carburettor body and can't be replaced without damage, nothing can be done. If the carb comes off a post-83 car, choke cable fixing is different but can be easily adapted to early type.

Edit: I just saw your photo and you seem to have the 22mm carburettor. Going to 28mm would be more than an improvement - in fact, the 22mm was only fitted on very early 747cc engines, so it's incorrect for the Rodeo anyway.
 
Brilliant. I'll fit a 28IF and hopefully the Rodeo will go a little faster.
 
I have a 28IF off a GTL on my 68 model 845, and been running it since 2001. Initially ran it without any emission type gear but it would fart smoke randomly so eventually hooked up a semblence of mid-70's-early eighties breather arrangement and orifice and it seems better behaved. I ended up not changing any jet settings and it runs well- I wonder if it would be worth opening them up. Hot weather is an issue here in traffic and I ended up making a thicker insulating gasket between the carb and manifold.

If you are fitting your old air cleaner, or one of a similar vintage to it you may need to tap the top casting of the carb body to take the M5 (if I remember correctly) stud through the middle

The early 845 Australian cars all had 28IFEs with a rather nifty cyclone dust seperater on the intake. Angel, did the Greek cars have the same?

Also, is there much difference in performance between the 28IF and the Solex 32 with a correct manifold? Reason being I have both and are tempted to try fitting them but the solex and its extra external breather arrangement and multiplicity of cams etc looks fairly tricky to set up properly.
 
Piet said:
I have a 28IF off a GTL on my 68 model 845, and been running it since 2001. Initially ran it without any emission type gear but it would fart smoke randomly so eventually hooked up a semblence of mid-70's-early eighties breather arrangement and orifice and it seems better behaved. I ended up not changing any jet settings and it runs well- I wonder if it would be worth opening them up. Hot weather is an issue here in traffic and I ended up making a thicker insulating gasket between the carb and manifold.

If you are fitting your old air cleaner, or one of a similar vintage to it you may need to tap the top casting of the carb body to take the M5 (if I remember correctly) stud through the middle

The early 845 Australian cars all had 28IFEs with a rather nifty cyclone dust seperater on the intake. Angel, did the Greek cars have the same?

Also, is there much difference in performance between the 28IF and the Solex 32 with a correct manifold? Reason being I have both and are tempted to try fitting them but the solex and its extra external breather arrangement and multiplicity of cams etc looks fairly tricky to set up properly.
Click to expand...
Several options;
1) In hot weather conditions obtain a Zenith 28IF - V05085 this version is special made for those conditions.
1686310533600.png

2) Apply a ceramic coating around the complete manifold.

3) Use a heatshield

20220131_102753bqkat.jpg 20220131_102805swkap.jpg
img_1196o0j2w.jpg img_1199wsk2i.jpg
 
Piet said:
I ended up not changing any jet settings and it runs well- I wonder if it would be worth opening them up.
Click to expand...
I've just put the standard 1108cc main jet back in as the car ran too rich on the jet I drilled out. If the car is running OK then the existing jet us probably fine.
 
I have a base 1984 TL R1123 with the 800 BIB motor, it comes as standard with the Zenith 32 1F 7
 
Piet said:
The early 845 Australian cars all had 28IFEs with a rather nifty cyclone dust seperater on the intake. Angel, did the Greek cars have the same?
Click to expand...

They should have it, according to the parts book. I have never come across such an early car, though.

Piet said:
Also, is there much difference in performance between the 28IF and the Solex 32 with a correct manifold? Reason being I have both and are tempted to try fitting them but the solex and its extra external breather arrangement and multiplicity of cams etc looks fairly tricky to set up properly.
Click to expand...

A friend of mine has a 1972 R4 equipped with the later B1B engine with the Zenith 32IF7 carburettor. I always get outpaced when I drive my 28IF equipped R4 along hers, despite my engine being in better shape. This is more noticeable in low- to midrange, top speed is more or less the same. I think it has something to do with the distributor, too, as these carbs were always paired with a vacuum advance distributor.

@JdeW: did this 28IF come off an R4? Throttle linkage looks different. Have you opened the additional device to see how it works and what is supposed to do?
 
angel said:
@JdeW: did this 28IF come off an R4? Throttle linkage looks different. Have you opened the additional device to see how it works and what is supposed to do?
Click to expand...
Spanish and Portugese FASA produced R4's are equiped with those Spanish build Zenith 28IF with enricher pump. Also on the TL (Savane) with the Cléon 956cc (C1C) engine.
There are two versions, either vacuum operated or mechanical.
The system is used to enrich the air/petrol mixture when the engine power demand is high (throttle valve open wide but low speed.) On the other hand, the recovery pump injects the gasoline during acceleration for a specific time ( avoids the hole during acceleration) mechanical control rod generally.
1686477125974.png 1686508609619.png

Throttle linkage is easy to change.
v05085.jpg
 
Last edited:
DAA said:
@JdeW thaks a lot for your tips.

Did you have this heatshield applied?
Click to expand...
Not yet, my GTL is still in restauration mode. But my intention is to apply ceramic coating on the complete manifold as well as a heatshield.
 
OK, so it's a vacuum operated enrichment device, similar to those fitted on many other vehicles. I had seen a 28IF with an accelerator pump on a FASA 1108 R4 but not this arrangement.
 
This is an interesting thread.

I'll be trying to fit one of these:

Holley Sniper EFI 550-552 Holley Sniper EFI Autolite 1100 - Gold

Are you tired of struggling with the old Autolite model 1100 series carburetor on your classic Ford? Does your street cruiser currently hesitate at extreme temperatures? The team at Holley has designed the perfect solution for your problems. The Sniper EFI replacement throttle body for Autolite...
www.holley.com www.holley.com

To my R4 1300 probably later this year. I've had to do too many fixes to my carb, and where we are in Colombia, one can easily go from 3,000 meters to near sea level in a day, which are not ideal conditions for carbureted vehicles.
 
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