403 motor in 203?

B

bathst

Member
Tadpole
Joined
Nov 5, 2015
Messages
49
Location
New Zealand
Can anyone tell me what is involved with doing this? Can i use the flywheel and clutch of a late 403 to put in an early 203?
How do i sort a cable accelerator for the 403 carby?
203 is 1951.
Thanks for any advice!
John
 
Clutch is OK, they are all the same, unless you are thinking of a bigger 9 spring 404 clutch, if so you will need to pack out the carbon thrust a few mill, you will need the earlier thrust bearing with clamped in carbon to achieve this. As you have an early model car you may possibly have trouble with starter motor clearance depending on model, body and/or sump. 403 exhaust manifold will require a special down pipe, otherwise use a 203 one. Just put an extra pivot point on the firewall opposite the 403 carby and lengthen the accelerator actuation rod.
 
GRAHAM WALLIS said:
Clutch is OK, they are all the same, unless you are thinking of a bigger 9 spring 404 clutch, if so you will need to pack out the carbon thrust a few mill, you will need the earlier thrust bearing with clamped in carbon to achieve this. As you have an early model car you may possibly have trouble with starter motor clearance depending on model, body and/or sump. 403 exhaust manifold will require a special down pipe, otherwise use a 203 one. Just put an extra pivot point on the firewall opposite the 403 carby and lengthen the accelerator actuation rod.
Click to expand...
Thanks for the advice! The clutch is standard 403. Yeah the starter i may have to just wait and see as the 203 is the cable start non solenoid one but i will just try it in situ. Same with the sump i will just compsre when both motors are out. I do have a spare 203 manifold so that may be the way to go. The Accelerator might be interesting as i don't want to change anything permanently as i will put it back to 203 engine at a later time.
 
as Graham says 403 starter solenoid orientation probably will interfere with the early 203 chassis trianglation in that location ,

you can use a long cable to replace the accelerator rod from the pedal for 403 motor, dont have to modify anything
 
alpine said:
as Graham says 403 starter solenoid orientation probably will interfere with the early 203 chassis trianglation in that location ,

you can use a long cable to replace the accelerator rod from the pedal for 403 motor, dont have to modify anything
Click to expand...
I was going to try and use the early 203 starter without solenoid. Ah that is great if i can just cable from the pedal!
 
the other thought is to put the 203 head on 403 block , that way you dont have to change the accelerator or exhaust !!
 
alpine said:
the other thought is to put the 203 head on 403 block , that way you dont have to change the accelerator or exhaust !!
Click to expand...
I don't have a 203 head all good to go but i just did a 403 head up while it was off. I had a look at the 203 head and i can see it has a flat flange mount on an angle. But it also has a carby above it. Do you just leave it like that with no carby on? I have plenty of 403 exhaust i could have cut below the flange and joined? that might be the better option i think?
 
if you use the 203 head, use the 203 manifiold and carby that solves the linkage change
203 manifold has exhaust at an angle and thinner 203 exhaust pipe ,
if you use 403 head and manifold the 403 pipe will need to be bent to clear the steering column
 
bathst said:
I don't have a 203 head all good to go but i just did a 403 head up while it was off. I had a look at the 203 head and i can see it has a flat flange mount on an angle. But it also has a carby above it. Do you just leave it like that with no carby on? I have plenty of 403 exhaust i could have cut below the flange and joined? that might be the better option i think?
Click to expand...
You mean 203 manifold has the angle? Of course just leave the carby off, the manifold has no where to go when it reaches the head.
 
I may have a usable set of headers that might need small mods by a good exhaust shop
 
re before spending on more power ,
Graham Wallis who has lots of experience once suggested , keep it simple ,
ensure your distributor and distributor are perfect running order and the exhaust in manifold area has maximum flow area.
maybe take fan off and fit a 2 blade or an electric fan for a couple of more horse power, and fit a late 403 flywheel as they are lighter,
extractors, head relief and different carbies/ manifolds, cams , will give more power but at a cost
 
alpine said:
re before spending on more power ,
Graham Wallis who has lots of experience once suggested , keep it simple ,
ensure your distributor and distributor are perfect running order and the exhaust in manifold area has maximum flow area.
maybe take fan off and fit a 2 blade or an electric fan for a couple of more horse power, and fit a late 403 flywheel as they are lighter,
extractors, head relief and different carbies/ manifolds, cams , will give more power but at a cost
Click to expand...
Thank you. Yes the engine is 1960 403 so perhaps that is the lighter flywheel? I am using a 123+ electronic ignition. The pulleys on this engine are the narrow ones so i would need to sort a narrow one with the disengage fan which i can see online. yeah i might ask around the car community locally to see if there is someone recommended for the exhaust side or i might stick with stock 403 and have that pipe sorted.
 
The aussiefrogs facebook group recently ( 20/4 ) had a very interesting worked-up 203 engine posted by a Richard Anderson from Napier, with a bit of discussion about the exhaust ...
 
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