Part 6: 903cc Engine and Cooling

Updated:  Feb 9, 2017

The 903 is still in process, but I wanted to share with you all what I am up to.

Fiat 903cc Timing Gears
In order to install the 903cc engine from a Fiat 850 into a Fiat 600 you have to reverse the rotation of the bottom end. The top ends rotate the same direction. Chris Obert wrote a pretty good guide. The easiest way, I think, is to replace the timing chain with timing gears. The gears can be purchased from Exotic+Raceparts here or from Fiat Plus here.  You will also need a spacer because the timing gears are thinner than the chain sprockets, which you can have a machine shop make or purchase here.  Also, you’ll need to replace the front and rear main seals with non-directional or clockwise seals.

The other way to go about this is to leaving the timing chain alone and installing a reverse rotation camshaft from a Fiat 127 or 1050cc motor and use the distributor/oil pump drive gear from the 600.

Fiat 903cc Reverse Oil
I’m reversing the oil flow and using an external oil filter. This process is fairly common and well documented: Paul’s guide or in Fiat and Abarth Tricks by Greg Schmidt or Cosentino’s Fiat 850 Competition Manual. The latter two you can find for download on my literature page. I’ll say more later.

Fiat 903cc Cylinder Head Flow Test
I sent the head out for a port match and polish. Here it is getting flow tested with the 3B headers and Alquati intake.

Weber 32/36 Rebuild
Here is the Weber 32/36 torn down and ready for a rebuild.

Weber 32/36 carburetor on an Alquati intake with a Bayless air filter.

Weber 32/36 carburetor on an Alquati intake with a Bayless air filter.

Weber 32/36 carburetor on an Alquati intake with a Bayless air filter.

Weber 32/36 carburetor on an Alquati intake with a Bayless air filter.

The Weber is now rebuilt and on the Alquati intake. It’s topped off by the Bayless Racing air filter.

More later.

If you have any questions or comments, contact me using the contact page or email me at myfiat600d@gmail.com. Cheers.

Advertisements

3 thoughts on “Part 6: 903cc Engine and Cooling

  1. Hmm…. I put a 600 camshaft in the 850 engine with just a modification on the middle camshaftbearing. Then WV valves in the top and the Weber carb. One problem was that the 600 starter collided with the 850 clutch because the 600 clutch was slipping with the increased power.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s