Hey Guys - 120 Kmph In A Fiat Is Very Common For Me. I Have Done Baroda To Mumbai (440 Kms) In 5 And A Half Hours. I Have Done Mahabaleshwar To Mumbai In 3 And A Half Hours Many Times. I Have Touched 70 Mph (112 Kmph) In A 1964 Left Hand Drive Fiat 1221 Cc.
There Is A Correct Way To Do It. It Is All About Tuning. Obviously The Engine Must Be In Perfect Tune, But You Also Need To Tune The Chassis For Ride And Handling. Surprised ? Read On ! the Engine:
The Most Important Thing Is Valve Timing. First Of All, You Need To Know Whether The Camshaft Lobes Are Still Having Full Lift. If No, Then Whatever You Do Will Not Work. The "chaal" Of An Untuned Engine Will Tell You Whether The Cam Is Ok And The Engine Is Tuneable. I Can State Here With Full Confidence That I Have Yet To Come Across A Single Mechanic Who Knows The "exact Procedure" To Set Valve Timing (in Common Jargon - Replacing The Timing Chain). Once This Is Done As It Should Be Done (the Process Is Quite Long So I Will Send It Across To Karlosdeville And Request Him To Put It Across To You All), The Next Thing To Tackle Is The Much Maligned Distributor. the Distributor:
I Have Yet To Come Across A Single Mechanic Who "does Not Put Grease" In The Distributor. It Is Common Sense. The Centrifugal Advance Can Only Work If The Weights Fly Apart. How Will The Weights Ever Fly If They Are Constrained By Grease ? Then Everybody Blames The Car. A "greased" Distributor Takes Around 4 Hours To Clean. I Have The Patience To Do All This. Once Done, The Dwell Angle Is 60 Degrees, The Ignition Timing Is 10 Degrees Btdc For Non-s1 Engines And 7 Degrees Btdc For S1 Engines, But You Need To Be Clear What The Timing Mark On The Pulley Indicates. There Are 3 Types Of Pulleys, So Be Careful. If There Is Only One Mark, It Is Tdc. If There Are 4 Marks, The Single Mark Is Tdc And The Other Three Marks Are 8 Degrees, 10 Degrees And 12 Degrees Btdc For Non-s1 Cars And 5 Degrees, 7 Degrees And 9 Degrees Btdc For S1 Cars. The Next In Line Is The Carburettor. the Carburettor:
The Best Carburettor Is The Solex Mcs1061. This Has An Internal Vent, Has An Econostat And Comes With A 97.5 Size Main Jet But For Optimum Performance without Deterioration Of Fuel Economy, You Need To Use A 102 Size Main Jet, Otherwise Do Not Disturb Any Other Part, Especially The Emulsion Tube. The Idling Speed Must Be Set To 720 +/- 20 Rpm. Vacuum Should Me More Than 480 Mm Of Hg Measured In The Intake Manifold. the Valves:
I Have Yet Come Across A Mechanic Who Has Correct Tappet Guages. The Specification Is 0.1 Mm In Dead Cold Condition. You Can Try This. If You Set To 0.1 Mm In Dead Cold Condition, You Will Get 0.35 Mm In Hot Condition, Which Will Cause A Good Amount Of Mechanical Clatter. The Process Is To Set The Tappets In A Hot Engine With The Engine Idling And Set It To 0.2 Mm (8 Thou) Intake And 0.25 Mm (10 Thou) Exhaust Valves. From The Fan Backwards, The Valves Are E-i-i-e-e-i-i-e. chassis Tuning: the Clutch - Use A Good Msl Make Clutch With Original Actuating Links. There Should Be No Undue Clearence In The Links. Free Play Is Around 15 To 19 Mm. the Suspension:
Most Important - Use Original Spider Assemblies Only - Nothing Else Will Work. Use New Control Arms And Thread The Spiders Without Any Clearence. Then Set The Camber To Zero And Caster To +2 Degrees Without Load (the Original Spec Is With Load But The Alternate Without Load Gives A Fairly Accurate Result). the Wheels:
Use Production 3.5j*14 Wheels. The Offset Is +31 Mm. There Were Some 4j Wheels Released In 1994 Cars And If You Can Lay Your Hands On Those, So Much The Better. Do Not Use 118ne Wheels. The Offset Is 37 Mm So The Track Will Reduce By 12 Mm. Set The Tyre Pressure To 25/27 Psi Front/back In Dead Cold Condition. the Steering:
Set The Steering Gear Clearence To Just Zero. Use 220 Cc Of Sae140 Oil In The Steering Gearbox. the Cooling System:
You Need To Have A Good Radiator And Hoses. If You Can Use A Degassing Tank, It Is Ideal.
Then Drive @ 120 Kmph. I Do It For A Short Stretch Everytime I Do Mumbai Pune Or Mumbai Nasik (at 50 Bucks A Litre, It Is Ok Only For A Small Distance). All My Cars Regularly Give Me 15 Kmpl. I Have A Mikuni In One Car But I Have Not Yet Evaluated It Much As I Use This Car Only Once A Year.
Do Send In Your Comments & I Will Be More Than Happy To Answer Any Queries That You Have. Bye For Now.
Behram Dhabhar |