Another try at posting the text directly. Trevor
Hi Gil,
I’ll comment on your various questions re 1300/124/850 coupes detail in the order you raised them in your Nov 7th posts . My response time comes from having to dig up some items from my “archives”
1. The “Abarth” alloy rocker (cam) cover on the 1995cc pushrod motor photo is an aftermarket replica of the original. They are available in that catalogue you were acquiring. They were made for 1197/1280cc 124A heads, and there a couple of minor items of adjustment needed. I have a sketch I can email you if required.
2. The pbs or Abarth bellhousing copy machining is straight forward; mainly ensuring the front faces of the bellhousing to engine bolt “knobs” are coplanar and that plane is at right angles (perfectly) to the axis of the crank and transmission imput shaft. I would take minimum off necessary to achieve this, but it is not too critical in fore/aft dimensioning, affecting only extent of imput shaft insertion in the pilot bearing at the rear end of the crank, the angular location of the throwout lever/bearing relative the pressure plate and the gearbox mounts clearances. The block rear face gives a good template for bolt locations relative to the crankshaft centreline, and the clearance of the bellhousing around the back of block water jacket plate needs only to be sufficient not to prevent the full contact of bellhousing bolt “knob”faces to back of block.
3. I assume you have a 124 to 850 imput shaft as per the illustration to carry a 124 clutch lining and sleeve connect to tha 850 box (pbs make the shafts)
4. I cannot tell whether your bellhousing is a copy of the pbs or the original Abarth pattern. I have used a VW beetle bosch starter in my pbs bellhousing as the new location of the VW starter on the motor side of my flywheel gives it the required rotation without rewinding, thus a simpler future maintenance item. If a strapped throwout face is on the pressure plate then these straps need reversing to suit motor rotation. The earlier photo of my bellhousing/starter shows minor relieving of the bellhousing to accommodate the bosch starter.
5. I have no information re mixing 1608cc cranks with 1438cc blocks, which would have some compression ratio issues to solve, depending whether suitable pistons were available or made. I took the simpler route of using the 131A1 1585cc and the 132AZ2C 1995cc pushrods for larger capacity. The 131AZ2C lower commercial vehicle compression ratio needed raising to reach a useful 9.3 to 1 as per 131A motor
6. As for downpipes the standard cast exhaust manifold onto replica 1300124 pipes muffler in the earlier photo has been replaced by an ANSA FA 3181 headers ( made originally for 131A1 1585cc pushrod motor heads, and there fit the 132A2 head sized as it is for 80mm bores common to both. I believe it will also fit the 1438cc head. I obtained several headers from Bayless April sale specials, which are still listed in that on line sale catalogue yesterday..
7. The factory water pump in my 1995cc motor, which was a reverse rotation motor as standard, is identical (ie no alternative impellor blades) to those on the standard rotation 124 131 pushrods & twincam waterpumps. Only difference was water pump pulley location and/or size. It was practice in the 80’s however to use a reverse bladed impellor
8. I attach photos of the rear of motor as requested. This motor with its standard opposite hand cam to provide reverse rotation of the motor uses its standard (131A1 type ) belt drive to cam, hence the cogged bolt drive sprocket on the crankshaft nose, and no “timing chain cover”.This particular motor is for every day usage, hence the installation of air-conditioning , with appropriate crank pulley. The oil filter housing, which carries a mount for airconditioning or other ancillariary, is a standard fiat item, from a regatta, if I recall.
9. There are several options for stronger drive shafts. Original 1300/124 drive trains were in the 1300/124 coupes and the OT1300 Scorpione(Lombardi). These were quoted as 75bhp @ 6000rpm except the SS version of the latter with 88bhp @ 6500rpm. All appeared to have standard 860 trailing arms ,driveshafts, flex joints and stub axles. The SS had tubular rear arms and thus I assume CV jointed drive shafts.
10. On my vehicle, I combined some components as follows:- inner CV housings and CV carriers fitted to the 850 standard box casing ( these from abarth type 137 box practice, a special length splined driveshaft, and a U-joint (cardan or hardie-spicer joint are alternative names) attaching to the standard 850 flex joint and stub axle. The carrier and typical shaft/U joint are in attached photos- also in that catalogue you are acquiring. There is also attached a drawing I provided the axle fabricator for my specific setup.You will notice that the CV carriers on the side of the standard 850 box are of different thicknesses to offset the off-centreline location of the 850 box, thus permitting use of same length axles on both sides.I adopted the arrangement for my needs as I was never able to find a double CV arrangement that fitted the standard 850 trailing arms and hubs/stub axles. I too had reservations re the silver soldered option that is available.
11. If you expect severe loading that double CVs would be needed to carry, then one option is to combine those gearbox side CV carriers via a special length axle to a Fiat 128 based CV joint axle arrangement as per an illustration attached. This hub /stub axle setup is not uncommon- 1980’s practice.
12. Gearbox and final drive options are a personal choice. I believe that the available close 3rd and 4th ratios for Fiat 850 boxes of 1.476 and 1.16 to 1 are more suitable than the wider apart standard ratios (usually 1.41 and 0.96 to 1) The power and torque of the larger motors is well suited to these closer ratios coupled with a “higher’ final drive such as the few new 3.9 to 1 ones currently available. If vehicle usage has freeway conditions then the original 4.875’s and even the simca 4.33’s would be too “revvy” for my taste, chosen as they were to reflect 850 to 1000cc motor performance capabilities. A different issue though if the vehicle is to be used on track. Changing 1st and 2nd gear has not been a commonly available option for the “road use” syncromesh Fiat 850 boxes, and the ratios seem to have served 1300/124 and scorpione owners OK.
13. I think I that addresses the issues raised , so good luck with the project,and if other matters arise please ask , and I will help if I can. .
Regards Trevor