Technical 594-A1 000 engine rebuild.

[BucsaBogdan]

Hello,
I bought a cheap engine and gearbox for the only purpose to have a spare engine and to rebuild my first engine.
I attached a couple of pictures of how the engine looked when I bought it.

 

[BucsaBogdan]

I started first with the restauration of the small bits since at the time I had no place to work on everything at once.

What is ready or almost ready is the fuel pump, carbouretor, cylinder head, valve cover. At the moment the engine is in pieces and the pieces are in the proces of cleaning.

I plan on an alternator conversion and found one online that seams in good condition ( will be testing it in a few days)
I started ordering the parts that 100% need changing like the , timing chain set, rocker gear, push rod tubes (the old ones were bent at dismantling, etc.

 

[BucsaBogdan]

Good morning.
I’ve reached a point in which I dont know how to procede. The problem is this.
After dismantling and mesureing the cilinder boors and pistons I sadly realized that the cilinders are worn.
I have come to 2 solutions.

a) replace the cilinders and keep the pistons. Cost is somewhere around 170€

b) buy new pistons oversized 0,20mm/0,40mm/0,60m and after I get the pistons rebore the cylinders so the clearence is between 0,070mm-0,090mm. Cost is somewhere at 130euros.

Can somebody give an advice on what would be the best solution? Since the diference in price is not that great I can go either way.

 

[Toshi 975]

I would say that the conventional ways to go would be to either hone the bores and fit new piston rings which would be quite cheap or go for the rebore and new pistons.

 

[the hobbler]

I would say that the conventional ways to go would be to either hone the bores and fit new piston rings which would be quite cheap or go for the rebore and new pistons.

Personally, I would go the new piston route. Have the bores measured so that you know the place where you are starting. Whichever pistons you get, get the best that you can, and do NOT have the bores opened up until you can hand over the pistons to the machine-shop with the barrels. Also, check that the machine-shop can correctly 'hold' individual barrels (as against a block). You might find that a machine-shop that specialises in motor-bike engines is the best bet as they are used to boring out individual barrels. A good '595' engine is a good up-rate, and driven sensibly, almost unburstable. Just for interest, the bore and stroke of the 126-A1 (594cc) engine is exzactly the same as Abarth used in his '595' variants. If you decide to use the 126 gearbox (with synchro on 2nd/3rd and 4th gears) you will have to change to 500 drive-shafts----the 126 shafts are too long. It is not a difficult job and again, get the best quality items that you can. The cheaper versions are not worth the money. Where are you based? Might be somebody in your area who can 'hold your hand' A good source of parts is "D'angelo motori" in Italy, or "Motobambino" in the UK. Always got good gear from both these suppliers.

 

[BucsaBogdan]

I would say that the conventional ways to go would be to either hone the bores and fit new piston rings which would be quite cheap or go for the rebore and new pistons.

Either way I wil be geting new piston rings. I would like the best solution since I want a professional rebuild even if it’s done by an entusiast)

 

[BucsaBogdan]

Personally, I would go the new piston route. Have the bores measured so that you know the place where you are starting. Whichever pistons you get, get the best that you can, and do NOT have the bores opened up until you can hand over the pistons to the machine-shop with the barrels. Also, check that the machine-shop can correctly 'hold' individual barrels (as against a block). You might find that a machine-shop that specialises in motor-bike engines is the best bet as they are used to boring out individual barrels. A good '595' engine is a good up-rate, and driven sensibly, almost unburstable. Just for interest, the bore and stroke of the 126-A1 (594cc) engine is exzactly the same as Abarth used in his '595' variants. If you decide to use the 126 gearbox (with synchro on 2nd/3rd and 4th gears) you will have to change to 500 drive-shafts----the 126 shafts are too long. It is not a difficult job and again, get the best quality items that you can. The cheaper versions are not worth the money. Where are you based? Might be somebody in your area who can 'hold your hand' A good source of parts is "D'angelo motori" in Italy, or "Motobambino" in the UK. Always got good gear from both these suppliers.

My plan is exactly as you stated. First get the pistons and after that bore out the cilinders.

If it’s not too complicated what are the diferences between the 594 and 595 Abarth engine? I mean what parts are diferent?

I am from Romania. Since the Brexit getting parts from the UK has become a bit dificult and expensive. A lot of paperwork involved.

Usualy I get my parts from FD Ricambi ( Netherland), Passione500 (Italy), Axel Gerst (Germany), fiat500vdlaan (Netherland) and also from D’Angelo Motori. Sadly what I have noticed it is almost imposible to get original Fiat parts.
Can you recomend a quality brand for the pistons?

I have a Fiat 500 F from 66’ that has a 594 engine and a sincromesh gearbox. This is the way I bought the car. So I think that the drive shafts have been changed.

This engine in the post is getting rebuild only for my plesure of working on cars and for the reason that when I will rebuild the engine from the car I will have experience and a spare engine to put in until the rebuild is done. At least this is the plan for the next couple of years. )

I attached two pictures from the car as it is in this moment.

 

[Toshi 975]

My plan is exactly as you stated. First get the pistons and after that bore out the cilinders.

If it’s not too complicated what are the diferences between the 594 and 595 Abarth engine? I mean what parts are diferent?

I am from Romania. Since the Brexit getting parts from the UK has become a bit dificult and expensive. A lot of paperwork involved.

Usualy I get my parts from FD Ricambi ( Netherland), Passione500 (Italy), Axel Gerst (Germany), fiat500vdlaan (Netherland) and also from D’Angelo Motori. Sadly what I have noticed it is almost imposible to get original Fiat parts.
Can you recomend a quality brand for the pistons?

I have a Fiat 500 F from 66’ that has a 594 engine and a sincromesh gearbox. This is the way I bought the car. So I think that the drive shafts have been changed.

This engine in the post is getting rebuild only for my plesure of working on cars and for the reason that when I will rebuild the engine from the car I will have experience and a spare engine to put in until the rebuild is done. At least this is the plan for the next couple of years. )

I attached two pictures from the car as it is in this moment.

The car looks very nice and tidy like you I enjoy building engines and if you have access to a workshop manual and a decent set of tools it is not too difficult to do.
Do you know what Weber carb you have on there, 24 or 28 IMB?

 

[fiat500]

These are probably much bigger oversize than you need...but a good price:

Fiat 126, 500 R 1972-1975, 73.5 > 74.5mm 2x pistons, 1mm oversize, New! Kolben. | eBay

Find many great new & used options and get the best deals for Fiat 126, 500 R 1972-1975, 73.5 > 74.5mm 2x pistons, 1mm oversize, New! Kolben. at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

 

[BucsaBogdan]

The car looks very nice and tidy like you I enjoy building engines and if you have access to a workshop manual and a decent set of tools it is not too difficult to do.
Do you know what Weber carb you have on there, 24 or 28 IMB?

Thanks. The majority of the work I have done is painting the underside and the back of the car where the engine is. I plan to eliminate the rust ( clean to metal and paint, pach if need be) the car is from Spain so I have only small rust isues.

I attached a picture of how the engine looked when I bought it. And 2 of the 4 repair manuals I have. I dont have pictures from the Haynes ones I have.

I have the tools and I been buying almost on a montly basis) since you need something every time.

The carb is a IMB 28.

 

[BucsaBogdan]

These are probably much bigger oversize than you need...but a good price:

Fiat 126, 500 R 1972-1975, 73.5 > 74.5mm 2x pistons, 1mm oversize, New! Kolben. | eBay

Find many great new & used options and get the best deals for Fiat 126, 500 R 1972-1975, 73.5 > 74.5mm 2x pistons, 1mm oversize, New! Kolben. at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

Thanks for the tip. The price is real good. And since they come with the rings and the pin it’s quite a deal.

I question i have if i buy these pistons will I need diferent jets for the carb? Or the increase in size is too small?

 

[fiat500]

Thanks for the tip. The price is real good. And since they come with the rings and the pin it’s quite a deal.

I question i have if i buy these pistons will I need diferent jets for the carb? Or the increase in size is too small?

You won't need to change jets. The pistons are cheap because that is a very large increase which will mean you would probably need new cylinders if you rebored again....but that's not likely to happen is it?

 

[BucsaBogdan]

You won't need to change jets. The pistons are cheap because that is a very large increase which will mean you would probably need new cylinders if you rebored again....but that's not likely to happen is it?

I dont think so. I think that they are worn this bad because of the engine beeing untouched and high milage.

 

[the hobbler]

I started first with the restauration of the small bits since at the time I had no place to work on everything at once.

What is ready or almost ready is the fuel pump, carbouretor, cylinder head, valve cover. At the moment the engine is in pieces and the pieces are in the proces of cleaning.

I plan on an alternator conversion and found one online that seams in good condition ( will be testing it in a few days)
I started ordering the parts that 100% need changing like the , timing chain set, rocker gear, push rod tubes (the old ones were bent at dismantling, etc.

NURAL is a good make of piston---and "Autodoc" (in Germany) have 2 pistons +.4mm in stock--and only 2! If you contact me direct ([email protected]) I will describe the differences between the 'Abarth 595' and the 126 '594' But, first of all, go for those pistons if they will suit you.

 

[BucsaBogdan]

NURAL is a good make of piston---and "Autodoc" (in Germany) have 2 pistons +.4mm in stock--and only 2! If you contact me direct ([email protected]) I will describe the differences between the 'Abarth 595' and the 126 '594' But, first of all, go for those pistons if they will suit you.

I’m very glad that I have joined this forum.
The pistons that you recomend have been in my Autodoc app basket since 2-3 weeks. I didnt know if they were ok or not. And since this engine build is a new chalenge I was postponing the purchase. Now I have ordered them. thanks for your help.
I addes a piston ring kit from Goetze as well. Hope they are ok.

 

[BucsaBogdan]

The car looks very nice and tidy like you I enjoy building engines and if you have access to a workshop manual and a decent set of tools it is not too difficult to do.
Do you know what Weber carb you have on there, 24 or 28 IMB?

This is what I have.

 

[the hobbler]

I’m very glad that I have joined this forum.
The pistons that you recomend have been in my Autodoc app basket since 2-3 weeks. I didnt know if they were ok or not. And since this engine build is a new chalenge I was postponing the purchase. Now I have ordered them. thanks for your help.
I addes a piston ring kit from Goetze as well. Hope they are ok.

I’m very glad that I have joined this forum.
The pistons that you recomend have been in my Autodoc app basket since 2-3 weeks. I didnt know if they were ok or not. And since this engine build is a new chalenge I was postponing the purchase. Now I have ordered them. thanks for your help.
I addes a piston ring kit from Goetze as well. Hope they are ok.

Yes, Goetz piston rings are good. I have done what you are doing---fitting NURAL pistons with Goetz rings. Never had a problem. Keep the rings that you remove from the pistons as a spare 'if ever needed' set. When you rebuild the engine, don't forget to use either a 'build-up' lubricant or, as I do, a home made 'build-up' lubricant consisting of 50% STP and 50% a thin (30) engine oil. Run the engine in with a 'high zinc' lubricant---there are some specific 'running-in' lubricants on the market. When you build-up the oil-pump, pack it with petroleum jelly (vaseline---but NOT grease)---this will give the pump something to suck on when initially cranking the engine over. As I said, if you drop a line directly to me and as well as telling you the difference between the Abarth and 126 engines (595), I will try and send you my thoughts regarding building up an "Abarth" engine.
You are correct---in fitting the 'synchro' box to your car, they will have HAD to change the drive-shafts from 126 to 500.

 

[BucsaBogdan]

Yes, Goetz piston rings are good. I have done what you are doing---fitting NURAL pistons with Goetz rings. Never had a problem. Keep the rings that you remove from the pistons as a spare 'if ever needed' set. When you rebuild the engine, don't forget to use either a 'build-up' lubricant or, as I do, a home made 'build-up' lubricant consisting of 50% STP and 50% a thin (30) engine oil. Run the engine in with a 'high zinc' lubricant---there are some specific 'running-in' lubricants on the market. When you build-up the oil-pump, pack it with petroleum jelly (vaseline---but NOT grease)---this will give the pump something to suck on when initially cranking the engine over. As I said, if you drop a line directly to me and as well as telling you the difference between the Abarth and 126 engines (595), I will try and send you my thoughts regarding building up an "Abarth" engine.
You are correct---in fitting the 'synchro' box to your car, they will have HAD to change the drive-shafts from 126 to 500.

Thanks for the tips. Will do when time comes. I will send you an email later in the evening. I just got home and will start the cleanup on the rest of the parts.
Since I’ve been working on the 500 I keep everyting, no matter how damaged. It is still helpful even as a reference. Thanks

 

[BucsaBogdan]

I finished cleaning the big end bearing. The one on the timing chain end has a deep scratch. The flywheel end one looks in good shape. I still need to get them mesured for ware since thats an important factor as well. I’m very courios for any imput you guys have on how they look.

 

[Bounding Bambino]

Thats a tough one to judge from photos.. There is alot of embeded debris in the bearing (doing its job). They dont look horribly scored, but again, dimensional wize they could be out of spec. best to measure and see where it lies.

If its a cost and availability issue, it could still be used. But if your doing a full to spec rebuild, and possibly adding more power, i would just replace it; it would depend on what the surface condition feels like. there is alot of embedded grit that is concerning. How to the crank journals look?
Keeping everything within spec will also keep oil pressure constant. But its hard to say without seeing it in person.

Typically crank journal/rod bearings have multi layer coatings on them. Its hard to tell if this bearing ever had multilayer coatings, and if they have been completely warn away.

During my rebuild, i did notice that the factory bearings wernt as "advanced" per say as a modern journal or crank bearing that has multilayer coatings. But i havent seen enough 500 specific original used bearings to make that judgement. Most of the engines ive rebuilt had multilayer bearings that you could "gauge" the wear patterns by.

Again in factory form, these are not 100hp/L cars lol.. yet.