Upgrade 600cc engine - need help

[alapimba]

Hello
This weekend i bought a 600cc engine to fit on my fiat 500.
But has 23hp isn't enought i wanted to upgrade it to have a better engine.
The car is for street use only but well i wanted it to be a bit faster.

My first doubt is... should i upgrade to 650 or stay with 600cc?? it's worth the diference?
second doubt is about the camshaft. one guy from poland has to offer me a camshaft with the following specs: cammshaft 39/64/79/24 (valve inake open/close
39/64 ) (valve exhaust open/close 79/24).
He also has to offer me a 650cc head with:
-inake valves - 35,7[mm]
-exhaust- 28[mm]
machined inlet and outlet channels
uneven surface of the head - 1-1,5[mm]

On my research i found that the must comum camshafts is 35/75 or 40/80. but i have this weird degrees.. what this means?

For this upgrade (cylinders, head and camshaft) i'll pay 482€
I'll probably use a weber 28 and as adviced by the seller of such parts i'll light the flywheel to 4kg.
Exhaust will be a record monza abarth replica

Do you think i'll be happy with this or it's better to spend the money other way to have a nice performance for street use on this 600cc engine? (maybe keep 600cc use a 35/75 cam and just do a std valve job keeping with the original size?

Thanks for your help

[Pete126]

Hi
It all depends on what you want to achieve and how much money you want to spend, The 126/500 will never be as quick as a Ferrari But you can make the standard engine better. as far as i'm aware you can fit 650 barrels and pistons to the 600 engine but you need to have the block machined to allow for the the bigger diameter at the base of the barrels.You can buy a complete set for around 90 euros.
1mm ground off the head will higher the compression ratio which equals more bhp [-/
Matching the inlet port to the inlet manifold and the exhaust knuckles to the exhaust port on the head and the exhaust down pipes gives you a little more power, cleaning out the inlet/exhaust ports in the head smoothing any sharp edges that can cause turbulence in the gas flow also helps

The idea of a sports camshaft is, it moves the power/torque further up the rev band which is ideal for a motor that is being used for Rallying or Racing but not ideal for every day driving, The down side being that revving the little horizontal twin up to 7500/8000rpm does result in more ware and tear on the engine and tends to break more often.

The biggest noticeable improvement is a lightened flywheel [-/ It does not increase the power of the engine but because it does not have turn a heavy flywheel to store energy, the engine revs more freely and the car accelerates quicker, The only down side to this is a slightly lumpy tickover.

The numbers quoted for the different camshafts refer to the valve timing have a look at the picture and you should be able to work out what they mean.
     

[gsxr126]

good explanation "little horse"

[alapimba]

Hi.

I want to spend top 1000€ and in this 1000€ has to be included about 200/250€ to take weight from the flywheel and to balance crankshaft and flywheel and rods and pulley and probably to machine the block to the new barrels.
so i have about 750€ for parts.

I know that the car wont ever been a ferrari and i don't even wanted one. i just wanted a bit more speed so when i go on the highway on uphills i don't need to go at 40km/h when the minimum allowed speed is 50km/h 

My doubts is, it's worth the upgrade from 600 to 650? it will cost so much to put the 650cc pistons as the 600 so the money is not the question. is only.. what is better?
My other doubts is about this camshaft that i described. as i can't find nothing like this on the net i dont' know what to expect from such camshaft...
Dont' seems very agressive 278º and 282º, the 35/75 is 290º and 40/80 is 300º.

The other option was to stay at 595cc and use a 40/80 (i guess it's the ones used on 595ss abarth and make my engine based on that...)

what would you do?

Thanks

[dajwid]

Are you really only getting 40kph from your engine? If so there something wrong with the engine very wrong, or your brakes are stuck on

[alapimba]

Are you really only getting 40kph from your engine? If so there something wrong with the engine very wrong, or your brakes are stuck on

On a straight and horizontal road i can go till 100km/h. but uphills in a road that with my fiat 600(30hp) i get on the top at about 60/70km/h with the 500 i was only reaching it at 40km/h thats why i want to get a engine a bit better.
Anyway the original engine (499cc) it's already in parts but i prefer to rebuilt the 600cc engine as i guess i'll have better performance

[Rusty's Uncle]

I am no expert at this but I would think that you could do quite a lot for 1,000 euros. You can also take things in stages so the balancing is a good idea so you will have your bottom end sorted out. I think that you should then look at the top end with the remaining 750 euros and get the induction , gas flow & exhaust to let the engine breath more freely . The specialist that is working on a 500 head for me , porting & enlarged inlet valves , estimates a minimum 5 to 6 bhp improvement. Then you can look at carb & exhaust options  [-/

[alapimba]

Yeah i'm thinking that way.

As i mentioned earlier i got an offer of a 650cc head with thsi specs:
He also has to offer me a 650cc head with:
-inake valves - 35,7[mm]
-exhaust- 28[mm]
machined inlet and outlet channels
uneven surface of the head - 1-1,5[mm]

I have been talking with a friend with lots of experience with fiat 600 engiens (4 cylinders) and also a bit with 2cylinders and he told me that sometimes isn't good idea to put big exhaust valves and from what i see here this head has the std exhaust valves only the intake is 2.7mm bigger so i believe it's ok.
My main doubt i guess it's with the camshaft. The most comun is 37/75 and 40/80 but the man selling the head said that for street that camshaft with that weird angles is the best. I guess isnt' too agressive but at the same time i think... i only need this? this is good? 35/75 is still good for street use?
The exhaust i need to buy a new one so i'll for sure buy right now a record monza replica and the carb is the part that i'll probably leave for later and try this combination with the 28 weber.

It's really worth the 77pistons vs's the 73,5? I ask this because keeping at 73,5 and with a 40/80 i would have a good 595ss replica engine... or am i wrong?

[Rusty's Uncle]

OK I would say if that head is in good condition & the price is good then go for it . All of the air cooled heads are interchangeable and I believe that some people fitted 499ccs heads to 652ccs engines to raise compression but the inlet port is 26mms on the 499ccs and 30mms on the 652ccs. I do not recognise that inlet valve size as the Panda 30 is 34mms so it could be a hybrid or a Lancia Fulvia valve. The standard 28mms exhaust valve is no problem on the exhaust side for a tuned engine as the valve , valve seat & port can be improved.  [-/

[alapimba]

OK I would say if that head is in good condition & the price is good then go for it . All of the air cooled heads are interchangeable and I believe that some people fitted 499ccs heads to 652ccs engines to raise compression but the inlet port is 26mms on the 499ccs and 30mms on the 652ccs. I do not recognise that inlet valve size as the Panda 30 is 34mms so it could be a hybrid or a Lancia Fulvia valve. The standard 28mms exhaust valve is no problem on the exhaust side for a tuned engine as the valve , valve seat & port can be improved.  [-/

the mentioned head is new. it's from poland. i have at home a head from a 499cc and one from a 600cc.. today i'll measure to see if i find any diference other then the intake valve.

[alapimba]

here is a picture of that head with 28mm exhaust and 35.7 intake.

[Pete126]

That L KS Impressive Another mod you might want to consider is the 126 gearbox and if you can find one, a 126bis water cooled final drive [-/ 

[alapimba]

hi again.
i'm about to give up from the head that i show before. i have been talking with a friend and he said that this valves are too big for a city car. he recommended me to don't install intake bigger then 33mm and exhaust stay with 28mm. he also recommended me to install a 35/75 camshaft and i'll be happy with the car.
The head if i bore it to 33mm or even 34mm valves it will be cheaper than the head that i just posted so i guess i'll go with the cheaper version. Now i have 1 doubts about the flywheel.
The original flywheel from the 126 is 7,4kg and the flywheel from the 500 is 5.5kg (or something like that).
Should i install a flywheel with 4kg?? isn't that too light? Can someone please explain-me how far should i go with the flywheel weight?

[michaelodonnell500]

Fywheel weight.....
You have to make that decision for yourself.
Take the 7.4kg wheel as a standard
If you reduce the weight the BHP increases, but the torque drops. Flat road accelleration will benefit, but acelleration on hills will decrease.
Heavier flywheel is great with momentum, getting to speed and keeping it there.

Think about your surroundings and base your judgement on that

[alapimba]

ok thanks for the explanation.

another doubt
if i install 77mm pistons (650cc) it's possible to use the 600cc original head? which head gasket i need to use? from 600 or from 650cc?