General Murphio's Meanderings

[Franko500]

They sure have been cut deep, maybe that could be the reason they were getting so hot?

 

[Vitesse]

That is some wear isn't it. At first glance you could be forgiven for thinking they had been cut differently. Is this the first time you have the valves out of this particular head?

 

[fiat500]

That is some wear isn't it. At first glance you could be forgiven for thinking they had been cut differently. Is this the first time you have the valves out of this particular head?

Sean's your man to help with that seeing that he has his head off at the moment.:spin:
I have had all those valves out when I rebuilt the engine. New valve-springs were fitted as well as one exhaust valve being replaced. As with my 650 engine where I also removed the valves and replaced the valve springs (I always would replace the springs), the exhaust seats were much narrower at the time and similar to the inlets.
The valve head has made a perfect imprint which misleads you into thinking it was made that way. It's not called valve-seat recession for nothing.

 

[Franko500]

its really strange that its the inlet one which went, as its the exhaust seats which look over cut to me.
Here's some dimensions from a manual I have.
Clearly your exhaust seats are wider than the required dimensions.

 

[fiat500]

its really strange that its the inlet one which went, as its the exhaust seats which look over cut to me.
.

The inlet seat simply dropped out probably because of high temperature; it was easy to tap back into place but seems firm enough that it would probably have stayed there. If I had better access I might have been able to repair well enough by the roadside to hobble home; there is nothing actually wrong with the inlets.
I doubt that anyone has ever re-cut the seats as the car only had 32,000 when I bought it and had been off the road because of a broken plug and a burnt valve, which hadn't been repaired in any case.
I'm planning to remove the head from my other 500 engine out of interest to do some comparisons with the seats. It's a bit hard to get at that one so failing that I will dismantle the 594 engine I have.
Next week I'm taking this offending head for professional assessment and pricing for new guides and hardened seats. Our local engine services firm is really good so if I can get it repaired it will be spot-on.
I would really like to rebuild the 594 engine, for once getting every detail measured professionally and splashing out on every bit of machining and replacement parts they suggest. I read somewhere that the 594 makes the most robust engine of the range but it would also need converting to unleaded.

 

[Franko500]

I have my old 500L head apart. I will take some photos tomorrow.

 

[fiat500]

I whipped the 594 head off and a look at the valve seats seems inconclusive to me. They are not as deep as those on my sore head but deeper than I thought they should be.
MAL_3938 by Peter Thompson, on Flickr

 

[Franko500]

They look about standard, possibly the exhaust seats have had a grind though going by the width.

 

[fiat500]

I also found a brand new exhaust valve and it doesn't seem much different to the used ones; so it is the seats that take most of the wear.

 

[jjacob]

Valves have a very high hardness. It is almost always the valve seats that will recede. Those exhaust valve seats look like they should be replaced with hardened ones.
John

 

[fiat500]

Check your pulley and see if it's coming into contact with the engine mount. If not sure, fit some spacer washers under the engine mount and see if the clunk goes away.

I had a good look at this and realised that I had fitted the rebound rubber stop the wrong way round which meant that the aluminium arm was permanently under pressure. This is the right way:
MAL_4306 by Peter Thompson, on Flickr
So now the engine is less jittery on tickover like the 500 used to be and the clunk is gone. Meantime, as I was onto VdL anyway I got hold of one of the 126-type gearbox stabiliser struts thinking that was the solution....it's massive! I may as well fit it now; perhaps it has a purpose to control the rotational torque of the bigger engine?

 

[Franko500]

The stabiliser should prevent any backwards and forwards movement of the gearbox mounting bracket. With all that extra torque when you change gear etc the engine/gearbox must move a good 5mm

 

[fiat500]

The stabiliser should prevent any backwards and forwards movement of the gearbox mounting bracket. With all that extra torque when you change gear etc the engine/gearbox must move a good 5mm

...not even 5mm now I've sorted my mistake.:bang:
Looking at it helped me to work out the purpose of those approximately triangular shims in the engine mounting. By adding or removing them you put the upper rubber stop more or less into contact with the aluminium arm. That makes the hold that it has on the engine harder or softer.

 

[fiat500]

I had nearly eliminated the clunk from the engine mounting without having to fit the stabilizer to the gearbox; but at odd times on a big undulation in the road I would hear a bit of a clank. I have removed two of the three shims on each side, which means that the rubber buffer is even less in contact with the alloy cradle; this has sorted the problem. The engine can be rocked more easily by hand but transfers less off its movement to the car. So it's a case of trying to find the optimum support/suspension of the engine.
Obviously, the bigger engine when fitted to the 500R had a different mounting. I have seen the reason for this being speculated as having been done for cost reasons...the alternative style being cheaper. But I am wondering if it was actually because the extra weight and different geometry of the heavier engine/gearbox combination required an alternative approach?

 

[Vitesse]

I doubt it. I would imagine that it was done for cost. I wouldn't imagine there was a great deal of R&D done so late in the 500's life. Probably a case of let's stick a bigger engine in, to keep them happy until we release the 126. Or maybe I am just cynical.

 

[fiat500]

I doubt it. I would imagine that it was done for cost. Probably a case of let's stick a bigger engine in, to keep them happy until we release the 126.

I think we would need someone who has tried both types of mounting in a 500 to be certain if it's better or not. But I'm sure you're correct that it would be cheaper than the complex aluminium mounting of the pre-1973 500s. It's been pointed out here several times that they actually undermined the performance of the 594 engine by fitting a smaller carb in the "R" than fitted to either the 126 or the 500! The "R" was available alongside the earliest 126 and I have seen images and hints of things which make me think that the "R" may have picked up a few other obscure benefits from the 126 design such as a stronger cross-member under the floor, possibly the strut that braces the front wheel-well to the front suspension cross-member and maybe even the additional chassis outriggers at the front which must give better stability to the steering and suspension but these might all have cost the factory more money although it may have meant that only one type of floorpan had to be manufactured.
Anyway, all knocks now sorted and after around 300 miles I can confidently say that Murf has accepted his new heart and lungs, and I feel as comfortable (if not more so), with hurtling him around the countryside as I did before the engine hiccup.
Today we had a good comparative test on a relentless, three mile, main-road hill which I always look at as being his nemesis. I used to need to change down to third pretty early on, on one occasion we overheated and I always used to have a queue of traffic behind me as I struggled around 30 to 35 mph. Now, with a bigger engine and not yet using full throttle, we stormed up at 50mph+ without any downward gear-change or even the threat of it.
So I'm forced to agree with the wisdom of others in the way the bigger engine transforms the car.
In my case I do have a slightly noisy gearbox, but the engine noise is much less than my 500 even though the exhaust is a bit more throaty.

 

[Toshi 975]

I doubt it. I would imagine that it was done for cost

A new one on me but I happened to be chatting to a guy a few weeks back who had built a number of tuned big bore engines and he said the preferred mounting was the 500R for stability. I have no experience myself but talking to a mate a few days later he said he had a new 500R rear crossmember / engine support panel which he did not get to use on a project. If anyone is interested I can put you in touch

 

[fiat500]

Although me and Murf like to go out in all sorts of weather, in The Highlands this week we have had the sort of conditions that would suit even the most rain-shy of Fiat 500 owners, (no names mentioned Sean Franko500).
So with a lot of appointments to keep we have notched up another 350+ miles over three days.
The new engine has a slight leak of oil "mist" from the pulley bearing. I was at great pains to fit a silicone seal and to install it very carefully. I'm wondering if the sealing surface on the pulley is worn.
The engine starts really well whether cold or hot and top speed so far has been 57.28 mph. It gets to that speed and stays there very easily; I can overtake lorries and take on with ease the sort of long incline that used to have us out of breath. Top speed is unknown but it's going to be around 70. I was expecting an increased petrol consumption but it is still around 55 mpg over this long range.
I don't want to worry anyone, but although I was initially a bit sceptical that it would matter, the brakes really could do with a bit more oomf now.
Note in the photo, ongoing painting work to the door botom; at some point I must have trapped a stone between the door and the sill and this crumpled a bit of the metal and pushed out some filler. It's all nice and smooth now and ready for paint.

Kennethmount 520 by Peter Thompson, on Flickr
The only trouble is that Murf is starting to feel a bit too much like a normal car...not his style at all.

 

[fiat500]

I shouldn't be surprised, because summer comes around every year (in my experience), but today caught me out by turning out so nice. We've done about a thousand miles on the new engine now; it's really smooth and powerful and great fun. It has started backfiring a little going down steep hills so maybe it's time to reset the valve clearances and combine that with re-tightening the head. I also need to get onto the leaky front crankshaft seal.
MAL_8563 by Peter Thompson, on Flickr
The car needs a good clean but looks a lot better now I've resprayed the door and the bonnet.
MAL_8578 by Peter Thompson, on Flickr
We did about eighty miles around one of the big sticky-out bits on the east coast of Scotland.
MAL_8606 by Peter Thompson, on Flickr
The oil-rigs are a real anomaly moored-up in the very deep water of the Cromarty Firth really close to the picturesque Georgian port of Cromarty.

 

[fiat500]

It won't stop raining but it doesn't stop us driving. Earlier this week was better down in Strathspey.....whisky country.
MAL_9996 by Peter Thompson, on Flickr
MAL_9998 by Peter Thompson, on Flickr