1971 Fiat 850 sedan

[a112]

Excellent purchase on the head. Regarding the gearbox, I heard for Škoda mod also, but used on Fiat 126.

If you're interested in stock 903 parts, I have few engines laying around for sale, and one A112 elite naked engine block.

[ditchdigger]

Well the head was a bust. What I recieved was not a PBS 8 port head but a modified 903 head.



I wouldn't have minded it being a modified stock head but the seller lied and some of the work was inexcusably awful.

It was listed as a PBS 8 port head in very good condition.

All of the combustion chambers were crudely ground in what I believe was an attempt to hide some of the damage that all 850 heads seem to have



The flange was acutally nicely welded to the head, but inside the head was a nightmare. There must be 3 pounds of epoxy packed in the intake ports. The short side radius of the intake ports was a total mess and the whole thing had obviously been ported by someone who only had a vague idea of what porting is supposed to accomplish.





The combustion chambers could be repaired by building up with weld and machining but I couldn't get the TIG torch inside the ports to add material where it really needs to be. I decided to give up on it and return it. For what I paid I could have purchased several good used or even a NOS stock head instead of one messed up one.

Who know. Maybe I will attempt my own 8 port mod. For now I am back to the 5 port head. It is a shame though. I was really looking forward to one injector per cylinder.

[nmretro]

Just stumbled across this thread, cool build.
Been messing with 850s forever, had em all except van. Now down to 2 Spiders 67&68.
Never seen the head damage that you have seen, bummer about the 8 port.
My personal goal is twin overhead cam, looking at the possibility of bike motors with similar bore spacing.

[fuglynutlock]

Bummer about the head. Do you have no redress with the seller?

[ditchdigger]

The head was an ebay purchase so through their dispute resolution process I am supposed to receive a refund. Hopefully any day now. I shipped it back last week.

The real bummer part is the fact that the moment I clicked the buy button the plans for my engine completely changed. 4 injectors, a hotter cam, log style short runner intake manifold combined to possibly see 150hp. Now I am back with trying to figure out how stick two injectors into a different manifold/throttle body combo and will still have siamese port charge robbing problems and might see 110hp if I am lucky.

nmretro I am with you on the bike head idea. I really think the BMW K100 heads would fit the 850 engine better than they do the A series motors the mini guys fit 'em on. We don't have a water pump on the front of the block so we wouldn't even need to extend the cams and fit a timing belt. Just run a long timing chain just like the bike engine does. The only problem is the reverse engine rotation of the 850. Custom cams? alter the firing order? Not sure about what would need to be done there.

[ettorebugatti]

The cams on the BMW K100 are symmetrical so you can run them backwards.

[ditchdigger]

Mar 23, 2011 19:05:06 GMT ettorebugatti said:

The cams on the BMW K100 are symmetrical so you can run them backwards.

Dude I want to hug you right now. Seriously. You are my hero for the next 48 hours.


Off to ebay for a deal on a motorcycle engine ;D

[nmretro]

Is the bore spacing of the K100 correct? They are cheap and available.
The Mini guys "drydeck" them and then run external plumbing. I like the timing chain idea.

[nmretro]

The K100 bore is only 2mm bigger that the 850 so combustion chamber itself shouldn't be a problem.
It might be worth getting a k100 head gasket to compare to the 850 block.

[Blown_Imp]

Good morning,

Really sorry to hear about the scamming 8 port seller Oh well, siamese injection is possible, have you spent much time here -

www.turbominis.co.uk/forums/index.php?p=vf&fid=29

Turbo mini injection forum, lots of interesting stuff including software to get megasquirt to run two injectors in a siamese application.

I tell you what, inbetween doing the bodywork on my imp, I would love to build up a crossflow imp head, would involve very similar problems to you doing an 8 port? Lets do a cross atlantic mega race head project!

I really wish there was a way of getting a motorbike head on an imp, the only one in existence is this one -



And it looks to have had a huge amount of welding and bits added to the crank case :/

Either way, I'm watching with baited breath as always!

J

[TerraRoot]

How hard could it be to make your own 8 port head? more then making a k100 head fit?

[ditchdigger]

K100 head borrowed for some final deciding.

The good news. Look at this!

curse word! oiling holes line up, coolant ports are workable the center head bolt holes line right up. I seriously stared at the center for a good 5 minutes congratulating myself on a part well chosen until it occurred to me to look at the sides


Foo!



5mm offset and to make matters worse there would not be any block where the outside headbolts would be happy to thread into it.

This pic is through a block with the center lined up showing just how far off it would be.


bummer! Luckily I did not buy the head....heeheee! I quite liked the idea of going with the K100 since the A series folks have done all the hard work and the information is all out there.

Next one to try looks to be a 2001-2005 Yamaha R6



Its 65.5mm bore is much closer to the 65mm fiat bore. Sadly when they punched the little 600 block out for larger displacement zero thought was given to even spacing or anything silly like that so all modern heads will have alignment issues.

I really wish gsxr heads would fit as they are so common as to be nearly worthless. There are a few on ebay with a buy it now price of $15. The gsx-r600 has a bore of 68mm and I would assume it would have the same valve interference issues.

Oh well. Back to building up a stock headed motor. I did get the rods modified for the ARP hardware last week. I plan on dropping the block off at the machine shop next week.

[miilor]

fascinating as always ¡¡¡¡¡.
Argentina is a type that uses a cbr 600 head on a similar engine, fiat 600, and a friend here in Spain are also using the same stock, I will seek a picture of your head

[miilor]

[TerraRoot]

An r6 head? are you making a 15500rpm fiat gbc ;D

[ditchdigger]

Finally have some progress on the 843.

Block is back from the machine shop. Bored to 65mm, honed and decked.


And then I remembered I hadn't finished the oil system mods.


The oil pump outlet was enlarged to 10mm and the relief port was tapped and a set screw was loctited in place to block it off. This way every bit of oil that leaves the pump will be filtered. The pressure relief gets to do its job solo.

Perhaps the gasket set will get here tomorrow and I can spend a quiet weekend building up the short block.

[ettorebugatti]

If you want to do your own head, check www.apfelbeck.nl

[vegar]

I know they used to modify the stock head to 8 port in 2 different ways. I have one wich is welded and machined in alu. I am not sure what they have done, but the manifoil is mounted on top using the head bolts: Here are a couple of pics:





And a friend had one head wich was milled and then had 4 brass pipes treaded as inlet ports.



As far as I know are mine from Italy and my friends are from Angsten in Germany

[ditchdigger]

The top one looks to be the same that vizza motorsports sells in Germany. I am told that all of these are made in Sicily by a gentleman named Guiseppe La Russa. I cannot figure out how it is done.



I have been meaning to email vizza and see how much they are asking for that head now.

For now though I am building a 5 port head and thinking about adding a 2nd injector ahead of the throttle body. I would use injector staging so it only operates at higher load.

[vegar]

Vizza is correct. I have 2 inlet manifoils, 1 for 2 x weber 40 and 1 for motorcycle carbs as on the pic I am hoping I break the magic 100hp/l with this setup

As far as I can understand he has machined a big lump of the head where the orginal carb is mounted and way down to the "1342" mark. Then welded in a new piece of alu anglebar or something with 4 pipes for the inlet. This is what I think of it anyway