Yugo 1300 head(scratching) and cam mods

E

Emil024

Low Mileage
So, I have a 1300 with an 1100 head on it, and am not happy with the performance.
I was torturing Fiatfactory for a while with private messages so I think it is time to post a thread.
I can get a tipo head, the 1500 head is much harder to find here.
A camshaft regrinded to around 24/68 64/28. Originals are very very rare here because the popularity of these engines in our country, and new is still to much for my budget..
The block is slightly decked, the pistons are coming out around 0,1 0,2 mm. How much would need to come of the tipo head to make this work? or can this combo work? I do have an adjustable cam gear as the current 1100 head is milled allmost
1 mm.

One more question..:) Is it possible that with the smaller comb. chamber of the 1100 head and so little squish the rings did not seat properly or are burned because of to much pressure? Or they simply can´t take the pressure? I have similar blowby from the crank case as before the engine rebild for 5000 miles now.. Measured clynder pressure around 10-10,5 bar. I somehow thought it should net more pressure.
 
Tipo heads come in afew different flavours... in your part of the world you should be able to find something suitable for your build...

For example there are 37.5/33.4 and 39.6/31 valve combinations for 86mm bores... and there are 80mm bore variants too, so there are Tipo heads with small combustion chambers as well... there is a 37.5mm inlet/31 exhaust variant with a small combustion chamber from a 1372 variant (80.5mm bore/67.4 stroke) .. this could give you the combination of more flow, no need to modify the piston crowns for valve clearance, and roughly the same static compression that you currently have... never flow tested one of these so can't give any comment on good or otherwise or port sizes etc... also comes in an Uno version with the correct thermostat housing mounts too.

What do you mean when you say "rebuild" ... if you mean a hone and rings... then this might mean the ring grooves are worn. The ring 'works' because combustion / compression pressure gets behind it and forces it onto the cylinder wall to create a seal... sure a little tension is provided by the 'spring' of the metal but most of the pressure comes from the combustion / compression process. If the lands are worn (i.e. not flat and true) then the top ring can't seat into the land face (the bottom face for combustion pressure and the top face for compression pressure) and it will have lots of blow by...

SteveC
 
I think the head I was looking at is 40mm intake 33mm exhaust from a 1.6 ie. Unfortunately many wreckers tend to sell older car parts as secondary raw material so less and less choises..
Is it possible to throat the 34mm valve seats to fit 36mm intake valves without loosing the seats after two high speed dashes?

The block was bored and honed to 3. owersize with new pistons (made in serbia so tolerances questionable:)) and rings. In an inactive serbian forum I red that supposedly using the 1100 head on a 1300 will cause the rings to "burn". So how much blowby is "normal" for a fiat sohc enyhow?
 
39.6/33.4 isn't a factory available combination... it's either a 39.6/31 (159A3.000) or a 37.5/33.4 (160A2.000) for a 1.6ie Tipo.

You already have 36mm inlet valves so I don't quite understand what you mean...but no the 37.5's won't fit on the stock 36mm seat, they will hang off the outside edge... you can throat the seat a little, but maybe 32 or 32.5 throat is about it for a reliable seal... 39.6 valve tipo is already 35.5 seat throat, can go out to 36 or 36.5 quite easily

1100 head on 1300 block is barely 10:1 ... I would question the quality of the rings... if they were a black cast top ring then they could be toast if your filtration isn't great... I prefer a chrome top ring as they are a lot more durable.

cranking pressure doesn't tell you much... do a cylinder leakage test.

SteveC
 
A, I only were looking at pictures, so I can only guess
ca44aa9c0a77-800x600.jpg

So what about the 36mm valve in a 34mm valve`s seat? Is it doable?

I think they were chrome rings but I guess Ill be pulling the pistons to check their status.. I use a standard ford fiesta 1,6gt filter and housing for bigger flow..
 
You already have a 36mm intake valve... and a seat to suit.

No, the 37.5 valve won't fit straight onto the 36mm valves seat, it will hang off the edge... you could turn the 37.5mm valve down to 37mm and then throat the seat right out ...max is about 33mm... the seat gets pretty thin but I've done it and it stays in the head ... but for all the effort you might as well fit bigger OD seats and get the throat out to about 34mm and have total relaibility, afterall your not intending to R&R the head to recut the seats after every couple of race meets...and your not limited by any racing rules... it's a road car.

37.5 valve and 34 seat throat is 125cfm of flow and still a high port speed of around 300fps if you do it right... plenty for a 1300 at 8k.

SteveC
 
If you have money go to person who can build engine what you like .But I think you only ask ask .... stupid questions. In Serbia have many who will do job for you , but best for you don't do nothing only installed LPG gas system and drive .
 
Thanks for the wise words Yugoracing!
I do feel stupid sometimes...
I know there are good engine builders in Serbia! But my point is not to have a Yugo wich has xy amounts of money thrown at it! It still is a rotten peace of yunk! The fact is that I became attached to it, and it's a learning experience!
So feel free to burn me! I guess it's all part of the experience..:)
 
Buy books read or open internet is full with info for engines tuning ... not ask stupid question but on end you must buy parts -you haven't money but need parts you like impossible thinks all wish go with money (in cars preparation)
 
Thanks again!
Yeah, its full and I do read, all what I can get my hands on..
I admit that I got carried away, I am really sorry to every one who got annoyed!
I finished the bodywork, more or less:), on the yugo so before installing the engine I would like to find the right direction. Steve C was helping with that as He is willing to share his experience unlike most people who want to make big $$ from it. I`m not saying that cashing in the hard earned experience is a bad thing I only mean that, nobody was born with it so there can be a little tolerance.
Sure I have to buy parts and I will. I know that the right way to do it is to build an all out engine, but this is my "go to work" car so it would be a waste!
So here are a few pictures of the work done to the old and tired body.
Another great opportunity to fry me and the work I have done!:)


 
Wow, there is a lot of work done!

I like how hard you are working on your car. In my opinion, replacing corroded pieces is the best way to go from a strength and integrity perspective.

Nicely done.

This is interesting. Send more pictures!
 
Lots of work... you should have put that effort into something that at the end of the day would be worth something... like a 128.

Yugo racing is right in a way though.... you can talk and think all you want, but in the end you have to spend something on parts ... decking the block down and skimming the head until there's nothing left is the 'compromised' way to build ...

The best way is to follow the five C's as I told you before.

First would be cylinder head, even if you go for a late type 1500 head... that at least has the biggest inlet valve seat throat of all at about 31mm and the largest ports standard... but the flow still tops out at around 85cfm, and drops away after anything above 250thou - 6.5mm of lift... with a little work you can get around 95/100cfm... with a lot of work the tipo heads are capable of over 160cfm

next would be compression, and really the only way to do that is with pistons and / or decking and shaving everything... but then you loose cam timing and belt tension, which is why pistons with taller compression height work better than decking the block by the same value. Big domes have their own drawbacks with ignition and flame propagation

the other way to raise your static CR is with capacity... overbore or stroke for more CC's going into the same sized combustion chamber...

then camshaft... more lift to justify the additional flow that the head has...and more duration to allow for higher cycling rates, but only after the static CR is high enough to not drop dynamic CR

then carburettor... to balance the head and camshaft capabilities...well in your case manifold flow with LPG/EFI.

that's it in a nutshell...and it will require spending some cash...which is probably the sixth C :wink2:

SteveC
 
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I know it has absolutely no worth to it.. Did not wanted to ruin something valuable.. My next project will have..
I think I'm getting the picture engine vise..
Thanks
 
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