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Can anyone help me identify my conrods?

 
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PostPosted: Thu Jul 29, 2004 9:15 am    Post subject: Can anyone help me identify my conrods? Reply with quote

I have aquired an engine of unknown specification and it requires a new set of rods and a crank to match. The engine has heavily modified cylinder heads with 37mm and 42.5mm valves, at least thats how they seem to measure up, the heads are heavily ported. The pistons appear to be 16V as they have four valve cut-outs. No 1 big end has chewed up and does not look like it will machine up as the bearing has spun in the rod. The rods are marked up SF35, as I have only got 1.5 twin cam rods to compare with I have not been able to identify them, any ideas. I think that the engine may be 16V internals built into an 8V block with 8V heads, I believe that this configuration gives a high compression ratio of 11.5:1 or so. Any help will be gratefully received.
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Lon
Alfasud


Joined: 28 Mar 2003
Posts: 29

PostPosted: Thu Jul 29, 2004 2:07 pm    Post subject: Reply with quote

Maybe you can post a picture of it to help us identify...
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Alfa 33 1.7 S 16v QV '92
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Matt Stolton
Alfa Sprint


Joined: 14 Mar 2003
Posts: 233
Location: London

PostPosted: Thu Jul 29, 2004 11:02 pm    Post subject: Reply with quote

Click here to take you to a site where they describe a engine mod with 37mm exhaust valve. The also describe a 41mm inlet valve, but could be worth a phonecall. AFAIK BLS are still around and racing, so could be a good start in you quest for history.....

With the enlarged valves, it may have been necessary to pocket the pistons for clearance, so they could be normal 8V pistons. If you click on the rest of the article, they do mention using 16V bottom end bolts for extra strength, so it is possible.
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Ex Alfa 33 'GTA' (P4 with Knobs On)
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PostPosted: Fri Jul 30, 2004 8:54 am    Post subject: Thanks for your help Reply with quote

Cheers for your efforts, I am certain that the rods are a standard part from one of the Alfa Boxer engines, I shall take a run up to my mate's workshop where the engine is on the bench and post some photos so you can see them.

Chris
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Sprintervention
Alfasud


Joined: 30 Jul 2004
Posts: 60
Location: York

PostPosted: Fri Jul 30, 2004 7:28 pm    Post subject: Pictures of the rods and pistons Reply with quote

Have taken a couple of photos as you can see below. I have brought a rod home top see if I can find any more useful markings other than the SF35 on the side of the rod. The bores appear to be in the region of 87.13mm and the big end bearing housing is machined out to the region of 52.56mm (this may be larger on other rods as there may be some bearing material welded to the one I picked up!) Looks to me like 1st oversize on the pistons and standard on the bearing housings. The bores still show cross-hatch honing marks so this engine was probably recently fettled before it chewed the bearing.

The pistons look to me to be 16V ones, but then as I have never seen one I really am guessing, any ideas?





Any further help would be really useful.

Chris
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lesthegringo
Alfasud


Joined: 23 Jul 2003
Posts: 97

PostPosted: Sat Jul 31, 2004 9:38 pm    Post subject: not standard 33 16v Reply with quote

The pistons are not the standard 33 16v items - I'll take some pics of mine on monday so you can see

the rods are not bored out for oversize shells - the thickness of the bearing material applied to the inside of the shells determine that.

One thing I have checked is that the 1.5 (84mm bore) and 1.7 16v (87mm bore) conrods are exactly the same length, and are more or less identical except that the 1.5 items have '70' cast / forged into them, whereas the 16v ones have '57'. As far as my research goes (ringing up places like Alfa II, just suds etc) there doesn't seem to be any difference, and they say they use them as if they were all the same. If it is good enough for them, I will not be worrying about the differences!

Les
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Sprintervention
Alfasud


Joined: 30 Jul 2004
Posts: 60
Location: York

PostPosted: Sun Aug 01, 2004 8:10 am    Post subject: Piston identification Reply with quote

I look forward to your pictures so that I can compare the pistons as I have not seen the 16V items.

I realise that the rods are not normally bored oversize but I notice that the Alfa workshop manual supplimement gives the dimension in a wide band of 52.696 - 53.708 , I have also heard of people using big end bearings that are manufactured on a copper backing rather than the white metal used in the 33/sud. I believe that some people have used the bearing from the Guilia range as they are of a much higher quality. The big end bolts are marked S F 12.9, are these 16V?

The rods appear only to be marked SF35 on one side and C on the other. The pistons are marked MP in a circle with a 1 next to it and 3597 on the other side of the gudgeon pin. There is also a 3 with 10 at 90 degrees to it in a circle.

Thanks to all for the help so far.

Chris
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