Rebuilding my 1.7 8v

[streamz]

So I took the Sud out for a track day and on the last run of the day I gave my little 1.7 a bit too much of a thrashing. I was sitting at 8000RPM up the hill and something let go. I came into the pits with what sounded like sheet metal being dragged under the car. Something is definitely loose in the sump.

Nothing has come out through the block. Any guesses what I'll find when i take the sump off? Hopefully its rebuildable.

The engine is the 1.7 hydraulic tappet carbed motor out of a 33.

[Veesix75]

Con rod bearings/shells?

Surprised it didn't lock up though

Could be busted rings but I'd go with shells.

[streamz]

correct!. Curiosty got me and I opened it up tonight. Bearing shell remnants in the sump. Nothing else looks damaged. Whats the recommend course of action. Pull it apart check tolerances. Will the crank need a regrind?

[Veesix75]

hmm...slightly optomistic on nothing else damaged.

whichever shell failed, expect a crank regrind (polish minimum) and a con rod ruined.

hopefully no piston hitting valves depending if the shells overlapped in the conrod.

[Marlow Sud]

Everything looks remarkably intact apart from the bits of metal in the sump. You must have caught it quickly. Do keep us up to speed on each step of your investigations and thanks for sharing so far.

All the best,
Simon

[KevJTD]

is it just the angle of the pic or does con-rod No.1 look bent?

agreed with above, could well be nasty once the caps are removed but equally lucky that everything is still bolted together!

[streamz]

thanks for the comments, i'll keep you updated. I'll start stripping the engine down tomorrow. What's the availability of conrods like? I have two spare 1.5 motors. Is anything interchangeable from them?

I think its just the angle of the pic that makes the conrod look bent. It all looked straight when I was under there.

[Marlow Sud]

So you have 87mm pistons and 72mm stroke giving you a 1712cc motor.
You have two spare 1490cc motors.

Why not stick a 1490cc crank with a 67.2mm throw in your 1712cc motor to give you a 1598.6cc over square zinger? The SC has this engine and produces 157bhp at 7000rpm.

No idea on much of the detail in terms of conrod lengths, skimming the block etc but lots of clever people on this site who do.

All the best,
Simon

[streamz]

So you have 87mm pistons and 72mm stroke giving you a 1712cc motor.
You have two spare 1490cc motors.

Why not stick a 1490cc crank with a 67.2mm throw in your 1712cc motor to give you a 1598.6cc over square zinger? The SC has this engine and produces 157bhp at 7000rpm.

No idea on much of the detail in terms of conrod lengths, skimming the block etc but lots of clever people on this site who do.

All the best,
Simon

this sounds very tempting. I'd like to know more.

[streamz]

got the engine out and heads off today. Not good news the inlet valve is bent on the cylinder with the failed bearing.

[streamz]

The bent valve and piston contact.

[Veesix75]

What are the spec of the 1500 engines?

You could rebuild he 1700/1600 using mechanical cams from the 1500 if single lobe which might be better than hydraulic . You will need valves also.

[streamz]

I have a 1500 twin carb mech tappet engine from a 33 and the original engine from the sud which is 1500 single twin throat webber mech tappet.

Are the cam boxes interchangeable with the 1700 heads?

Where is the best source for new valves? Will i need to replace the valve guides?

[streamz]

Engine numbers are

1.7 Motor - AR30550 0032452
1.5 Twin Carb - AR30588 0019816
1.5 Single Carb -AS30124 0098211

[Veesix75]

The cam boxes from a 1500 will fit 1700 heads, but you would preferably want the single lobe 105bhp 1500 cams also.

If doing the above then the valves I think are a different length than the hydraulic head valves so you may need a full set. I can't remember on valves so someone else might reply.

I don't know the engine numbers but just take the cam covers off, it's easy to identify a dual lobe cam as it has just that, two lobes with an adjuster in the middle. The single lobe cam uses shims for adjustment. A single carb engine is most likely twin lobe, a twin carb engine could be either, but 95bhp motors were twin lobe and 105bhp single lobe.....hence using the single lobe as I'm told it has a slightly higher lift.

[Veesix75]

To confuse things even further, I have an engine with 1700 heads, with 1500 single lobe cams and cam carriers and 38mm valves, it was done that way by an Alfa specialist in the uk, it gave more torque. It is a very lightly tuned engine, more 'road' in spec.

[streamz]

What would I need to do to use the 1500 crank in the 1700 block with the 1700 heads? Can I use the 1.7 pistons or 1.5 pistons? or a mixture of 1.7 and 1.5 pistons and conrods?

[Veesix75]

1700 Pistons in a 1700 block, they are larger than a 1500 (87mm 1700, 84mm 1500).

The piston looks like it will clean up in the pic, is it badly damaged?

[streamz]

Ok so 1500 crank in 1700 block with 1500 standard size crank journals. 1700 pistons and conrods will make a 1600 engine. No need to deck the block to adjust compression?

The piston has a groove where it contacted the valve. Should I just smooth out the rough edges?

[streamz]

I've managed to get a second hand crank out of a 145 1.6L which I believe has the same crank. So I'll put the motor back to stock.

[rsfruitbat]

Ok so 1500 crank in 1700 block with 1500 standard size crank journals. 1700 pistons and conrods will make a 1600 engine. No need to deck the block to adjust compression?

The piston has a groove where it contacted the valve. Should I just smooth out the rough edges?

This is the same format as the old engine out of my rallycar which is sat under my bench if you get stuck. Gave about a 100BHP at the wheels on carbs and a dizzy.

From what I can recollect the rods in the 1500 and 1700 are the same length. 16V rods do have a stronger bolt if you can get hold of them. A simple conversion is to get your rods rethreaded to take ARP bolts.

good luck rsfruitbat

[streamz]

Engine is dismantled. Pretty nasty damage on bearing number 2. There wasn't much left of the bearing.

[streamz]

Measured the crank from the 146 engine and it's been ground! I need .010 undersize bearings. I wonder if its been re nitrited? anyway to tell?

[streamz]

Well it appears the conrods in the 146 are slightly different to the 1.7 motor. They have extra metal on the end cap and the small end oil hole is different.

Anyone have a spare 1.7 8v conrod they want to part with?

[Alfasixnut]

Well it appears the conrods in the 146 are slightly different to the 1.7 motor. They have extra metal on the end cap and the small end oil hole is different.

Anyone have a spare 1.7 8v conrod they want to part with?

IMG_20160521_151240.jpg

Isn't the extra metal on the end cap just there to get the balancing of the set of rods correct?

[streamz]

Well it appears the conrods in the 146 are slightly different to the 1.7 motor. They have extra metal on the end cap and the small end oil hole is different.

Anyone have a spare 1.7 8v conrod they want to part with?

IMG_20160521_151240.jpg

Isn't the extra metal on the end cap just there to get the balancing of the set of rods correct?

Possibly but its a significant difference in size. Also the small end bearing has a different oiling slot. Incidentally the 1.7 conrods have more metal but weigh less than the 1.6 conrods. I think for the sake of my time putting it all together and finding it's unbalanced its better to put a correct 1.7 conrod in.

[streamz]

Today i removed one head from my 1500 twin carb motor and compared it the my 1700 head and as far as i can tell its identical. Even the valves seem to be the same length and size.

I checked the valves to make sure they have a good seal by filling the combustion chamber with fuel and blowing compressed air into the intake and exhaust and there were no bubbles in the fuel so I think instead or replacing the valves and valve guides in the 1700 head I'll just use the 1500 head.

[bobkelso]

Hi, interesting comparison beetwen engine parts.

Are you saying that the mechanical tappets head of 1500 Twin carb AR30588 have
the same combustion chamber design and valves diameters of the 1.7 hydraulic tappets engine?

What about camshaft? I thinked the 1500 AR30588 mechanical tappets camshaft
was a bit wilder than the 1700 hydraulic tappets camshaft but not sure about..

What about head exaust holes diameter ?

Also the valves length seems the same despite mechanical / hydraulic heads?

Ok..I 'm a bit interested

[streamz]

Yep the Mech tappet 1500 head is the same as the 1700 hydraulic tappet head. I measured the exhaust ports and they are the same diameter. Same combustion chamber design, diameter and depth. I havn't looked at the camshaft in the 1700 cam box yet.

I do know the 1500 and 1700 motors have different length timing belts. Not sure where the difference comes from. Perhaps just the cam pulley differences?

I'll take a pic tonight of them side by side

[bobkelso]

.. different length timing belts is from different cam box length,
hydraulic tappets need more space
(may be also valves lenght could vary 1-2 mm?? not sure about this,
also if they have same diameter, the valves of the two head type
have different alfa code spares)
but your comparaison is interesting, if the in / exaust ports are similar
it seams you can directly apply the 1500 head to the 1700 block and
you have a similar configuration to the very first 1700 were produced
for only fews months before they adopt the more quiet hydraulic heads,
they had mechanical tappets (+2cv for less friction and better behavior at high rev.)
and a bit wilder cams (maybe another +2cv at high rev but less torque at low rev),
something some people like for a soft tuned 1700 boxer engine..