Alfa Romeo Forums banner

1 - 20 of 38 Posts

·
Registered
Joined
·
1,169 Posts
Discussion Starter #1
My rebuilt engine has arrived and when I went to fit the water pump it stands proud about 1-2mm at the bottom edge. I haven't fitted the tacho drive yet and I'm wondering if the bevel gear that engages the tacho drive is too long.

The engine was in pieces when I bought the car and there were several 101 parts amongst everything else. The water pump is the proper rebuilt 750 unit.

The parts catalogue lists part numbers for the intermediate timing sprocket (number 1 in the photo) as

750 engine: 1315.30.704

101 engine: 101.10.03.013.00

My question is this - are they different and could a 101 sprocket have been accidentally fitted?

Thanks, as usual,
Chris
 

Attachments

·
Administrator
Joined
·
3,814 Posts
Chris - can you snap a picture or three of the front timing cover and post them, the early cars had a recess for the pump impeller, the later ones were flat

Also some of the pump, front & from the side

Ciao
Greig
 

·
Registered
Joined
·
1,169 Posts
Discussion Starter #3
Thanks for your help Greig.

I'm away from home for a couple of days with work and will post the photos when I return midweek.

Chris
 

·
Registered
Joined
·
5,980 Posts
Wrong intermediate sprocket at the very least, as your photo seems to show a 105 revcounter drive gear protruding from the front cover. Can you remove the cam cover and look at the sprocket itself? You should be able to see five elongated lightening holes in the rearmost gear and, if not, you might need to have a chat with the bloke who built the engine.
 

·
Premium Member
Joined
·
21,714 Posts
The 750 assembly is shorter, front to back, if I remember right, than the 101/105 type, by a few mm. Or maybe I have it reversed. Anyway, I put the wrong sprocket in the non-matching timing case and had a big front-to-back gap. So the other combo would mean it would protrude.

Andrew
 

·
Registered
Joined
·
816 Posts
Before you pull the whole engine apart, try pulling the tach drive gear out of the shaft. You should be able to change o the shorter gear without much problem.
Keith
Alfas Unlimited
 

·
Registered
Joined
·
1,169 Posts
Discussion Starter #10
OK - thanks so far.

Before I embark on pulling this engine apart, please answer a couple more questions -

Is the timing cover correct?

Is it possible to adapt this sprocket to fit by shortening the tacho drive gear?

Has anyone out there got a 750 sprocket that they are willing to sell?

I have a friend who has a Sprint and now a 101 Spider (I swapped him a few parts a while ago) and unfortunately, he has not got a spare sprocket.

The pitfalls of buying a stripped down basket case ...

Merry Xmas or Happy holidays or whatever,
Chris
 

·
Registered
Joined
·
7,759 Posts
I measured a 750 v. a 101/105 (like yours) and the total length was like .5 mm difference with the 750 shorter. I tried measuring the hole depth on the different water pumps and there didn't seem to be any obvious difference. A compromise might be to put a later water pump on to save all that dismantling. I'd trial fit it first..... and last but not least grind off the end of the drive gear in situ or bore the depth of the pump hole..neither for the faint of heart and implied warranty is strictly a figment of one's imagination.. Uncle. I have a sprocket if you go to plan A. (That is 1/2mm)
 

·
Super Moderator
Joined
·
11,587 Posts
From rebuilding a lot the 750 water pumps, there are at least 3 early variations plus who-knows how many after market replacements. Early 750 (2 snap rings) later 750 (3 snap rings) 750 / 101 variation with 2 snap rings. The intermediate sprocket pictured in your engine appears to be a 101 1300. Uncle, above, seems to confirm my suspicion.
 

·
Registered
Joined
·
1,169 Posts
Discussion Starter #13
Problem sorted, I think.

The front cover brass bush was about 1mm proud so with an appropriate sized socket and some gentle tapping, I drove it in until only the beveled edge was showing. The water pump now fits perfectly with plenty of room for the tacho drive gear on the front of the sprocket.

It seems then that a 101 sprocket is interchangeable with a 750 one though I haven't yet fitted the rest of the tacho drive as I'm waiting on a seal. They are commonly available, I just haven't had time to pick one up yet.

Chris
 

·
Super Moderator
Joined
·
11,587 Posts
Chris, if you source that seal in viton, it will last forever.
 

·
Registered
Joined
·
7,759 Posts
Welcome to the world of basket cases...It is good you found the issue, though. I would never have guessed the solution so we all learned. Unfortunately you were the learner and the teacher. Good luck on the rest of your adventures. Silly mm's can cause a lot of heartburn.
 

·
Registered
Joined
·
1,169 Posts
Discussion Starter #19
Update

I found a secondhand intermediate gear locally and bought it. I also had a spare 101/105 one in the pile of stuff that came with the car and have compared the two side by side. They are dimensionally and functionally identical.

Happy that I don't have to pull the engine apart.

Chris
 

Attachments

·
Super Moderator
Joined
·
11,587 Posts
The one on the right Chris, is a nice 101 1300 assembly. These are identical to later 101 1600, 105 1600 and 1750, except for the lightening holes. For some reason, these seem to hold up a little better than the later solid sprocket intermediates. They used to be favored by racers. They were pretty well made.
 
1 - 20 of 38 Posts
Top