Alfa Romeo Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
48 Posts
Discussion Starter #1
I recently got a new head for my 82 spider (old one cracked) and the when I installed the cams there was no gap between the lobes and the buckets.

The cams, buckets, and tappets that I used were from the old head and now im worried that my cams might not fit this head or something.

The new head is an 86 or 87, and I took it to a machine shop to get it surfaced and to check if the valves were burnt/ not seating correctly, and they said the valves were great.

There are not extra spacers or shims installed so I am kind of lost.

All of the forums that I read basically pointed to the valves being burnt or not seating right, but wouldint that just make the gap bigger not tight against the lobes? Am I just being dumb and missing something? or do I need all new everything?

:frown2: So close yet so far....
 

Attachments

·
Registered
Joined
·
8,891 Posts

·
Richard Jemison
Joined
·
7,783 Posts
Stop!

First, dont run the engine as it is!
You will need a person with a good collection of adjusting shims to set the valve lash on both cams correctly and likely the cam timing.

Where do you live? The members could probably suggest a proper shop for such work.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #4 (Edited)
are you saying you just used the old shims from the old head and transferred them to the new?
....if so, that won't work.

What are the present shim measurements? (you'll need a micrometer)

If with the smallest shim available (1.300 mm) you still have no gap, then that would be a worry.

Adjusting Valve Clearances

Oooh.....Well first off thanks for the reply!!
Secondly, I was under the impression that all shims were the same size and as the years went buy your valves get shorter (from regrinding and seating) and the springs get less push in them causing the distance between the lobes and the tabbet to increase. And the way to fix this was to buy a type of spacer that went between the shim and the tappet thus closing the gap.

But what you are saying is that the shims are actually varying sizes and I have to figure out what mine are right?

What is the standard shim size? or the size it needs from the factory? because I probably need to buy one of those and see how far off they are and then I can buy all the correct sizes. Or something. Ugh if only there was a gap I could just measure and buy the right shims for them....

And just to be clear the shim is the tiny little bucket (not the big one that covers the spiring) that goes on the end of the valve and it needs to be replaced with one of those circle things from IAP? Right? I just wanna make sure im doing this right.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #5
First, dont run the engine as it is!
You will need a person with a good collection of adjusting shims to set the valve lash on both cams correctly and likely the cam timing.

Where do you live? The members could probably suggest a proper shop for such work.
Dont worry the head hasnt even made it onto the engine yet. Still sitting on the work bench...

I live in utah (which is problably the worst place to house and Alfa becuase of all the salt, and because the weather cant seem to make up its mind so it is rainy and snowy today and tomorrow it is 105 degress out) and I havent heard of any shops that work on alfas yet...
 

·
Premium Member
Joined
·
14,818 Posts
You need a shim that you "know" is too thin and measure the thickness with a micrometer. Put it on one valve at a time and measure the clearance with feeler gauges. Then calculate the thickness of the shim that you need to get the correct clearance. Write it down and repeat for the other valves. I can lend you a thin shim.
 

·
Premium Member
Joined
·
3,776 Posts
Secondly, I was under the impression that all shims were the same size.

And just to be clear the shim is the tiny little bucket (not the big one that covers the spiring) that goes on the end of the valve and it needs to be replaced with one of those circle things from IAP? Right? I just wanna make sure im doing this right.
1. No, the thickness of the shims are not all the same. They vary so you can adjust the valve clearance.

2. Yes, the shim is the small bucket in the centre, not the large bucket. Yes, you will need to purchase the right thickness shim. That circle thing you see when you open the IAP is not the right shim for your year. Its just a picture. When you use the drop down menu for the size, they will send you the small shim bucket.

Its good that the head is on the bench. This eliminates possibility of bent valves.

You will need to measure the current valve clearance, which I believe you have done using feeler guages.

You will need to measure the thickness of the shims as well using a micrometer.

I used this chart to tell me what the size of the required shim I need to use.

View attachment Shim%20Calculator mm.xls

I have set it to your year, clearance.

valve clearances.JPG

To use the chart, you enter the current clearance and the current shim thickness and it will spit out what size you need to use.

I put in examples to show you how it works. For the intake the current clearance is too large and the exhaust is too tight.

Hope it helps.

Good luck,

Vin
 

·
Registered
Joined
·
48 Posts
Discussion Starter #8
1. No, the thickness of the shims are not all the same. They vary so you can adjust the valve clearance.

2. Yes, the shim is the small bucket in the centre, not the large bucket. Yes, you will need to purchase the right thickness shim. That circle thing you see when you open the IAP is not the right shim for your year. Its just a picture. When you use the drop down menu for the size, they will send you the small shim bucket.

Its good that the head is on the bench. This eliminates possibility of bent valves.

You will need to measure the current valve clearance, which I believe you have done using feeler guages.

You will need to measure the thickness of the shims as well using a micrometer.

I used this chart to tell me what the size of the required shim I need to use.

View attachment 793218

I have set it to your year, clearance.

View attachment 793210

To use the chart, you enter the current clearance and the current shim thickness and it will spit out what size you need to use.

I put in examples to show you how it works. For the intake the current clearance is too large and the exhaust is too tight.

Hope it helps.

Good luck,

Vin

Oh my goodness thank you so much yes that helps!!

the only problem now is that there is no clearance, so my plan was to buy a couple small shims and then use those to measure the gap, then buy the correct size shims. I used my friends digital meaure thing (i forgot the name.... kinda embarrassing) and the current shims are
Exhaust: 2.50, 2.16, 2.14, 2.18
Intake: 2.32, 2.06, 2.31, 2.10

So I can defiantly get smaller ones, and hopefully there will be a gap. Thank you!!!
 

·
Premium Member
Joined
·
3,776 Posts
Oh my goodness thank you so much yes that helps!!

the only problem now is that there is no clearance, so my plan was to buy a couple small shims and then use those to measure the gap, then buy the correct size shims. I used my friends digital meaure thing (i forgot the name.... kinda embarrassing) and the current shims are
Exhaust: 2.50, 2.16, 2.14, 2.18
Intake: 2.32, 2.06, 2.31, 2.10

So I can defiantly get smaller ones, and hopefully there will be a gap. Thank you!!!
Glad to help.

Let us know how it works out.

Good luck,

Vin
 

·
Registered
Joined
·
8,891 Posts
you could buy 4 of the smallest shims (1.300 mm) and put those under one camshaft side....those will (hopefully!) give a largish valve gap reading to start with.
*Remember the camshaft needs to be torqued down correctly*

Then work out what size shim you need to get it back up to spec.
*Remember too, as you turn the camshaft to measure each valve gap, that some of the valves will be wide open and stick out from under the head, so you need to protect them!

Then do the other camshaft side in the same manner, re-using those 4 thin shims
 

·
Registered
Joined
·
2,984 Posts
Try the thinnest 2.1 in all 8 spots you might have a gap on some to at lest get a start.


P.S. that xl chart is cool. I do it the old way paper and math.
The first time I did a alfa head I forgot to add the clearance. and got all 8 perfect set to 0.
and had to start over....
 
1 - 11 of 11 Posts
Top