Alfa Romeo Forums banner

1 - 16 of 16 Posts

·
Registered
1978 Spider
Joined
·
343 Posts
Discussion Starter #1
Well I installed new throttle end links yesterday...and now the engine idles way high...like almost 3K...I obviously did not measure the links correctly when replacing the ends. I thought I had it pretty close. I should have done only ONE rod at a time and test run the engine. It started and idled just fine before.

My initial observation is that the metal end links are "one-sided" meaning you must screw them one full turn when adjusting...so they get longer or shorter one full thread at a time.

The old ones I took off were the plastic type that are "two-sided" in that they only have to be turned 1/2 turn for every adjustment...obviously better for fine tuning since you can change the rod length 1/2 thread at a time.

anyway....I have both Wes Ingram's SPICA book and the AROC Oregon tech article on setting the pump gap (I did NOT touch that, either the external screw nor the one under the TA) and setting the bell crank idle stop screw and short/long rods...but they seem to read a little different to me...plus my TA is gone...there is a Shankle kit installed....

short of just putting the old (and likely brittle) plastic ends back on and trying to reset the lengths...how should I try to re-sync this?
 

·
Premium Member
Joined
·
561 Posts
Best anyway to start from the beginning of the Spica set up procedure and follow the whole thing right through to the end. Confirm that the shankle kit extension is correct for the installed Spica pumps T number. Don't ever adjust the external screw for the pump gap. Ever. If it has been fiddle with already by a PO then the best you can do is an OK tune. Your car runs so that's great. Best to make a dummy actuator for initial set up, then you can also see if your Shankle sure start is shrinking on install too.

Cheers,
 

·
Registered
1978 Spider
Joined
·
343 Posts
Discussion Starter #3
yep..gonna have to do that. Bummer cause it was running smooth up until I put new link ends on...

I hope the pump gap screw wasn't messed with. the tamper cap is gone but I don't think the PO messed with it. Before him, member "Bill" used to own the car.

Definitely need to make a dummy TA.
 

·
Registered
Joined
·
1,348 Posts
I'm not understanding why you need to make a dummy TA.
Put the SureStart in with the tip fully extended and adjust your .019" or less pump gap.
 

·
Registered
1978 Spider
Joined
·
343 Posts
Discussion Starter #5 (Edited)
the surestart is spring loaded...it moves...kinda hard to be 100% sure it doesn't move a teeny bit when adjusting things. every time it's removed to adjust the screw underneath and reinstalled to measure the gap there is some force being exerted against that spring. a dummy TA would be "fixed" and 100% "known" length. But I'm probably worrying over nothing on the shankle.

But that is how the factory does it...a fixed dummy insert. And the Shankle is a "work around" for the proper TA.

now that I think about it...since the TA is gone and the Shankle is in it's place...basically the substitute "TA" is normally at full extention...so the "hot" pump gap setting of .019 would be the same on a dead cold engine in this case...so I just need to adjust that screw under the TA/Shankle until I reach .019 hot or cold or whatever...so long at the shankle is fully extended and lever is fully seated. or should the lever end even be tight? I should probably loosen the cable end at the lever and make the adjustments then tighten the lever end?
 

·
Registered
Joined
·
1,348 Posts
the surestart is spring loaded...it moves...kinda hard to be 100% sure it doesn't move a teeny bit when adjusting things. every time it's removed to adjust the screw underneath and reinstalled to measure the gap there is some force being exerted against that spring. a dummy TA would be "fixed" and 100% "known" length. But I'm probably worrying over nothing on the shankle.

But that is how the factory does it...a fixed dummy insert. And the Shankle is a "work around" for the proper TA.

now that I think about it...since the TA is gone and the Shankle is in it's place...basically the substitute "TA" is normally at full extention...so the "hot" pump gap setting of .019 would be the same on a dead cold engine in this case...so I just need to adjust that screw under the TA/Shankle until I reach .019 hot or cold or whatever...so long at the shankle is fully extended and lever is fully seated. or should the lever end even be tight? I should probably loosen the cable end at the lever and make the adjustments then tighten the lever end?
Okay then.
I wonder why mine works so well?
 

·
Premium Member
Joined
·
561 Posts
Yes, you could use your sure start as a dummy TA if you know it's consistent. You can also use the sure start to do hot settings on a cold engine. You still want a fully warmed up engine to do the final mixture adjustments at 2500 with the FCS.

Cheers,
 

·
Registered
1978 Spider
Joined
·
343 Posts
Discussion Starter #9
started from scratch...removed the links...pump gap was .019" with Shankle lever fully in...I made no changes there at this time.

Two issues I noted...the metal link ends do not thread as far onto the link shafts as the OEM plastic type (a design difference), thus making the short link too long. and the idle limit stop screw was way off from the full throttle limit setting (I read where they should both be the same, but that makes no sense to me as they should be set/adjusted independently).

Anyway, I made the short link as short as possible and then adjusted the idle limit screw to allow the throttle plates to completely close (which was I think the screw being flush in it's bracket in my case). I think the plates are fully closed but I can't adjust it any further at this point with the current short link. I may fashion a shorter short link in the future to better fine tune the idle limit screw and throttle plates.

The long link was adjusted to fit the pump control lever without moving the pump gap.

Also the limit screws are way out of "balance" but seem to allow travel from throttle plates closed to full open...stuck my camera phone down there and tried to get a decent picture. I used a mirror to try to set the full throttle limit screw. I think the throttle plate pics are upside down but not sure.

Fired the car up and idles smoothly again...just like before...As I have read, I put my thumb over the idle air supply port to see if the engine would die...it almost dies but manages to barely stay alive...so I suspect my throttle plates are not "quite" completely closed...again, a new "shorter" short link may allow me to get this just right.
 

Attachments

·
Registered
Joined
·
610 Posts
Those plastic linkage ends look pretty old and ready for retirement.
This is what you need. This is just one style, there are a lot more around.
Just an example.

 

·
Registered
1978 Spider
Joined
·
343 Posts
Discussion Starter #11
that's why I changed mine. hairline cracks are starting. I got metal end links from Classic Alfa. about $12 for a set of 4.

I would prefer the standard plastic ones as they offer twice the adjustment increments as the metal ones. But I have not seen any source of the OEM type end links.

Are the ball joints a "universal" size or is the alfa unique from other makes?
 

·
Premium Member
Joined
·
561 Posts
Hi there, do you have a 27mm or 29mm protrusion spica pump? Your sure start needs to match that before you go for the .019"
You can set your throttle plate stop screws with a machinists protactor like this one, it has a bubble level on the other side. In combination with the angles given in the manual, which I believe you have. It can be tough to hold everything ball joint/pivot centreline.
In your last picture if that is on the full throttle stop, the throttle plates are not full throttle at all. If rigging is way out I've see the leaver on the back of the spica pump that you connect the long rod too, hit it's own max stop.
Another way to see if your throttle plates are closed when the bell crank is on the min stop is, with a warm engine, at idle, you should be able to hold the palm of your hand against an individual intake and have little or no change in rpm. You can also use this to test throttle balance between forward and rear pair.
Nice you got your car fired up and idling smoothly, well done.

Cheers,
 

·
Registered
1978 Spider
Joined
·
343 Posts
Discussion Starter #13
it's a 1978 so pretty sure it's 29mm unless the pump was swapped...unlikely in my opinion.

I can't do the protractor thing since the metal end links result in a too long of a short rod to close the throttles. I would have to either cut the short rod or go back to the old and cracking plastic end links. So for now all I can do is adjust the stop screw to allow the throttle to completely close. This is much more important than getting full throttle I think for now.

Now since the bell crank is not set at the initial 10'...that the rotational arc, starting and finishing degrees relative to the "baseline", of the ball joints may not achieve full throttle with the accelerator pedal linkage travel limits. The camera was not centered perfectly when taking the pictures. It's possible that the throttle plates are moving past full throttle. When using the mirror it did "appear" I could move the bell crank by hand (not pedal) all the way to the stop limit and over rotate the throttle plates. Or am I just seeing a revered picture?

I'll try the palm and individual intake trick to see if there is any perceivable change in idle.

But I think the right way to get everything correct is going to involve either cutting down the short link by a few threads or perhaps better to fabricate a substitute from a long bolt or threaded rod so as not to ruin the original so that I can set the bell crank at the 10 degrees specified and the throttles can still close.
 

·
Registered
1978 Spider
Joined
·
343 Posts
Discussion Starter #14
If rigging is way out I've see the leaver on the back of the spica pump that you connect the long rod too, hit it's own max stop.
yep...you nailed it...SPICA pump is hitting the max stop first. When the long link was disconnected the throttles would go to full open and beyond. So I set the max limit screw and assumed I was good. then I adjusted the long link to match the ball studs and snapped it on...but I didn't re-check the bell crank travel to the max limit after.

so yes, the starting position/angle of the bell crank is as critical as is the total degrees of bell crank rotation.
 

·
Registered
1978 Spider
Joined
·
343 Posts
Discussion Starter #15
Another way to see if your throttle plates are closed when the bell crank is on the min stop is, with a warm engine, at idle, you should be able to hold the palm of your hand against an individual intake and have little or no change in rpm. You can also use this to test throttle balance between forward and rear pair.
Excellent tip...yep, still some suction on the intakes...strong on the rear but nothing really noticeable on the front...definitely need to sync the throttles too. Bummer I just sold my mercury synchronizer (long ago sold my last Japanese bike). Bummer that is seems you can't fully sync the throttles like motorcycles(sync 1&2 separately from 3&4, then balance both synced pairs). only 1/2 & 3/4. On mine #4 is a bit stronger suction than #3 so there is a slight imbalance that may not go away. #1 & #2 feel the same.
 

·
Premium Member
Joined
·
561 Posts
I’ve just used the hand on the intake thing to balance between pairs, if individual pairs are out just means the throttle shaft is twisted. I have a liquid manometer that I’ve tried using by teeing into the four idle hoses but I prefer the hand over the intake method.
 
1 - 16 of 16 Posts
Top