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Discussion Starter #1
59 1300 spider veloce.750 with 101 head programmable cam's what is the backlash for In. and Ex.
 

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Richard Jemison
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What?

programmable cam's what is the backlash for In. and Ex
.

Well, First you can`t program a cam.... So what cams? Stock Alfa should be .016-.018 int and .018-.019 exh. Aftermarket cams are very different. Generally a function of the base circles and lobe design.
 

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The specs given in the factory manual for the Giulietta Veloce are .015" (.4mm) for intake and .021 (.535mm ) for the exhaust. These will work fine.
 

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Richard, given the buckets are in good shape and fit in the head without wobble and the cams are not worn, I was told by a guru that correcting the gaps won't necessarily quiet down any audible valve noise (tap tap).. Is there a threshold of out of adjustment that when set to specs will quiet them down? like how much out of adjustment will make a difference?
 

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Richard Jemison
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Cam clearances

Again, ignore 101-105 guy`s info. Nothing but assumption...

<edited by staff>

As to lash factory settings are not an absolute even with factory cams.
These have soft "setting & lifting" ramps to reduce wear. As long as your lash setting on either intake and exhaust are above the start of the "slow closing/opening ramp`s beginning point" then the noise from the cam followers bounce can be reduced. If lash is above .016 that is good enough to clear the slow ramp and will quiten the noise. Factory cams are too mild for 3 or 4 thousandths lash change to make a noticable difference, although owners have closed the lash since the beginning of these engines trying to get more duration..

As for the lash suggested by 101/105 only the original 10106 0032 00-00 the 1300 Veloce/SS cam used those lash #s as they were cams without closing ramps. Those cams would be worn out by now. Any regrind / repair would call for a lash setting based on resulting base circle and ramp rate of the new lobe.

If cams are properly identified then lash settings could properly be suggested.
 

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Sorry, those are the factory numbers for factory cams. Not made up.....
Some may prefer different settings for modified cams, but this is what Alfa specs.
 

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Richard Jemison
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Cams

Sorry, those are the factory numbers for factory cams. Not made up.....
Some may prefer different settings for modified cams, but this is what Alfa specs.
Your "assumption" was that they were factory cams. From his engine description it was pretty obvious that the cams would NOT be the 1300 Veloce cams as used in the early 750 engines. That`s why I ask specifically what cams he had, as "programable" doesn`t describe the cams as stock 1958 camshafts.

There were clues that the engine was not original in that the 750 block was fitted with a 101 head as well. If you were knowlegable, you might have known that the 101 head uses camshafts of totally different design than those in 750 heads. Both base circles and lobe position, but obviously you were not aware of such.

Some with experience in engine building have found there are better settings for lash and lobe centers with factory Alfa cams as well, not just modified camshafts or aftermarket cams..
 

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So Richard, my 750 V cams are at intake -16,17.17.19 and exhaust 19, 20,21,19..5000 miles ago. Before I go do this to specs will I expect a quieter valve train or should I not screw with it? We know about sleeping dogs. This is not a race car and performs sweetly. .I need a reward for the t-shirt lead. Arf Arf ,Uncle
 

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Discussion Starter #9
have the 750 block. 7281 stamped on the flange where oil pan bolts to block serial #?small mains. found .020 under main bearings and .010 under rod bearings. 101 head with 9mm valve stems. sprockets on both cams that can be adjusted #76l8 cs.on the cam. lobe around 35mm.front to back I just have a lot of nuts and bolts.question: have a bolt 1.25" long 8mm thread with a adjusting bolt going through it with a straight screwdriver slot where does this thing go. lots more to come.total engine rebuild.
 

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Richard Jemison
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SV camshafts (10106 03200 00)

These cams are difficult to get to run well due to lobe design with lots of overlap.

They came in two applications with different lash settings and different lobe centers.
Neither were happy at low rpms and minor LC changes made for spitting through the carbs at idle and low RPM.

In the Veloce cars the LCs were 104.5 int and 106.5 exh lash .015 and .021.
These settings reduced to total overlap to 64 degrees. (still a bunch!)

In the SS aplication and tuning to higher RPM use and higher idle RPM settings (to keep the motors from blowing out the intake charge) the LCs were 99.5 intake and 105 exhaust with lash settings of .011 int and .019 exh. Total high RPM output was only 10CV more (90 vs 100 cv at 6500 rpm)

Knowing what we know about valve timing events today setting the cams up at a tighter lash to prevent the wear issue on lobes and cam followers and then opening the lobe centers to improve the power curve mwould be a good change.
I would suggest the lash settings be closed to .014 intake and .017 exhaust. (the wider exhaust lash settings were an attempt to keep the old alloy exh valves from burning at the higher RPMs needed for these mouse motors to make any power. If valve components have been upgraded to current metals then that wide lash setting is just increasing wear.
The LSAs for the cams should be widened and the "centers" biased to a position to improve drivability at lower RPM (6500 is not considered high RPM any more.).
An intake LC of 108 and exh LC of 108 would have the cam position "straight up". If you use old school cam timing rule of thumb retarding the cams "centerline" would improve higher RPM output and advancing the centerline would bias the output lower in the RPM range.
For a Twin cam motor retarding the cams centerline (for higher RPM power) could be LCs of 110/106 (but keeping the same LSA of 108 degrees.)
Advancing the centerline similarly would be 106/110

From experience the wider LSA as suggested will give more torque/power with the long runner intakes on the Alfa motor, and with a wider LSA you might need to lean down the idle and main jets a bit.
 

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Richard Jemison
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toprope`s engine

I doubt the 8mm bolt with internal screw came from these engines.
As to cams you need to find a casting # on the cams if there are any. If not measure the base circle and then overall length of the lobes. That length less the base circle measurement will be lift of the lobe. Measure both intake cam and exh cam. The true 106 series veloce cams were different durations .
Post some pictures of the cams.
 

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Discussion Starter #12
got my head back from valve job.he reversed the cams. where is the back lash measured whidest point or some where else? ken 440-897-8718 cell#
 

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Richard Jemison
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Cams

Lash is measured between the heel of the cam and cam follower.

How are you going to set them if you don`t know what they are??

With the questions you are asking, you need to think about getting someone knowledgable to work on your motor. Just an observation.............
 

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Discussion Starter #14
so true. I measured back lash on the intake. first two were .034&.028 next two both .016 plus the cams were reversed. been building 2 strokes racing outboards since75 gramps started napa in ohio 1921 good info does the trick for me.have pics don't know how to insert
 

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Discussion Starter #16
I doubt the 8mm bolt with internal screw came from these engines.
As to cams you need to find a casting # on the cams if there are any. If not measure the base circle and then overall length of the lobes. That length less the base circle measurement will be lift of the lobe. Measure both intake cam and exh cam. The true 106 series veloce cams were different durations .
Post some pictures of the cams.
toe to heal of lobe is around 35mm C/L of cam to toe around 21mm I believe the circle you are talking about is26.5 dia. I've built a lot of racing 2 stroke outboards first time for cams.
 

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Richard Jemison
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Cams

toe to heal of lobe is around 35mm C/L of cam to toe around 21mm I believe the circle you are talking about is26.5 dia.
27.5mm (+-)is STOCK cam BCs. If you measure the centerline of these you will get about the same or a few thousandths more. If you are measuring yours and you get 21mm you don`t have stock cams. They are obviously reground cams so lash will be VERY different from stock.
However if your measurements were "accurate" then 35mm less 21mm means lift is 14mm and that "just ain`t right". There is no clearance for cams with this lift in these small heads. (Or any alfa head) Period.

Again, either you are not measuring with an accurate device, or as stated earlier, you should get competent assistance.
 
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