VX pulley again

[Pope1]

I'd like to hear from those that have actually been able to fit one of the Evocars pulleys. I know some people have had belt problems and Hamish managed to fit one quite easily but what about everyone else? I've had one sitting around for ages waiting for me to put my car back together. Now it's finally happening I've been advised not make the VX pulley any smaller. Does anyone have any stories (either good or bad) to tell about this conversion?

Thanks.

Chris

[Fingers]

I'll let you know how I get on with mine after I've received some bits from Hamish, and he'd e the person to ask, he's had the new pulley on for a while so he should've seen by now if there were going to be any adverse effects. I have read in the Guy Croft book that it's safe to do, and I think you could probably trust him, he seems to be the authority on the twin cam.

[Pope1]

Actually Guy suggested in a recent e-mail to me that I should not do it but I have not been able to find out from him yet whether I should not do it at all or whether I should not use a particular supplier's pulley. My engine was modified by Guy and I have a copy of his book so perhaps some further research on my part is called for.

Please let me know how you get on though.

[Hamish]

I chatted with GC about this about the time that I added the 'overdrive' pulley to Mario and he reckoned that the crank shaft pulley would be the better option for modification - it was 2 years ago so I don't recall exactly why but I'm sure GC would tell you. Might have had something to do with the bearings in the blower but as my blowers were low mileage and had been carefully checked I saw no problems with fitting the pulley. It's probably also a much cheaper alternative to a different crank pulley which would be a tad more expensive to fit or produce.
I had no difficulties with the installation whatsoever using a standard VX belt tensioner - it took any slack and ran perfectly for the 10K miles I did in the car before (sadly :cry: ) having to part with it.
My only thoughts on the problems associated with this modification are fuel related. You do need to re-jet the standard carb or even better swap it for a 40DCNF - I did both as I had the bits to hand. The DCNF modification is a revelation in conjunction with the 'overdrive' pulley or even on its own on an otherwise standard VX engine. Highly recommended :wink: Before long I played around with the head etc and reverted to a standard (but brand new) VX carb. With the pulley the car was desperate for more fuelling especially with a 'heavy' right foot.
I took the car to a rolling road and they re-jetted the carb to suit the engine - not expensive, think it was about the best £95 I spent. Naturally, you'd need to do the same with a 40DCNF - GCs' book has the 'starting' point choke and jet sizes to get you started.

[Wallace]

Persumably, as you're making the blower pulley smaller, it's going to have less contact area with the belt and go through a tighter bend radius - which can't be a good thing for belt life given that it's going to run a bit harder as well.

But unless the thing flies off and lunches itself in the cambelt, is this a problem ?? !!

W.

[Pope1]

All Guy said in his last e-mail to me is that it is not advisable to make the blower pulley smaller because there is little enough wrap as it is. Have not been able to discuss this further with him since then.

On the subject of fuelling, Guy did some head work, fitted a 40 DCNF to my car and set everything up on a rolling road before it left the UK. However, the car always ran rich here at anything less than 60 mph or above for the 2 years that I had it on the road. I've just got it going after a rest of 6 years and the mixture still appears to be very rich at low revs. I have an oxygen sensor that I intend to fit as soon as I get rid of the crap and the carb cleaner that is in the current tank of fuel. I plan to monitor what is happening mixture-wise in real-world running conditions before I mess with the jets. Don't think that anyone here has a rolling road but I have to investigate further what the rally guys do to set their cars up.

Hamish, did you fit a new tensioner and belt when you fitted the pulley? BW at Evocars claimed the pulley was good for a 20BHP increase when I bought it many moons ago. Was that consistent with your experience? What sort of numbers did you seen on the rolling road?

[Hamish]

Yes, I fitted a brand new tensioner and belt at the same time ( was rebuilding the engine anyway) and had no problems whatsoever :wink:
I cannot see that the 'wrap issue' really exsists.... fair comment the actual diamater of the pulley is marginally reduced - but it's not excessive. I seem to remember that BWE/Evocars offered a different/larger tensioner to help take up any additional slack (making the whole process quite expensive for what you actually got) but I found that with a new standard VX item from Betacar it all worked tickity boo.
As far as a 20hp gain - I don't think so :? Response is quite dramatic compared to standard, certainly the car 'went' a lot better. Sadly I didn't rolling road it as standard (would have served as a useful benchmark) but with a Fiat Strada 130TC/Abarth inlet camshaft, the blower overdrive pulley and a 40 DCNF the rolling road recorded approx 120bhp at the wheels (anyone work out what that translates to at the flywheel :?: ), latterly with a new standard carb and standard cams this dropped to about 92 bhp but since parting with Mario I have binned all the print outs so these figures are from memory :roll:

[Otto-valvole-per-tutte]

I recently had a go with a friend in his Cpe VX that had a 2000IE gearbox fitted and the car really went like stink.

Much more responsive then with the VX gearbox.

Cheap and easy mod i think?

Just a thought ... :roll:

[Hamish]

Odd, I thought they were pretty much the same other than 5th gear..... :?: VX box is definately better for cruising, doesn't seem too shabby off the mark either :twisted:

[Pope1]

Hamish,

My guess is that you were probably getting about 150-160 BHP which is pretty good for the changes that you made.

Can anyone tell me how many revs their VX engine is showing at 60mph in 5'th with the VX box please? I had to fit a gearbox from another VX to my car and I'm wondering whether the gearing in 5'th is correct. I think it's probably just me getting old and not being able to remember properly what the car was like but....

Chris

[wellingtonvx]

Hi Chris,

My VX shows 2500 RPM @ 100 kph in 5th (should be close to 60 mph)
Had to test this out today since I like 4th better :D
(and 5000 RPM @ 160 kph in 4th :twisted: )

Colin

[Pope1]

Thanks Colin. Seems about the same as mine but my car just "feels" like it needs an extra gear. I guess I've got used to the intergalactic gearing of my everyday VW.

[andybeta]

The gearing of the VX box was 22.4mph per 1000rpm in 5th, red lining at 5,500 giving a theoretical top speed of 123.3mph.

The 2000ie had a gearing of 19.4mph per 1000rpm red lining at the same 5,500rpm and a notional top speed of 106.7mph, but I think this figure is too conservative.

With 6,000rpm red line top speeds become 134.4mph for the VX and 116.4pmh for the IE. The Ie and normally apirated 2000 gearing were pretty much identical.

Hope this of help,

Andybeta

[Pope1]

Cheers Andy, very useful. I definitely have a VX box.

[chrisc]

A top speed of 123 eh. well in that case mine (and my friends alfa) speedos are out.....

[Fingers]

Of course they are, they're Italian, I've only ever owned FIATs and Lancias and none of the speedos have been accurate above 100kph, infact my old FIAT 132 used to read 20kph higher than my 124 Sport at 150kph, and the 124 was higher than my next 124, but that's why we love them eh!

[Will]

The deal with the belt is that from an engineering standpoint, I believe you'll find making making the blower pulley smaller increases the tensile load on the belt significantly more than making the crank pulley larger.
Sadly, it's a lot cheaper to make the Vx pulley than the crank! And, of course fewer teeth and tighter radius.
There's also the question of which drive you are using, Gilmer or HTD.
-Will

[Pope1]

Sorry to be dense but please explain Gilmer and HTD.

[Will]

The later volumexes use the HTD (High Torque Drive) type belts/pulleys, this is the one with half-round teeth close together. Supposedly this is both quieter and more durable than the square drive (early) type belts. I can't fill you in on the specifics, I've only seen them a few times and never used them. Could make the difference though as far as being able to reduce pulley size on the blower significantly. I don't know for sure how much, or what the new bend radius could be- Vx pulley is already pretty small. Doing an internet search for HTD belts/pulleys might help you make a determination.

-Will

[Pope1]

Will,

Thanks once again. My belt is the square tooth design. My intention was not to reduce the pulley size significantly, in fact, the pulley that I have only has one tooth less than standard so I don't think that it will make a huge difference to the bend radius. However, if the existing radius is on the limit then of course that last little bit could be the straw...

I've spoken to Guy Croft about this and his view is that it is not good engineering practice to make that wheel smaller. Everyone agrees that maeking the crank pulley bigger would be better and we all know why that has not been done. Guy's view is that people have fitted the smaller pulley and have managed to get away with it but it is not something that he would recommend as a good practice. Hence, my approach is to try and find out how many people have done it and determine how many have had problems like belts jumping or breaking before deciding whether to chance it myself.

Chris

[Will]

....IMO you can listen to the naysayers, or just do it. What's the downside, it eats belts? Big deal, you are out the cost of a belt, then switch it back.
Assuming the pulley you have uses the same taper-and collet arrangement, it's easy enough to switch. You may have to change the tensioner center as well to get one that has more eccentric to take up the additional slack in a stock belt, or sleeve the pulley, I don't know.
If it fails, maybe you'll have to clean a little black residue out of your engine compartment, but so what? I might take the precaution of putting in a shield to guard the timing belt from a flying SC belt if a) I was running a 3/4" belt on the SC and b) also had an aluminum flywheel but otherwise, I'd say go for it.
If you are running a 1" belt on the SC, you should be good to go. You might want to carry a spare in case your belt gets chewed up, because your car won't go without one. However, a stripped supercharger belt is likely to make a mess and smell bad, but not likely to do any real damage unlies it flies off into the timing belt. The SC will just wind down on its own. I have a crate volumetrico motor, which has the larger blower, and it was run w/ a 3/4" square-tooth belt. Yes, this is how it came from ABARTH. A larger belt could be fitted, but wasn't. No belt wear on that motor's 10K miles, when I got it.
I'm not in any position to tell you what you should do, but I know what I would do.
-Will

[Pope1]

Will, we're pretty much on the same track with this issue. I have a 3/4" belt at the moment and my car has been off the road for 6 years so a 1" belt swap is on the cards anyway. I'm just trying to deal with all my other issues before I go and up the boost so I will probably leave that towards the end. I also want to fit a boost gauge before I make any changes and I should probably check out the supercharger bearings too. Afterwards fuelling may be an issue so I plan to monitor what is going on with an oxygen sensor in the exhaust. I guess the final decision will come when I get the existing wheel off and compare the sizes of the two pulleys together.

[Will]

...if it's only one tooth smaller, you are talking about something nominal like 7~8 percent or so boost increase, fueling should not be an issue, would be similar to running the system in cold air. Likewise, detonation should not be an issue, a moderate boost increase like that should still leave you well within limits, especially with the volumex dished pistons. The volumetrico has flat pistons and very smal valve cutouts, overall a higher CR than the volumex and still no ping issue, and I suspect the distributors are one and the same, although I haven't had the dizzy bench mapped as of yet. Be glad to offer the results when I do, for comparison.
Incidentally, the bearings at the front of the volumex (the ones that really count, are loaded by the belt) are difficult to source and require making a fixture to locate the rotors so you can get the beast reassembled. I would leave them alone if they still feel smooth and not "crunchy". The tail end bearings are available at your standard transmission supply house, I got mine from Beardslee along with the seals for the front shaft and tail bearings- I have the information for that posted over on the FIAT_TC_Motors group on yahoo, in the files section.
IMO going to the 1" belt should provide an adequate margin of strength for the small drive ratio increase, and while a boost gauge is handy to check things like vacuum at idle, you may not have much opportunity to observe it at WOT- which, of course, is the only time the manifold is under boost. I have yet to see one with a "maximum" pointer, I thought about putting a schrader valve in line with a "push to bleed" (reset) solenoid.
My boost gauge is best used for diagnosing vacuum leaks.
-Will

[Hamish]

Folks,
I was speaking to a friend of mine who is a better qualified than I with regard to belts ands pulleys. He tells me the VX pulley system is neither Gilmer nor HTD, it is 3/8 automotive pitch. This is apparently unique and has a different pitch line differential to other trapezoidal 3/8" pitch belts. They are not interchangeable, which is why it could be said that unlress the firm/engineer producing an overdrive pulley knows the correct 'co-ordiantes' for 3/8 automotive pitch then the final product they produce will not engage in the belts correctly :evil:
The supposition has been that the overdrive pulley from BWE/Evocars was machined with HTD in mind...... so therefore wrong.
Now, I've said it before and I'll say it again - mine ran fine without any problems. One point I would make is that I was a bit careful with belts - everything got changed once a year and I changed oil religously every 5k miles, so I took the opportunity to check the blower belt tension at the same time.
I had no problems :wink:

Now, fuelling. I speak from experience as far as fuelling on a Beta VX goes with an overdrive pulley. You do need to change mixtures/get the carb set up properly with the overdive pulley fitted - as I've said before the better option (simply for the gain in performance as a whole) is a 40DCNF instead of the rather asthmatic standard carb. Without setting even the standard carb up right the engine starves of fuel under heavy loads - and yes, before anyone asks the rest of the fuel system was in optimum condition, it would be a pointless exercise otherwise!!

[Will]

Feel like a moron, I've been so wrapped up in FI that I wasn't even thinking about carbs when I wrote "like running in cold air". Duh!
Yeah, I dunno what you'd have to do with carbs, assume stepping up the mains might be in order. I'll defer to Hamish on that one. I've been so closely looking at FI and volumetricos lately, I'm slow to change gears!
-Will

[Fingers]

I have finally got around to fitting the Evocars supplied pulley, and thanks to Hamish got the trapeziodal crank and power steering pulleys too. It ws a bit of a mission getting the pulley off the supercharger, the other 2 just pulled of, but I needed a puller for the sc. The whole process only took about an hour, not including running off to work for the puller. I haven't driven it much since and can't really test it around my residentail living area, but it's definitely a little quicker. The only thing I don't like is that the old supercharger whine is almost gone.

[Guy Croft]

Hi good people.
Just a small word of caution. When the belt goes, the blower can - and I've seen it happen - go out of phase and smash itself to pieces.

Freewheeling steel rotors at high engine speed do not present not a happy scenario, even the Lancia supplement refers to this unfortunate phenomenon if I'm not mistaken.

GC

[Fingers]

Yes it does mention that, it also says that you shouldn't actually remove the supercharger pulley in service, it says that you can mess up the position of the rotors, but I see from the blower overhaul on your site Guy that this shouldn't be possible, as there are large nuts holding the synchronising gears in place. Is this right?

[Will]

...blowing a belt in and of itself should NOT cause the rotors to go out of phase. There are two very simple reasons for this. The first is that there is no load on the SC if the belt breaks, it should just wind down.
Second, even if the belt were to somehow get lodged in such a fashion as to hang up the pulley, the collet should slip BEFORE the gears, that's what it is designed for.
This is assuming that your blower was assembled correctly, and the pulley is not frozen on. If you have any doubts, remove it and clean the inside of it and the shaft with scotch-brite or fine sandpaper, and if you are really paranoid, you can use a tiny bit of anti-seize or cosmalene on the mating surfaces. If you do this, mark the pulley and the shaft so you can double-check for slippage after a couple of big downshifts. The boys at ABARTH marked everything with that trademark white and pink paint.
The bigger blowers have no such collet taper, they pressure fit on a shoulder under massive compression. I think the theory there is that they probably have enough momentum to just snap the belt, and they also have bigger gears.

Forgot to mention earlier- belts are also a lot stronger today than 25 years ago. May seem obvious, but warrants mentioning. Most motors today go 100K miles on the SAME belt.

I have no doubt that other things could whack the rotors- say, a throttle plate screw getting inhaled by the blower- or even perhaps a bearing malfunction. Also, watch the lengths of the screws on the manifolds!!!


If you do have to take it apart, you'll need a reliable, strong way to reposition the rotors at exactly 90 degrees from each other. I made my own fixture for one of the bigger blowers for about $15 in materials, photos in the photo section. You could employ the same technique for the smaller blowers, took me about three hours to make it, but could realistically be done in under an hour with solder and angle iron handy.
Sorry, can't loan you mine. Won't fit the standard Vx.




-Will

[Hamish]

Interesting comment about the whine from the blower 'vanishing'...... I found that when I re-built the engine in 'Mario' with all new belts/tensioners etc etc I didn't have the right tool to set the blower belt tension, so it whined loudly 8O I got a loan from somone else of the right Lancia tool and bingo presto hey.... the whine vanished :P so I sort of work on the principal that if it's whining the belt is too tight.
Anyone care to comment :?:

[Pope1]

That's worrying, mine has quite a whine.

[Fingers]

Sorry, I meant was the rotor whine was a lot quieter. It's not belt noise, got that the first time I tried to change this pulley and realised I had a different belt. I've made sure I tensioned it correctly this time, have a factory service suppliment for the VX, the belt when tensioned correctly should yield 14mm ±.5 on the longest part of the run(between sc and power steering pump) with a 5.35 kg load applied, I even used a spring balance. You can definitely hear that it's spinning faster.

[Pope1]

Fingers, thanks I understood what you were saying. The concern about mine is in relation to Hamish's theory about it whiniing when the belt is too tight.

[Hamish]

I've heard noisy blowers before, usually not a lot to worry about :wink: But there's always the possibility that there's a bearing on the way out. I'm sure we discussed this before, but it is worthwhile draining out the blower lubrication oil and replacing with nice new oil whilst checking the blower belt tension :mrgreen:
There's always going to be some mechanical noise with a blower (silly comment I know :oops: ) but I've never known a VX blower to be very noisy when in good health - some whining is acceptable...... If it's annoying rather than worrying, take off the airbox and fit a cone filter to some 'plumbing' fed to the carb..... the induction noise will take your mind of the blower :twisted:

[Pope1]

Hamish, once again you've shown yourself to be a man of the world with a wealth of experience :wink:

My blower seems to make more noise than I remember but, as I've said before, six years have gone by without hearing in on the road so I'm not sure any more. I've already changed the oil and I'm due to tackle all the belts when time allows. I'll see what it's like after that.

Don't think that the long rest will have done the bearings much harm as the engine was turned over many times during that period.

[Will]

.....your whine might go away after you've used it for a while, or if you spray it with carb cleaner. I've noticed tha volumexes built up a "giraffe pattern" sludge of varnish on the surface of the rotors that may contribute to the whine. Liquid paraffin (lamop oil) cleans this off well, but you have to split the blower to use this. Likewise, corrosion on the pulleys, even a little bit, can make for a noisy belt. You can check for noisy bearings by turning the unit by hand- if I remember correctly, the bearings in the tail end of the unit are susceptible to contamination from fuel mixture getting sucked through by the evacuator pump. At any rate, they are readily available at transmission shops around here.

-Will

[Pope1]

Many thanks for that Will. I'm trying to avoid taking it apart unless I have to. At present I am still restoring various bit of the car but have it to the stage where I usually take it for short runs (2-5 miles) about once every 10 days. It's due a precautionary belt change soon so will investigate further at that stage.

[rossocorsa]

far from unusual for italian speedos to be 10 mph plus out at these speeds although this seems to apply to fiat era cars more than those built before

[ismith007]

whilst on this topic, it has been suggested to me that changing the venturis in that wonderful DCA carb on the Vx to 28mm rather than 26mm is worthwhile. as this is a whole lot cheaper than a DCNF or DCNVH i was wondering has anyone out there tried it?