Engine tuning - what to do please

[SimonGTV]

Hi all,

Its running fine but I'm planning to have the 2ltr engine tuned in my spider when it's back on the road next month just so it can perform at its best. I'm thinking about tackling it myself provided it's not too much of a dark art?

Ive set the timing myself before but have read if you don't know what you're doing then don't touch the carbs ( I don't know what I'm doing!).

Any tips or guides on what to do or what a pro does would be great so I can judge if it's worth having a go at or am I best leaving it to a pro? Also what sort of money would you pay to have it done professionally.

Also if I do have it done, what things is it a good idea to replace beforehand, air filter, plugs, distributer cap ( it's got accuspark electric points)

Thanks

[CT1]

If it's running ok you can't improve it by playing with the carbs. So long as the plugs are the right colour and it ticks over evenly don't touch. Change the plugs by all means but again if it's running ok leave it, Make sure you replace with the same type as they are particular about their plugs. Air filter yes change if dirty. If it has electronic ignition leave it alone. They perform pretty well without interference.

[Cosmo]

Tinkering with the carbs is one of the joys of Alfa ownership. You get a real sense of achievement when you get it right.

First thing get the timing correct - electronic points are a definite benefit here, or better still a complete electronic dizzy like the 123.

Then you need to balance the carbs to get the same flow through each one. An expert should be able to do this by ear with a listening tube but it is much easier to use a 4 port vacuum gauge. That is also a great indicator of air leaks - check that the rubber mounts aren't leaking by gently lifting the carbs to see if there is a change in the gauge. You also sometimes have problems with the vacuum take off for the brake servo and distributor (if it has vacuum advance).

After balancing the airflow set the mixture on each cylinder using a colortune. It is a see-through spark plug and allows you get the mixture spot on. Again, an expert will do this by hand using the engine revs as a guide but it is so much easier with the colortune. I also have a portable tachometer that I can set up in the engine bay to monitor the engine revs which helps a lot.

It sounds daunting at first but gets a lot easier with practice and the right tools.

[SimonGTV]

thanks, it is running well but i do fancy a tinker!

i'll check out those tools mentioned and see if its cost effective to buy them

thanks

[Erik Loye]

When you have or had it done by someone who knows how to, leave carbs and ignition alone. If you need to adjust the mixture remember to turn each of the four screws same number of clicks in the same direction until you get the fasted idle speed. Lower idle if too fast at the idle screw between the carbs.
Apart from all the good advise you've got, all I'll is give it a good Italian tuneup*) every now and then.
*) A long spirited drive to get rid of all carbon in the combustion cambers and on the valve heads.
Erik

[VeloceMitch]

I'd recommend Bogg Brothers over in East Yorkshire, near Malton if you want to have it sorted professionally. The 'old man' really knows his stuff with Carb engines and will check it out on his Rolling Road. Last time I had it done it coast about 100 quid, but was well worth it. It's a fair trip from Shefield, but wen it's done you will enjoy the run back over the Wolds, I guarantee it

There is nothing stopping you having a fiddle about but always try and remember what settings you had to start with so you can go back to them if you make things worse. Use tricks like winding idle jets right in until they stop and counting the turns will give you an indication of your base positions.

[Cosmo]

Originally Posted by SimonGTV

i'll check out those tools mentioned and see if its cost effective to buy them

You may get lucky at an auto jumble (although it isn't really the season right now) that's where I picked up my spare rev counter from for about a fiver.

Also, have a look on eBay. Lots of people selling Colortunes for about £30, but I note that the newer ones only come in one plug fitting so you need to specify the correct size. Also on eBay you'll find vacuum gauges easily if you add motorcycle to your search. The 4 cylinder ones look to be about £50 for the type with round gauges. The one I have is the Carbtune with vertical bars which makes it very easy to get the balance matched.

Well worth the cost in my opinion.

[SimonGTV]

Thanks folks, i dont mind paying a £100 to get it running at its best but i'll have a play around before it goes in, yes ive seen the items you'ev mentioned on ebay so i'll keep my eyes open for baragins.

Peak Alfa is my nearest specialist and he's very good so i'll probably go there.

I like the Italian tune up though, it gets one of those whenever i can

[karlssondesign]

£285 for 3 hours on rolling road at wilsher garages in cambs = 105bhp from 1300 with just k&ns (alfa quoted 85bhp).

cant beat a good old fashionrd rolling road based tune up.

[SimonGTV]

I hadnt thought about a rolling road but i like the sound of that

Off to find one local!

[Cosmo]

A rolling road tune up is a really good idea when you have changed something from standard, especially in the area of the air flow. Certainly if you had any work done on the head but even going to a less restrictive air filter may benefit.

The advantage over just tinkering with the carbs as I detailed above is that you actually change the carb jetting and measure the result. Keep making changes and test again until you get optimum performance. This is super easy on the Weber DCOE as the jets are under the little Mickey Mouse hat and take just a minute to swap out.

[VeloceMitch]

Originally Posted by SimonGTV

I hadnt thought about a rolling road but i like the sound of that

Off to find one local!

That's why I mentioned Bogg Brothers, a Rolling Road and experience with carbs, lot's of places have rolling roads, but you want one that is used to carb engines. Motoscope at Northallerton also come to mind.

[SimonGTV]

Thanks

Mitch thanks for the tip but thats still a fair distance from me.

Phoned JPAutotechnics who are local after several recomendations on other sites.

He's very familiar with the Alfa engine and Webers, cost is £90 to £140 all in depending on how much adjustment is needed.

I asked about what I could do/replace beforehand to help and he said you don't need to do anything but recommended the K&N air filters which I might get or the Pipercross ones. Anyone have experience of either of these?

Ta

[SimonGTV]

Looking at the K&N, they're £135 plus vat on ClassicAlfa but there's several pairs on eBay for much cheaper.

Does anyone know the specific size I need, they are listed by length, width and depth.

Thanks

[VeloceMitch]

I use K&N's on my 2000GTV, can't remember the length, but it all depends how much space there is between the back of the carb and the inner wings, you want the longer the better as you would get more torque. Ideally you should use ram pipes inside them too (more expense!), though to be fair I'm too cheap to have forked out for them and it goes well enough without. Classic Alfa should be able to advise on length.

A couple of words of warning though, using a free filter like a K&N or Piper Cross will probably mean going up a size or two on the main jets, so your tuner would need to have some to hand and be prepared to exchange them, you could buy in advance but you trial and error is the best way of choosing the jets. When I took mine to Boggs, it was on a standard airbox and just wasn't running right, he quickly identified it has having been jetted for K&N's, took the filter element out and power jumped up 10% or more. It's now fine on K&N's with the bigger jets. Mine was running 120BHP at the wheels after he tweaked it and feels just as strong now two years on.

Also beware these things are noisy, if you want your car as a rorty snarly thing for charging about in, go for them. If it's mainly for touring and a pleasant day out with company you might get tired of the induction roar. Performance difference is marginal and then only if you re-jet.

[SimonGTV]

Thanks,

I do like the idea of the K&N's but the price seems to be creeping up with jets etc and if performance gains are minimal then I might leave it for this time, especially as I need 4 new tyres next month!

Also, I read a thread on Alfabb that said the original air box and stock filter is very good but can easily be improved by drilling more holes in the centre tube so I might try this first.

[VeloceMitch]

Yes that's true, I drilled the one I had on my 1750 and it felt better, sounded better too. The standard airbox (drilled) is a much more 'cultured' sound than K&N's, more in keeping with a Spider IMO

I think you can buy a free flow air filter to go in the standard box too, so that might be worth thinking about.