GTI ones fit but don’t expect huge gains, no point in going more than 266 – 270 deg. would suggest looking at a Newman cam there resonably priced and no vernier is needed to time them up properly as they are cut at 110 deg like the VW cams and not the 106 deg like Kent and Piper, personally I would recomend a 270 Newman, there is no point going for more than 270 with GU head and syncro downpipe, it don’t work
Keeping the GU head and fitting a sharper cam is a waste of money, as you will only get about 1/2 the power it would make when fitted with a GTI head!
other thing i noticed with gu heads the valves bounce at lower rpm than gti heads but that may have been due to mialage wear on springs
The valve springs are identical for all the 8V 1800 motors, btw there is both an inner & outer spring, you did have them both fitted didn’t you Danny?
I don’t know chris, I built my last GU engine with very little care from bits I found in the garage and fitted it the same day and thrashed it for 6mths til it gave up!
I never quite worked out how it lasted that long, had a serious thirst for oil but it pulled well to about 6100 – 6300 then gave up gti used to pull on to just over 7
Can I get a bit more info on blocking the injector holes on the PB head please.
Sounds like it might be my next move as well …. anyone done a PB head with twin 40’s 
Remove injector seat, insert 1p coin refit injector seat, job done
GTi lumps on twin 40’s have been done plenty, twin 40’s are very outdated now tho and the setup has a few major flaws on the 8v engine, it’s so tight you’ll only just get the filters in, forget ram pipes, and the brake servo gets in the way so you have to cut it defeating the point in fitting them. bike carbs however work much better, its also worth fittng an early gti ( k – jet dizzy )
Thanks for that dannyp. I thought that 40’s would be a tight fit but didn’t realise they’d be that tight, I think I’ll give them a miss then and just go for the PB head and single weber.
Is a k-jet dizzy an improvement over the standard one then? I’d not heard of that and might even have a spare one lying around somewhere.
Has the K-jet dizzy got the vacuum advance then?
yes and a better advance curve than the gu item
Sounds a good swap to me then.
is there any diference between the bottom end of a gti say pb engine code engine and the gu engines that the syncro use or is it just the head that is the main difenance between the engines. thanks
Just the Head and the Fuel & spark delivery systems (carb or injection, with or without motor management computer)
On my car I’ve got a GU bottom end, with a rattly old PB head fitted to it, with a Weber and the shaved-down hedgehog DannyP’s mentioned. I’m running a standard GTI cam at the moment, but this might change before next spring.
The injector port blocking mod really is as simple as it sounds – 4p and you’re away. The head all just bolts up, but you will need to use the Syncro exhaust, including the exhaust manifold, unless you’re going to get seriously involved (isn’t that right, Danny?).
About the only thing I’m not running at the moment is a k-Jet dizzi – it’s definitely something I’m on the look-out for and with a cam should form a sort of ‘stage 1’ complete Syncro upgrade (for tightwads).
To be honest, all of these improvements have been done over an extended period, so I’ve not really noticed that much difference. The biggest (and cheapest) difference anyone will make to their Syncro out of the box is to jettison as much trim and stuff from the interior as possible. I’ve removed most of the interior from mine, so much so that it rose over an inch on the springs! This may sound like something of a dumb solution for someone using their car every day, but as a toy it’s given my motor a massive boost in speed.
The best other modification is the Weber – not only does the car breathe massively better and thus goes better, mine also gained about 10mpg vs the Pierburg.
The GU motor & the 8v GTI share the same bottom end, while the GX motor has a different (reduced from 10 to 1 to 9 to 1 compression ratio) piston so is not as good a bet as the GU for tuning.