You'd be better off without the progressive ICTs are fine, but I'd go for a CSP centremount linkage, if they do one for type 4s.
Sorted For the record, I tried the CB crossbar linkage and didn't really like it. It's well made, but...it's still got that crossbar. CSP much simpler and a doddle to set up.
I still have the CB crossbar linkage on my 40IDFs, the crossbar isn’t really a problem on a Type 4 but I have a CSP bell crank linkage in the box of bits to fit when I get aroundtoit.
@Milky its your van so obviously it’s your choice, I’ll tell you my experience, I had badly worn stock solex carbs, I decided that I was going to fit a centre mount progressive carb, I found one on eBay which was nearly new and had come from a camper with the same engine as mine a 2ltr T4 bay, it was terrible the van ran like a bag of Marmite, I changed to Weber twin 34ict s , they are brilliant
Completely disagree. I had mine running quite nicely. Wasn’t great when cold/winter but once warm was fine.
Also you need to have a dizzy with a vac otherwise you end up with flat spot. Also get it rolling roaded if you can as the standard jets will be crap. If needs be I can attempt to tell you the jets I had fitted but it was suited to my engine so may differ with yours.
I call that ‘reasonably well’. A good carb setup will run very nicely whether it’s hot or cold and a single progressive can't do that.
A progressive can be made to work quite well on a T1 engine where all the heat is available to stop the big puddle of petrol forming in the manifold and destroying any attempt at tuning on a T4. But its a lot of work. You do get low end torque with the longer runners on a T1 engine with a centre mount carburettor, and at wide open throttle there is as much flow as a pair of ICT34's. On a T4, if somebody finds a progressive carburettor makes their bus better, it must have been really bad before. Did that bus run happily at 70mph like any well set up T4 should ? If it only pootled around at 50mph and was driven gently, it doesnt even need 4 cylinders working to keep up that speed , three will do OK. The progressive looks a cheap option but its a waste of time diversion on a T4. Any solution with a carburettor per cylinder (dual twin) will beat any solution with one carburettor each side (dual single) which beats one carburettor. The problem with the splitting of the inlet manifold after the carburettor with dual single barrel carburettors (ICT's) , is the way the cylinders suck the mixture immediately after each other with a long gap, so one cylinder gets a different mixture. With a centre mount where it is not even in the centre, there is another asymmetry. So the result is what I found on my progressive - the spark plugs come out different colours because there is a difference. My setup probably dropped a valve because the rear No4 cylinder ended up lean because No3 had just had all the mixture. It also did not help that after 50000 miles , the spindles wore out the crude steel on aluminium bearings in the carburettor and started air leaks round the spindles. So yes, I have just re-bushed a progressive carburettor. Spend the money , do it properly and may your engine live long and prosper. Apologies for a rant but ..
Ive never been one for pootling and my eperience was the opposit of what you describe. Low end was ok but not as good as twins. Mid range was ok but not as good as twins.... top end ie higher speed motorway cruising was better id say. Dare insay it was noticeably quicker. That said Whe i had larger vents in my dells then my description of the prog would be about right. I am much happier with my current set up. That said id love to xperiment with a pair of progressives on short manifolds!
Indeed I have. And I did have the dreaded flat spot and chased a cure for about 5 years finally I gave up and went to Peter Baldwin’s Rolling road and had it tuned and the result was fantastic it’s been absolutely faultless since drives smoothly and relatively economically I use the bus as my daily as well as ridiculously overloaded long holiday drives the only fault I’ve ever had since the RR was I knocked the electric choke wire off whilst I was replacing the snail fan relay. The only regret I’ve had is not getting it tuned/set up on the rolling road in the first place. Sent from my iPhone using Tapatalk
I’m glad youve had success with you progressive carb, I tried and I tried but I just couldn’t get my van to run right, I ditched it last year and fitted twin Weber 34 icts and it’s a new beast, it runs like a dream
