Engine: 2.1 Carb B21A: Twin carbs

[Chesh740R]

Well with the cost of carbs and the constant adjustment needed, then surely what is really needed then is a set of Throttle bodies. Properly mapped they'll never need as much tinkering and they'll deliver a fantastic sound as well.

[Steve and his 244]

Nah, I dont have the time for doing the modification, its not as easily reversible, its not period (the whole "Thor" theme...) and wouldnt be as epic IMO.

[classicswede]

Hi Steve,

there are more options available. You could build a manifold to take twin 1 3/4 su's or strombergs. The other option would be a single webber conversion. Well know amoungst old school engine builders is that dellorto's make just slightly less max HP than webbers but fuel consumption is better. As a rule webbers for race dellortos for road. Dont forget always run with ram pipes and cleaners.

You would be better swapping to a 405 head and wleing up the injector holes. Cam wise I would go for a k or H cam for good town manners. I have a H cam in my 2.1 on LPG and that is perfectly fine on K jet. Your oringinal exhaust will be quite restrictive for this kind of set up and will need changing for something better. A good 4 branch and well build system is the answer. If built correctly sound levels can be kept low without giving too much restriction. The other thing to consider is the advance curve of your distributor will not be ideal. It is possible to adjust by adding to the weights or removing.

If you are spending out on teh head I'd recomend fitting bigger valves (as per R sport) but this would depend on your budget for teh project.

[myatt1972]

Hi steve, I might have a couple of SU's at work. I was gonna put them on my Rx7 but went down the turbo route. I will have a look when Im back at work on monday.
Keith...

[john h]

Steve,

On twin 45 webers, with no internal engine mods, I'd have a guess at 125 -130bhp and 13-16 mpg (maybe 18 or 20mpg on a steady motorway run).

At mid-range revs, you'll get fairly good torque and a crisp throttle response. Cold-start and low speed town driving will be lumpy and it may have a tendency to foul plugs.

At high revs, there will be a little power gain, but less than you might think because the standard cam profile is designed to work with the breathing and fuel supply of the standard single carb.

You will need to change to an extractor manifold and a free flowing exhaust system to get the benefits of big carbs. To make more power, the engine needs to be able to breathe-in and breathe-out better.

As a very rough comparator, the 2 litre Fiat Mirafiori twin-cam goes from 115bhp on its standard, 2-choke single carb, to about 145bhp with twin 45 webers + extractor manifold + free-flow 2.5 inch exhaust system. Fuel econony (driven quite hard) goes from mid 20s to about 16mpg.

Have you considered throttle bodies, with mapped injection? They look and sound like carbs, but are vastly more efficient. You'd get about the same power as webers, but better fuel economy than you get now. They are not cheap, but don't underestimate the cost of webers - they're either expensive or need a rebuild (or sometimes both!).

Cheers

John

[Clan]

fit a B23A or E simple and cheap :-)
if you are tuning a car you start with the manufacturers most powerful engine and if thats not enough you go from there ... you would find a turbocharger the best starting point too for real power . but you are too young the insurance will hurt ... and i know you dont really want to go that far ;-)

[Steve and his 244]

I definitely definitely dont want to change the engine. That engine belongs in THAT car and I dont want to make it so unoriginal. Plus I dont have the facilities to change and engine and I dont have anywhere to store the original.

Im probably going to go with a set of solex carbs the same as would have come in the R sport kit (the same as FoggyJames has in his 343). I dont want to change the exhaust either.

Im happy to take advice, but its twin carbs and a cam, or leave it as standard.

Definitely dont want throttle bodies - they do make sense, but the kind of "Theme" going on with Thor is period/genuine volvo so throttle bodies would be completely out of place

One other option if I go with the twin solex carbs are that because its the sameas the genuine volvo kit, Im hoping when I tell the insurance, itll sound much better saying "ive fitted a genuine volvo mild tuning upgrade" as opposed to "ive rammed some aftermarket twin carbs on there"

Steve

[loki_the_glt]

Originally Posted by Steve and his 244

One other option if I go with the twin solex carbs are that because its the sameas the genuine volvo kit, Im hoping when I tell the insurance, itll sound much better saying "ive fitted a genuine volvo mild tuning upgrade" as opposed to "ive rammed some aftermarket twin carbs on there"

Steve

Don't bet on it - I couldn't get a sensible quote from one insurancer/supermarket, where every little helps, for SFSS because - Wait for it, Drum roll - it had a factory tow-bar and I had installed the factory auxiliary gauge pack from Sven the Station Vagen into, thereby affecting the performance and standardness of the car! Was I amused?

[OldBlueVolvo]

Maybe you should check with the insurers first. My insurers were not happy when I told them that I had fitted genuine Volvo alloy wheels. Not only that but I had fitted them all by myself! They got back to me a day or two later and said that they were okay with it.

I know this is a long-term project but I look forward to seeing the pictures when it's done.

[Rich 264]

Have you thought about just leaving Thor as he is and getting a cheap GLT to play around with?

At least that way you already have a 2.3 and a reliable 140bhp (nearly) straight out of the box?