bike carbs on 1.7 340

[guitardudetom]

hi, i was wondering if it is possible to fit bike carbs to the 1.7 340 engine. i have seen it done to the 1.8 16v renault engines. if you can how would you go about attaching them? would i need some sort of custom manifold? thanks tom

[jpv]

I'm going by that route as well...

I haven't had time to study the conversion yet but I already have some things aready mapped out:

- fabricate a new intake manifold
This is obviously necessary due to the new carburettors. It's a simple but long job. You need to take out your standard manifold and make a template of intake holes and bolt holes. Using this template fabricate a steel plate with the correct holes. In this plate you will weld short tubes to conect to the bike carbs.

here is an example:





- fabricate a new exhaust (tubular) manfiold
This will be necessary becuse the standard exaust manifold is bolted to the intake manfiold to heat up the intake air. I prefer to build a tubular, equal length manifold becuse I am thinking performance wise. The fabrication process is similar to the intake manifold described above but the arrangement of the exhaust pipes is much more complicated so you need to talk with a specialist...

here are some photos of examples



I think that you can use a Volvo 440 2 liter exaust manifold that will fit as well (but don't quote me on that, please check this.).

- Install a electric fuel pump
It will be needed almost definitely because I doubt that the standard mechanical fuel pump can pump that much gas to 4 carbs...

If the carbs don't have a fuel return line than you'll need a interrupter fuel pump. This pump will sotp pumping if the carbs fill up the resorvoirs.



If the carbs have a fuel return pipe than you can use a solidstate pump.



- Fabricate an intake plenum
This one is optional but I think it's important. The carbs will work right above the exhaust manifold. They will suck a lot of hot air. It would be best plumb fresh air in to them and fit an air filter as well...





Regards

[classicswede]

You can keep the std 1.7 one but it will cause a restriction and could give issues melting the down pipe with the extra power. The B18u manifold can be fitted and that flows much better than the 1.7 but you will need to adapt the down pipe to fit. The 2ltr has slightly diffent size ports and they are in a slightly differnt position. If you wanted to use the 2ltr 4 series manifold you would have to mod it slightly to fit correctly.

I did have a stainless 4 branch exhaust manifold made but I have since sold it to another forum ember. I could get another one made if you are serious about doing the conversion.

[jpv]

The B18u manifold can be fitted and that flows much better than the 1.7 but you will need to adapt the down pipe to fit.

I think I found a manifold today at the scrapyard. It's from a Volvo 440 Injection rigth? Do you think that the manifold would interfere with any of the 340 hardware (crossmember, chassis legs, LHD steering rack)?

Can I fit this exhaus manifold and keep the standard B172 inlet manifold?

Thanks for the help!

[jpv]

Here is a photo of the 440 exhaust manifold. I don't think that it wll fit with the standard 1.7 carb manifold.



What do you think? Thanks!

[seannaayy]

Dug this up out of the dark ages, just wondering how you got on with this mate?