Twin Carbs

Throttle linkage - either an off the shelf or a hand made one. Then you will more than likely need a session with your local rolling road operator, because the chokes and jets will all need tailoring to your engine and they will more than likely have to fiddle with progression drillings to get part throttle running sorted out. This is more important than you may think - you don't want to end up with a big hole in the middle of the throttle response. You may also need to look to your dizzy, if it has vacum advance. That will more than likely be very tricky to get working on a 1 choke per cylinder engine. Lastly, will the carbs and manifold fit your installation ? Most CVH engines in a transverse installation have DCNF because of limited space.

Hopefully Dave Baker will be along in a moment to give the correct advice - this is all amatuer advice. Twin carbs look and sound fantastic, but I sometimes wish my locost didn't have them - throttles bodies and mapped ignition and fuelling management are the way to go if you want the drivability that you're probably used to.

Wouldn't cost much more than £150 to convert to a mapped injection system on throttle bodies. Get a Megasquirt engine management system for $130, weld some injector bosses to the inlet manifold and use the twin carbs as throttle bodies..

Thanks For the advice, yes they will fit in the engine bay. I would like to have fuel injection but I am only a student and connot afford the price of them. The car I am puting twin carbs on had a dodgy carb already so i dont think it could get much worse.

I'm afraid with twin carbs it can get much much worse.

ooops

Ford CVH

Twin 40's

i feel an XR2 Rob and bolton moment here

Good job I do an average of 25 miles a week - Tops - in the locost.

Nick raved thus:

:: Hey, :: :: I have recently bought some twin 40 DHLA Carbs, Can anyone give me :: some advice on what i would require to fit them onto my CVH engine. :: I already have the manifold and air filters for them.

'leccy fuel pump, like a Facet. The carbs will foul the mechanical fuel pump.

Bob Sherunckle raved thus:

:: Lastly, will the carbs and manifold fit your installation ? Most CVH :: engines in a transverse installation have DCNF because of limited :: space.

Good point. I squeezed a pair of DHLA into my mk3 Escort years ago, but forget a big airbox; you're looking at trumpets and socks...

Thank for the help, people say that lots of problems can occur when fitting twin carbs, what sort of problems will i be facing?

In order of most annoying:

Dont bother fitting them til you have rebuilt the carbs with new needles and gaskets, and correct float heights, checking the throttle shafts arent twisted.. Trust me yoou'll save alot of hassle later.

Initial danger of a pillock who doesnt know what he is doing setting them up, high labour, and several hours on the rolling road (£££), plus sorting secondary problems whilst setting the carbs up on the 'road, like overheating, timing, throttle linkage etc etc etc and general ripping you off at the setting up stage, which *will* take serveral hours. If you are pretty mechanically minded and can sort alot of the problems yourself rather than paying the 'road operator to do it, that will save you afair bit.

Hassles getting the vacuum advance to work properly and the spark somewhere in the right place at all loads and throttle positions with the clockwork distrubutor.

Propensity to go off tune most weeks. Necessity to retune them for summer running.

Variable cold start performance and icing up in cold weather unless you use a ducted airbox.

Danger of fuel vapourisation on hot days in slow traffic with inadequate air flow. ( FPR and return line helps enormoously here)

I would *seriously* look again at DIY fuel injection / mapped ignition; its so much easier, and carbs are really past it now.

Tim..

Agreed.

Carbs are rubbish in the extreme. A modern fuel injection system is better in every way !

Thanks for all of that, it helps to know what im gonna be facing. Would like fuel injection but it's too expencive for me, I can afford to shell out £2000+ all at once, unless there are cheeper ways about?

By far the cheapest and easiest way, is to just fit a fuel injected engine !

If you already have a CVH engine, then just swap it for one from an XR2i or similar. Expect to pay a few hundred quid for the lump, and another couple of hundred quid to get it fitted if you can't do it yourself.

What car and engine do you have right now ?

At the moment I have a 1600 cvh carb, Ford Escort GL. Is it possible to just get the Injection system off an XR3i and put it onto mine?

Go and find yourself an XR3i then, and just swap the whole engine over.

No idea :)

If you want to use the MFI setup then either get the whole engine or the MFI cylinder head complete with inlet manifold/ injectors etc and plumb it all in- you'll need the MFI fuel tank and pump, accumulator and filter and several meters of high pressure line, and the complete engine bay wiring loom. This isnt an overly hard swap, most plugs straight in. The carb and MFI cylinder heads are different, so its best to use the complete MFI engine or a known good cylinder head (preferably a hemi, not lean burn) on your engine. Get the MFI dizzy- dont use the standard carb one.

OR (this is preferable)

Get a complete EFI CVH with engine bay wiring loom and manifolds etc. Best without the ECU and use a home mappable ECU (could be a pro type like Weber Alpha, or Emerald, etc or a megasquirt- alot of ppl have had excellant results with these and they're cheap) and use it to drive the Ford injection system.

Which route you choose to go try to use the EFI exhaust manifold- its much better flowing than any other of the CVH ones. If you are using the engine north south instead of transverse, you can cut it and weld the elbow back on to face the right way.

Tim..