Help, need to get this car running 8v with 40mm solex carbs.

[Minty_Fresh]

The long story short is a buddy of mine has acquired a $500 rabbit

motor in the rabbit is a JH 8v with 288 TT cam with head work to match and we got a hold of some cheap solex 40mm carbs to replace the trashed CIS.

i know this is one of those your in over your head situations but when in the end neither of us lack mechanical knowledge just don't know anything when it comes to carbs. from searching (and mostly roaring the FAQ) I've came across lots of different information.

Many threads describe solex carbs to be a lot like webers but in other threads i see different information. so I'm going to break my questions into different categories.

Fueling.
the FAQ states that the Carter rotary pump is a good choice but in any builds and threads i find with solex carbs it seems people like to use aftermarket pumps with a regulator set around 10PSI. the carter pump is around 4psi. will the carter pump be a solid choice and the higher pressure in other systems are to over come the lack of volume?

as far as the factory pump goes just bypass it all, leave the intake pump operational, and run a relay to the new pump? (mostly because the factory wiring is pretty hacked on this car)

for a filter can just any type of inline universal filter be used? just cap the return

ignition.
right now factory distributer is in place, with a MSD blaster coil. will this be enough or should after market ignition be installed? as far as the factory vacuum advance goes I've heard on duel draft setups you cant run vacuum advance.

tuning.
yea, no clue. there is a local guy who is known for tuning air cooled's. so we will try to see how he can help us out. but id like to have the car ready to go before taking it to some one. but just for the sake of is what are some good links to read up on?
the carbs came off of a running 8v. they are compel with everything. so what are the chances that damage will happen if we do try and fire it and mess with it our selves?

thank you.

[VenaGTi]

Fueling.
the FAQ states that the Carter rotary pump is a good choice but in any builds and threads i find with solex carbs it seems people like to use aftermarket pumps with a regulator set around 10PSI. the carter pump is around 4psi. will the carter pump be a solid choice and the higher pressure in other systems are to over come the lack of volume?

What kind of solexes?
Most recommend 2.75 to 4.5 for the mikuni which is solex. at 10psi, you will blow every seal out.
No carb I know of takes 10. 3psi will work in all but the most outrageous race engines.

as far as the factory pump goes just bypass it all, leave the intake pump operational, and run a relay to the new pump? (mostly because the factory wiring is pretty hacked on this car)

Pull the factory pump. Your rabbit has only one pump outside the tank. It runs at 80psi. Needs to go. Wire your new pump anyway you like. Relay or straight switch, as long as you remember to shut it of. Stock wiring will work.

for a filter can just any type of inline universal filter be used? just cap the return

Inline low pressure filter, pre regulator in engine compartment. Cheap.

ignition.
right now factory distributer is in place, with a MSD blaster coil. will this be enough or should after market ignition be installed? as far as the factory vacuum advance goes I've heard on duel draft setups you cant run vacuum advance.

stock ignition will work, but as you note, there will be no advance because you will lack port vacuum. Msd timing computer(8980?) to a 6al box combined with the stock icu, or one of their newer offerings(features combined into one unit) will do the trick.

tuning.
yea, no clue. there is a local guy who is known for tuning air cooled's. so we will try to see how he can help us out. but id like to have the car ready to go before taking it to some one. but just for the sake of is what are some good links to read up on?
the carbs came off of a running 8v. they are compel with everything. so what are the chances that damage will happen if we do try and fire it and mess with it our selves?

Ha! Get everything else set up and re-read the FAQ's and then come back. Get the book for the carbs you have.

good luck.

[Minty_Fresh]

stock ignition will work, but as you note, there will be no advance because you will lack port vacuum. Msd timing computer(8980?) to a 6al box combined with the stock icu, or one of their newer offerings(features combined into one unit) will do the trick.

there are vacuum ports on the manifold we have but like stated they won't work?

are there any tricks to running with out vacuum advance?


thank you so much.

[VenaGTi]

the port on your manifold is for brake vac. port vac is different, it's for advance and doesn't exist with sidedrafts. 6al box with 8980 timing controler would do, but that's old school now. they sell a single unit that does the work of the two, or get the old boxes used and fire it up.

[ca180]

I've got Solex C40 ADDHE's... which is what I assume you have, and I'm pretty sure there are vac ports on the carbs themselves that you can use for the advance reference.

Good luck! I still haven't gotten mine going cause I had to replace one of the bearings on the throttle shaft....

[Minty_Fresh]

the port on your manifold is for brake vac. port vac is different, it's for advance and doesn't exist with sidedrafts. 6al box with 8980 timing controler would do, but that's old school now. they sell a single unit that does the work of the two, or get the old boxes used and fire it up.

there is the large port for the brake booster, and then 4-5 smaller ports. pre and post butterfly.

[B4S]

VW vac advance distributors have centrifugal AND vac advance. Without vac, you will still get a timing curve, you'll just lose out on a few extra mpgs. Some carbs have the ported vac reference required too, you need to research solex carbs to find out.

You're in for a headache with those IMO, the tuning parts are hard to find.

[VenaGTi]

side drafts with port vac? I thought that was theoretically impossible without an intake plenum. The big port on the intake mani is for the brake, the other smaller ones on the mani are intended for tuning sticks. you have pre-butterfly vac ports?

[Minty_Fresh]

side drafts with port vac? I thought that was theoretically impossible without an intake plenum. The big port on the intake mani is for the brake, the other smaller ones on the mani are intended for tuning sticks. you have pre-butterfly vac ports?

the carbs are at my buddys house but if i remember correctly there is 1 pre butter fly port and a couple post.

[Minty_Fresh]

VW vac advance distributors have centrifugal AND vac advance. Without vac, you will still get a timing curve, you'll just lose out on a few extra mpgs. Some carbs have the ported vac reference required too, you need to research solex carbs to find out.

You're in for a headache with those IMO, the tuning parts are hard to find.

i thought you could use jets and parts from Mikuni carbs?

[ca180]

the carbs are at my buddys house but if i remember correctly there is 1 pre butter fly port and a couple post.

I just went and checked mine and oddly enough only one of the six I have has the port...

i thought you could use jets and parts from Mikuni carbs?

I spoke with a company called RMCarburetors (I think it was them) and they said the Mikuni stuff was not compatible... but if you check ebay.de or italy or even .co.uk you can find a load of Solex stuff....

[VenaGTi]

isn't that your mixture screw right there? doesn't that go on the intake side?

[B4S]

side drafts with port vac? I thought that was theoretically impossible without an intake plenum. The big port on the intake mani is for the brake, the other smaller ones on the mani are intended for tuning sticks. you have pre-butterfly vac ports?

75% of the sidedraft carbs on the market were made and sold as OE equipment on cars in the 70s when smog rules were getting stronger. They're known as emissions carbs and usually have a single ported-vac port to run the vac dizzies. They also ran a signal buffer inline, to calm down the pulsing due to getting the signal from one runner.

[B4S]

i thought you could use jets and parts from Mikuni carbs?

Certain models, yes. Mikuni bought the blueprints for some of the later solex carbs, and then went through a couple of design changes on their own. Some mikuni carbs can use jets from bike carbs, but I don't think the solexs can. Certain mikuni parts are definitely NLA, unless you're lucky, like emulsion tubes, chokes, etc. Wolf Creek racing has a large stock though, and they're good folks.

Solex parts can sometimes be found on Alfa romeo sites, since they did use them as OE equip in the 70s. Ebay too.

[B4S]

I just went and checked mine and oddly enough only one of the six I have has the port...

That's a ported vac port for a vac advance dizzy. In a matched set of carbs, there will be a single port. The OE stuff always had that, and the universal webers don't. That's where folks get mixed up. All sidedraft carbs are NOT the same .

[ca180]

That's a ported vac port for a vac advance dizzy. In a matched set of carbs, there will be a single port. The OE stuff always had that, and the universal webers don't. That's where folks get mixed up. All sidedraft carbs are NOT the same .

Yeah, that's what i was trying to depict... The dizzy port....

Anyways, I have 6 total and two are matching numbers.. but the matching number set doesnt have it oddly enough.

[B4S]

Might have come from a pre-smog car, before the gas panic in the 70s. Pre-smog carbs are the best .

[ca180]

Might have come from a pre-smog car, before the gas panic in the 70s. Pre-smog carbs are the best .

Interesting!

Sorry to derail your thread OP

[VenaGTi]

well......mr. b4s rears his ugly head! i stand corrected. when are you gonna help me jet me carbs right? first time i ever saw that on a sidedraft. i guess plug in and go!

[B4S]

Ugly? I prefer beauty-challenged .

[VenaGTi]

what happened to you? i heard you sold all your carbs and ran away and joined a convent? or went megasquirt? same difference.....

[B4S]

Haha, nothing so extreme. I'd been working on understanding the code in the ABA OBD1 ecu since 09, and wanted to play with it a bit more, so I swapped and boosted my rabbit on the factory ecu . It's in my sig, OBD1 is now tuneable like megasquirt .

I've got a stock of carbs still, but I'm on the hunt for a set of tri-jet DHLAs before I swap back .

[der hare]

Go on eBay and search solex Addhe and there's a guy in Italy who has rebuild kits, jets, chokes, etc.

Had to go thru him for my parts.