2.0 8v Bike Carb Manifold. Homebuild.

[8valve-craig]

Gauging interest. After loads of messing about with my nova decided the only way of getting it to run right is to run it on carbs.

The whole thing has been a budget build. 92 "j" nova £200, rebuilt seh, (with kent AST15 cam, - Belt and vs37 springs), £150. along with all the usual Gsi interior, dash, Bumpers, skirts £100. Sport 15" steels with toyo 45's £50, Full magnex with de-cat and 4 branch £50

Not to mention however at least 50hours fully stitch welding and strengthening

You get the idea. I dont like to put a lot of money into it.

So just recently bought a set of FZR1000 mikuni 38mm carbs which are very very similar to the R1's (without the price tag). Came in at £29 delivered.

Started today to fabricate an inlet manifold, just out of mild steel with the MIG.

Just gauging interst really as to weather it deserves a thread. quite happy to take pics and post if theres a bit of interest

[run_pug]

yea ad like to see a thread on this, av got a 2,0 8v in ma corsa that i would love to run on carbs so wuld be good to see how its done cheaply

[8valve-craig]

yea ad like to see a thread on this, av got a 2,0 8v in ma corsa that i would love to run on carbs so wuld be good to see how its done cheaply

ok well il get some pics up along the way then. Basically to start with i was looking at having an inlet flange laser cut from a manifold gasket, Visited a few places and it seems about £40 for the first one then about £8 each there after. As i only want one and im a little tight this is not very appealing to me

Decided that if i make it myself out of thinner steel (4mm) theres a bit of money to be saved. I know that it is likely to warp under the heat of welding, but with a few more holes drilled near the ports (as well as the 10 for the studs) it will be well and truly screwed down to a piece of timber. Hopefully this will stop it from distorting.

Now there are two choices, The carbs have 38mm chokes and the tube im planning on using has a 38mm internal diameter. The first hurdle is that the seh head has just 33mm ports. So i can either port the head or use smaller tube,

Neither of these are very appealing, porting the head will be a pain in the ass as im using a mock up head, so will in effect have to do it twice.
And using smaller diameter tube will just strangle the carbs. The answer is to construct 4 individual pieces of tube which are 38mm at the carb end and 33mm at the entrance to the port.

This will also have what i believe to be a positive effect to the induction. Pics to follow

[8valve-craig]

Hoping to get the inlets and stud locations punched out today, Local steel fabricaters.



Started working on one of the runners. The four slits obviously aid shaping the end of the tube down to 33mm. All will be welded up and smoothed off inside and out. Hopefully there will be no sign of them when the manifold is complete



Obviously its early days. Once all the holes are punched out i will screw it upright to a block of wood and make a little jig up for carb spacing to aim all the runners at.

[run_pug]

quality mate al keep ma eye on this one, good luck

[8valve-craig]

The idea of having the port holes punched out fell through as there wasnt enough space around the outside to clamp it down. Could have started again from a larger piece of steel and cut it down after the holes were punced but decided to keep with this one. (further saving a tenner i would have given the guy to do the holes)

Went back to the school days and cut them out by hand. Using good old maths.



got one of the runners pretty much there, can now be sealed up and tacked into place



When meausuring up for the rest of the runners am very plesed to find that the middle two have exactly the same spacing as the 8v head. thus meaning that the ports 2 and 3 can have straight pipe simply angled upwards and not needing to angle inwards.

will be doing a bit more tomorrow evening. Cost of manifold so far £3 for a hole cutter and £3.60 for gasket to work from

[corsadonk]

You should of said I can squash pipe on my van, I'm more than willing to help.

[8valve-craig]

You should of said I can squash pipe on my van, I'm more than willing to help.

Interesting. The only problem i see with squashing it is that when its cut at an angle , as is required, the internal bore becomes an oval shape. The only way to keep it circular is to manipulate it very carefully with grips, Closing up the slits and then re cutting them. There is a lot of trial and error involved

Its good your up for helping, How are you with installing megajolt / EDIS ? Im not farmiliar with it atall, but once its up and running on the dizzy that will be a closely followed next step

[8valve-craig]

I take it you dont mean your corsavan? as that would be impressive

[corsadonk]

It does this to pipe.

[corsadonk]

Megajolt wise it ain't too bad, but I never tested it.

[8valve-craig]

Megajolt wise it ain't too bad, but I never tested it.

Soz dont understand the post?

Pipe squashing machine sure looks a handy tool mind. Just makes a bit too much of a step for what i need. Looking to keep the induction as smooth as possible.

[8valve-craig]

Spent 5 hours on the manifold today, got the flange cut out and screwed to a big block of timber



Welded up the slits in reduced part of runner #3



All smoothed off inside and out and welded up to flange



Thought it best to add another screw between port 2 and 3. Really do not want the flange to warp and with it only being 4mm seeing how hot it was getting under welding (obviously) i wanted as many fixings as possible.



Started on runner #2, Trial fitted before welding.



All welded up, angle and distance Checked, checked, and checked again



Trial fitted carbs, Very pleased



Float bowls will be spot on level too which is a great relief



So far so good. Have spent 9 hours and £46 including the carbs and rubbers. I have used no specialist tools, Just a welder, grinder, dremmel, digital vernier, Cordless drill and steel ruler.

The hardest bit is done, getting the flange made from scratch and the angle of the carbs correct, The two outside runners will need a bit of thinking But i reckon another 3 or 4 hours and it will be ready for a pressure test.

Finished item will be sprayed silver with heat proof galvanise coating.

All comments welcome, good and bad

[corsadonk]

Good stuff. Has the 8V head got a water port?

[8valve-craig]

Good stuff. Has the 8V head got a water port?

I hope not! Nah Theres not one on the 8v, Just the alternator bracket, (Which hopefully will be cut off and re-used)

off topic,,,,, How did you get on trial fitting the wilwoods? Happy? Money was all spent today, on bills and a tax disc

(how the other half live ey)

[corsadonk]

They went ok, but they catch on the inside of the spokes. I think I've spent nearly as much on a car I don't own, this week, as it cost to buy my daily runner

[8valve-craig]

Ah i know the feeling. Got the nova 8v and astra GTE swallowing up all funds, Not to mention the LET rebuild. Daily corsa needed taxing today and mot 22nd this month.

Vauxhall enthusiasm is an illness.

[8valve-craig]

No progress on the manifold for the last few days, Been busy with other stuff. I did manage to get a manual choke lever and cable from early nova in the breakers today though. Another tick to the shopping list.....

[8valve-craig]

Got the carbs mounted up and fixed on to runners 2 and 3 with the yamaha clips today, Put in place the straight sections for 1 and 4.



Then welded in some tempory supports to hold them in their correct locations while i aim the runners at them as they need to taper inwards. I know it doesnt look very pretty anymore and the light is making them look uneven but i assure you (if anyones actually reading this) that they are all level and in line.



Than "corsadonk" turned up and i kind of got a bit sidetracked so it was left like this, until hopefully completion this thursday evening

[Joker]

nice thread mate, Pure home building goin on there. I've just bought a set up for my xe, r1 carbs, inlet and distributor, pump n everything needed. Will be interested once they arrive to have a play with them.

Joker

[8valve-craig]

If you dont mind me asking,,, How much did you pay for it all? I wouldnt imagine it was cheap.... Im hoping to bring mine in for under £100.

Ive got the dizzy to get me started Bargain at £15 from the scrappy a few months back but once its running ok it'l be going on megajolt /edis. (obviously not included in the £100 budget),



So far it all stands at about £65, Just need a bike fuel pump and some air filters.

[8valve-craig]

so finally got a few hours to work on the manifold today and have now got it very nearly finished, Just a little more welding, grinding and painting and it'l be ready to fit



Got runners 1 and 4 in, welded up the joins for the straight sections and smoothed inside and out. Cant properly smooth until the tempory braces are removed



Just need to weld the runners to the flange now and tidy it all up. fitted the carbs and took LOTS of measurements. They are perfectly level in every way possible so when all cleaned up they should look pretty tidy under the bonnet





If i was to give any advice to somebody wishing to do this themselfs it would be that you can never take too many measurements.

I can also understand why bogg brothers charge £200 for a pretty aluminium one. Almost seems quite reasonable now

[corsadonk]

Fairplay nearly done, I've got a R1 pump you can have it just needs to be re-coned, you can get a repair kit for them.

[8valve-craig]

Ahh that would be great mike, am watching a fzr1000 pump which matches the carbs at the moment, but R1 would do the trick if you just want beer money... You got any air filters?

just looking through todays progress... amature mistake... forgot the brake servo vacume take off

[8valve-craig]

Finished all the fabrication today, Just needs a lick of paint now.









Pretty much all done now, will overhaul and re-jet the carbs, paint the manifold and post a few more pics when fitted, Sometime this week hopefuly