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im doing the dcoe with solex 40mm, same as the webers. awhile ago someone had a post saying what the manifold needed to be, like runner lenghts, runner angles,.... i have a friend that just opened up a perforance shop and he said he'll help me made the manifold. he was wondering if anyone had a "blueprint" that could help.
zach :help:
The manifold needs to be tipped down about 10-15° to compensate for the forward tip in the engine. I used 2" as a runner length, its more a space issue then anything. I cut the flange off a stock carb manifold for the engine side and bought some precut flanges for the carbs from pierce manifolds. I eyeballed everything, no blue prints. It's a very simple design.
zach,
PhydeauX is one of the experts on this, I'm not, but one of the things I have learned is that to make a custom manifold requires welding different metals which requires a tig, a good tig at that, and some real talent. I have yet to find anyone that wnats less than 300 bucks for the labor, if your friend manages to put one together and is willing to do a nother one. let me know. thanks. Doug
i know he has the skill to do it, he also has a brother that was a welder. i thought someone said that it was a 3degree tilt up. but you, phydeauX, used a 10-15? also someone said awhile ago about tapping holes for brake boosters? do i need to, where at, how many, what are they for..? thanks
zach
hey,
you will have to tap in a brass fitting for your brake booster. Just take a look on the old manifold where the line runs from the booster to the manifold. Fine a new fitting the same size and tap the new manifold to fit.
Matt
The motor tilts 15° forward. Dcoe carbs are supposed to sit with in 5° of level. I tiped my manifold down 10° so the carbs are tipped 5° up when the car is on level ground. I only taped one runner on my manifold. Some will say two or all 4, but one works fine. The only thing its operating is the brake booster (I don't use the vacuume advance). I don't use a reservoir or anything, brakes work fine.
andy
whats the vacume advance?. I don't have a reservoir either. i aslo did the vacume removal. do i need anything esle? thanks again
zach
also PhydeauX what did you use for your runners? do you know the diameter? or thickness? did you have to shape the runner to fit the motor side or did you leave it round?
zach
I used some aluminum pipe. The closest id I could get to 45mm, 1/8" wall. You need to reshape one end of the runner to match the shape of the port. I ground a piece of scrap into the shape of the port and pounded one end of the runner to match it. Need to heat up the aluminum a bit not too much, so the other end keeps it shape when you pound it. I didn't exactly get the perfect shape when I made the runners. Sean's got the manifold right now, he flowed and reshaped them a little better. Aparently an even taper isn't the most ideal shape. I haven't got it back yet so I can't tell you what the ideal shape is.
The vacuum advance is the plastic thing that sticks off the side of the distributor. I unhooked it, the base timing has to be bumped up a bit. I also use a 1.8 prelude distributor it's got a tad more mechanical advance. I'll never understand peoples obsession with removing all the emissions controls from the stock carb, but what ever floats you boat. All that crap will get pulled when the new carbs go on anyway.
[edit]
Here's a link that has a bit on fabricating an intake. Most of it doesn't apply, as they are making an efi manifold, but its got a good shot of the tool to form the runner.
http://www.sdsefi.com/air12.html
You could use steel to make the intake as well. Its alot cheaper and easier to work with. I didn't use it because I was able to buy prefabricated aluminum flanges for the carbs and cut the engine flange from an old carb manifold. In the end I kinda wish I had gone with steel. The cost of getting the flanges fabricated from steel would have been offset buy the savings of not haveing to tig weld the manifold. Plus shaping the aluminum runners with a mason's hammer, propane torch, rail-road track anvil, and angle grinder wasn't the easiest thing to do.
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andy
can't you just buy a B18/B16 inlet manifold for twin webers and just re-drill the holes or mount it onto another aluminium flange with crrectly mounted holes? Wouldn't that be easier?
thanks PhydeauX. sounds great.
zach
that other aluminum plate would have to have an angled surface to it so the carbs are at the right tilt.Quote:
Originally Posted by rjudgey
The B16 sits straight in the chassie, the A20 is tilted.
thanks guys, i think i have what i need. i'll see if he wants to make some more to sell here. thanks
zach
well i have a few more questions. what did you do with your coolent lines? did you plug them or hook them together? also did you cut both sides of your runners at 10degrees? did you make the two plates parallel to each other? did you cut one at 10degrees and the other side -10degrees? thanks
zach
any help?
zach
total should be 10°. Doesn't matter how you get it. You can angle one side all 10°, angle each 5°, or put a 10° bend in each runner. Just as long as the carbs sit level when mounted on the motor. Hook the coolant lines together.
andy
cool, thanks
zach
Coolant pipes i removed and plugged of the take offs from the main pipe on the back of the block, this just makes it easier for the coolant to flow round. Or if you live in a cold climate might be worth getting some pipes welded to the intake manifold and runt he coolant pipes onto those this will help heat the manifold a little and stop petrol from freeezing!! But those only really for extreme climates anything above -5 degrees up shouldn't have to worry too much!!
It gets down to -35c here in Calgary, i removed all of my coolant lines and i have not yet in two winters had a problem with the carbs freezing, so you won't have to worry!! Mind you, it is very dry here in the winter here, not much moisture in the air at 3300ft so that could be why i have not had any problems.
thanks
zach
