Alpiners,
For those who have purchaced the long awaited side draught intakes
from TWM, here are some blurbs from my mounting notes that I took this
weekend.
If you have questions of comments, please drop me a line.
Jarrid
These are the problems and solutions that I have come
up with over the weekend, while trying to install my
TWM dual weber intake. It appears that some machining
will be needed, so perhaps TWM will need to be notified,
and perhaps can perform these mods at no charge.
The only errors I could see in the manifold was the center
mounting bolt is NOT in the center of the ports, and thus
does not even match the gasket.
I dont think that the outside mounting faces being the wrong
dimention should be classified as an error, as it would be
aabsoulutely impossible for them to have been the correct
dimention due to the required runner configs.
1) PROBLEM WITH CENTER MOUNTING BOLT.
With the manifold bolted in by the center hole, The
ports didnt line up well, so the manifold needs to
be raised about .100 inch.
Moved the center mounting hole done about .100 inch.
This also requires re-facing the washer relief .100
inch as well so that the washer can slide down as well
as the mounting bolt.
The center mounting bolt can be used to locate the
manifold for port matching (by looking in the manifold ports
you can see right inside the ports to determine best port
match). To do this, fill the manifold center
hole "after modification" with JB WELD then redrill
the hole in the correct location (with a tight fit on
bolt).
You cant use a stud here because the manifold must slide
in order to engage the outer fasteners.
The JB WELD serves as a guide, and will allow you to pivot
the manifold for the best port match.
2) OUTSIDE CLAMPING FLANGES HEIGHT
The stock intake and exhaust manifolds have faces cut on
thier edges so that they are clamped to the head simul-
taniuosly. The dimension for this face on the stock
manifolds is about .650 inch. The TWM manifold is at
.530 inch, and since the 1 and 4 runners mask the faces,
it is not possible to shim up the TWM manifold. This
is because the notch that was cut into the runner for the
maounting face could not be made any higher, or it would
break into the runner.
I suggest machining both the intake and exhuast faces down
to .400 inch. This will provide the proper clamping height,
plus it will give better accessability to the inner and outer
mounting fasteners.
The outer fasteners can be bolts, but I recommend using a stud
here too as if you use a bolt, you will have to hold the intake
in place as you turn the fasteners to engage the threads. It
will not be possible to place the manifolds then put in the
bolt as the outer runners interfere with its placement.
The exhaust will have to be placed first, then the washer and
nut installed to just before engaging the ex manifold faces.
The intake is slid down, the center bolt is installed, then the
ports are alligned. The outer nuts are tightened, as well as
the center bolt.
3) CARBURETTOR CLEARANCES
I am using Solex Mikuni 40 PHH carburettors, these carbs
have the same bolt pattern as the Weber DCOE carbs/SK/Dell'orto
side draught configurations, but uses different internals.
Jetting rules are the same.
The front carbs set very well, the velocity stacks will need to be
rather short to accomodate the #2 stack against the cockpit strut
mount. In the rear, the carb easily cleared the steering box (and
all bolts) without the phenolic heat spacer, and barely clears the
accelerator pump housing when using the phenolic heat spacer (5/16
inch thick).
The rear carb did hit the master cyl prior to mod (see below).
Since 45mm carbs are bigger, I doubt an early car will be able to use
45mm carbs due to the master cyl clearance "the added 2.5mm will eat
up all the clearance I got from grinding the master cyl".
Without the stacks, the stock cockpit strut nearly fits. Likely late
model (series 4,5) will not have any probs with the strut.
Running air cleaners will likely require some really clever fabrication.
4) MASTER CYLINDER CLEARANCE.
On my series II, I knew I would need to remove the brake
spacer for clearance of the rearmost carb, but after I did
this, there was still interference. I had to grind about
.150 from the rear of the brake master cyl. This proved
satisfactory, and now I have about .075 clearance between
the rear carb and the master cyl.
I suspect I will have to shorten the master cyl push-rod
a tad to allow the master cyl piston to fully return, but
I havnt put my master cyl back on.
5) LINKAGE.
Weber makes a carb to carb linkage device that links the two carbs
together. This should serve well in this application, provided
the one that you get will fit between the two carbs. I had to
fabricate my own, and this was very time consuming.
If this proves unsuccessfull, a cross bar linkage using hiem-joints
to the outsides of the carbs will serve as well. You will need to weld
some struts to you manifold for this type of linkage.
It is important to know that the idle speed adjustment levers and the
return springs be on the same lever. Also the throttle lever should
be on one of these two adjustment levers. This prevents the throttle
shaft from twisting, which causes damage and synchronization problems.
6) PCV/SERVO DETAILS.
TWM left two ports, one on the #1 and one on the #4 runner.
These ports are 1/4 NPT "pipe thread". Plugs/fittings for these
ports are available at better hardware stores.
I will be running a PCV valve so I am going to modify the manifold
to have a small tube that interconnects all of the runners together.
This is so that all runners get the PCV fumes, not just #1 or #4.
Also it will be a lot easier to adjust the idle mixture, and the
carb synchonization is not as touchy.
7) WEBER DCOE SOURCE.
The lowest price I have seen on new DCOE Webers is $233 USD each.
Webers are no longer made in Italy (now Spain), also the price appears to be
going up due to the fact that Mikuni, Dell'orto and SK are no longer
producing
equivs.
The company is NOPI in Georgia.
(800) 277-6674 phone
(404) 366-4700 phone
(404) 366-8536 fax
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 09:32:28 CDT