|
|
|
Jul 19, 2011 15:34:43 GMT
|
|
I'm planning on fitting a Vacuum gauge to the Fiesta soon. The engine is a standard Carb'd 1.1 OHV.
Am i ok to simply stick a "T" piece in the line from the carb to the distributor? Would this cause any problems with the timing advance?
Or would i be better to get the manifold off, drill and tap another feed? Of course i'd like the first option to be ok as it's a damn site easier! lol
thanks
|
| |
|
|
scruff
Part of things
Posts: 621
|
|
Jul 19, 2011 15:42:45 GMT
|
|
The carb vac line might be a tapping from the carb throat so will give a lower pressure than actual manifold pressure. A tapping off the manifold would be better but carb vac line will still work.
|
| |
1994 Lotus Esprit - Fragile red turbo with pop up lights.
1980 Porsche 924 - Fragile red turbo with pop up lights.
I spy a trend...
|
|
RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
|
|
Jul 19, 2011 16:58:51 GMT
|
|
A half way house would be to take a T off the vacuum line to the servo, just means finding a T-piece with the appropriate sizes. That's actually where my Scirocco took it's feed for the vacuum advance from the factory, and happened to have a 2nd blanked off feed that I used when I fitted a vacuum gauge.
|
| |
|
|
|
|
|
|
|
|
The vacuum advance will normally see full manifold vacuum at anything much above idle. However in most cases the take-off on the carb is designed to close off the vacuum port when the throttle is closed, reducing the advance on the over-run and therefore (a) improving the engine braking and (b) preventing the car from 'hunting' or surgin on the over-run.
What this means is that at idle the vacuum gauge will drop to ~0. Not a problem if you're fitting it purely to keep a check on the throttle usage but perhaps less than ideal if you want to be able to diagnose running faults, such as burnt valves (whcih will cause the vacuum to drop a little whenever the cylinder with the problem is on the intake stroke.
Tapping into the maifold is probably the best bet, but the servo pipe (assuming that there is one) will be a very close second.
|
| |
|
|
|
|
|
Jul 20, 2011 15:41:11 GMT
|
|
thanks for the feedback folks, i'll have to take a look see what else i have on the manifold, Failing that it'll be a drill and tap job into the manifold it's self!
|
| |
|
|
barty
Posted a lot
Posts: 1,088
|
|
Jul 22, 2011 10:12:36 GMT
|
|
ive heard of people using grease to catch the swaf when drilling into the maifold, whilst it may be ok, i would always take it off to drill and not risk it
|
| |
|
|
|
|
|
Jul 22, 2011 20:47:54 GMT
|
|
I had one off the MAP sensor feed on the Fiat- which in turn came directly off the same port the brake servo did.
Just note that most Bourdon-style gauges will be quite springy, and it is adviseable to have a restrictor piece (I wedged a piece of WD-40 can straw into the neck of the T piece) else the gauge will have a tendency to rattle at low engine RPM.
|
| |
|
|
