Falcon 170-200 Diagrahm




After posting a lot of problems about my engine, a lot replied it has a vacuum leak. My dilemna now is where do I locate it? I'm a really a newbie when it comes to this. Do you know any sites that I can download and study and as well as a how to troubleshoot 170-200ci?

And please, explain to me in layman terms how a vacuum leak occurs, what causes it and how to remedy it.

I stalled 4 times in a row this morning en route to my office. I don't want to be the last guy to leave the car park later tonight. :(

Thanks and more power to Ford Six people! :)
8) vacuum leaks occur when hoses and gaskets deteriorate, or when bolts lose there torque through vibration. to find a vacuum leak use something like wd40, and spray the hose, where the hose connects, the gasket sandwich, etc. anyplace where you find things attached to the intake log. hit each area one at a time. when engine rpm increases you have found your vacuum leak. at that point fix what needs fixing, example, you spray the carb base and the engine rpm goes up, the gasket is leaking. try tightening the carb bolts. if that does not fix the problem, then remove the carb and replace the gasket. you might replace your vacuum hoses anyway as a normal maintenance procedure.
Howdy 66Bunny:

A vacuum leak causes an engine to run badly because, ideally all of the intake air is sucked through the carb. The carb suck causes the vacuum. The incoming air and atonized fuel are mixed in this high velocity envirnoment at a ratio of about 15:1, that's 15 parts of air to 1 part of fuel. Typically engines draw any where from 7 to 18 inches of mercury, or more commonly called pounds of vacuum.

A vacuum leak occurs anytime air is drawn into the intake tract somewhere other than the air horn, or top of the carb. That causes the 15:1 ratio to lean out, or increase the ratio of air in the mix. A bad leak can cause an engine to stall at an idle or surge and over heat at cruise.

Sources of leaks are typically vacuum hoses and gaskets. Rubber gaskets dry and harden with time heat and the severe conditions found on an engine. Gaskets dry out and deterioate.

When trouble shooting don't overlook the distributor internals. You didn't say what year you're working with, but many so-called carb problems on 170-200 from '62 to '67 can be attribute to the Load-A-Matic distributor. When working as designed and properly, it is a marginal system, when less then that, it gives very inconsistant results.

PS. One of the hardest vacuum leaks to spot is a leak in the vacuum diaphram of the distributor. It's hard to hear and you can't get to it with WD40. Check by disconnecting the vacuum hose and running the engine. If the idle improves and the engine runs more consistantly, you've got a strong indication. It is also one of the most troublesome because it effects distributor advance curve and carb function.

In addition the the WD40 diagnostics described by rbohm, you might try using a piece of hose as a stethescope to listen for the leak. A leak will make a sound rangeing from a hiss to a small roar.

I must of missed the details of symptoms and what car you're working with.

Adios, David
Thanks for the replies!:) I'm working on a 200cid 66 Mustang. I bought new spark plugs, condenser, contact point and hopefully tomorrow an engine oil. I'll tell my mechanic all the advices I got since he too is not knowledgable when it comes to pony problems.

Awhile ago while parking, I noticed my right backlight died and strangely enough, without lifting a finger my dashboard light went on again. I think I'm going to a different mechanic for electrical problems.

For the love of ponies,