ported vs. manifold

Reply Subscribe

Thread Tools

Search this Thread

Aug 30, 2010 | 10:16 PM

#16

krewat

FTE Leadership Emeritus

Joined: Jul 2002

Posts: 42,561

Likes: 423

From: Long Island USA

Quote:

Originally Posted by dinosaurfan

Oof, your truck may well have come with manifold vacuum. Krewat, you should know this.

I'd be VERY interested in hearing when manifold vacuum was ever used for vacuum "advance" on a Ford from the early 1960's (eg. FE) through forever. I only said using ported vacuum was "better" because it was the stock setup and it's easier to get it to run like "stock" that way. Of course, it's "better" to tune the setup to whatever cam/compression/tranny you have. Like I did. But that's not for the faint-of-heart

If you have a basically stock setup, even a slightly mild cam, it's "better" to keep as close to stock as possible.

If you have a radical cam (low idle vacuum), high compression (better to retard the timing under load), or a few other things I can't think of right now... you are definitely better getting an adjustable vacuum can and hooking it to manifold vacuum, recurving your distributor and getting ready to WORK on it.

But I can't think of any situation where a stock 2bbl (or even a 4bbl) setup with "regular" compression and a "normal" cam would be better off with manifold vacuum, especially for the "regular" people

Aug 30, 2010 | 10:17 PM

#17

dinosaurfan

Cargo Master

Joined: Aug 2000

Posts: 2,931

Likes: 12

From: SW Michigan

why not......

Bear, manifold vacuum came first, and ported was the emissions BS. All of the big 4 ( at the time ) manufacturers used it, and very successfully, until the feds wanted to attcak the smog problem without understanding what they were doing. Trying to clean the air ws the right thing to do, but that should have been left to the engineers, not the feds. LOTS of unintended consequences.

So, manifold vac has always been out there, you just don't understand what you are looking at when you see it. Just because YOU don't understand doesn't mean it isn't so. Get out your 40 year old schematics and look. Or, better yet, come over here to Michigan and I'll show you what it looks like on my unmolested '69............

DinosaurFan