520H - Vac gauge actually useful?

[seuadr 488]

Hey all,

now that my motor is swapped and running, i have been working my way through shoring up other issues that were either created by the swap or existed before and i ignored (like no gauge lights!)

 

next up on the block is the vacuum gauge - i didn't have a spot to hook this up on the replacement engine, (except that i have an electric fuel pump so i guess i could hook it up to the pulse pump port?) so i left it unhooked.

 

but now i'm wondering - does this tell me anything that i need to know? am i missing out on some useful function of the vac gauge? "100% work" doesn't mean much to me, unless i need to know that for some kind of future troubleshooting...

 

what is your opinion?

[Achto 27,577]

Personally I really never saw a big value in the vacuum / power gauge. 

 

I was always taught that there are only 2 gauges that really matter on an engine. Oil pressure and water temperature. All other gauges are only there for convenience.

Edited April 14, 2021 by Achto

[seuadr 488]

12 minutes ago, Achto said:

Personally I really never saw a big value in the vacuum / power gauge. 

 

I was always taught that there are only 2 gauges that really matter on an engine. Oil pressure and water temperature. All other gauges are only there for convenience.

good point - though, gas gauge is pretty nice

[squonk 41,118]

19 minutes ago, Achto said:

Personally I really never saw a big value in the vacuum / power gauge. 

 

I was always taught that there are only 2 gauges that really matter on an engine. Oil pressure and water temperature. All other gauges are only there for convenience.

Not so!! I remember riding in my Uncle's 65 Impala SS with the big honkin vacuum gauge on the dash. I could have watched that thing all day! 

 

In all seriousness , the Toro gauge may not be the most useful one , but I diagnosed many an 8 cylinder engine with a hand held vacuum gauge. " late timing, sticky valves,bad cams ect. Still in the tool box!  

Edited April 14, 2021 by squonk

[johnnymag3 2,520]

A Vacuum gauge is a very good diagnostic tool. if you know how to use it !!! A nice gauge to have in my opinion.

 

John

 

[seuadr 488]

8 minutes ago, johnnymag3 said:

A Vacuum gauge is a very good diagnostic tool. if you know how to use it !!! A nice gauge to have in my opinion.

 

John

 

alright - so what can i diagnose, and how?

[lynnmor 7,306]

4 minutes ago, seuadr said:

alright - so what can i diagnose, and how?

About the only use would be setting the idle mixture, but doing it by ear works OK.  I see my gauge at or near 100% most of the time that the engine is working fairly hard, like mowing.  I believe it is most useful as a conversation piece, and it should work if one has a bit of OCD.  If there is a boss cast in the intake, drill and tap it for a 1/8-27 pipe thread.

[seuadr 488]

1 minute ago, lynnmor said:

, drill and tap it for a 1/8-27 pipe thread.

so as luck would have it, it already has a connection sticking out of the block for the fuel pump. Doesn't have barbs, but the hose did fit snug so i am sure with a pipe clamp it would be OK. but i'd have to take all the tins off to hook it back up and i'm not sure i actually care, unless it is going to tell me something useful

 

[lynnmor 7,306]

Just now, seuadr said:

so as luck would have it, it already has a connection sticking out of the block for the fuel pump. Doesn't have barbs, but the hose did fit snug so i am sure with a pipe clamp it would be OK. but i'd have to take all the tins off to hook it back up and i'm not sure i actually care, unless it is going to tell me something useful

 

 

That is probably a crankcase pulse connection and won't work correctly.

[seuadr 488]

1 minute ago, lynnmor said:

 

That is probably a crankcase pulse connection and won't work correctly.

you are correct - i didn't read your post correctly. there is NOT a boss nor a connection in the intake of the replacement motor (there was on the original, of course.)

 

[squonk 41,118]

Yes. Setting idle mixture you would want to obtain the highest reading with no flutter or hunting back and forth. Flutter/ bouncing would indicate a valve not sealing good for example. Hunting up and down-  lean mixture. Low reading late timing

[johnnymag3 2,520]

What Squonk said ….!!!!!  

 

Those are things you can do...us old timers remember them well !!!

 

……...well me anyway.....

 

 

[DougC 2,641]

Yep when the time comes the vac. gauge starts fluttering wildly you know your running on borrowed hours.........

 

[johnnymag3 2,520]

Gotta teach the young ones a thing or two...............

 

 

If you learn something everyday....your still living !!!!!

[squonk 41,118]

Ol' Reliable. Had to get it out of the toolbox just to look at it again in all it's glory! 

 

 

 

 

[Handy Don 12,232]

My spouse's Subaru Impreza (2013) has an "economy" gauge, which is a vacuum gauge in disguise. It gives a visual to let you know that when the engine is pulling harder you are using more fuel.

Edited April 15, 2021 by Handy Don

[johnnymag3 2,520]

6 hours ago, Handy Don said:

My spouse's Subaru Impreza (2013) has an "economy" gauge, which is a vacuum gauge in disguise. It gives a visual to let you know that when the engine is pulling harder you are using more fuel.

Simple word for todays people.......Something they can understand....