Welcome Guest [Log In] [Register]
Posted ImageWelcome to the all new Geo Metro Forum. We hope you enjoy your visit.

You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are features you can't use and images you can't see. Registration is simple, fast, and completely free. If you're already a member please log in to your account to access all of our features:

Join our community!




Username:   Password:
Add Reply
Tofuball's '94 XFi; It's all about city MPG
Topic Started: Mar 12 2011, 08:59 AM (39,442 Views)
Tofuball
Member Avatar
Strange Mechanic

Crazy busy.

Head still in shop.

Finally had some time to work on the Geo, changed trans fluid with synchromesh. Noticed I have a fluid leak from the seal for the passenger side half shaft. Also noticed I have an exhaust leak behind the cat, and the exhaust hits my front swaybar (yay!).

I advanced the cam gear one tooth past the line and retimed the ignition back to 8 degrees. According to MPGuino I'm getting 50mpg combined now. I definitely have much more low end power and vac flutter has been cut in half. Debating advancing it another tooth to see if vac flutter goes away entirely.
Offline Profile Quote Post Goto Top
 
Woodie
Member Avatar


Tofuball
Apr 16 2011, 12:11 PM

I advanced the cam gear one tooth past the line and retimed the ignition back to 8 degrees. According to MPGuino I'm getting 50mpg combined now. I definitely have much more low end power and vac flutter has been cut in half. Debating advancing it another tooth to see if vac flutter goes away entirely.
Something wrong there, one tooth is 18° or so, way too much to just move it around without making a huge difference in driveability,
Offline Profile Quote Post Goto Top
 
Tofuball
Member Avatar
Strange Mechanic

I consider +10MPG, greatly reduced flutter, and way more low end to be a pretty huge difference :)
Offline Profile Quote Post Goto Top
 
Tofuball
Member Avatar
Strange Mechanic

Any idea what could cause this? Since currently I can only adjust it by the tooth for now, or "by ear" if I make an adjustable cam gear, I'd really like to just get it "right" :)
Offline Profile Quote Post Goto Top
 
mcmancuso
Member Avatar


mwebb has noticed that advancing 10 or more(cam timing) with the econo-cam traps some of the combustion mix in the chamber, not ideal for power, but may be additionally beneficial for reducing the volume of fresh charge entering the cylinder which reduces the effective volume of the engine, that, in some cases, can result in better FE.

If you had valve flutter and lousy low end power, you were off by a tooth on the cam gear, moving the timing one tooth one way or the other from proper position will result in a working, but not spectacular, engine. More than 1 tooth will usually keep it from running. Sounds like your current location is correct.

Where is the distributor in its adjustment with it at 8°? if its near the center of its potential movement you definitely have it correct now, and it was off a tooth the way you had it. Typically when someone installs a cam off by a tooth, the distributor ends up near the end of the adjustment groove to time it correctly.
Offline Profile Quote Post Goto Top
 
Tofuball
Member Avatar
Strange Mechanic

Good info, thanks. The more I think about it the more I bet something is up with the CRANK wheel side of things . . . somehow.

I have to resolve this before I can get a baseline and plug my Megasquirt in! I have all the parts for almost all of my plans, but without a baseline, I can't brag about gains!

Head is still in the shop.

Allright, since you guys love pictures so much, here are a few random ones:

Two weeks ago or so I cleaned up the TB, cut a lot of material off, when I got the TB the screws were stripped. Even in a max MPG setup, I recommend replacing those screws with set screws as it cuts down on turbulence where you really don't want it.

Posted Image

Also, I painted my hubcaps because they looked like crap.

BEFORE:
Posted Image
DURING (sanding):
Posted Image
AFTER:
Posted Image
Offline Profile Quote Post Goto Top
 
dayle1960
Member Avatar
Fastest Hampster EVER

Wow, what a difference on the hubcaps. Good work so far. :thumb
Offline Profile Quote Post Goto Top
 
bogs
Member Avatar
Duct tape heals all wounds

Very well done :thumb
Offline Profile Quote Post Goto Top
 
Tofuball
Member Avatar
Strange Mechanic

Tonight I cut the throttle body up (cut off the cold start) and put an epoxy plug in it. Once that dries I'm going to sand it all down, polish the bore and paint it.

Then reinstall the butterfly with set screws and all the accessories.
Edited by Tofuball, Apr 21 2011, 10:53 PM.
Offline Profile Quote Post Goto Top
 
Metro Fanatic
Member Avatar


Good progress. Nice looking hubs....way better curb appeal I bet!
Offline Profile Quote Post Goto Top
 
Tofuball
Member Avatar
Strange Mechanic

On the right, a nice clean and painted TB.

Posted Image

On the left, weight savings.


Whats the effect of running without a dashpot? It lets the throttle slam shut, so it's easier to shoot flames out a catless exhaust . . .
Offline Profile Quote Post Goto Top
 
Tofuball
Member Avatar
Strange Mechanic

Metro Fanatic
Apr 23 2011, 08:21 PM
Good progress. Nice looking hubs....way better curb appeal I bet!
Thanks :D
Offline Profile Quote Post Goto Top
 
Coche Blanco
Member Avatar
Troll Certified

Tofuball
Apr 23 2011, 10:35 PM
Whats the effect of running without a dashpot? It lets the throttle slam shut, so it's easier to shoot flames out a catless exhaust . . .
...really? My interest is...sparked... ;)
Offline Profile Quote Post Goto Top
 
Tofuball
Member Avatar
Strange Mechanic

The cat works as a flame arrestor. Without it flames can travel all the way from your combustion chamber to a tailgater near you!
Offline Profile Quote Post Goto Top
 
mcmancuso
Member Avatar


:thumb
Offline Profile Quote Post Goto Top
 
1 user reading this topic (1 Guest and 0 Anonymous)
Go to Next Page
« Previous Topic · Project Forum · Next Topic »
Add Reply