Car almost dies when I apply brakes

Status
Not open for further replies.

GuysMonteSS

Royal Smart Person
May 21, 2011
1,449
1,541
113
Kentville,Nova Scotia,Canada

dickeymoore

G-Body Guru
May 6, 2009
924
113
43
Atlanta,Georgia
Checked the floats and the rear one was way too high got it adjusted down and it seems fine but I notice on the brass plug one of the black little gaskets are missing should I buy new plugs with the new gaskets or can I run it like this and it be okay ,really want to clear plugs but i heard they are promblems. Thanks
 
  • Like
Reactions: 1 user

Gonzo1970

G-Body Guru
Sep 30, 2018
898
1,302
93
winner winner chicken dinner


-Gonz
 

pontiacgp

blank
Mar 31, 2006
29,270
20,391
113
Kitchener, Ontario
The clear plugs are only for settting the floats. You may want to invest in a good A/F gauge which would have told you the engine is running rich which could cause it to stall. If it was the front float too low the lean mixture would have told you what to look for.
 
  • Agree
Reactions: 1 user

TomDisab

Apprentice
Nov 16, 2016
69
67
18
How much vacuum are you pulling? Could be it's over-cammed?


I have a 1980 Chevy Monte Carlo with a small block Chevy 400 in it and some high performance parts like cam ,intake , holley street avenger 670 carburetor, headers,when I come to a stop mostly going downhill when I apply the brakes the car acts like it wants to die out but it doesn't, I checked for vacuum leaks there's none thanks
 

MrSony

Geezer
Nov 15, 2014
6,793
6,678
113
Des Moines, Iowa
If you have low vacuum in a performance engine it usually means the cam has a lot of overlap where both valves are open for a while. With the valves open you won't make much vacuum. And vacuum is measured in inches of mercury (inHg, HG being the atomic symbol for mercury), not PSI as it's not pressure it's measuring.

Low vacuum is nothing to be concerned about if the engine has a big cam in it on purpose. Stock engines (even old carbureted ones) usually were 14" to 20" depending on things like wear, if it was a factory "high output" engine, etc. My worn as hell 350 still got 17-19" of vacuum with a cam with 276/281 degrees of duration. That was mainly due to it having a 112LSA... but i digress.

If it's a steady 11" and your cam isn't too much for this engine (doesn't matter what your other engines did, what matters is what this engine is doing), try messing with the timing (advancing it) and turning the idle back down and adjusting the mixture screws. If that does nothing, that's just what the engine does I suppose unless you take it apart and change the cam timing physically.

Apologies if I come off as preachy or like a shop teacher, I'm just on a roll.
 
  • Like
Reactions: 1 user
Status
Not open for further replies.

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor