1978 Pontiac Bonneville needs more brake vacuum?


Asked by Jun 05, 2014 at 08:24 PM about the 1978 Pontiac Bonneville

Question type: Maintenance & Repair

Okay. So I'm fixing up this 78
Bonneville and the thing is, it's been
sitting because of a problem no one
wanted to fix about 10 years back.
My uncle switched engines and
dropped a 400 hp 6.6 L engine in it.
The problem is...the brake booster
doesnt have enough vacuum in it to
stop the car...it has about 6 lbs and I
need somewhere above 11 lbs...how
can i increase vacuum? Thanks!

4 Answers


An engine that size should have excellent vacuum, enough to run your booster, test the vacuum inches at the manifold supply port then compare it to the vacuum at the supply hose at the booster, the readings should be the same, if not, there is a problem with the supply line, if it is the same, but drops when you hook it up to the manifold vacuum then there is a leak in the booster. HTH

Best Answer

Unless the engine is supercharged then it won't work that way at all. You will have to install an auxiliary vacuum pump on the engine to provide enough stable supply for your brakes.


You know alot about this can you get in touch with me?


I guess I could, give me your number or e-mail and I'll try to get back to you in the afternoon pacific time, got a lot going on Friday..

Your Answer

Add photo

Related Questions


Looking for a Used Bonneville in your area?

CarGurus has 863 nationwide Bonneville listings starting at $1,450.


Search Pontiac Bonneville Questions

Pontiac Bonneville Experts

#1 ticklemedaly
Reputation 350
#2 dandyoun
Reputation 300
#3 John Saffrahn
John Saffrahn
Reputation 280
View All

Related Models For Sale

Used Pontiac Grand Prix"
30 Great Deals out of 4,397 listings starting at $1,972
Used Chevrolet Impala"
994 Great Deals out of 35,760 listings starting at $700
Used Buick Regal"
191 Great Deals out of 10,603 listings starting at $1,995
Used Chevrolet Monte Carlo"
17 Great Deals out of 2,070 listings starting at $2,000
Used Dodge Charger"
656 Great Deals out of 29,890 listings starting at $1,995
Used Pontiac Grand Am"
2,001 listings starting at $1,995
Used Chevrolet Camaro"
830 Great Deals out of 38,801 listings starting at $2,650
Used Buick LeSabre"
16 Great Deals out of 2,571 listings starting at $1,700
Used Pontiac Firebird"
11 Great Deals out of 895 listings starting at $2,900
Used Chrysler 300"
585 Great Deals out of 21,017 listings starting at $1,490
Used Chevrolet Malibu"
1,195 Great Deals out of 72,633 listings starting at $695

Used Cars For Sale

2005 Pontiac Bonneville For Sale
3 Great Deals out of 156 listings starting at $2,950
2004 Pontiac Bonneville For Sale
96 listings starting at $1,450