HELP. Everytime I step on my brakes, I literally have to stand on the pedal to get it to stop, definately will not lock up. I'm guessing its the cam (232 degrees at .050) in the motor (455). When i had the stock motor in the car, it would stop on a dime, lock up brakes real easily if I pressed to hard). I had this same problem in my 70 skylark which i had a big cam in also but always thought it was a brake problem till I started driving the cutlass and notice the brakes felt just as stiff. Today I installed a crane vacuum canister figuring that would solve my problem but it made no change in the way the brakes feel. For the record, I've been a mechanic since the late 80's so I know a lot about cars and yes the cutlass has all new brakes (shoes, hardware and wheel cylinders in the rear and new pads and hoses in the front. Also a new master and power booster and new steel brake lines in the front as well as a new proportioning valve and yes rears were properly adjusted and calipers compressed easily). When I first started driving this combination the brakes locked up (real responsive) a few times but it had been sitting for years so I figured some of the rust was grabbing on something. The only thing I have done since i put car on road was to back down on the ignition timing (got a new timing light) since I thought it was a bit high, not that it was pinging or anything. So my question is what gives, I have to 70 A body cars with the same exact symptoms. I can drive it but I definately must keep my distance cause the car doesnt feel like stopping. Allen allioop108@aol.com
Allen, How about the hold off valve? If it is stuck, it can limit pressure to the front brakes. On the 70 Buick, it is attached at the master cylinder. Samr for the Cutlass? In 71 and up, GM went to a Combination valve on the frame rail, but in 70, the hold off and metering valves are separate. Other than a defective booster, I can't think of anything else.
I have the 71 type of valve mounted on the frame and that is new. When I first put the car on the road in November the brakes felt more responsive but not like they used to be with stock motor. Now they feel like I went through a huge puddle and must real push down hard but car seems to keep going. I will measure vacuum this weekend and search the board for what an acceptable vacuum level should be for power brakes. My only guess is that its vacuum related as my slightly lumpy buick motor had had brakes that felt the same. Also occasionally you will feel the pedal getting good vacuum like if you bring up the rpms and hit the brakes immediately but then the effort lessons. I thought the crane vacuum canister was going to store extra vacuum and help my booster more but like I said it feels the same and i dont think I hooked it up wrong. Vacuum line from engine to check valve fitting (looks like the one on the booster) on canister and then other hose from regular fitting to check valve fitting on booster. Allen allioop108@aol.com
10" is minumum I believe. Running more initial advance with a shortened mechanical advance can help the vacuum level at idle. Vacuum advance with manifold vacuum will give you extra advance at idle. Just some ideas.
Ok I was driving home from work this evening paying close attention to what the brakes are doing so that I can report back here. If I step on the brakes 3 quick times in a row after driving a bit. the first time there is decent vacuum as the go down easily, the second time the are harder and the third time they are to hard with little stopping power. The way it would act if the engine were not running and you were using the reserve vacuum. Now if you drive a bit and mash down on them you can start to feel them wanting to go down but then they harden up right away. Thanks for info Larry, will check with a vacuum gage this weekend. Allen allioop108@aol.com
