First thing i noticed with this 70 442 is the cam. second thing when you step on the brake the first time you stop is ok but the 2nd time it's too hard to stop.
I checked the hose it is not collapsed and is getting vacume but dosn't seem like enough vacume to keep up with the brakes.
i guess the cam is too much too have power brakes like the W30? external vacume can? booster assist? or change cam.
i will try and post vid of engine running for you guys too hear it, maybe try a new booster?
where can i buy a decent booster if thats the case?

 

First thing to check would be engine vacuum. If you are not regenerating enough vacuum, you may want to check engine tune up specs. You may want to hook up a vacuum gauge for a while to see whats going on.

 

I agree with the above. Proper tune can make a big difference in the vacuum level and quality. My engine with the 217/221 cam idled a bit rough, had around 14" vacuum, and was very bouncy. The power brakes just barely worked, and the pedal was harder than it should be. After tuning the distributor for 18º initial plus 12º vacuum advance, the idle is smooth, the vacuum is steady at 16", and the power brakes work like factory.

 

Hook a vacuum gauge up and tell us how much vacuum the engine is pulling.

 

If you have a vac advance distributor, try hooking the vac line to manifold vacuum if it is not already.

 

My '67 4-4-2 with 400ci and AT has a Lunati Voodoo 310/320 cam, approaching a manual W30 328/328 cam, and it will not pull enough vacuum to run power brakes without a vacuum collection canister. Not an ideal situation for sure, but I love the way it runs and sounds, although I am thinking of switching to an electrical vacuum pump at some point. Note collection canister on the driver's side fender well.

 

I neglected to mention that helped increase my vacuum significantly.

 

Your 9" booster isn't doing you any favors either. OEM booster for a 67 was 11". You're giving up 33% of the available power assist just from the reduced booster diaphragm area.

 

wow had no idea a tune could make the difference thx!

 

will do!

 

So your saying after 67 they went to a 9 inch booster from the factory?

 

more storage more vacume?
I’m wondering if an 11 inch booster would fit from 67 on my car?

 

Scroll up and read it again.

All 1967 442s left the factory with one notched valve cover on the driver side to accommodate the new-for-67 larger brake booster.

 

I have an MSD dist with no vacume can, must be centrifical advanced only, with 6 al box on it.

 

No. The storage area will only increase the amount of time that the brake booster will provide power assist. The vacuum level is still limited by the manifold vacuum the cam provides.

The power booster works by using a rubber diaphragm as an actuator. Atmospheric pressure is on one side of the diaphragm, manifold vacuum on the other. The difference between those two pressures is pounds per square inch. You can increase the amount of force by either increasing the pressure difference (ie, use a cam that generates more manifold vacuum) or by increasing the number of square inches (use a diaphragm with a larger diameter. Your 9'' booster has 63 square inches of area. The original 11" booster has 95 square inches. Since you don't want to change the cam, at whatever manifold vacuum level you have, the 9" diaphragm provides only 66% of the area and thus only 66% of the braking force for the same manifold vacuum.

Only an aux vacuum pump will increase the vacuum level. Conversely, lose the power brakes and just use a 1" master cylinder and manual brakes like the MT W30 cars. My heavier 1970 stops just fine.

 

Thx Joe, that would intale changing booster and master only?

 

Joe - There was so much done right by the guys who restored my car that it's hard for me to complain, but the brake set-up is my one complaint. Car stops just fine if you're patient and give it a moment to build a little vacuum, you just don't want to peel out of the parking lot like a Bat-out-of-hell and then hit a red light only 100-feet down the road.

 

You can change the booster without changing the M/C. If you want to convert to manual then yeah, you need a different M/C.

 

I've found that few people (including most aftermarket brake kit vendors) have absolutely no clue about how to design a properly matched braking system.

 

In reading through this, I think there is some miscommunication (or maybe cross-communication?). Joe's comments about the 9" booster were directed at Dream67Olds442 post with a picture of his 1967 engine compartment.

At this point we do not know what size booster is on Johnny's 1970 442.

 

Hey Joe, Would you have a part number on the 1 inch Master?

 

Will this $9 gauge work?

 

If it reads vacuum accurately - yes.

 

As noted in that ^^above^^ vacuum gauge description:

"ASME B40.1 Grade B Accuracy Compliance ± 3-2-3 % of span"

You get what you pay for - you can do the math.

 

In the situation you're attempting to diagnose - possible leaking vacuum or low vacuum - the first two readings (on the left) of this chart are most likely the most applicable. In all cases, you expect to achieve a "steady" vacuum. Review the first two readings in your case - these will provide some insight.

 

Of course, if you have power steering, you can always add hydroboost as an alternative to vacuum powered brake booster.

 

Interesting. They make a hydroboost system for these classics? I didn't know that. My 2003 F-250 diesel has OEM hydroboost. Fascinating.

 

I dunno what 3-2-3 means. If it’s 3% of the span of 30” then its accuracy is +/- 0.9 “. Sounds good enough for the job at hand.

 

Kenneth - I did a copy/paste - didn't realize it pasted most likely incorrectly, I believe it was+/- 3% as you stated & I agree that variance should be just fine.

 

I looked it up - says same as I posted. Who knows - I reckon ~3%...

 

I have a HB unit from a 2008 Dodge Ram 2500 in my '66 Toronado.

 

Pretty interesting...