Engine swap ... brakes worthless

[slepr1]

No offense but I call bullshit on that IF you have a vacuum booster.
I ran a '509 and that cam did not produce enough vacuum to adequately support the power brakes.

Yes I have a factory booster but nothing aftermarket was needed with the larger cams I've used. I thought for sure I would need something with my latest cam but I don't unless I can't recognize low vacuum (I haven't measured it).

 

[slepr1]

What kind of vacuum were you pulling , I'm going to get a hand bleeding them, using my vacuum bleeder yesterday was alot more awkward then I remembered on the fronts . If it's not air in the lines I'm thinking maybe a leak around the carb or spacer because I'm getting 7 at idle with my idle screws about 3 .5 turns out best I could get it.

I've never measured the vacuum. I would've if I had an issue with anything. I was certain I'd need something aftermarket with my latest Hughes cam but I don't. My breaks work great.

When I bleed brakes I always gravity bleed them. I find it so easy especially when I'm working alone. Once my car was in a well known speed shop getting some work done that involved having to bleed the brakes. Afterwards they mentioned that I'd need new brakes soon because the pedal was still soft after bleeding. I went home and gravity bled them and everything returned to normal.

 

[diesel_lv]

What is your initial timing w the vacuum line disconnected from the distributor, if you have one and the line plugged? It is possible to increase initial timing a bit and then reduce idle and gain a little vacuum.

 

[Long4door]

I did just that yesterday, all in at 39 right now moved my vacuum up to 10 at idle. Tried turning up the vacuum advance next but can't tell if it's even turning inside the little can

 

[diesel_lv]

I did just that yesterday, all in at 39 right now moved my vacuum up to 10 at idle. Tried turning up the vacuum advance next but can't tell if it's even turning inside the little can

What is your base timing at idle? I run 18°. Some run more, some less, depends on what your engine n cam like. You need a advance limiter plate. If you have 39° all in w vacuum disconnected, which is how it's done, then you have way too much. You should be down around 32°-34° all in. With an example 18° idle, you would need the mechanical advance limited to 14-16°. Don't mess w the vacuum port on the distributor yet. You are mixing too many things together without understanding how they work.

 

[Long4door]

What is your base timing at idle? I run 18°. Some run more, some less, depends on what your engine n cam like. You need a advance limiter plate. If you have 39° all in w vacuum disconnected, which is how it's done, then you have way too much. You should be down around 32°-34° all in. With an example 18° idle, you would need the mechanical advance limited to 14-16°. Don't mess w the vacuum port on the distributor yet. You are mixing too many things together without understanding how they work.

I have taken it as high as I can to see if it will make a difference I believe it was 20 initial. I think I will need to get some light wieght springs , if it matters I run a hei

 

[Geoff 2]

No, NOT lightweight springs. If you are going to use VA connected to manifold vacuum [ a veeeeeeeeeeeeeeeery good idea ], then you will have a lot of timing at cruise & lower rpms.
If you put light springs in the HEI, you will probably have too much total timing. This may cause detonation. Total timing at cruise is initial + VA + part of the centri curve. The engine doesn't know the difference, it just sees the total amount of timing. So if you have heavy/std springs, leave them for now until idle, cruise & WOT is sorted. HEI, great choice!

 

[Long4door]

No, NOT lightweight springs. If you are going to use VA connected to manifold vacuum [ a veeeeeeeeeeeeeeeery good idea ], then you will have a lot of timing at cruise & lower rpms.
If you put light springs in the HEI, you will probably have too much total timing. This may cause detonation. Total timing at cruise is initial + VA + part of the centri curve. The engine doesn't know the difference, it just sees the total amount of timing. So if you have heavy/std springs, leave them for now until idle, cruise & WOT is sorted. HEI, great choice!

Your suggestion is to switch from ported to manifold on the vacuum advance ? Worth a try . I did just test drive it after double checking my total timing at 38* my brakes are better taking 5 ft to stop instead of 10 ft. I still wouldn't venture onto the Seattle freeway in this condition

 

[Long4door]

You may have a vacuum leak.
3-1/2 turns is quite a bit.
I have a .484" in a 383 and it's close to 1-3/4.
Power brakes work well.

Upped the timing and I'm back at 2.5 turns, are you running ported or manifold vacuum

 

[Don Frelier]

Upped the timing and I'm back at 2.5 turns, are you running ported or manifold vacuum

Ported

 

[Long4door]

For the update I am the fool didn't even notice me rear cylinder went out somehow during or after the engine swap mind blown thanks for all the help

 

[Bighouse]

That’s just your car messing with ya.