MAnifold vacuum

[Dinosport]

Well looking at cams right now. I have an LY6, I was looking at a cam kind of close to the specs of the Gm Ls hot cam. In the description they made mention of very low manifold vacuum will not operate power brakes.
I obviously have power brakes, plus I might run a carb with a vacuum secondary.
Does anybody know roughly at about what point or size of cam for an ls does vacuum become a problem and how does that affect a vacuum secondary carb?
Oh btw the car will be a weekend driver, cruise with the family, occasional burn out and I would like it to have a little choppy idle and some good power. Possibly take 2hr driver to NY to visit family.
There is a very good deal on stock ls3 camshafts with the cam gear. Ive been looking around at other options. I know the ls3 cam will give good drive-ability, vacuum, A hotcam or equivalent will give more power and a choppy Idle.
As I type I guess I should just go with the LS3 cam but I guess a little more info and opinions wont hurt.
Thanks guys

 

[Texas82GP]

I have the LS hot cam in my daily driven 2008 GMC Sierra with a 5.3. No issue with having enough vacuum for power brakes. The cam has been in there for four years/60,000 miles. We have the same cam in the 6.0 (L96) in my brother's 78 Z28. No issue having enough vacuum for the brake booster on it.

The Hot Cam is a very good cam in my view. Do other cams make more power? Absolutely. However, it sounds great, makes good power and is a reliable setup. It is engineered by GM. With the correct LS2 valve springs, I dare say it is as reliable as any factory setup. I'm fairly suspicious of these popular aftermarket cam setups that have 0.600"+ lift and radical cam lobe profiles. I want to put the cam in and forget it. I don't want to be changing valve springs every 10,000 miles because I'm sweating a valve spring failure.

 

[Dinosport]

I have the LS hot cam in my daily driven 2008 GMC Sierra with a 5.3. No issue with having enough vacuum for power brakes. The cam has been in there for four years/60,000 miles. We have the same cam in the 6.0 (L96) in my brother's 78 Z28. No issue having enough vacuum for the brake booster on it.

The Hot Cam is a very good cam in my view. Do other cams make more power? Absolutely. However, it sounds great, makes good power and is a reliable setup. It is engineered by GM. With the correct LS2 valve springs, I dare say it is as reliable as any factory setup. I'm fairly suspicious of these popular aftermarket cam setups that have 0.600"+ lift and radical cam lobe profiles. I want to put the cam in and forget it. I don't want to be changing valve springs every 10,000 miles because I'm sweating a valve spring failure.

Well that answers my question, thanks. Im not looking for the most power I can possibly make. I would like a slightly choppy idle just because it cool, good power, and reliability. I dont want to be on a cruise with the family and have issues.
Any ideas if it would affect a vacuum secondary carb? or would that just be a matter of tuning. Im most likely but not for sure yet going to run an edlebrock. I would love to go EFI but my combo is going to be mixed matched to a point of over complicating me doing that for now.

 

[Texas82GP]

Shouldn't be any issue with a vacuum secondary carb. It will have to be tuned to the combination. You will need a higher stall torque converter and deeper rear gears with that cam or it will be a dog down low. I am running a 3200 stall Circle D converter in my truck with 4.10 rear gears. The truck has 32" tall tires so you don't need that much rear gear.

 

[Dinosport]

Hmm 3200 stall. I have a lower stall converter than that. Somewhere in the 23-2500 range. Atleast thats what I was told it is. I dont have good memories of running that high a converter on a street car but then again that was a long time ago and I cant say I know the motor actually needed that much stall. I also have so many things I need to get this running I dont want to add anything at this point. Decisions decisions. lol
Im wondering if I should just economically get the ls3 cam and a carb set up, get it in and running, enjoy it for a while like that. Meanwhile in the background I can slowly gather a better cam, better trans, better rear end, efi system, Then down the road upgrade it all.
Actually might be a really good idea for to change the car around, and upgrade things that way I don't get bored with it.

 

[Texas82GP]

The converter sounds higher than it actually is. I had Chris at Circle D give me a recommendation on what converter to go with given my combination (heavy *ss truck with tall tires). It might not necessarily be the right choice for yours. I can tell you, it's not a super loose converter. It is fine for daily driving. Don't forget, it's a lock up converter. Here's what I have....
http://www.circledspecialties.com/p-6-gm-278mm-hp-4l60-ls-torque-converter.aspx
There is something to be said for getting the car going and enjoying it. I just don't like to buy things twice or do them twice. If I put a cam in, its the one I want.

 

[Dinosport]

The converter sounds higher than it actually is. I had Chris at Circle D give me a recommendation on what converter to go with given my combination (heavy *ss truck with tall tires). It might not necessarily be the right choice for yours. I can tell you, it's not a super loose converter. It is fine for daily driving. Don't forget, it's a lock up converter. Here's what I have....
http://www.circledspecialties.com/p-6-gm-278mm-hp-4l60-ls-torque-converter.aspx
There is something to be said for getting the car going and enjoying it. I just don't like to buy things twice or do them twice. If I put a cam in, its the one I want.

Your right on doing it once. I usually go that route. Ant thats why Im kind of torn with what to do. I can for 130 get the LS3 cam with gear, LS3 valve springs for roughly 100 to 140. Install that, get the rest of the stuff I need and get the car running all else left alone. Then I can enjoy the car at roughly 280 to 300 at the wheels (im guessing). I can then take my time maybe even start with a fresh motor, work on having a better rear, trans, suspension, reinforce the frame, choosing a good programmable EFI set up
Or I can spend 1200 to 1500 for the Hot cam, trunion upgrade, springs, pushrods etc, Another Huge amount of money on a EFI set up because I have to mix and match parts from different yrs to make it work the way I want. Probably will set me back till next fall and once its running the yr after I still have to worry about the rest of the car holding up.

 

[Texas82GP]

I would get the car running and then go from there. It's better to have a running car to enjoy. A 6.0 with the LS3 cam will make well over 300 HP with either a well tuned carb or with a good EFI tune. With a good exhaust system it will sound good. It won't have much idle chop though. It will have great manners and will work with the stock converter.

 

[Dinosport]

Over 300! I guess I was being conservative lol. I think Im going to go that route even though I really am fighting just taring the car apart and doing everything. I just have to remind myself that I can enjoy it for now and then take my time gathering everything for a future make over. That way it doesn't take 5yrs to finish it.
Thanks for the reinforcement. 300hp should be a huge improvement over the tired 350 in there now and keep me happy for a little while atleast.