I'm getting ready to tear into my motor again to swap cams (going back to old setup) and was looking into calculated quench. Is it really just Deck Clearance + Compressed Head Gasket? If so, my quench comes out to .041 and I was looking to maximize efficiency. It doesn't make sense that the piston cc (-5cc) is not figured into this...
Bore = 4.030
Stroke = 3.75
CYL Head Vol = 65cc
Piston cc = -5 cc valve relief
Deck Clearance = Zero decked
Compressed Head Gasket = .041

This gives me a 10.96 SCR with a .041 quench. Does that sound right?
I'm going back to my old cam to re-gain some street manners. The cam is 230/236@ .050 .544/.555 lift, HR 112+4. I also plan to have my converter stall changed from the current 3800 stall to something more street friendly, maybe 2800 or so...

My old setup with the AFR 190's and this cam ran a best of 11.7 @ ~116 mph (its been a while) and I loved it. The newer cam I put in with the AFR Eliminators doesn't provide the vac for power brakes...which makes me regret the swap. It screams into the 6500 RPM range, but getting it to slow down is sketchy. The old heads were AFR 190's milled to 64cc and the new AFR COMP Eliminators are 65cc. Since I'm tearing into this again, I was considering milling the heads to maximize power/efficiency. I'm not sure though if it will benefit or if it is even worth it. Would love some insight from you guys with some engine building experience. Thanks.
~Magman

 

You don't "calculate" it. You measure it.

Yes that's all it is.

Piston CCs are the valve reliefs. Not a factor in this matter.

Don't "assume" for even ONE SECOND that your short block has zero deck clearance. CHECK IT. I'm not the betting kind; but if I was, I'd bet it has more. ALOT more.

 

Start here: http://www.wallaceracing.com/Calculators.htm
Look at the SCR and DCR calculators.
Less than 8:1 DCR is sluggish response and/or leaving performance and economy on the floor.
8-8.5:1 is the sweet spot.
Above 8.5 DCR requires race gas to prevent detonation.
These are general guidelines that depend on the rest of the package (cam lift, head flow, operating temp, etc).

Is it really just Deck Clearance + Compressed Head Gasket? YES.

 

I might add, milling the heads won't change your quench, it will raise compression among other things.

 

Optimizing quench with a milder cam is not going to give you the performance of the current cam you have and there are other ways to get back your power brakes for less time and effort:

A storage can will give you few good stops (and replenish while driving)

A vacuum pump, or hydroboost system will give 100% use of power brakes

Manual brake conversion will work too. ( this stops my 10 second car just fine)

 

Thanks for the feedback fellas. I changed the oil today, warmed it up, and took it around the block. The first time on the road since 2015. Wow, I am amazed at the power and responsiveness. It is definitely a "Street Nasty" car! I would love to keep the engine/cam setup I have in it now. Any chance this cam would make the vacuum to run the power brakes? I did the big brake upgrade to LS1 rotors/calipers in the front and removed the power brake setup. Since I lost the power brakes, stopping is the problem - it's like stopping a 5,000lb+ truck with standard brakes; feels like a trailer is pushing me while standing on the brakes. The cam I'm running was discussed with COMP Cams tech line and is as follows:
CS 3017/3018 HR 112.0+4
ADV DUR 286/292
DUR @ .050 236/242 Lobe SEP 112.0
Valve Lift: .579/.584 w/1.6 RR
The block is Zero Decked to the highest piston. Yes, I get it, the block is not perfectly square, but I spent good money to have it square decked and align honed to get it as close as possible. I'm certain the machine shop did me right.

If I can figure out the brakes...I'm all set. This car and motor is a super sweet combo, plenty of power and torque for what I want. So, can this cam run power brakes? What do I need to do to figure out the best route to take to get it to stop better?
Thanks again, I appreciate your help.
~Magman

 

Couple of things, what idle vacuum do you have now?

Also, I've been looking into the LS front brake swap as well, budget pads just don't cut it, look through the Brake section for recommended pads to run.

 

hint: The vacuum brake booster assist is 3x more powerful than your foot.

 

Good catch, missed that he removed it.

.

 

OP
You removed the power brakes so you have manual brakes. Did you modify the brake pedal to compensate?
You need need to drill a new hole for the master cylinder piston rod.. typically 1" up from the original hole to increase your moment arm, this will provide more leverage and improve pedal force.
You may need to change the OEM master cylinder (bore size) if you changed the OEM calipers or drums.. (calipers w/ more pistons or converted drums to disc) to provide sufficient brake pressure to the new calipers.

I grew up with manual brakes so if you had power brakes your whole driving career you are not used to them.
You have to "pump" the brake pedal, to build-up pressure. (depending on how fast your are going) "Pumping the brakes" does scrub off some speed then when you "feel" a nice firm pedal you fully depress the brakes to stop.

They are called manual brakes for a reason... and before storage cans, vacuum pumps, and hydroboost, they were the only way to run hot cam in car... MANY muscle car from the factory came with manual brakes.
and alot more non-muscle cars came from the factory with manual brakes.

Power brakes do all this work for you, so you don't have to think about it you just press the pedal.
Power brakes will stop you faster if you don't know how to use manual brakes or they are setup incorrectly.

Back in day; automatic transmission, power brakes, power steering, air conditioning, power windows, power anything were all optional accessories on most cars and only standard equipment on Luxury Vehicles.
Nothing wrong with manual systems if they are setup and used correctly.

 

Thanks guys. Vacuum at idle is 11" and I changed to manual brakes at the same time I changed the cam. Luckily, I kept everything. I'm going to keep the cam/head/converter combo I have now and see about fixing the brakes. I'm moving myself over to the brake board for some reading...

 

with 11" of vacuum at idle a vacuum storage can would be your cheapest & simplest solution, but you need to re-install the power brake booster.
You will not have unlimited vacuum with a storage can but enough for 2 to 3 power stops but the can does store vacuum as you idle/ drive so it does replenish.
I don't know your driving style or application you need to choose an option that you are comfortable with.

 

I've more cam than that in the 355. 288/294, 110 LSA on a 104 ICL. That's 71 degrees of overlap compared to 65. Vacuum is at or around 10-11" at idle. I give it plenty of idle spark advance for a boost to the vacuum but this particular shortblock is worn out so the actual amount should a point or two higher. Stopping with factory power brakes and LS brake upgrade (front and rear) is fine. The only time it gives any trouble is when the engine isn't thoroughly warmed up and the idle speed is a bit low. Idling out of the driveway doesn't make for a lot of stopping power. Give the throttle a blip and the pedal firms up. In traffic there are no issues.

 

If you have power steering a hydroboost conversion is where its at. Way more brake boost than any vacuum boost.

I have a 232/244 on 108 cam in my 383. It pulls 14 in/hg @ 750 rpm. Vacuum brakes would have been a terrible choice given its a 6,200 lbs van pulling a 6,000 lbs trailer.

Running empty at 70 mph the hydroboost swap felt like it cut my stopping distance in half. It made that much of a difference.

 

Is that your Lunati Bootlegger? That's a pretty healthy idle vacuum for the 80 degrees of overlap. Gives me a little encouragement for my next go around in engine building. Perhaps it's the weight of your combined payload but I wouldn't hesitate for a minute to use the factory power brakes with 14 in/hg in the Camaro.

 

Thanks fellas. I'm having trouble locating the right brake lines/fittings to return to stock. Apparently GM changed the thread size on the lines from the master cylinder to the prop valve in 1989/1990, so I had to order some replacement lines from another member. I also ordered a VAC canister from Summit, so hopefully I'll have it back on the road next weekend. Appreciate all the feedback, I'm looking forward to getting power brakes back!