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Better Brake Vacuum for Erson Cam?
https://www.slantsix.org/forum/viewtopic.php?t=39027		 Page 1 of 2
Author:  Adrenalin [ Tue Feb 16, 2010 10:23 pm ]
Post subject:  Better Brake Vacuum for Erson Cam?
Dear Sirs,

I have a stock cam at the moment and an Erson RV15 lying on my floor for installation. Even with the stock cam the engine vacuum does not seem efficient for the brake so with a hotter cam I think it will be worse. The cheapest solution that I found was a belt driven vacuum pump but I have no spare place to belt it!!! I need a double water pump pulley or do you you have any suggestions? Can I find a double pulley for the vacuum pump or should I build it myself? I know that there are systems powered by steering hydraulics and engine oil flow. I do not feel comfortable with the engine oil thing and the hydraulic one is too expensive.. any suggestions? Thanks a lot...
Author:  Reed [ Tue Feb 16, 2010 10:45 pm ]
Post subject: 
What is your engine vacuum at idle and in gear? If your power brakes don't work with a stock cam then you have a problem with something other than the cam.
Author:  Adrenalin [ Wed Feb 17, 2010 12:04 am ]
Post subject: 
Well its my bad that I do not know the vacuum, I did not measure it but the brakes are ok in the first hit if I pump the brake it looses power which I think its normal with this kind of a system. Or it not? should I check it? I thought that if I pump the brakes I loose braking power because of engine vacuum system... or...hmmm
Author:  66aCUDA [ Wed Feb 17, 2010 5:58 am ]
Post subject: 
I dont think the RV15 is big enough to give you a problem with the brakes. But I dont run power brakes either.
I do have a double water pump pulley if you find you need one.
Frank
Author:  SlantSixDan [ Wed Feb 17, 2010 6:20 am ]
Post subject: 
I think you have a problem with your brake booster (or its supply hose, or its check valve, or its check valve grommet), not with your engine vacuum.
Author:  ceej [ Wed Feb 17, 2010 7:59 am ]
Post subject: 
I run the RV15M RDP. There is no difference in idle or cruise vacuum when compared to the stock cam. I have a console mounted vacuum gauge.

Idle quality is very similar to stock, even with extensive engine modification. Your going to gain some torque, with very little, if any, downside.

2¢

CJ
Author:  Adrenalin [ Wed Feb 17, 2010 8:05 am ]
Post subject: 
ok I got your point, first priority is booster check then.. fair point. Anyhow can you please inform where to buy a double line pulley? I may need it for another thing in the future?
Author:  Adrenalin [ Wed Feb 17, 2010 8:12 am ]
Post subject: 
Quote:
I run the RV15M RDP. There is no difference in idle or cruise vacuum when compared to the stock cam. I have a console mounted vacuum gauge.

Idle quality is very similar to stock, even with extensive engine modification. Your going to gain some torque, with very little, if any, downside.

2¢

CJ
Wow! I am really curious about the performance differance! I run with a carter BBD (dual barrel) 0,05" head shave, electric ignition, port and polish. Rather than torque does the engine come alive? I need to shave moore for the cam to get 9,5:1 comp ratio, I am afraid the valve pushrods will not allow for lash setup, did you have an issue like this? And vacuum info was more than enough, so I need to check my booster first!
Author:  Adrenalin [ Wed Feb 17, 2010 8:22 am ]
Post subject: 
Quote:
I run the RV15M RDP. There is no difference in idle or cruise vacuum when compared to the stock cam. I have a console mounted vacuum gauge.

Idle quality is very similar to stock, even with extensive engine modification. Your going to gain some torque, with very little, if any, downside.

2¢

CJ
Also do you have some horse power figures?
Author:  ceej [ Wed Feb 17, 2010 7:44 pm ]
Post subject: 
I'm not running the RV15M in an engine that is stock. That's an important point to make.

According to the 1/4 mile, car weight and so forth, the calculators compute ~250 crank HP.

This is on a 248" Stroker, 10.3:1 compression, 7.0" long rods, Toyota 3.445" pistons, Ford 300 valves... See where I'm going? Apples and Oranges.

This is subject to revision. The head is being modified as we post. :D

With a stock intake, exhaust, and head, you will likely see a boost across the board. It's unlikely you will experience the HP numbers above without modifying the engine a tiny bit. :wink:

CJ
Author:  ceej [ Wed Feb 17, 2010 7:50 pm ]
Post subject: 
In most cases, going to .100" off the head won't mess up your valve geometry too much. I went with Smith Brother's push rods to make things right. I have .125" off the deck, and .040" off the head. This is not Grandma's slant six...

I think your setup should do very well with the BBD. Run your numbers and find out exactly where you are in respect to compression before going too far. Have you modified your ignition curve and so forth?

CJ
Author:  Adrenalin [ Wed Feb 17, 2010 10:43 pm ]
Post subject: 
Quote:
In most cases, going to .100" off the head won't mess up your valve geometry too much. I went with Smith Brother's push rods to make things right. I have .125" off the deck, and .040" off the head. This is not Grandma's slant six...

I think your setup should do very well with the BBD. Run your numbers and find out exactly where you are in respect to compression before going too far. Have you modified your ignition curve and so forth?

CJ
Well I totally understand its totally apples and oranges... and you hit me in my weakest point, I did not recurve the ignition since I do not know how to do it and I guess no one has an idea here in Turkey. During my chats with some work shops I mentioned the cam degreing and they even did not understand what I meant, so I guess I will not recurve the ignition unless I learn how to do it myself or find a shop who knows how to do it. There should be a some measurement system for me to deal with it so that I can deal with the setup, if its all about experience then I will leave it as is. hufff... anyhow I am not totally abused with the power, its far far better than the stock now, a lot more alive... I wonder what will happen with the cam... without recurving :(
Author:  ceej [ Thu Feb 18, 2010 3:57 am ]
Post subject: 
OK, You've been here?

We really need a FAQ that we can put up on the subject of using a degree wheel properly. Doc? Fopar? Josh? I may go out with the camera this weekend and get some quality time with a dismantled slant. It looks like the cam in Linda's GT is coming out for something a bit nastier, and the Hooptie engine will be out this weekend as well.

There was a "card" that came with your cam that gives you a bunch of numbers that relate to when "Events" happen as the cam turns, For instance; where the .050" Intake lift event occurs when referenced to top dead center on piston #1. By comparing when the cam events occur you can correct for variation in the grind, or modify the characteristics that the cam will exhibit when running by either advancing or retarding it.
I found my Erson to be fairly close to the specs, and that it ran best straight up in my build. It's still very nice to know that it's right. Some folks have found errors in cam grinds of several degrees. In that case, the engine won't operate as expected.

I think you'll be happy with the RV15M For a driver. It isn't going to have a choppy idle or anything like that. When my engine is warmed up, it's smooth as silk.

CJ
Author:  65cuda [ Thu Feb 18, 2010 7:33 am ]
Post subject: 
Ceej you are happy with the RM15 for a driver. i am still trying to decide which cam for my driver. it's going to be about 9-1 with a BBD 2bbl. want best MPG on reg. grade gas.
Author:  carlherrnstein [ Thu Feb 18, 2010 3:34 pm ]
Post subject: 
Im with dan on this one its most likly not the vaccume.
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