Big cam vs. Vacuum
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Big cam vs. Vacuum
Whats the biggest cam for a small block 383 roller cam build you were able to use and still have enough vacuum to operate lights and wipers
well in your C3?
well in your C3?
Last edited by 0311 jarhead; Jun 13, 2021 at 06:39 PM.
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
This cam will provide over 13 inches of vacuum in a 383.
Good vacuum is a plus for the headlights and/or wiper door to work but remember that it is only as good as much as the system leaks. I only pull 10 inches of vacuum but everything works fine as it is leak free.
Jebby
Good vacuum is a plus for the headlights and/or wiper door to work but remember that it is only as good as much as the system leaks. I only pull 10 inches of vacuum but everything works fine as it is leak free.
Jebby
Le Mans Master
Joined: May 2007
Posts: 5,019
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From: North tonawanda NY
comp xe 270 retro roller cam with 1.6 rockers here in a 355 and headlights work fine at idle or driving. Brakes too... Before this cam I had the lunati voodoo 262/268 cam and the everything worked about the same va vise the boost in power with the 270 cam is noticable even with the 3.08 gears still in the car. kinda wishing I went one step bigger now.. lol.
Last edited by augiedoggy; Jun 14, 2021 at 07:50 AM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
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From: Cool Northern Michigan
What's the biggest cam . . . . .?
This is not a proper question. The proper question is what cam will work best for the engine, drivetrain and driving style I have. The vacuum estimate is secondary in your search.
Use the cam companies 800 numbers and give them a call with all your engine specs printed out in front of you.
This is not a proper question. The proper question is what cam will work best for the engine, drivetrain and driving style I have. The vacuum estimate is secondary in your search.
Use the cam companies 800 numbers and give them a call with all your engine specs printed out in front of you.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
That's a very poor choice for a H-roller. Do you know that roller cams create motor vacuum with more duration than their flat tappet counterparts? The other problem with roller cams is the superior cylinder filling causing detonation at lite throttle cruising. My first 383 with 10.7 c/r had horrible detonation with a 232/238 .620/644 112 cam.
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get the best cam you can and if it doesnt produce the vacuum you need, install a electric vacuum pump. Use a Hella vane style not a diaphragm style. Its loud with the motor off but its not noticeable with the motor running. I have one that came with a pressure switch so it is on /off demand as long as you use the one way valves
something like this
https://www.summitracing.com/parts/h...content=GSAPI1
something like this
https://www.summitracing.com/parts/h...content=GSAPI1
Last edited by Rescue Rogers; Jun 14, 2021 at 11:28 AM.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Oh, the biggest that I use on a 383 is a custom billet steel 236/242 .644/.660 112 brakes and everything worked fine. It got the lazy head lights. I could turn them on in the garage and the first head light would pop up backing out and the second would slowly come up when I started driving down the street. At speed in the evening one would come up then the other. Brakes were never a problem.
If you think about it a L-82 rated at only 225 hp or something was a 222/222 on 114. So there is NO reason to go the way lower duration with a roller. Most cams in the advertisements are talking about 350 ci NOT 383 with much more TQ. I was truly amazed in my first drives of my 383 with a 232/238 roller
If you think about it a L-82 rated at only 225 hp or something was a 222/222 on 114. So there is NO reason to go the way lower duration with a roller. Most cams in the advertisements are talking about 350 ci NOT 383 with much more TQ. I was truly amazed in my first drives of my 383 with a 232/238 roller
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
What's the biggest cam . . . . .?
This is not a proper question. The proper question is what cam will work best for the engine, drivetrain and driving style I have. The vacuum estimate is secondary in your search.
Use the cam companies 800 numbers and give them a call with all your engine specs printed out in front of you.
This is not a proper question. The proper question is what cam will work best for the engine, drivetrain and driving style I have. The vacuum estimate is secondary in your search.
Use the cam companies 800 numbers and give them a call with all your engine specs printed out in front of you.
Happened before and I was very unhappy.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Do you know the 383 C/R That is the determining factor with Dynamic Compression ratio and what size min cam duration that you can run.
Engine vacuum can be increased by idle rpm and timing
Engine vacuum can be increased by idle rpm and timing
Last edited by gkull; Jun 14, 2021 at 06:40 PM.
Burning Brakes
Joined: Jan 2006
Posts: 1,223
Likes: 174
From: Fort Wayne IN
I had a Speedway circle track in mine and I could not operate the headlight doors. I switched over to the McSpeed electric kit for the headlights and just recently went to a milder cam anyway.
Last edited by bluthundr; Jun 14, 2021 at 07:32 PM.
Le Mans Master
Joined: Aug 2017
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From: Cool Northern Michigan
They have the software that will be very accurate in determining exactly what cam is best for your needs. No hype, Just data.
Later you can chose from whom you wish to buy from.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Why would any cam company try to sell anyone the wrong cam? They have a rep to protect. Talk about shooting yourself in the foot.
They have the software that will be very accurate in determining exactly what cam is best for your needs. No hype, Just data.
Later you can chose from whom you wish to buy from.
They have the software that will be very accurate in determining exactly what cam is best for your needs. No hype, Just data.
Later you can chose from whom you wish to buy from.
Last edited by gkull; Jun 15, 2021 at 12:15 AM.
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Comp Cams is number one in sales and number one in respect for their products and the way they do business.
They didn't achieve that rating by hiring dummies.
Come on boy's its time to go out and get real.
Le Mans Master
Joined: May 2007
Posts: 5,019
Likes: 1,119
From: North tonawanda NY
I disagree. That is not how they became a multi-million dollar business.
Comp Cams is number one in sales and number one in respect for their products and the way they do business.
They didn't achieve that rating by hiring dummies.
Come on boy's its time to go out and get real.
Comp Cams is number one in sales and number one in respect for their products and the way they do business.
They didn't achieve that rating by hiring dummies.
Come on boy's its time to go out and get real.
Last edited by augiedoggy; Jun 15, 2021 at 09:03 AM.
Le Mans Master
Joined: Oct 2010
Posts: 6,930
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
I disagree. That is not how they became a multi-million dollar business.
Comp Cams is number one in sales and number one in respect for their products and the way they do business.
They didn't achieve that rating by hiring dummies.
Come on boy's its time to go out and get real.
Comp Cams is number one in sales and number one in respect for their products and the way they do business.
They didn't achieve that rating by hiring dummies.
Come on boy's its time to go out and get real.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Comp Cams has facilities in Miss, Tenn, ILL & Mich. They have 28 CNC machines at the factories that make long production runs of thousands of cams and other machinery for producing custom racing cams of 20 units or less. They have 250 employees and it takes ten workers to make a cam from start to finish.
This does not sound like they farm-out to me.
This does not sound like they farm-out to me.