Slant Six Forum :: Cam Selection

Well that really stinks. I spent half an hour on the phone with him explaining what I wanted. He told me any more cam than that and I wouldn't be able to reap the benefits because I told him my stock bottom end would only be revving to 5k to 5200 with 5500 being the absolute max.

I would like to be able to hit 14-15 seconds in the 1/4 mile without nitrous, 13 with it.

Mpg is my least concern though I would like decent mileage but the car has to sound aggressive and be able to perform much better than stock

They told me the duration being raised to 230 would make it sound lopier and move the rpm top of the power band to 6k.

I was also told that even up at the higher duration raising the lift from 465 to 485 would only yield an additional 1 or 2 ft torque lbs.
The lobe center at 111 seems to fall right in line with what tech support told me. FITech says nothing below 110 lobe separation for their throttle body injection unit to run properly.

I'd like to run super and don't mind using octane booster but I don't want to have to use actual racing fuel. Too much of a hassle.

I definitely want single exhaust with duals into a y pipe if that'll be sufficient. I don't want the added weight unless it's necessary.

I would like to think that the cam I want would necessitate the use of a high stall speed converter because the cam is so aggressive but I'm told that's not good with nitrous or for gas mileage or vacuum which is needed to run the fuel injection system. I want it to sound bad ass!

Author:	B Body Bill [ Mon Jan 30, 2017 4:17 pm ]
Post subject:
Thank you. I understand everything up to 108* .558" lift 300* duration intake lash-.028" cold exhaust lash-.030" cold C/L 108* Why is lobe lift less than the 558 stated lift? .372" lobe lift I understand duration. Must it be stated at .050"? How is this different than "advertised" duration? Why is there no standard on exactly how to describe the numerical characteristics of cams? I see different variations and get confused on not only how to order but also on how to understand the specs and how they effect the overall operation and performance of that particular cam. Duration @ .050"-262* I&E I'm sorry. I don't mean to sound so ignorant. This is a very confusing topic for me. I have yet to hear a simple explanation of how it works. Maybe it can't be explained simply. All the more reason I need to know what's going on. What is overlap? Is that like lobe separation? 46* overlap @ .050" These next 4 ratings tell me what? Does the cam grinder need these numbers? Ex opens 59* BBDC In opens 23* BTDC Ex closes 23 ATDC In closes 59* ABDC Is this cam meant for a stick or hi stall auto trans? How will it work with a hyperpak? Would the problems with a hyperpak disappear if I were to install direct port fuel injection system?

Author:	Rick Covalt [ Mon Jan 30, 2017 6:27 pm ]
Post subject:
The lobe lift is less due to the rocker arm ratio of 1.5 to 1. Cam lobe lifts .372 and the valve moves .558 1.5 X .372= .558 The duration at .050 is generally what is used so the you can compare the different cams at a known lift. I believe the advertised duration can be measured differently by different companies. So if everyone looks at the at.050 lift number you are comparing apples to apples. I believe the advertised duration is measured by some companies at .002 and .004 and probably others. I am no expert on any of this so experts please correct anything that I may have been wrong on. Hope that helps a little. Rick

Author:	Dart270 [ Mon Jan 30, 2017 7:21 pm ]
Post subject:
Rick has some nice info there. Cams are not a simple topic in general. Typically, gases do not start to flow much until the valve gets lifted around 0.070" off the seat, so that is a more fair number to compare how "wild" a cam is. Overlap @ 0.050" is the amount of degrees of crankshaft rotation where both valves are open more than that lift at the cam lobe. You multiply that number by the rocker ratio (1.5 for Slants) to get the lift at the valve, as Rick said. Cam manufacturers often state "advertized" duration as the duration the valve is open at 0.020" although sometimes they use something else like 0.008". Here is a very basic intro to cam features: http://www.hughesengines.com/TechArticl ... ngacam.php Hope this helps, Lou

Author:	B Body Bill [ Tue Jan 31, 2017 12:44 am ]
Post subject:
Thank you Rick Lou and Hughes Camshaft articles. I feel like I just got some sure footing on a very rocky path. I appreciate the help. Now to go back and reread everything again.

Author:	slantzilla [ Tue Jan 31, 2017 10:17 am ]
Post subject:
Cams are measured @.050" or whatever to get the lash and entry ramps out of the equation.

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Cam Selection https://www.slantsix.org/forum/viewtopic.php?t=60657	Page 4 of 4

Author:	B Body Bill [ Tue Feb 07, 2017 12:04 pm ]
Post subject:
Thank you. That makes sense. Sorry for the delayed response. Been busy this past week. Just took the Belvedere out for a ride last night for the first time in a long time. This car runs so well for a stock 1bbl. I hate to mess with it but it just doesn't excite me. I'm planning on turbocharging this car. Are there cam specs that would work well (much better than stock) with a turbo setup and doing head work (larger valves and port and blending work)? I'd like to get the fuel system in order as well as the intake and exhaust, manifolds and the head and cam. This way when I'm ready to turbo charge it that's all I'll have to deal with. I'd also be able to enjoy, hopefully, a much more powerful setup in the mean time while I'm planning and saving for the turbo setup. I'd also like to get as much of a "cam sound" as is prudent and possible for a car that will be turbocharged? Is that possible or will the cam still sound stock (it may not be worth it to me of it still sounds stock)? Or should I just wait until I'm ready to do it all? It seems overwhelming to do it all at once and, at the risk of not getting to it, I'd like to do pieces of it along the way so I can manage it financially and enjoy the various stages as well as force myself to continue along. I was also considering using a super six setup in the mean time but, as stated in an earlier post, I'm not sure I'd be happy enough with it. I also thought if it ran will I might be less inclined to keep going for a while. While that's not the worst thing I don't want to do things twice or toss what I've invested good money into the install. Lou, you had mentioned that I could do quite well with the super six setup. What kind of carb would I use for a blow through 2 bbl turbo setup. I was planning on using the 4bbl offenhauser I already have and a fitech TBI unit. They are rated as a blow through turbo unit as well. I want to run dutra duals on the car and tie the 2 exhaust ports together before putting the exhaust gasses into the turbo. For now I'll just run then into a y pipe 6-8 ft under the car. I just went through the car mechanically, did some upholstery repair, didn't need much though. Now I'm pulling the front and back glass out to do some rust repair, change old gaskets and possibly install a vinyl roof on the car. I look the way it looks on the 66 Belvedere hdtp.

Author:	Dart270 [ Tue Feb 07, 2017 12:31 pm ]
Post subject:
Hi Bill, Forgive me for being direct, but didn't you recently ask about cams for a turbo in another thread? This is a ton of questions for a single post. It would help us if you could break it down into bite-sized pieces. I'll answer two questions: 1) If you want a bigger sound on a turbo car, but put on a big pipe. 3" from turbo to rear bumper on my Dart sounds pretty healthy. 2) I personally plan to never run a turbo with a carb, but if I were to do so, I would either use a Carter BBD (low boost and power), or a Holley 500 (higher boost and power). Both should be relatively easy to tune relative to any 4bbl. Best, Lou

Author:	B Body Bill [ Tue Feb 07, 2017 1:01 pm ]
Post subject:
You're right. I'm sorry. I hadn't been on in a while and got excited because the Belvedere is moving along nicely. I just rechecked the prior post you you're referring to and pick up there where I left off.

Author:	Dusterdave1971 [ Mon Apr 18, 2022 2:04 pm ]
Post subject:	Re:
Quote: Well that really stinks. I spent half an hour on the phone with him explaining what I wanted. He told me any more cam than that and I wouldn't be able to reap the benefits because I told him my stock bottom end would only be revving to 5k to 5200 with 5500 being the absolute max. I would like to be able to hit 14-15 seconds in the 1/4 mile without nitrous, 13 with it. Mpg is my least concern though I would like decent mileage but the car has to sound aggressive and be able to perform much better than stock They told me the duration being raised to 230 would make it sound lopier and move the rpm top of the power band to 6k. I was also told that even up at the higher duration raising the lift from 465 to 485 would only yield an additional 1 or 2 ft torque lbs. The lobe center at 111 seems to fall right in line with what tech support told me. FITech says nothing below 110 lobe separation for their throttle body injection unit to run properly. I'd like to run super and don't mind using octane booster but I don't want to have to use actual racing fuel. Too much of a hassle. I definitely want single exhaust with duals into a y pipe if that'll be sufficient. I don't want the added weight unless it's necessary. I would like to think that the cam I want would necessitate the use of a high stall speed converter because the cam is so aggressive but I'm told that's not good with nitrous or for gas mileage or vacuum which is needed to run the fuel injection system. I want it to sound bad ass!

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