Vizard/Jones BBC Cam Specs for the Shootout

[dbusch]

I asked DV about the cam and lobe seperation selection and he said that it was based on cylinder head flow of the heads being used. He says in the book that this is the best way to do it but because the average hot-rodder does not have access to a flow-bench the chart has been modified basing flow off of intake valve diameter vs. bore area. He stated that if you had an extremely efficient valve/port arrangement that it would require a wider lobe seperation than an inefficient one. He also stated that exhaust efficiency and header tuning can have an impact on lobe separation as well. This is all in the How to build Horsepower book. He went on to say that the engine does not know if it has a 2.0" valve that flows 400 cfm or if it has a 3.0" valve that flows only 300 cfm. All the engine knows is flow. Now we are getting into the low-lift flow argument and a whole other can of worms. The engine only sees airflow, getting the airflow at the correct time and using the airflow the most efficient way possible is the big trick here.

Call any camshaft manufacturer other than Mike Jones (I put that in there so I didn't get scolded ) and they will give you a different camshaft recommendation every time you call. Call a different company and get just as many more recommendations that aren't based off of anything more than experience and trying to guess what catalog cam will fit the motor best. If you use David's chart, it will predict a camshaft that is much closer than just ordering a "recommended" cam almost every time, unless you get very lucky.

One other point he made. At lower compression it is best to "err" to the tighter side of things with LSA because it doesn't hurt power as much as being too wide. As compression goes up, this situation reverses and it is best to "err" to the slightly wider side of things as being too tight may hurt power more than being slightly too wide.

this last paragraph pretty much says it all. if the engine was only 10.5 compression, then you may see a 107 or 108 lobe sep cam in it, with less duration split. I dont think Vizard or Jones went wide enough. 113-114 is where i would be for best on track performance. if its a dyno queen, then 111 is probably ok. the power will fall pretty fast past peak though.

[CamKing]

And as most here noted, including Jones, Vizard went way wider than expected.

I just want to say that I was just basing that off of other engines we both spec'd cams for.
I know nothing about how Vizard calculates his cam specs, and have no opinion on it. I've never even read any of his books.
We've been discussing engines for almost 10 years now, and we agree more then we disagree, but I've never asked him about calculating cam specs.

[brad_m]

I think some people are looking at one spec and one chart and ignoring the rest of whats involved.

What I like about the two people and the cams they have selected it how damn close they are.
We have here two people that incredibly good at what they do and with out knowing what each other were thinking, were both almost on the same cam.

What it shows me is that you can talk to either of them and KNOW you getting told what you 'need' to here, Not what you 'want' to here or what will make a sale.


I would find it interesting though to see one of the cams tested at 113 and 108. The engine could then do the explaining of why both people chose 110.5/111

[superjunk]

Anything ever happen with this test??

[900HP]

I have been told that we should be seeing some results in the next few months, there has been a problem getting the 55mm cam cores and Mike is very busy. One of the cams has been delivered and the machine and assembly work are in progress. That is all I know for now

[rewguy]

almost two years later.......results?

[900HP]

The Vizard cam and Jones cam were so close to each other we just decided to run the one cam. 1031 hp @ 7500 rpm, 565 inches, ootb Dart Pro-1 355 heads, Sniper intake, single BLP 1050

[GARY C]

The Vizard cam and Jones cam were so close to each other we just decided to run the one cam. 1031 hp @ 7500 rpm, 565 inches, ootb Dart Pro-1 355 heads, Sniper intake, single BLP 1050

Was this a race or street engine?
Just wondering if you got to take it to the track?

[Nick Campagna]

Reading back over the post, I would like to ask some questions:
What was the barrel diameter on that cam
What was the base circle diameter on that cam
What was the cam bearing diameter on that cam
Did the lobe profile ever go concave
Thanks

[900HP]

Reading back over the post, I would like to ask some questions:
What was the barrel diameter on that cam
What was the base circle diameter on that cam
What was the cam bearing diameter on that cam
Did the lobe profile ever go concave
Thanks

55mm cam bearing diameter. I don't know the base circle. There is a small amount of inverted radius on the opening side.

[900HP]

The Vizard cam and Jones cam were so close to each other we just decided to run the one cam. 1031 hp @ 7500 rpm, 565 inches, ootb Dart Pro-1 355 heads, Sniper intake, single BLP 1050

Was this a race or street engine?
Just wondering if you got to take it to the track?

Race engine. It's going to the track first thing this spring. The engine has been in storage waiting for updates to the chassis. The car was only certified to 8.50's and it was running 8.55's with a 898hp 505 so we expect to go a little faster than that with the 1031 hp 565.

[Mag00]

Does that mean you will have to change your screen name?

[900HP]

Does that mean you will have to change your screen name?

LOL The screen name is an inside joke between me and my friends and has nothing to do with any engine I have ever been around. My nickname is "Throttle" hence "Throttle's Performance" and that is because I tend to drive "on the throttle" quite a bit. For a while (many, many years ago) I was driving a 1977 Olds full size wagon with a 403 in it and my friends said I drove it like it had 900HP. Since then, the "standard" number for a high performance engine has been 900hp, it doesn't matter the size, brand, or build, if it's a hot rod motor it's the 900HP model.

does that make any sense to anybody other than me

[Mag00]

Makes perfect sense to me.

[DanK]

I just read two whole threads curious to see the difference.