Rocker arm ratio

[RaceActionCentral]

I have a Herbert cam on hand that I plan to use (since I have it on hand) and have entered it into a computer dyno program using the specs of the engine I plan to build. I have used 1.5 ratio specs and 1.6 ratio specs and it seems the desktop dyno thinks the 1.5 may work best. I have mostly heard that the 1.6 ratio rockers would be the better choice. What gives? This is a 383 chevy 13:1 alky 850cfm carb,single plane Wiend w/2"plenum, 1 3/4" X 3.5" headers, 190cc intake runners 2.05 / 1.6 valves, CC6H cam (mid 90's specs, not current specs.) .590I .610E 256/268 duration @.050 (106 or 108 CL (not sure)) specs with 1.5 ratio, 6" con rods . In your experienced opinion which rocker ratio will perform best for me?

[T]

Your heads might be the factor. That sounds like a small head for 383 on alky, and thats more than likely why it's not going to like the 1.6's added lift. IMO you should have 215 or 220cc heads on that thing. Good Luck

[AA Performance]

Your heads might be the factor. That sounds like a small head for 383 on alky, and thats more than likely why it's not going to like the 1.6's added lift. IMO you should have 215 or 220cc heads on that thing. Good Luck

x2. YOU NEED MORE HEAD

[axegrinder]

If you can get duration numbers at .200 on that cam you will probably find that it is a very mild profile. I think I remember Mike Jones saying that you might as well run a flat tappet if you are going to run a Herbert cam. In that respect I think it will need the 1.6s (on the intakes anyway).
I agree with T and mitch on the heads. 190cc is smaller than I would run on a hot street motor that needs mid range.

Denis

[AA Performance]

it seems the desktop dyno thinks the 1.5 may work best.

I don't think that the desk top dyno thinks at all. Did it say it will or won't work better & by how much or is it still thinking about it? Just curious.

[CamKing]

I think I remember Mike Jones saying that you might as well run a flat tappet if you are going to run a Herbert cam..

I didn't say that.

[CamKing]

it seems the desktop dyno thinks the 1.5 may work best.

I don't think that the desk top dyno thinks at all. Did it say it will or won't work better & by how much or is it still thinking about it? Just curious.

The Desktop Dyno is as accurate as throwing darts.

[nabx22]

Heres my question how much are you really giving up using a herbert roller.I have a 383 with ported mildly ported dart 200 cc heads 11.1 compression team g intake 150 shot of nitrous.this is in a 1978 Z/28 camaro that weighs approximately 3800 lbs with me in it.I am currently running a herbert solid roller 598 in 625 ex advertised duration 289/299 at 50th 251 261 106 center.I run this car on the street and 1/8th mile.It has a 4.56 rear and 4200 stall.What do you think Mike could I do a lot better?Also running 1.6 rockers

[axegrinder]

(he was thinking the comp cam was to big),proved him wrong .

No you didn't.
You just proved that the Herbert cam isn't very good.
You might as well have put a flat tappet in it.

Mike, Im not tryin to start sh!t. I know this is a completely different thread that I am quoting you from but my point was; I dont think much of Herbert cams and I dont think CamKing does either.

Denis

[1989TransAm]

I have seen a couple of posts here by respected members in that Herbert cams has not kept up with the latest design technology. A search would probably reveal those posts.

[kirkwoodken]

If you are going to the expense of running a roller, spend an extra 100-200 dollars, and get the best cam you can get for the parts you have. Having a real pro recommend the best cam is much better than "running what you have." I would be willing to bet if you tried the one you have and then installed one recommended by Mike or Harold, you will think you should just throw the one you have in the trash and forget about it. Don't ask how I know this.

That being said, check out what you have. Degree it and get seat, .050" and .200" numbers and compare them to others listed in catalogs. Same with LDA. If you know what you have, you will be better able to make a choice about how much you are giving up, if anything. Just because it was sold by Herbert, (Notice I didn't say ground by) does not mean it won't be suitable for your app. A cam does not have to be perfectly matched to be suitable. That decision is up to you. (I'd spend the extra money now.)

Another thing: look at the fillets between the lobes and make sure there are no square corners that can act as stress risers. You don't want your cam snapping in half. Some of the older Herberts were made rather crudely. (My present "Street Roller" is a Lunati and a very well manufactured piece, about three years old.)