bence13_33

... :crazy: I was reading my "How To Hot Rod BBCs" book and was checking out head & cam combinations. I discovered that the old LS6 454 used a cam that had a .500" lift and a 306 duration solid lifter cam. Here are the heads that I will be using:

Cast Iron Merlin Heads, R-Port, 345cc Intake Runners, 119cc CCs, 2.30Intake/1.88 Exhaust Valves, Supports Up To .700" Lift

I have my cam decision narrowed down to two different cams:

Comp Cams Magnum 294S Solid Lifter Cam
.595"/.595" Lift, 294 Advertised / 248 @ .050 Duration, 110 Lobe Seperation

Comp Cams Magnum 306S Solid Lifter Cam
.629"/.629" Lift, 306 Advertised / 260 @ .050 Duration, 110 Lobe Seperation

I'm nearing my purchase of a cam and lifter kit and really need to make up my mind. Tony (MoMo) said that my engine will handle 6750 RPMs with forged rods. With the 306 cam I'll have to run 11:1 CR, with the 294 I'll have to run 10:1. I am worried that the 294 cam won't be enough cam for the heads that I am going with. I am also looking at achieving at least 550HP (I would always like more though :) ). This whole engine build up is going to cost me $3300 (the heads were the kicker ; costing $1250).

I would like to hear your suggestions. I don't take the car on long trips...mostly just cruising through town. The rough idle and loud exhaust won't bother me.


[Modified by bence13_33, 10:23 PM 11/22/2001]

Steve439

Bence,

Those old Chevy solid lifter cams have a duration of
242 degrees at .050

MARKUS_P

Hi Bence!
I envy you that you´ve found sombody to help you building up an engine.
That´s just what I want to do....

I have an eye on your project, and whenever I read your posts your horsepower numbers get bigger and bigger;)
Didn´t you say that you´d be more than happy with 500 HP? Just a while ago? :D
Not that I would do anything different....
Do you plan to reinfore the drivetrainparts? U joints, halfshafts and so on??
I´m specially interested in this because I own a 76 vette and I wonder when the point comes up to reinforce the whole drive train....
Good luck, Markus

Vetterodder

The cams that you are considering use advertised (total) duration figures taken at a higher lift (.006?) than GM used so don't be missled by that comparison. I don't know the exact comparative figure but I think the GM cam was under 290º total if measured by normal standards. Someone here probably has more accurate info on that. In any case, modern cam and valve spring technology allows for higher lifts with reliability. I'd recommend the smaller cam, especially for street use. Besides being gentler on your valve train and provide better drivability, it'll give more power where you use it.

A major consideration is your gearing and how low you're willing to go. The later your power arrives, the lower the gearing you'll need to take advantage of it. Don't be suckered in by max hp figures that won't occur in your car until you're looking at some ricer's tail lights! If ya want to scare them at the traffic light, get the biggest cam you can find. If you want to actually beat them, get the cam that's best matched to your combination.

69ttop502

Bence I would be very wary of the heads with the 345 cc ports. That is a huge port and velocity would really suffer with anything but a huge cam. I mean 290 cc oval ports can make over 600 horsepower so I would stay with a rectangular port of no more than 320 cc's.

norvalwilhelm

Of all the cams that I have run through the years my favorite was a Crane F 256/3634-2S-8. It has .618 intake 256@ .050 and 638 exhaust and 264@ .050. Lobe seperation around 108. This cam really had a mid range charge and wild idle. It was advertised 4200-7000 but it pulled down low and right to 7500. I spent $1500CDn on a roller setup and have never been as happy as with this flat tappet solid cam.
As for the heads they are tooo big.
I know " shut up about the heads" Just want to get a last plug in before the weekend.
Have a nice weekend.

bence13_33

Norval:
I am very tempted to go with the 306 solid lifter cam, it is very similar to the Crane cam that you mentioned....what do you think? :)

As for the heads, could you recommend a set that would work well with my setup? MoMo suggested going with 2.30/1.88 Valves. Any help with the heads would be greatly appreciated. Thanks.

P.S. I just noticed that Jeg's also has a smaller set of Merlin heads. They are 310cc R-Port Heads w/ 2.25/1.88 Valves. Maybe those would better suit my setup.


[Modified by bence13_33, 4:24 PM 11/23/2001]