Which cam ?

[Scott Calabro]

Hello All,

Which cam will 44 IDF Webers function best with on an 11 TO 1 C/R 289?

The C30Z-6250-C, 289 HI Po cam.

The C7FE-6250-A, Le Mans cam.

The primary concern here is how good will the Webers work according to cam selection.

Do they like lots of overlap?

I'm trying to decide which setup to use, Weber 44 IDF's, Blue Thunder 2x4 Hi Rise, or Blue Thunder 1x4 Hi Rise.

Thanks,
Scott

 

[Randy V]

Scott - I don't know the answer to your question but I can tell you that *no* carburetor likes a lot of camshaft overlap, just that some are more tolerant than others..

 

[Scott Calabro]

Thanks Randy,

I guess I should re-state the question. Are Webers particularly intolerant of overlap?

I'm struggling with which stick to put in the engine and which intake is best suited for each particular cam.

Best,
S

 

[Randy V]

The webers I've worked with and other carburetion systems that use individual runners were far less tolerant of overlap than intakes with a common plenum that dampens the reversion pulses.. The lower the vacuum signal that the carb sees the more poor it will perform at lower RPM / velocities..

Webers (in my honest opinion) are one of the more finicky carbs out there.. They are less tolerant of density altitude changes, dirt (more like microscopic dust - which renders the emulsion systems almost inoperative) and lastly - long duration camshafts..

 

[Scott Calabro]

Thanks Randy,

So....... Webers will function best with the 289 Hi Po cam ?

Best,
Scott

 

[Bill D]

Webers prefer a cam with high lift and short duration along with high compression.

 

[Scott Calabro]

Hi Bill,

So maybe 1.65 rockers on the Hi Po cam for addded lift ?

What are the complete specs. on the cam installed in your mill ?
I'll look it up myself if you just want to give me the mfg and P/N.

Best,
Scott

 

[Bill D]

I am using a Comp Cams hydraulic roller cam (.598/.598 lift, 230/230 deg dur @ .050 lift), part number 286HR. This was recommended to me by Gordon Levy

 

[Scott Calabro]

Thanks Bill.
S

 

[Bill D]

I am also using 1.6 roller rockers

 

[Scott Calabro]

Bill,

So.... 66 deg. of overlap (your cam) will work good with 331 CI and 48 IDA's.

Then I'm thinking the 38 deg. of overlap of the "Le Mans" grind will work good with 293 CI ?

Maybe Gordon could weigh in on this ?

Best,
Scott

 

[Randy V]

I always advise people to use the rocker-arm ratio that the camshaft was designed for - there are a number of reasons - only some of which follow;
1) Lift is changed by ratio (this is the only parameter most people look at)
2) Duration is changed by ratio
3) The cam has a spring spec and installed height that will be compromised by changing the ratio
4) The pushrod geometry is changed when changing ratio

Basically - you can throw what you know from the manufacturer in regard to performance specs out the window when you change the ratio..

If you want to change the functional parameters of the camshaft - change the camshaft..

 

[Scott Calabro]

Thanks Randy,

Don't want to drift too much here though.

I've already verified the use of different RA's with the total setup.

Best,
Scott

 

[Jac Mac]

Bill,

So.... 66 deg. of overlap (your cam) will work good with 331 CI and 48 IDA's.

Then I'm thinking the 38 deg. of overlap of the "Le Mans" grind will work good with 293 CI ?

Maybe Gordon could weigh in on this ?

Best,
Scott

"Le Mans" cam has " 94° " of overlap- not " 38° ". This plus using 1.65 ratio rockers will further compound valve to piston clearance problems that you will no doubt experience with the 5.4" rods you intend to use.
Personally I would use the 1.65 rockers( Actually an Aussie Holden 308 part. I find they have a better contact pattern on the end of the valve stem ) & the 5.4 rods for the better rod ratio since you state that you are going to rev the c*** out of this thing ( But I have all the gear at my disposal to cut piston notch's etc which I assume you are going to have to pay/educate someone else to do for you.) . I have mentioned the fuel issue before. But still feel a smaller duration cam is going to be more beneficial, but I have a gut feeling that you are not going to be satisfied until you have tried it for yourself.

Jac Mac

 

[Scott Calabro]

OOPS ! , I read my cam spec card wrong.


So Jac your thoughts are to use the Hi Po cam with the Webers, or either of the other two intakes ?

Or... just not to use the "Le Mans" cam in a street car.

Thanks,
Scott

 

[Neal]

Go with the webers!
Call Gordon Levy. He set me up with a Isky custom grind that has a very flat TQ curve and good HP. It's a split duration cam. Here's a link to my 347 build dyno results.

 

[Jac Mac]

OOPS ! , I read my cam spec card wrong.


So Jac your thoughts are to use the Hi Po cam with the Webers, or either of the other two intakes ?

Or... just not to use the "Le Mans" cam in a street car.

Thanks,
Scott

Scott, if your 'street' driving is going to include intersections controlled by lights and day time traffic etc then you will 'hate' the Le Mans Cam, you may even find the Hi Po cam a pain in these circumstances.
Now while the Le Mans cam gave good service in the Cobra/GT40 race cars with Webers it really does not have a lot of tractibility down below 4000rpm particularly in a small cube motor like you have in mind- even with a 4bbl its not going be lots of fun at low RPM.
While the hyd roller that Bill mentioned is more in line with the duration I feel you require, you run into a problem where the hyd roller does not like to run up above the 6500/7000rpm range due to weight etc.
Personally I would go with the single 4bbl if I was interested in having the easiest driving/tuneable combo on road or track. Hell if an unrestricted 355ci Nascar unit can pump out 800+ on ONE 4bbl, do you need all the webers or twin 4bbls- just more fuel leaks and things to go wrong in my book!

Incidently, I ran a Le Mans cam in my old Race car with a Boss302 which was not all that clever when you consider the 1.73 rockers & huge ports. To get some miles on the motor we fitted it to a MkIV Zephyr that my Employer used for this purpose for his race engines- I can tell you that after a couple of hundred miles I was sick of trying to keep below our 55mph speed limit with that thing @ about 3000rpm- only bit of excitement was when this Holden ( Aussie GM ) tried to pass us- just could not let that happen could I.

Jac Mac

 

[Lynn Larsen]

Scott,

If you ever decide to go with a solid roller, you might consider this cam. It is a reasonable cam for a road race engine with a reasonable price since it is a Comp Cams off the shelf:

Part Number............35-769-8
Engine....................1969-1995 Ford Windsor, 8cyl.
Grind Number.........FW XR268 R-10
Description.............Solid roller lifter

Valve Adjustment (0.016/0.018)
Gross Valve Lift w/1.6 rockers (0.589/0.602)
Duration At 0.015 Tappet Lift (268/274)
(Intake/Exhaust)

Valve Timing At 0.015 (Open/Close)
Intake (28/60)
Exhaust (71/23)

Cam Installed At 106 Intake CL (Intake/Exhaust):
Duration At 0.05 (230/236)
Lobe Lift (0.368/0.376)
Lobe Separation 110°

 

[Scott Calabro]

Hello again !

Neal,
If the budget allows, Webers will be the choice, as they are far more expensive than other choices. Nothing looks or sounds like them that's for sure!

Jac Mac,
It seems that you can read my mind. I know the C30Z cam is best for all around use and is somewhat mild, since they were available with automatic boxes, but my juvenile thoughts are toward the C7FE grind! Since heads have not been purchased yet my options are still open.

Lynn,
Great minds think alike! That is quite close to a Comp solid roller that was one of my early choices (31-760-8). But I fear that since solid & hyd roller lifters (without going to exotic ones) are too heavy, requiring a prohibitive spring pressure, in the end requiring regular lifter inspection and maintenance. Too bad no one makes a "rev kit", like the ones for the SBC, for the SBF 289. This is why I want to go with a solid flat tappet. Only 120# on the seats and with Crower "coolface" lifters and Ti retainers I can rev my brains out !

I really am thankful for all the thoughts.
Please keep it coming.

Cheers,
Scott

 

[Lynn Larsen]

Scott,

I am using Crower lifters with the high pressure pin oiling option, Comp 939-16 springs w/Ti retainers and Jesel 1.6 shaft mount rockers. I am building to 7.5K but will rev limit at 7.25K.

Lynn