[M.Rydell]

What do you guys think about the nostaliga cam from comp cams I listed?

[hpete]

Thise old factory grinds belong in a museum with 8 track tape players and stromberg carbs. I hope I don't sound snotty or anything but cam science has changed a lot in the last 10 years, embrace it.

[ap72]

[quote=hpete;1599643]

Originally Posted by ap72

Of the cams you listed the xe274 is the best. If you insist on using that cam the Vortec heads would really bennefit from a good valve job and porting.[
A good valve job that includes 2.05 intakes, 1.6 exhausts, swept chambers and enlarged bowls

no. 1.94/1.6 valves. Using larger than that is just going to cost you, your peak flow is limited by the pushrod pinch in the runner, taking it all the way out will allow you to effectively run 2.02" valves but more than that is going in the wrong direction.

[hpete]

ap72 I don't agree. Although it would be better to fully port the heads along with the bigger valves, they'll still flow better even at lowlift with pocket porting and bigger valves. I would agree that 2.05's may be overkill for the application they won't hurt anything and at least here in the states 2.05's don't cost any more than 2.02's. If I stayed with 1.94's I'd be very careful who I let touch the seats.

[ap72]

Originally Posted by hpete

ap72 I don't agree. Although it would be better to fully port the heads along with the bigger valves, they'll still flow better even at lowlift with pocket porting and bigger valves. I would agree that 2.05's may be overkill for the application they won't hurt anything and at least here in the states 2.05's don't cost any more than 2.02's. If I stayed with 1.94's I'd be very careful who I let touch the seats.

They won't flow any more and your coefficent of discharge goes to ****. bigger valves are NOT always better.

[Roy36]

I have the extreme energy hydraulic cam. 274 in my 69 Nova SS 355 very close to your set up and it euns very well I'd go with 274 if your looking to drive often.

[Silver Surfer]

I have read that adding larger valves to Vortecs is bad because it decreases intake charge velocity. Also the casting is pretty thin and close to the water jacket and cutting for larger valves increases chances of a crack developing — which is also a factor that needs consideration when porting Vortecs. The intake flow numbers for Vortecs are pretty awesome. They are lackluster in exhaust flow, so if you port, do the exhaust side.

[F-BIRD'88]

Xe274H-10 needs 4.10's for that car.

Xe274 or 12-672-4 cs nostalgia 30-30h+ or Isky 278 mega cam
All these cams will need 4.10's. a 3500 stall is best with all a these.

3.55:1 use a smaller cam .

12-672-4 This cam will be particilarly lame with just 3.55's.
Needs a 3500++4000 stall and 4.30-4.56

You must fully port a vortec heads to see the benefit of a large than stock valve.
Larger valves and full porting will work well.

[vinniekq2]

how are camshaft profiles related "directly" to rear gear ratios? An engine doesnt run any different in a boat and their "gearing" is totally different?

[M.Rydell]

I have a np440 gearbox laying around, do you guys that would be better then the th350?

[cdminter59]

Originally Posted by M.Rydell

Hello! This is my first post here.


I'm just woundering what cam will be the best for my engine. Car is Camaro 69 with a th350 with 3000 stall and 3,55 gears. Vortec heads 10:5.1 cr Air gap intake quickfuel 750 e85 headers
Xe274 or 12-672-4 cs nostalgia 30-30h+ or Isky 278 mega cam

thanks alot for the help!
Cheers from Sweden!

Your Vortec heads basic operating range would benifit with a cam like this. Lunati 301A3LUN - Lunati Hydraulic Flat Tappet Camshafts - Overview - SummitRacing.com The heads don't have anything left after 5500 rpms. It would also improve them with bowl blending and mild porting.

[ap72]

Originally Posted by Silver Surfer

I have read that adding larger valves to Vortecs is bad because it decreases intake charge velocity. Also the casting is pretty thin and close to the water jacket and cutting for larger valves increases chances of a crack developing — which is also a factor that needs consideration when porting Vortecs. The intake flow numbers for Vortecs are pretty awesome. They are lackluster in exhaust flow, so if you port, do the exhaust side.

Their exhaust flow really isn't "lack luster" when compared to any other OEM castings, and the fact that they don't have a exhaust crossover is a huge plus. They're way down compared to an aftermarket head, but no bad for a stock as cast OEM head.

[ap72]

Originally Posted by vinniekq2

how are camshaft profiles related "directly" to rear gear ratios? An engine doesnt run any different in a boat and their "gearing" is totally different?

They aren't related directly BUT what F'bird is getting at is that with a 26-28" tire size and a 1:1 final trans ratio those rear gears and stall would help put the operating band of the engine closer to where the cam causes it to make most of its power. If you move your power band up then you need steeper gears to make your car run at that RPM.

Changing gears is not totally necessary but in most cases it enables the driver to make the best use of the new found power at the higher RPM ranges.

[vinniekq2]

AP72,you are correct"They aren't related directly"

most cars and trucks have multi gear transmissions,to say a car with a flat tappet hydraulic cam "needs" 4.30 or 4.56 gears?
Im trying not to correct or call out anyone,but,,,,,,,?lets think about gear choices and applications.I use 3.5 gears and my cam is 256/264@50 with valve lift over 600,is my gear choice wrong?

[F-BIRD'88]

Originally Posted by vinniekq2

AP72,you are correct"They aren't related directly"

most cars and trucks have multi gear transmissions,to say a car with a flat tappet hydraulic cam "needs" 4.30 or 4.56 gears?
Im trying not to correct or call out anyone,but,,,,,,,?lets think about gear choices and applications.I use 3.5 gears and my cam is 256/264@50 with valve lift over 600,is my gear choice wrong?

Not of you are running bonneville. Or have a very high horsepower to weight ratio.
On the street you will have sluggish initial acceleration with a big cam and no gear. ( assuming typical car wight and HP to weight ratio).
You will also be "on the converter" for a long time when you rug it.
Inefficient, creates converter heat. Long wait for the power band to hit.
Bad choice when a high stall converter is used (unless the power to weight ratio is very high)

Unless your car is very light weight or your don't care about acceleration.

Of course if you have no tires traction It won't matter much.

You average camaro malibu muscle car #3200-3600# with a 350 and a 256° cam and 28" tall tires wiill want a 4.30 to 4.56 gear It wil alos want 10:1 to 10.5:1 cr (for pump gas)( if you want strong acceleration.)
The motor will want to cruise at 60MPH at around 3200-3400rpm in Drive (1:1)

At the track you would be way under geared with 3.50:1 gears. Your ET will be 4 to 8 th's slower than what It could be with the right gears.

You can run what ever gear you want in your car. Its your car. But don't expect stong acceleration performance with a big cammed 350 and hiway gears in a typical weight car or even worse in a heavy truck) and a stock low stall converter. All the torque power will be at higher rpm ...very high vehicle speed. Initial Acceleration will be lame untill the rpm gets up to where
the cam makes power. 3000+++ 3500++rpm for a racey 256° cam.
Unless you got 5 or 6 transmission speeds (with a low 1st and 2nd ratio) to work with. Not the typical 3 forward gears and a 2.5:1 first gear as in most cars.
If you want to optimize it to break the land speed record thats a different thing.