Hey guys. I got another 350 long block a few weeks back and now I'm struggling to figure out what I want to do with this motor. I want to put a bigger cam into it but I'm unsure as to where to go and how big to go. I want a torque monster that will slam you into the seat and just rip. The motor is an 82 block that's a 4 bolt main, its got 487 heads on it, aftermarket pistons, double roller chain and gears. It has shat looks like a stock cam in it but I also want a good lopey idle.

 

Well 383 ya know

 

Big block with tiny cam. 383 TPI.


You cant get a lot of low end torque and a lopey idle. Pick one. Do you want speed? or do you want low end torque? Low end torque is a lot cheaper, as that's what these cars did stock.

 

id prefer the torque since my car is a street runner. iv been tossing around the 383 idea but that may be on the next rebuild. but i might toss the idea around more before making my final decision. the motor will be carbed, iv already got a victory jr intake for it and a 600 eddy carb sitting back for it. but since im not use to beefing up motors past a stock rebuild, im more hung up on what cam and springs i need to run.

 

Truth be known the L31 you have listed in your signature is by far a much better engine to being doing any mods.

It is a huge mistake to be thinking a cam is a stand alone part.It just doesn't work that way.Do a search of my user name and you will find out the how and why in the numerous posts made with ref links.

 

You need to be careful when you throw around terms like "torque" and "Street runner". Torque does not win races. Horsepower wins races. If torque won races tractors would be great drag race vehicles. If you have an engine that runs great from 3000 to 7000 RPM it will still slam you back in the seat and likely win a bunch of races...

What you want isnt reasonable because you're attributing a lot of importance to abstract terms for emotional reasons instead of actually talking about what it is you actually want.

Do you want a fast car? Go for horsepower and a bigger. If you want what you are likely referring to as torque you want a stock cam. Torque is determined by airflow (essentially cylinder heads and displacement), horsepower/speed is determined by how fast the engine can intake and expel that air. If you think torque is going to win you races, go race a tractor and see what happens. Obviously, there's a length of asphalt where a faster car with a torque curve centered higher in the RPM range will lose to a slower car with a factory cam that makes a lot of off-idle torque, but a good driver will know how to stall/gear/shift the car to get it into the power band immediately. There are plenty of cars that have 3000-7000 RPM power bands that do 1.5s or less 60 foot times, even thoguh they have very little of what you are likely calling "torque".

Torque is just the amount of force applied. Power is how quickly the force is applied. In domestic car enthusiast circles torque is interchangable with "low RPM power". The only way to make more horsepower at lower RPMs is to buy heads that flow more or increase displacement. Heads can only flow so well with small cams, most are geared towards flowing as much air as possible and that has inherent tradeoffs in low RPM port velocity which, again, affects what you're calling "torque". But within reason this will still make a big difference, but not as much as increasing displacement. Displacement is the primary factor in increasing the raw amount of force applied at the wheel. The drastic differences in the flow quality of modern aftermarket vs antiquated factory cylinder heads blur this difference, but essentially your torque is determined by the amount of air you flow through the engine. Displacement is the major factor in that equation but heads are very important.

So, like I said, the only way to do what you're saying you want is to get a 454+ ci with a factory cam in it and some medium level cylinder heads that can maintain port velocity at low RPMs and still flow well. But that's not going to be the fastest thing you can build.

Also, I agree with 1gary, the Vortec engine is a much better engine than the old school engine you're talking about playing with. It's got modern heads with great port velocity AND great airflow and a roller cam.

 

With all due respect(do think after all these yrs we know each other pretty well) do have to disagree with you on torque. On a primary street driven vehicle,torque should be the main focus. It is a element you can build for to use more often in the rpm range that is the driving range normally used for street driven vehicle. The greatest return on your investment.

I'm stating this for those who don't know me.Many,many yrs of racing 9.90 cars.Have won a national in one of them(guys can and do their whole racing career without ever do that)as well as more than our fair share of track and regional races.The things we know:

Torque is = to ET

HP is = to mph

Many races won is = to the RT's + the first 60' + 330' is equal to torque mainly. So where I disagree is you can and do see cars win races that don't have impressive mph.A huge chunk of the ET is made in the first 330' and that is factor for both 1/8 and 1/4 racing.

So to compare race car's normal rpm to a street car's normal rpm is a comparison of apple to oranges.Most certainly you do not want to build for hp where the power curve is almost never used.Yes hp has been hard sold to all of us for way too many yrs.But if the goal in a street car to have off idle to have a car that presses the flesh to the seat,torque is the answer and should be for any street car.

Alot truth to the fact the size of a engine helps in torque and a lower rpm range.By far the 383 engines are more capable to produce bigger torque numbers. Built right you are well on your way to 400 foot pounds of torque at only 2,000 rpm.

Lastly the item to consider heavily is these cars are very heavy needed those lower torque numbers to perform best on the street. It takes torque to move them street light to street light.

 

If youre even remotely considering doing a 383 get it over with and do it now. Youll look back and wonder what were you thinking wiht the 350. Always go bigger!

 

A carb'ed 383 is going to need 750 carb and matching manifold,heads that are at least a 195cc intake runner and matching cam to the SCR that should be almost with iron 9.5 with a DCR of 8.5 and a quench in the range of .040 to .045. If you do the D-cup style of pistons it is the best of two worlds.That is a smile per mile for you.

If you have question about which style of EFI use a tpi that is a sfi over a tbi.The tpi's work best in the lower rpm ranges/mid ranges that a 383 works in.

 

If your are building a street engine with a focus on torque one other thing I would do that was not yet mentioned is to change the manifold. A victor jr single plane is not what you want for a street engine. If you want to do this right and one time only how about selling this 350 and building up the roller block in your car now? A roller cam will allow you to make more power with better street manners and there is no worry about wiping out cam lobes like a non roller cam.

 

Good point.A air gap intake will cool the intake charge and help in a non-detonation effort.

 

I've driven cars on both sides of the spectrum and torque is definitely more fun to play with. For a street car that's all that's needed. I rarely ever see 5500 rpms and if I do I'm slowing down shortly after that because of cars in the way or a stoplight. Like hell if it don't win races. I raced a gti that has 270 or so horses. 30 mile roll and I was in 2nd gear and as soon as I punched it I took off and he never caught up! I think I have only about 200 or so at the rear wheels, but I think my torque is in the 300s. I mainly drive between 1800 and 4200 rpms on the street, no sense in not making power till 3200rpms, unless it's a track car as well.