Cam help!!!

Hey guys i needed to know if anyone knew of a good cam to put in my computer controled tbi 350 i am starting fresh i had the block bored 30 over and the crank polished i am going with trw 30 over pistons i think not sure yet. The computer has a super chip in it and i plan on upping the injectors in the tbi i have a high flow exhaust and the heads are having a 3 angle valve job and i am installing crane cams roller rockers 1.6 (silver) i want to go with a hydraulic roller cam and basically convert the block to roller the truck also have 3:73 out back so i wanted  a cam that will help me be real street cleaner any help is greatley appreciated.

well if you want a opinion from experience we recently did a TBI 350 in a 91 surburban that is a tow rig with stock computer slightly modded exhaust and mildy ported heads the cam that was ran was a 252 4x4 Extreme Energy from comp the engine's mileage improved very much over stock, it tows more and has more power throughout the RPM range it operates in. Now to be very general maybe you can go a "step" up because you have lower gears and want more top end performance but remember not to overcam for compression being used and remember what the consequences are for duration and lift and larger cams and you'll be fine. My philosophy is that if you've read a few CC/Hot Rod/CHP cam articles and have some common sense about it you will probably pick the cam that a adviser from a company will. Which saves you time because a lot of cam companies are next to impossible to actually get some time in to talk with their advisors

hope this helps!

You need to keep your MAP sensor happy without dropping too much idle vaccume for one thing. Reserch this even call Crane  orComp cams also Summit racing can help. But if you go with too much duration on a whim you will not be happy.  

Actually i called comp and the guy told me to keep my duration between 212-218 thanks for the info  

Thanx alot for the info i called comp and they gave me part number 08-502-8 he told me to keep the duration between 212-218 but you pointed me in the right direction thanks.  

See if there is a extreme series cam I remeber a dyno test back when they first came out.It was put into a sbc that was not too radical on the heads might of ben stock heads on it.Anyway I think it made about 50 more ftlbs of torque and 7" more vacume then a old factory cam might have ben a 350/350 HP cam. Anything newer technolicy wise is better then a 1970 design but I feel these cams are the latest state of art computer design.OOPS I foregot you said roller cam.Do you know what the cost of the lifters are?! Well a roller cam  can have more duration and still  idel good  and have the bottom end torque because of a smaller base circle . It just scares me if the thing runs way too rich and the computer stays in closed loop.Then you would have to pull the cam or have the computer reprogramed. Dont rush into this get some imformation you can trust . I think you allready did .Check out last months issue about the 305 camaro . It ran lean in some areas and rich in otthers .It wound up beeing on car reprogramed. I wish it said how much that cost.  

i dont doubt the large gain in torque but i doubt the gain of 7 inches of manifold vaccum. Manifold Vacuum is a direct function of compression and overlap and you cant convince me that the aftermarket cam has less overlap and improved dynamic compression.

Also can you explain to me that a roller keeps the same low end because of the smaller base circle? i was pretty sure that base circle had nothing to do with duration/lift/ramp rate figures the only performance problems with them are steeper nose radius and more problems with valve float without more over the nose spring pressure

I think I am wrong on a lot of things. All I try to do is use the imfo in my head that I have read. I do remeber something about the added weight of roller lifters and valve float. The less weight in the valve trane the better . The springs on a roller set up have to be stiffer and this adds drag. Chevy went to roller  cams from the factory to improve gas milage with reduced friction on the cam lobes. The gains did not work out as well as planned with the stiffer springs. I think what I should have said was the roller cam can achieve higher lift with less duration.Due to the roller on the bottom of the lifter having less of a contact on the cam lobe as opposed to a somewhat flat surface on conventional lifters.I think you allready know all this and are trying to have me get this stright.The other thing is just to prove that computer designs have taken the gussework out of cam grinding to make as much power and still have driveability. I have a friend with a 70 charger 440 he is gooing to order a factory grind cam .Allthe body and undercarriage is ground up restored. He is gooing through the engine now. I am having a hard time convincing him to use a newer design cam to get the same power or more and have more bottom end and driveability. This is possible right?  

remember this about a roller having more lift for the amount of duration, this is only possible in the already large profiles. In small profiles, hydraulic rollers actually have more seat duration for the same amount of lift as a hydraulic flat tappet due to lifter acceleration. A hydraulic roller will experience horrible side loads from too much acceleration and will wear them quickly or if your talking something that isnt feasible it will just snap them off, where as a flat tappet can accelerate any amount yet they are limited by the diameter of the tappet, or as in how fast the lifter can travel up the ramp before edge-riding and destroying itself. So in small profile engines a roller is almost not nessacary because it will not retain the same amount of low end power yet the roller design decreases valvetrain friction and improves mileage and for stock cam engines that are made to peak @ 3800 RPM and pass emissions the springs dont have to be very stiff so there isnt much loss there

about your friends 440, yes a newer age cam will improve everything except maybe mileage. Power will be improved at every RPM point and they will be drastic, old profiles are made very "soft" and dont give much area under the valve curve for cylinder filling (less valve area less charge gets in the cylinder less emissions and better mileage (to a point)). But if the factory grind is so mild that the engine cant produce enough torque to keep the car at a very low cruise RPM, RPM must be raised for interstate speed and thus mileage will be reduced so the loss/gain of mileage is a delicate balancing act

Okay I see. But If  you modify your engine to make peak horsepower and torque at higher rpm levels like 5200  wouldent spring preasure becone more of a issue then a flat tappet ?

Are you sure the only benifits roller in stock engines is reduced friction? I see what you mean about handeling side loads. The roller lifters dont have half the strength.But issint there some key factor about the roller only contacting the cam lobe in a area half as big as a flat lifter.Does this allow a advantage on the duration ? I thought you could run more lift without as much duration. Something that is impossible with a flat tappet?

Okay I see. But If  you modify your engine to make peak horsepower and torque at higher rpm levels like 5200  wouldent spring preasure becone more of a issue then a flat tappet ?

Of course! i was referring to a low RPM bone stock motor

about the roller lifter advantages, i have never heard of anything involving the roller is better because it contacts less area, i believe that that falls into the less friction category. In many situations you can run more lift for the same amount of duration but not in small duration street hydraulic roller profiles where side loads are kept to a minimim to keep the lifters alive a long time. A good example of the the roller having more lift for the duration is the fact that solid rollers allow .700-.800 with the same seat duration of a solid flat tappet

What I mean is set a flat lifter on a flat surface. Then touch a roller lifter to the flat surface. The roller I think will only contact 1/4 of the area the flat lifter does.Now Imagine the two on the high spot of the cam.This is what I am thinking and what I am talking about.