hey guys i'm in need of some assistance. I have a sbc 350 thats rebuild and .030 over. right now it has a real mild cam and some stock chevy heads. I'm having trouble figuring out how to pick a head,cam,rocker arm combo. Money is a real problem being married and all so i have decided to deffinately go with the cast iron 64cc vortec heads, but now i'm stumped with a few questions....

1) what profile cam should i get to maximize performance out of this head? the springs on the head are good for .475 lift.. does that mean i go with a cam with lift specs around .460-.475?

2) theres a hydralic flat tappet in the engine now. does that mean i'm limmitted to a hydralic flat tappet cam?

3) do i need to replace the lifters and pushrods or will the ones i have already work? if i need to get them new do i just get them the same size as the ones i have or do i need different sizes for the different cam and heads? on the same note will i need a different timing chain or distributor or is all that stuff usable?

4) whats the deal with rocker arm ratio's? i know that if you go from a 1.5 to a 1.6 it raises lift, is 1.5 like the stock ratio or something. my real question is if i go with a cam thats rated at like .475 lift would a 1.5 rocker raise it further?

Theres a lot i need to learn about small blocks and hopefully you guys can help me out. i hope to have the new combo in by spring.

 

It means that you can't use a cam with higher lift than that, or you'll start breaking things.

Not necessarily. If it's a 1 piece RMS block, then you could use a factory-type roller setup. If it's a 2 piece RMS block, you could use a retro-roller setup, if you wanted to pay the money.

Flat tappet lifters absolutely must be replaced when installing a new cam. Your pushrods might work if they happen to be the right length for the new combination. Pushrods are cheap in any case. So are timing sets, not much point reusing them.

1.5 is the nominal stock rocker ratio. The valve lift of most cams is usually quoted using this number instead of the actual lobe lift. To figure out the lift with a different rocker ratio, divide by 1.5 to get the lobe lift, and then multiply by the other ratio.

 

cool what about duration on the cam, whats a good thing to look for there? higher the better the more spaced apart the better? i'm a newbie to this sort of thing, but i'm deffinately learning a bunch off you.

I'm deffinately not gonna switch over to a roller setup at this point. i really just wanna replace the stuff i have with some thing affortable that will give me some decent power from what i have now. the vortecs seem like a good deal. I'm trying to mimic the gm 350 HO, 330 hp motor, but if i can make little more power with a bigger cam or what not then better yet. So then i need to be looking for a aftermarket hydralic flat tappet cam then?

So on the pushrods,lifters,and rocker arms will i need to get them in a different size and if so how will i know witch size /length to get. or am i just lost and pushrods,lifters and rocker arms are just all a standard size?

Heres what i'm thinking of so far. the vortec heads, the vortec style performer rpm intake manifold, and a bigger cam, but matching these three has me lost a little cause the intake operating range is 1500-6500. most cams i'm seeing don't operate at these levels most are like 1800-5800 or 2200-6400.

 

Don't worry too much about advertised "operating ranges", they don't correspond well with each other, or reality.

What's your intended use for the car?

 

well i wanna make it as fast as i can on this tight budget i have, but i don't wanna throw reliability or gas mileage totally out the door either. thats why i figuring the vortecs and the manifold and the cam should give me a modest 50-60 hp. with that increase and some decent rubber i should deffinately be deep in the 13's. then i plan to rebuild the transmission with some performance goodies and pop some 3:73 in the rear end. that and some suspention attention should produce some lo 13's if not high 12's. thats the theory i'm going on anyways.

Let me ask you this... if you were me and you were gonna go with the vortec heads, and the performer rpm intake, what cam would you run to get the best results? if you have something in mind that would help me out a lot and if you have a part number handy i'd like to look into it too.

 

well i was you about 4 months ago... i built a 10.9:1CR vortec engine and used the comp XE274... i like it... Drive it every single day to work... now gas is another story about 9-10 MPG without much tunning at all... still runs rich but some of that is the cam...also you cant just run the 274 the vortecs will need some clearancing... it is called the Ghetto grind. by grinding the bottom of the retainer and the locks i gained enough clearance to run a cam with about .500 lift and some safety margin...

although i dont know how it will like a 700R4... shouldnt be to bad comp says you can run it on the stock converter... mine has buttloads of torque around 2000...

 

I'm assuming it's a non-factory roller block?

 

not bad. i wanna just throw this stuff on. i wanna stay away from modifying the heads. my issue is i just need to find the biggest cam i can run thats a hydralic flat tappet. and along with that the appropriate pushrods,lifters, and timing chain.

 

Without some work on the heads you're not going to be able to fit much of a cam. A Comp XE262 is as big as you can get under .475" lift. Having the guides and springs pockets machined is cheap work though, and you could run a lot more cam afterwards.

 

+.050" offset locks are about $20, and are about as cheap as it gets to get more lift out of a set of heads with tall guides. Or of course, grinding your retainers (yuck), or my preferred way - grinding the guides down a hair. Grind off .040" and you're set, .040" isn't a lot of grinding.

A compxe 268h is a good match for what you want, a touch with the angle grinder to the top of the guide bosses and you're done.

 

sweet i checked out that cam and it seems to be what i need, i also saw that they sold it in a kit with the timing chain,lifters,springs.... what do you guys think will i have to get the lifters and chain and springs? would i make more power with them?

 

Which cam?
And yes, the package is a good setup, it ensures you have the right parts that'll work well together.

 

hey what do you guys think about this cam? it has a little more lift, would it work better and make more power? I noticed it has a little higher rpm range too.

CS 270H-10(comp cams)
CCA-12-211-2(summit)


Brand: COMP Cams
Product Line: COMP Cams Magnum Hydraulic Camshafts
Part Type: Camshafts
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 1,800-5,800
Intake Duration at 050 inch Lift: 224
Exhaust Duration at 050 inch Lift: 224
Duration at 050 inch Lift: 224 int./224 exh.
Advertised Intake Duration: 270
Advertised Exhaust Duration: 270
Advertised Duration: 270 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.470 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.470 in.
Valve Lift with Factory Rocker Arm Ratio: 0.470 int./0.470 exh. lift
Lobe Separation (degrees): 110
Intake Valve Lash: 0.000 in.
Exhaust Valve Lash: 0.000 in.
Computer Controlled Compatible: No
Grind Number: CS 270H-10
Quantity: Sold individually.

 

You'd get better results out of a more modern dual pattern cam instead of that old single pattern grind.

 

have you tried contacing comp about a cam, they have a nice info sheet to fill out about it

 

whats the difference with a dual pattern cam and the 270h? is dual pattern still a hydralic flat tappet?

 

A single pattern cam has the same grind on the intake and exhaust valve. Most older cams did this because it was cheaper to make. Newer cams are dual-pattern, they usually have a larger and longer exhaust lobe.

 

its actually been done for a long time as OE
eg the ford 351 cleveland ~1970 had a split pattern cam
I'm sure you can go back alot further

 

gotcha, so it's a hyrdralic flat tappet with just some newer technology aka dual pattern yata yata...I'm pretty sure i'm gonna use this cam then. the other thing i wanna run by you guys is the stall converter i'm thinking of.

I'm thinking of a 2000 stall converter. i believe it's the holeshoot 200 from b&m. reason i'm thinking about this one is i really don't wanna use any higher then a 2000 stall cause i don't wanna cruise around burning more gas then i already do. so the 2000 would be good for a little more sling out of the hole but it wouldn't make the engine rev like crazy just cruisin. and i figure a 1800 stall really wouldn't be much better then stock ya know. what do you guys think is that a wise choice or do you guys have something better in mind? Not to mention i'll be running 3:73 gears too.

 

I'm running a very mild 204°/214° 278°/288° cam and i feel i need approximately 800 more rpm of a stall than factory, so i'd say don't be shy about the stall

 

yea i wish i could go with something crazy but my car right now without better heads, bigger cam, gears and a modest stall gets real shity gas mileage so i'm already looking at a big loss with these parts. price to play the game i guess it takes about 40-45 bucks to fill my tank and it goes real fast i maybe get 200-250 miles out of a full tank. how bad are your fellas gas mileage?

 

Almost 18 highway in the 383 with a whole lot more cam than that.

 

i get rather poor mileage, around 11, but i feel that is part tuning, and part poor gearing. I'm a believer that a person can run to fast of a rear end and lose mileage.

i note that in my 5 speed 2.73 ford pick up that i have to keep it around half throttle to maintain highway speed, while i haven't tried it yet i would almost bet that i could get better mileage running in fourth and keeping my foot around 3/8s the way down. basically i have the throttle greatly open but rpms very low which would cause low manifold vaccum. generally you can gauge your economy by observing manfold vaccum when you drive. the higher the better

 

Your engine setup is planned to be similar in cubes and cam to mine. I get 20mpg on the US gallon, highway, with no overdrive gear, and 3.23 rear gears, maintaining the speed limit.
Specs in sig.

 

man i'm getting pretty bad gas mileage compared to some of you. my speedp and odometer doing work since i tossed the ecu in the carb setup so i can't truley see how bad it is. i'm thinking it's partcially my tune to cause it's not really tuned well. kinda just good enough to run lol i'll be taking care of that with the new setup though. i really wasn't even gonna run the car with this setup but i had to drive it. it was my plan the whole time to do the heads and cam before i dropped the motor in, but money was tight and i could only use the garage for a certain amount of time so.

 

I think I can get around 16-18 around town(back roads), but I have a very small cam and good heads. If I'm on it a lot, I can watch the needle go down.