[Bonhorst]

Hey guys, i looking for information on building a mild 350 sbc, I have a 350 crate motor here is the information i know

-(4) Bolt main block with a (2) piece rear main seal.
-Cast Iron Crank.
-Forged steel connecting rods.
-Cast Pistons, (dished).
-Hydraulic flat tappet cam, (.383� intake / .401� exhaust) and a 112-degree lobe separation.
-Cast Iron Cylinder heads with a 76cc combustion chamber. (Non vortec design)
-8.5:1 compression ratio.


Im not wanting to go all out just yet, being this is my first build, i would like to put on some better heads, and a mild cam, i will go after the pistons later, when i get more time and money. will i run into any problems with the conecting rods and rings due to the higher compression ratio? im going to stick with the stock exhaust manifold (i have been told that headers dont really make any noticable gains, unless you are in the 380hp+ range, is this true?) what heads, cam, lifter, rockers, springs, should i go with? im not looking for a whole lot here, just a litte more than what i have. so far i have put on a 600cfm edelbrock carb with an edelbrock performer intake, and an HEI distributer. aso i was thinking about putting 4.10:1 gears in, do you think this would hurt me? i have a TH350 and im not sure if the 4.10 would put the rpms to high on the high way. my car is a 72 el camino custom, (vin letter H) im not sure how much it weighs though, or how much the wieght would affect my gear choosing. if i had to estimate id say around 3500 lbs any input is helpful. thanks

Chris

[DoubleVision]

Headers help period no matter the power level. No, higher compression won`t hurt the rings or rods. For your combo since your looking for a basic power gain I would use Vortec heads, factory heads have 062 or 906 casting numbers, they have a 8 bolt intake pattern, older heads have a 12 bolt pattern. So if you find someone trying to sell you vortec heads with 12 bolt intake pattern you know they aren`t the real mccoy`s. If the heads are stock you will need to have the valve guides clearenced for the higher lift.
You`ll also need self aligning rocker arms, but these are common on engines from 1987 up. Couple the heads with a edelbrock performer vortec intake, a comp cams magnum 268 cam, This cam will give you a lopey idle but has excellant low end torque and doesn`t need a stall converter.
1 1/2 inch headers, dual exhaust with crossover pipe, low restriction mufflers. Double roller timing set, springs to match the cam. I would also use a K&N air filter, moroso blue max spiral core spark plug wires routed correctly, a pertronix flame thrower coil and module. get a advance curve kit for the HEI, and install the lightest springs in the kit. Set the base timing to 12 degrees before top dead center with the vacuum advance disconnected and plugged.
Lock the distributor, then connect the vac advance to a full time manifold vacuum source (one that pulls vacuum full time, even at idle) recheck timing, it should be around 20 - 24 degrees before TDC. The edelbrock carb will work fine. This combo will kick up your power output by about 60 horses and give it close to 100 ft lbs more torque. Keep your foot out of it, it`ll also get nice mileage. I would use 3.42 gears, this will give it a good balance for street and race use.

[kevs79]

Originally Posted by DoubleVision

Headers help period no matter the power level. No, higher compression won`t hurt the rings or rods. For your combo since your looking for a basic power gain I would use Vortec heads, factory heads have 062 or 906 casting numbers, they have a 8 bolt intake pattern, older heads have a 12 bolt pattern. So if you find someone trying to sell you vortec heads with 12 bolt intake pattern you know they aren`t the real mccoy`s. If the heads are stock you will need to have the valve guides clearenced for the higher lift.
You`ll also need self aligning rocker arms, but these are common on engines from 1987 up. Couple the heads with a edelbrock performer vortec intake, a comp cams magnum 268 cam, This cam will give you a lopey idle but has excellant low end torque and doesn`t need a stall converter.
1 1/2 inch headers, dual exhaust with crossover pipe, low restriction mufflers. Double roller timing set, springs to match the cam. I would also use a K&N air filter, moroso blue max spiral core spark plug wires routed correctly, a pertronix flame thrower coil and module. get a advance curve kit for the HEI, and install the lightest springs in the kit. Set the base timing to 12 degrees before top dead center with the vacuum advance disconnected and plugged.
Lock the distributor, then connect the vac advance to a full time manifold vacuum source (one that pulls vacuum full time, even at idle) recheck timing, it should be around 20 - 24 degrees before TDC. The edelbrock carb will work fine. This combo will kick up your power output by about 60 horses and give it close to 100 ft lbs more torque. Keep your foot out of it, it`ll also get nice mileage. I would use 3.42 gears, this will give it a good balance for street and race use.

Wow.....can't get more detailed advice than that!!

[Bonhorst]

thanks! i think that is the best advice i have been given so far, i never would have thought to upgrade the valve seals for the lift, because i was thinkking about installing a slightly bigger cam with the stock heads to begin with, but i think i will hole off till i can do the heads and the cam together. Also, i was told that using a 4 hole carb spacer as opposed to an open one would be better, and not to use a spacer period with such a low power engine, due to the weakend signal between the manifold and the carb. any truth in that?

[Rickracer]

IMHO, the above is a great recipe for a strong, capable, efficient street motor,

4 hole spacer = stronger vacuum signal
Open spacer = larger effective plenum volume (more like a single plane intake)

If you are running the manifold that was recommended, chances are you will not see a benefit from using a spacer, but it never hurts to try it and see.

[Bonhorst]

i was looking on com cams.com and i see that the 268 is a high energy cam, i dont see one for the magnum cams, also it is saying that i DO need a converter for the magnum cams. please let me know if im looking in the wrong place

[BigEd36]

The 268H is the largest cam in the High Energy series. The 270H is the smallest cam in the Magnum series, and (according to the Comp Cams site) is the largest cam that can be used with the stock converter. Camquest6 recommends a 1100-1900 RPM stall converter for either one. For the 280 and 286 Magnums Camquest6 recommends a 1400-2400 RPM stall.

It would be hard to go wrong with the 268, it's Comp Cams #1 selling cam for good reason!

To really compare different cams in the Comp Cams line download their Camquest6 program. You can enter your setup and it will give you appropriate cams to use, and will even give HorsePower and Torque simulations. It's a FREE download at Comp Cams Camquest6 download

Ed

[Bonhorst]

i think this may be a dupble post cause my internet cut out last time, but here goes again. I need help understand the relationship between the cam and the stall converter. How do the two affect eachother. running the operation through my head, the only thing i can come up with is, the rpms of the engine need to come up a little before the cam can realy start to take affect, but if the engine is under load due to trying to move the car, the cam wont be cougt up with the demand, and cause crappy take off, am i close?

[DoubleVision]

Your as close as you need to be. I was mistaken it is the high energy 268. I really don`t keep up with flat tappet cams anymore ever since I went to rollers, sorry for the mistake. However, as mentioned, the 268 high energy is all the cam you need for your combo. It has a lope at idle, doesn`t need a stall converter (even so one would likely be of benefit to eliminate idle creep)
it`s on the small side but still has excellant low to mid range torque. If you want to get a converter, get a B&M torkmaster 2400. When you get finished doing to the mods and get it tuned in your going to be shocked at what it`ll do. You`ll want to break in the new cam with valvoline racing oil and keep running that type of oil there after. It has the much needed ZDDP additive, without it, the cam will go flat.
Here are the links:
http://www.summitracing.com/parts/CCA-CL12-210-2/
http://www.summitracing.com/parts/BMM-20404/
If you get the converter, make sure you get a aftermarket tranny cooler with it. Don`t rely on the stocker. Make sure it`s of good size as well. Heat is the number 1 killer of automatics and the higher stall speed makes the tranny run hotter. You will need a posi rear for the power this combo will pack. once you finish the whole package and have it tuned in, stall it up, let off the brake and nail it to the floor, Then, Hang on,, Tight. I won`t tell you the rest of the details as I don`t want to spoil it for you. Lets just say as mentioned. Your going to be shocked.

[Bonhorst]

Yea, you are right, i might as well do it right te first time. I looked on comp cams and found this kit
http://www.compperformancegroupstore...Code=K12-210-2
it will be a while before i start in on it though because this is my only car, and i dont have time to pull the engine to install the cam. im just going to start collecting the parts and puting them on the shelf for a rainy day. i also never would have thought to go with an after market cooler. i didnt know that the stall would heat up the tranny. i also see a very wide range of differant rocker sets, do they make a specific set for this cam kit? i would like to get as close to compatible parts as possible. thanks again for the help.

Chris

[DoubleVision]

Any small block rocker 1987 and up will work fine. After 1987 chevy went to self aligning rocker arms. The stock rockers will work fine with the cam as it`s not too radical. If you found a set of vortec heads in the junkyard you can use the rockers that came on them if they are present. You don`t have to pull the engine to install a cam, I`ve installed many with the engine still in the car. You will have to remove the radiator and the A/C condensor if there is one still on the vehicle.