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Vortec heads, SBC 350 and camshaft options

16K views 15 replies 7 participants last post by  Rickracer 
#1 ·
Another new to SBC guy here. I'm in the early stages of my 350 build, still collecting items to use. I'm looking for something that has enough power to spin the tires and show it's teeth, but also something that is tame enough to use as a daily driver with decent gas mileage. It's going in a '54 2wd pickup with a 700R4 and 4.10 rear gears.

Here is what I have so far:

350 SBC - 14010207 casting#

New L31 062 Vortec heads with seats machined for double springs and clearanced for .530 lift.

Comp Cams 986-16 dual springs

Comp Cams 743-16 retainers

For a cam, right now I'm looking at the Lunati Voodoo 60103 hyd tappet cam or the Comp cams EX274H cam.

Is there an obvious better choice for a cam for my set up and will I need to use a better rocker arm like the Comp cams 1417-16 SA rockers as suggested to use with their cam?

Can you think of anything else I will NEED while I am collecting parts for these heads?
 
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#2 ·
either cam would be a nice healthy cam in a 350, either one will require a higher stall speed tq converter than stock, and i hope that the 700R4 has been rebuilt to hold some power. with the vortec heads you will need to use self aligning rocker arms, but a simple set of stamped steel ones would really be all you need, i would stick with a 1.5 rocker as both these cams have very aggressive ramp rates.
 
#3 ·
OK thanks, I have the option of picking up the Comp rockers listed above for $150, so at that price it might be worth it.

I was also told to do the initial cam break in without the inners of the dual springs installed for 15 minutes with the tappet cam. Is this something that is strongly recommended and why?
 
#4 ·
ive never done this but i can understand the principal behind it

the spring is what will put pressure on the cam lobes as they try to open the valve so during break in they are recomending that you reduce the pressure on the lobes as to not flattin one of them, but if the springs aren't too strong for the cam then there shouldn't be a problem in the first place
 
#5 ·
It`s recommended because of the high spring rate of pressure. When the spring pressure is this high during break in the excessive pressure will force the lube off the cam lobe and wipe the cam out. Since I`m not sure if your new to sbc`s or new to builds period make sure you do a rag test on the cylinder bores. Spray a paper towel with WD40 and wipe the bore, if you see gray on the paper towel the bores are impregnated with hone grit. If this is the case the bores will have to be scrubbed to get clean. This is a important step, if the grit is left in it causes excessive ring and bearing wear.
Make sure you use a lube with ZDDP during break in. Use valvoline racing oil after break in also or the cam will go flat.
 
#6 ·
This is the kind of info I'm looking for. I am fairly new to engine internals. I do have a friend that has built numorous engines that will be helping me along with the project, but I really want to come away with all the knowledge to do it myself next time. The hardest part now is choosing exactly what components will be needed to do this right the first time. I'm still up in the air on buying the Comp rocker arms. What does a set of "good enough" rocker arms usually sell for?
 
#7 ·
You`ll need self aligning rocker arms for use with vortec heads. Any good name brand will work such as crane, comp, isky. Don`t use the cheap brands like proform or cat. You get what you pay for. I used comp self aligning 1.6 roller tipped rockers on mine and they`ve served me well.
 
#8 · (Edited)
You seem to be hung up on aftermarket rockers. OK, but at least get rockers that will do you some good. Now, any aftermarket rocker will improve on the GM production rocker if only by being manufactured with a true 1.5 or 1.6 ratio instead of something less (production rockers are less than what is advertised).

Rocker operation under good lighting and high speed cameras has proven that the roller tips on roller rockers do not roll across the tip of the valve stem, they skid. So, don't waste your money on a rocker like you're looking at that only has a roller at the tip. What you want, that will make a difference in horsepower and lower oil temperatures, is a rocker that has a roller trunnion where it pivots on the rocker stud instead of the production solid half-ball arrangement.

You'll want narrow body rockers to fit under the Vortec center bolt valve covers and you'll want them in 1.5:1 ratio if you're gonna use a camshaft with aggressive ramp rates. Using 1.6 rockers with an aggressive flat tappet cam profile is just asking for it in my opinion. A flat tappet lifter has a tough enough time just trying to survive in the environment where it lives without you shortening the lever length it sees as it works. As an aside, it is the lifter that fails first, then takes the lobe out with it.

Here's the rocker I would use in your build....Scorpion part number SCP1035...
http://www.scorpionperformance.com/newsite1/scorpion.php?category_id=51

Roller solid or roller hydraulic, completely different story. Use all the profile you want with any ratio rocker. It'll be fine. No special oil, no break-in period, just clean the storage grease off the parts, oil, install, crank and go.

I don't know where you got that 15 minute break-in period, but it should be 45 minutes. Read this list of screw-ups I wrote that will frag a flat tappet cam.....(none of this applies to a roller cam)....

DISCLAIMER: THE FOLLOWING INFORMATION WAS GLEANED FROM MANY DIFFERENT SOURCES. SOME OF IT MAKES SENSE TO ME AND SOME OF IT DOESN'T. USE WHAT YOU THINK IS REAL AND THROW OUT THE REST OF IT. I HAVE NOT USED ALL OF THE SUGGESTIONS LISTED HERE. THROUGH THE YEARS, I HAVE ACCOMPLISHED MANY SUCCESSFUL FLAT TAPPET CAMSHAFT BREAK-INS, BUT I HAVE ALSO ROACHED A FEW. USE THIS LIST AS A GUIDELINE SO THAT YOU REMEMBER TO CHECK ALL THESE THINGS WHEN INSTALLING A NEW FLAT TAPPET CAMSHAFT. DO NOT TAKE EVERYTHING POSTED HERE AS GOSPEL. IF THE MANUFACTURER OF THE CAMSHAFT YOU'RE USING RECOMMENDS PROCEDURES THAT DIFFER FROM WHAT IS SHOWN HERE, USE THE MANUFACTURER'S RECOMMENDATIONS AND DISREGARD THIS INFORMATION.

Mistakes that may "frag" a flat-tappet camshaft and lifters.

1. Failure to remove all rust-preventative from cam and lifters with solvent once you get them home. (This advice does not include removing coatings applied at the factory such as phosphates. It is only suggesting to remove rust-preventative grease that may or may not have been applied to the cam/lifters to prevent rust in storage. This grease will not have the extreme pressure characteristics that Molybdenum Disulphide has and should be removed so that MD can be applied properly. MD is the black, tar-like extreme-pressure grease that is recommended by some camshaft manufacturers to be applied to the lifter crowns/cam lobes for initial camshaft break-in).

2. Failure to wash the cam and lifters with hot soapy water to remove the remainder of rust-preventative not removed with solvent. CAUTION; WASH ONLY THE CROWN OF THE LIFTERS. (THE VERY BOTTOM OF THE LIFTER WHERE IT CONTACTS THE CAMSHAFT LOBE). DO NOT ALLOW WATER TO GET INTO THE INTERIOR OF THE LIFTER BODY. BE VERY CAREFUL HERE IF THE LIFTER HAS AN OILING HOLE THAT HAS BEEN EDM'D INTO THE CROWN TO PROVIDE OIL FROM THE INTERIOR OF THE LIFTER BODY TO THE CAMSHAFT LOBE. Dry the cam and lifter crowns thoroughly with hot air from a hot air gun or hair dryer to remove all traces of moisture before applying Molybdenum Disulfide.
WARNING: DO NOT USE ANY ABRASIVE MATERIALS SUCH AS SCOTCHBRITE PADS OR SANDPAPER OF ANY KIND TO ACCOMPLISH THESE SOLVENT AND SOAP CLEANING OPERATIONS. USE ONLY SOFT, CLEAN RAGS. THE WHOLE INTENT OF CLEANING THE CAMSHAFT IS SO THAT WE CAN REMOVE RUST-PREVENTATIVE OILS AND GREASES THAT MIGHT HINDER GETTING DOWN TO THE BASE METAL IN ORDER TO PERFORM OPERATION #3 SHOWN HERE.

3. Failure to properly massage an extreme pressure lubricant such as Molybdenum Disulfide into the pores of the metal on all lobes and lifter faces. Moly will actually bond with the metal and give maximum protection to the lifter crown/lobe.

4. Failure to use an extreme pressure lubricant additive in the engine oil for camshaft break-in. Each cam grinder has his own specific product to facilitate valid cam break-in. Since most all off-the-shelf motor oils available today have had extreme pressure lubricants removed from them, it is your job to add these lubricants back into the oil so that there will be extreme pressure lubrications available for the lifter crowns / cam lobes. Pay attention to this every oil change or suffer the consequences. :pain:

5. Failure to use the proper valve springs for cam break-in. You can't use the 300 lb over-the-nose springs that you'll eventually use in the motor and expect the cam to live at break-in. Assemble the heads with stock or weak single springs to break in the cam, then use one of the many tools available to change the springs with the heads on the motor. Alternately, assemble the heads with the springs you will run and use reduced-ratio break-in rockers, then change out the rockers after break-in. These rockers are available from Crower in different ratios for different motors. A popular ratio for a small block Chevy would be a 1.3:1 rocker. In other words, let's say the lift at the cam is 0.350" and the theoretical lift at the valve with 1.5:1 rockers is 0.525". Using the 1.3:1 rockers would result in lift at the valve of only 0.455", thus reducing stress at the camshaft/lifter interface during the crucial break-in period. These rockers are fairly pricey, so would be maybe a little expensive for the fellow who is building one or two motors a year, but for a shop that is in the business, they would work great.

6. Failure to check for valve spring coil bind at max lift. If you cannot tell by eye, verify by inserting a .010- inch feeler gauge between the coils. A .010 space between five coils would give a total of .050 safety margin before stacking solid. If you cannot pass the feeler gauge between the coils, the spring is either coil bound or dangerously close to this condition, and you have probably overshimmed the spring (the fitted dimension is too short) or used the wrong retainer.

7. Failure to check for retainer to valve guide/seal clearance. 1/16"-1/8" clearance at full valve lift is considered sufficient.

8. Failure to check for binding at the rocker/stud interface with stamped steel rockers. Long slot rockers are made specifically to cure this problem. Aftermarket rockers with needle bearing fulcrums also eliminate this problem.

9. Failure to check for piston/valve clearance..... 0.080" on the intake and 0.100" on the exhaust is considered by many to be the minimum clearance acceptable. You will probably find the closest near-miss at the exhaust valve on overlap, when the piston is chasing the exhaust valve back onto its seat.

10. Failure to run the motor at high rpms (2500 or higher, alternating 500/1000 rpm's up and/or down to allow the crank to throw oil in different places at different revs) for the first 40-45 minutes of its life. NO IDLING. NO IDLING. NO IDLING. The motor should not be run at less than 2500 rpm's for a minimum of 40 minutes. If a problem develops, shut the motor down and fix it, then resume break-in. The main source of camshaft lubrication is oil thrown off the crankshaft at speed, drainback from the oil rings and oil vapors circulating in the crankcase. At idle, the crank isn't spinning fast enough to provide sufficient oil splash to the camshaft/lifters for proper break-in protection.

11. Failure to clearance lifters in their bores so that they spin freely. Lifter clearance should be 0.0012" to 0.002", with 0.0015" (one and one/half thousandths) considered close to ideal. Too loose is as bad as too tight.

12. Failure to initially adjust the valves properly. Using the "spin the pushrod until it feels tight" method will normally result in valves too tight. Holding the rocker arm tip down against the valve stem tip with one hand, jiggle the pushrod up and down with your thumb/forefinger of your other hand until all play is removed, then turn the rocker nut 1/2 to 3/4 turn to set the preload. Builders who have done hundreds of engine builds may have the "feel" to do the "twist" method, but those fellows who are doing their first few builds lack the experience to do this and will have better results with the "jiggle" method.

13. Failure to inspect the distributor drive gear for wear. Too much wear can allow the cam to walk in its cam bore and contact an adjacent lifter.

14. Failure to have everything ready for the motor to fire on the first few turns. Fully charged battery, good starter, known-good carburetor with full fuel bowl, source of fuel to the carburetor to allow minimum 40 minutes of uninterrupted running. Ignition timing set. NO GRINDING ON THE STARTER. NO GRINDING ON THE STARTER. NO GRINDING ON THE STARTER.

15. Failure to prime the oiling system prior to firing the motor. Prime until you get oil out of the top of each and every pushrod. Observe the oil pressure gauge to be sure pressure is registering. Priming will aid lubing the valvetrain at initial startup. It's the last area of the motor to get lubed on dry start. Use a special, aftermarket priming tool to get oil to the passenger side rocker arms....
http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=25140

16. Failure to use new lifters on a used cam. Used lifters should only be used on the very same cam, in the very same block and in the very same positions they were removed from. Chances that the lifter bores will be machined on the very same angles on a different block as the block the lifters came out of are about equal to you hitting the lottery.

Now, this last bit of advice comes from Racer Brown, world-renowned camshaft manufacturer/engineer who ground the hot cams for Chrysler Corporation during the horsepower wars of the 60's.
"Overfill the crankcase by at least 4 or 5 quarts of oil so that the oil level comes to within an inch of the top of the oil pan. Install a set of fairly hot spark plugs with a gap of 0.050" to 0.060" to prevent oil-fouling of the plugs, which is otherwise inevitable under no-load conditions with all the extra oil aboard. During this operation, we want near-maximum oil flow, together with a maximum of oil vapors and liquid oil thrashing about in the crankcase so that the cam lobe and lifter interface lubrication is considerably better than marginal."

This advice from the Racer is too scary for me, but I included it so that you know someone, somewhere has done it.

Just a note to make you aware of the loading between the camshaft lobe and lifter crown. That pencil-point of contact, if carried out to a square inch, would be somewhere between 250,000 and 300,000 POUNDS PER SQUARE INCH.
 
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