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Discussion Starter · #1 ·
Does anyone have any input about this cam?? I am not familar with camshafts, and it seems like there are endless pages of information about cams. I was just thinking about buying this Speed-pro cam, and was wondering if anyone is currently running this.

Intake: 420 / 278
Exhaust 442 / 288

Any information about cams would be helpful too, especially this one. I have no clue how to read cam specs.

thanks
 

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71Nova400 said:
Does anyone have any input about this cam?? I am not familar with camshafts, and it seems like there are endless pages of information about cams. I was just thinking about buying this Speed-pro cam, and was wondering if anyone is currently running this.

Intake: 420 / 278
Exhaust 442 / 288

Any information about cams would be helpful too, especially this one. I have no clue how to read cam specs.

thanks
Hi Nova, that's an R.V./towing/gas mileage "stick". It has a "rated" RPM range of 1500/4000. Excellent "grocery-getter" cam. The .050" duration is 204/214, the lift you have posted, and uses a 112 ICL. Thanks, Gary in N.Y.

P.S. I don't what the price of that cam is now, but personally I would choose a Crane "Blue-Racer" series grind for about $75.00. If it's for a 350" unit you're going to want something just slightly "bigger" for any type of decent performance.
 

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Discussion Starter · #3 ·
Thanks Gary,

I want something streetable, decent idle and sound, good gas mileage, daily driver, and of course the ability to rip your neck back when you want it to. There are just so many different choices. I need something for my 400 SB.
 

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I don't like Speed Pro cams.

What size engine is this for and what is the parts combination?

What do you want your engine to do?

:D
 

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Discussion Starter · #5 ·
This will be going into a 400 SB. The possible combination will be 882 heads, cam, 750 Holley, and an Edelbrock Performer.

I am hoping to achieve more power without compromising a decent aggressive idle (not too irrate or irritating), streetable for a weekend car and a nice cruise, and the ability/confidence to be able to occasionally burn some rubber on the street.

Will a set of rebuilt 882 heads and the cam make a difference? I currently have stock heads, and an unknown "mild" cam.

I appreciate any advice. Thanks!!!
 

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I would like to recommend a CompCams grind number 265DEH. This is a hydraulic flat tappet cam (part number 12-208-2) with a split pattern (more exhaust lift and duration) whose numbers are 211° intake / 221° exhaust duration @ 0.050" lift, and 0.442"/0.465" lift with a narrow LSA of 110°.

This cam works with stock exhaust (as in using mufflers like most people instead of running uncapped), and has a lot of midrange torque because of it's narrow LSA. It makes power with low (pump gas) compression and doesn't need a high gear (especially with a SBC 400) for street manners. It is at the upper limit on lift for a set of Vortec heads, which I would recommend over the '882 Power Pack 76 cc heads (hopefully you are not running flat top pistons, if so the 56 cc Vortecs would put you in detonation with pump gas).

If you are running flat tops, you will need a 76 cc head such as the '993 (has steam holes from factory for the 400), or the '71 Z/28 head number 3973487. With the exception of the steam holes these are identical heads with right facing stairs cast in the front of the head. But even with a 76 cc chamber you will still be running close to 10 :1 with an iron head (93 octane only).


Larger Dave
 

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Big Dave said:
I if so the 56 cc Vortecs would put you in detonation with pump gas).
I'm not trying to argue here but I always thought vortec heads had the 64cc chamber:confused:
 

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Discussion Starter · #8 ·
Thanks for all of the information.

How does the combustion chamber's size affect performance?? I know the common sizes are 64cc and 76cc. What are the advantages and disadvantages? Can late model "vortec" heads work on an 70's block?

thanks

Jack
 

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Vortec is a family of engines (started with the ad campagin to beat Ford at the "We sell more trucks game". As a family the heads are available in 56 cc and 64 cc and 72 cc depending upon the application and engine size. The small 56 cc heads are off of a 305 and every one likes this small chamber head because it raises your static compression ratio. This is great way to wake up a mid eighties 7.75:1 dish toped piston powered 350 with 76 cc heads installed. However it is a real quick way to get you to the 11.0:1 range with a flat topped piston and the longer stroke of the 383/400.

You should shoot for a static compression ratio of about 9.5:1 max for a carburetored pump gas engine driven on the street (even then expect to pump High Test 93 octane). If you browse through a piston catalog you will see that pistons come in three flavors now; dished, flat tops, and domed. With the same compression height (a word that is used to express stroke and rod length dimensions) for a given bore (305, 350, 400 to name a few small blocks) you will see nine to twelve sets of static compression numbers depending upon what piston and head combination you choose. This gives engine designers choices for rod length, stroke, bore size, and combustion chamber volume when specifying an engine (there are compromises and trade offs associated with each of these choices).

Most of the aftermarket head manufactures offer at least two "street" heads with advertised differences in combustion chamber sizes (they have standardized on the 64cc small chamber and the 72 cc big chamber). I say advertised because often they sell only one or the other and hope no one notices the difference. And unless you CC'd the head odds are you wouldn't notice an appreciable difference. Because of this they err on the side of a head that is too big, because they are very aware of the damage that will be caused if you get an internal combustion engine into detonation (that pining metallic noise a diesel engine makes accelerating next to you from a light).

Once you get into detonation the engine must cut back on timing, richen the mixture, or reduce compression to get out of it. Modern computer controlled cars use knock sensors and a 50MHz processor to monitor and change fuel mixture and engine timing allowing them to run 93 octane gasoline with 11.0:1 static compression. You are not fast enough to change the tune on a car manually 50 million times a second, so we must reduce compression when we build them. The combustion chamber size is one of the choices we initially make.

Chevy's Vortec heads can be used on any first generation small block, the only difference is in the intake manifold which has a different bolt pattern (fewer of them at a different angle) than the old design. The advantages of the new computer designed and manufactured Vortec head are the phenomenal flow bench numbers below 0.400" valve lift (very few engines have cams with more than that; and the valve spend 70% of it's open time at or below 0.400" inch lift). Now no one races flow benches, so what does this mean? It means great throttle response, with lots of tire shredding bottom end and mid range torque. The problem is it uses a push in, rather than a screw in rocker stud mount, just like every other production head Chevy has ever made including the ones found on Z/28's and early Corvettes. The second thing people complain about is that they go into coil bind at about 0.500" lift; which isn't to bad as very few cams for the small block have over 0.500" lift. Finally people complain that the castings are light weight and their isn't enough metal left in the heads to hog them out at their local head grinding shop. Like I said they out flow most every head made as is.

Combustion chambers effect more than static compression. Their shape and the actual placement of the valves in the chamber effect performance. Finally there are differences in spark plug angle and placement. The small block Chevy uses a 23° degree wedged shaped chamber from the factory. There are 18° and 15° heads but we will leave them out (race only). The Vortec head has a kidney bean shaped chamber to enhance turbulence (called swirl in the ads). Anything that keeps the fuel and air mixed and turbulent promotes a fast and complete flame propagation across the cylinder for more power. Race car heads have nearly flat heads with tiny heart shaped chambers for this reason.

The intake valve is moved closer to the center of the chamber on the Vortec than earlier heads and the spark plug though not angled (like on race heads) is moved towards the exhaust valve for a better flame kernel. Speaking of valves, they are swirl polished stainless steel with a tulip head just like on the race car head (though not sodium filled, or made of titanium). The exhaust valve is a Inconel treated valve, with beryllium valve guides. Sounds exotic doesn't it. The 3973487 head I recommended was designed in 1969 by engineers with slide rules (calculators hadn't been invented yet, or computers as we know them for that matter) and was "state of the art" at the time.

Hope I haven't bored anyone to much, and that this answers your question.


Big Dave
 

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71Nova400 said:
This will be going into a 400 SB. The possible combination will be 882 heads, cam, 750 Holley, and an Edelbrock Performer.

I am hoping to achieve more power without compromising a decent aggressive idle (not too irrate or irritating), streetable for a weekend car and a nice cruise, and the ability/confidence to be able to occasionally burn some rubber on the street.

Will a set of rebuilt 882 heads and the cam make a difference? I currently have stock heads, and an unknown "mild" cam.

I appreciate any advice. Thanks!!!
My Partner (the guy with the '71 Nova :D ) has a very similar engine in his '67 El Camino and it flat hauls. Here it is:

- 400 small block, stock crank and rods with forged pistons
- 882 heads with 1.94/1.5 valves
- Comp Magum 280H cam and lifter set
- Comp Pro Magnum full roller rockers #1301
- Edelbrock Performer RPM intake
- Holley 3310 750 vacuum secondary carb
- Dynomax 1 5/8" x 3" ceramic coated headers with 2 chamber flowmasters
- Accell HEI ignition
- Th350 trans with a TCI Saturday night special converter 2000 RPM stall
- 10-bolt with 3.08's

This truck is his daily driver and is very well mannered! It will drive anywhere and will spank most anything that pulls up next to it except for the really fast cars. A great budget combo that is "Real World" tested!!! Your Nova is lighter and would be faster yet. :D

Good Luck
 

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Discussion Starter · #11 ·
Motorhead62 said:
My Partner (the guy with the '71 Nova :D ) has a very similar engine in his '67 El Camino and it flat hauls. Here it is:

- 400 small block, stock crank and rods with forged pistons
- 882 heads with 1.94/1.5 valves
- Comp Magum 280H cam and lifter set
- Comp Pro Magnum full roller rockers #1301
- Edelbrock Performer RPM intake
- Holley 3310 750 vacuum secondary carb
- Dynomax 1 5/8" x 3" ceramic coated headers with 2 chamber flowmasters
- Accell HEI ignition
- Th350 trans with a TCI Saturday night special converter 2000 RPM stall
- 10-bolt with 3.08's

This truck is his daily driver and is very well mannered! It will drive anywhere and will spank most anything that pulls up next to it except for the really fast cars. A great budget combo that is "Real World" tested!!! Your Nova is lighter and would be faster yet. :D

Good Luck

Thanks Big Dave and Motorhead62. I appreciate all of your input and information. Is there a site with casting numbers, specs and information????? What, how and why is there a fear about cracking some of them??

There are too many combinations and setups to chose from. I'll definetly look into your friend's 67 el camino setup. How does it idle??....It must sound awesome. This is a great site!!! Thanks guys......I'll take any information or advice I can get.

Jack
 

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Bookmark this page:

http://www.mortec.com/castnum.htm

As to why heads crack. That is usually because someone got them too hot and then cooled them too quickly. (someone some where overheats engine, boils out the coolant, then puts in cold water to get to were you want to go).

GM is always trying to get a lightweight casting because it saves them money in terms of nodular iron and it increases the miles per gallon by reducing the overall weight of the vehicle. (or to compensate for the added weight of the next addition of the "can't live without" option). Thin wall castings are more prone to cracking because there is less material there to resist the thermal stresses placed upon the heads.


Big Dave
 

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thanks for the info, I didnt realize there were so many different versions of the vortec heads...I learn something new everyday....thanks again:)
 

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They also apply the Vortec moniker to LS-1, LS-6 heads as well even though they won't interchange onto the gen I & II SBC. Like Yogurt (Mel Brooks) said in "Space Balls" "It's all about marketing, marketing, marketing!"


Big Dave
 

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Discussion Starter · #16 ·
Here is another question that came up. What is the difference between hydraulic, solid, and a roller cam? How can I tell what I have? Are there any some distinguishing marks or designs?? What setup do you need in order to run each combination?

Thanks guys!!

Jack
 

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Solids are easy, it doesn't compress, because it is solid steel.

Hydraulic rollers have to have either a flat spot machined on the top of the tappet for a dog bone retainer, or they will have bars that look like a solid roller if aftermarket. The bars and the dog bones serve one purpose, to keep the roller in the bore with the wheel (roller) on the cam lobe. (A roller that goes sideways will take out the cam in moments, self-destructing as it takes out the cam.)

Flat tappets are not really flat. They are concave on the bottom and get that way in the first 25 minutes of their life span as they wear in and seat. Each lifter (tappet) has to stay on the exact lobe of the cam it came off of. They are a matched set that stay together for the life of the cam.

Hydraulic flat tappets are hard to tell apart from solids once they are full of oil. You can lean on the top of a hydraulic tappet and it will gradually collapse as you force the oil out of the piston bore (internal to the lifter) through the bleed hole (small orifice on side of lifter). Once the oil is out as you remove the pressure it will quickly pop back up due to an internal spring and flapper valve that is now sucking air instead of resisting compressed oil.

To run a roller cam you need roller tappets (either factory dog bones (limited to about 0.500" lift) or the bar type sold aftermarket. You can run solid roller tappets on a hydraulic cam with about 0.018" gap, it is pointless to due so since you are giving up about 0.020" inch lift lost at the at the valve. Conversely you can attempt to run hydraulic rollers on a solid cam, and it will work if you stay below the RPM were failure occurs due to the hydraulics collapsing in the attempt to follow the more aggressive solid grind. A roller run on the correct cam is the best solution, and it plays to the strengths of each system. The hydraulic roller gives maintenance free performance which is up to 13% more efficient than a similar flat tappet hydraulic grind (exact same cam card specs). The Solid roller is the 800 pound gorilla of the racing world, has the highest range of operating RPM, with the most lift. It requires special everything when maxed out (specialty springs, retainers, roller rockers, usually shaft mounted, glimmer style timing belts instead of chains, rev kits and special light weight solid roller tappets on a custom steel billet reduced circle (to get those huge lobes to fit inside the cam bore) cams). Did I mention none of this is cheap.

The cheapest solution is a flat tappet hydraulic cam. There are hydraulic flat tappet grinds out now that were reserved for a solid flat tappet cam only twenty years ago (improved metallurgy and spring winding technologies). Your next cheapest is a flat solid cam, which is still en-vogue in sportsman racing (because of class rules), it's only draw back is that you can not run the radical grinds of a roller as the tappet would dig into the flanks of the cam lobe rather than riding up the lobe, and it requires occasional maintenance to adjust the valve's lash.


Big Dave
 

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A simplified way to look at them...

Hydraulic Flat Tappet-Inexpensive/simple/limited perf (OEMs don't even use this now)/rpm limits of ~6000 or so.

Solid Flat Tappet-Inexpensive/simple/decent perf/much less rpm limited

Hydraulic Roller Tappet-OEM's use predominantly for MPG (less friction) and low end power as well as high end)/significantly more expensive than flat tappets/still rpm limited to ~6500 (although I turn my LT4 to 6900 with a rev kit and beehive springs)

Solid Roller Tappet-Much more expensive/typically don't like street use/no rpm limits/did I mention expensive!

I was sold on roller...solid for my Nova, but just couldn't justify the easy 1000 bucks for quality components that will live on the street predominanty. Used a 'modern' solid flat tappet and am super happy...for the cost it is dirt cheap! I even find the valve adjustment much less tedious than the hydraulic (I had run a CC 280 Hydraulic, but now a CC XS282 Solid)...:)
 

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Discussion Starter · #19 ·
How can I tell what type of camshaft I have, and what type of lifters I need? Are all the camshafts the same, and able to run with any type of lifters??
 

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Easy...

99% sure your cam currently is a flat tappet hydraulic-most 'old' cars are this unless a relatively super high performance car (ie L88/L89/L78/etc)

More definitive is see if you can compress the lifter-if it does a bit-hydraulic-this takes up the clearance-hence they are quiet.

Diff between roller and flat...the roller tappet has to have someway to keep it from rotating in the lifter bore-either 'dog bones' or guides or something...as the little wheel only wants to roll in one direction. Flat tappets are typically just little metal cylinders that DO rotate in the lifter bore.

Sounds like purchasing a book on high performance engines is the ticket for you level. Seeing pictures, etc worked wonders for my knowledge to learn the basics.

All cam manufactures will say you have to run the correct lifter with the correct cam...some have done solids on a hydraulic, but that isn't the way they were designed and may not help.

Good Luck!
 
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