Hot Rod Forum banner

Best cam profile for this setup for MAXIMUM performance keeping RPMs 6500 & under

1 - 15 of 15 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter #1
so i got a fresh 327 with flat top pistons and 462 camel hump heads all good, just need a cam. Im thinking around 282-286 degrees of advertised duration and around 470-500 lift, if i can go more duration i will. Ive read other threads of people recommending somewhere around 268 duration. are you kidding? come on, I'm a 16 year old punk with some serious testosterone and need this engine to be a good fit.
 

·
Registered
Joined
·
12,338 Posts
Its not going to be all that fast with those heads. I personally would use an Isky Z-27 and recommend an Isky Z-25 with "Vortec" heads. The vortec heads should have a split duration cam. I would kake it up with a very free flow exhaust system and a custom 780 double pumper Holley. I would not buy a flat tappet hydraulic cam.
You tube the Z-25 cam. Its not that lumpy at idle but it pulls very hard mid range and will easily take you to 6500 rpm
use a Z-28/edelbrock rpm intake. depending on heads 1 5/8 to 1 3/4" long primary tube headers.
Hope your car is set up for this type of power?

don't judge a cam by advertised duration
go by duration @ .050 valve lift
 

·
Registered
Joined
·
32 Posts
Discussion Starter #3
Its not going to be all that fast with those heads. I personally would use an Isky Z-27 and recommend an Isky Z-25 with "Vortec" heads. The vortec heads should have a split duration cam. I would kake it up with a very free flow exhaust system and a custom 780 double pumper Holley. I would not buy a flat tappet hydraulic cam.
You tube the Z-25 cam. Its not that lumpy at idle but it pulls very hard mid range and will easily take you to 6500 rpm
use a Z-28/edelbrock rpm intake. depending on heads 1 5/8 to 1 3/4" long primary tube headers.
Hope your car is set up for this type of power?

don't judge a cam by advertised duration
go by duration @ .050 valve lift
Thanks! I really appreciate your response! i'm not very familiar with aftermarket heads and vortec heads. do any vortec heads work or only a specific kind.
 

·
camarodriver67
Joined
·
434 Posts
The two Vortec heads casting numbers are 10239906 or 12558062. The only differences are most of the 906 heads have hardened seat inserts in the exhaust. These can be made to flow very well with a competent three angle and some bowl blending.
 

·
Registered
Joined
·
4,166 Posts
Cam selection is dependent on application. A daily driver in 3/4 ton p/u truck needs an entirely different cam than weekend warrior, mid 60's Nova.

Sell those heads to someone that is completing a nolstagia build and use the money towards a set of Vortecs, at a minimum. You mention you're a young man, keep your goals with a 327 in a reasonable range if you are on a budget. What are your expectations?
 

·
Registered
Joined
·
300 Posts
Nothing wrong with 462 double hump heads on a 327. If your 16 years old and already have them run them. We've built alot of 327 Chevys with those heads and they work good. Instead of picking a cam based on "what is the biggest one I can put in it" you should pick a cam by the rpm range the engine will be in for the vehicle your installing it in. Also other things like manual or automatic transmission, rear end gear ratio, what are you going to do with vehicle, and etc should be considered before selecting a cam. If its a daily driver/street performance car then a 268 duration cam would be perfect. If your building a drag car then a 280 duration cam would be a better choice. It all depends on the application.
 

·
More for Less Racer
Joined
·
19,370 Posts
Nobody could give you a good recommendation without knowing a lot more about the rest of the vehicle combination what is it?? Car, 2wd half ton truck, 4wd truck?? Vehicle weight??

Need to know rear gear ratio, rear tire diameter, transmission type, torque converter type and stall, intake manifold, carb type and size, header type and size.
Was the block deck-cut to maximize compression with the flat-top pistons or left uncut??
How far down the bore is the piston when it is a top dead center....this can be measured with something as simple as a good straight edge placed across the bore and stacked feeler gauges used to determine the clearance....this dimension can easily affect the compression ratio by a whole full point, so it is very important to know...so do your homework :mwink:

Next, what do you expect??>>> is it a daily driver that needs to get some type of reasonable gas mileage....a hot daily streeter where mileage is second to power...., a weekend stoplight-to-stoplight killer??
Something you expect to see occasional dragstrip use and want to favor a good time there??

Let us know by filling in the gaps.

There can be a lot more options than just the very basic three you put in the poll.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #8
Cam selection is dependent on application. A daily driver in 3/4 ton p/u truck needs an entirely different cam than weekend warrior, mid 60's Nova.

Sell those heads to someone that is completing a nolstagia build and use the money towards a set of Vortecs, at a minimum. You mention you're a young man, keep your goals with a 327 in a reasonable range if you are on a budget. What are your expectations?
It will go in either in a 68 nova or a 69 el camino nova or el camino. i couldnt sell the double humps because im collecting them.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #9
Nobody could give you a good recommendation without knowing a lot more about the rest of the vehicle combination what is it?? Car, 2wd half ton truck, 4wd truck?? Vehicle weight??

Need to know rear gear ratio, rear tire diameter, transmission type, torque converter type and stall, intake manifold, carb type and size, header type and size.
Was the block deck-cut to maximize compression with the flat-top pistons or left uncut??
How far down the bore is the piston when it is a top dead center....this can be measured with something as simple as a good straight edge placed across the bore and stacked feeler gauges used to determine the clearance....this dimension can easily affect the compression ratio by a whole full point, so it is very important to know...so do your homework :mwink:

Next, what do you expect??>>> is it a daily driver that needs to get some type of reasonable gas mileage....a hot daily streeter where mileage is second to power...., a weekend stoplight-to-stoplight killer??
Something you expect to see occasional dragstrip use and want to favor a good time there??

Let us know by filling in the gaps.

There can be a lot more options than just the very basic three you put in the poll.
_________________________________________________________________________________________________________________________________________________________________

This engine would go into a 2 wheel drive 68 nova or a 69 el camino with some larger tires 26-27 hoping to stick and GO. The block has'nt been decked, and the camel humps have 68 cc chambers if i dont decide to use aftermarket heads. The transmission will most likely be a TH350 with a shift kit. And this would be more of a stoplight to stoplight Killer which will be familiar with the track
 

·
Registered
Joined
·
17,612 Posts
Most of the savvy fellows on this forum will know not to put too much static compression ratio into a motor that will use iron heads. No more than 9.5:1 would be the consensus of opinion I believe, to prevent detonation on pump gas. Now, I don't know how many motors you've built, but I can tell you that you will not be able to run a very large cam in a 9.5:1 motor without turning it into a pooch. Everything is a balancing act of creating a cylinder pressure that will make the horsepower you are looking for without building too much cylinder pressure so that the motor will detonate on pump gas. The limiting factor in building a motor today is the fuel you have available and most of it is just barely better than cat pea. Back in the day, we had over 100 octane pump gas available to us on every street corner, so we could build some pretty wicked motors for the street. But like I said, with what fuel is available to us today, we have to scale it back quite a bit.

Now, I'm not one of them, but there are fellows on this forum who will tell you to build it 11.0:1-11.5:1 static compression ratio and use a ton of cam to allow use on available pump gas. With using a very tight (0.035"-0.040") squish/quench by cuttting the block decks and maybe using some alcohol injection, you may be able to run the motor on available pump gas. Like I said, I wouldn't do it, but you may want to try it. You will need some gear (4.10/4.44/4.56) and a 10" torque converter, 3500-3800 stall minimum, and a good quality (read expensive) valvetrain that will stay together at the 7,000+ rpm blasts that you will do with the motor. (7000 rpm's with a 4.56 gear and 27 inch tire is 123 mph). I'd use some good quality aftermarket rods like Scat Pro Stock 6", Keith Black KB155-030 pistons, and a Crane solid flat tappet cam with oiling holes in the crowns of the lifters made by the Electrical Discharge Machining (EDM) process.

The KB155 pistons will give you a 10.98:1 static compression ratio when used with a 0.025" piston deck height, a Fel-Pro 1094 head gasket and 68cc chambers. Squish/quench will be 0.040" with a stock (0.025") piston deck height. You also have the option of cutting the block decks to zero and use a thicker composition gasket. This would give you the advantage of beginning the build with a square block. If the block is square, then the heads will sit squarely on the block and the intake manifold will sit squarely on the heads and seal up like it is supposed to. Your stack of parts (crank radius, rod length and piston compression height) will be 9.000", so if the block were cut for 9.000" block deck height, then the block would be square and you could run a 0.039"/0.040"/0.041" head gasket to set the squish/quench. Doing this would also set the motor up for aluminum heads later, if you wanted to try them.

https://www.summitracing.com/parts/fel-1094

KB155 pistons will give you an 11.43:1 static compression ratio when used with a 0.025" piston deck height, a Fel-Pro 1094 head gasket and heads milled for 65cc chambers. Squish/quench will be 0.040".

Either of these static compression ratios should work well with the cam I'm suggesting here.

https://www.summitracing.com/parts/uem-kb155-030

https://www.summitracing.com/parts/sca-26000

https://www.summitracing.com/parts/crn-114681
Use with Crane 99250-16 flat tappet solid lifters that have been EDM'ed for a small hole on the crown to feed oil directly to the lobe of the cam and use Crane 96877-16 valve springs.
NEVER, NEVER, NEVER, EVER USE CAM AND LIFTERS FROM DIFFERENT SOURCES. ALWAYS USE THE LIFTERS MADE BY THE CAM GRINDER FOR THAT SPECIFIC CAM. THERE IS TOO MUCH OFFSHORE CRAP FLOATING AROUND IN PLAIN WHITE BOXES THAT WILL BITE YOU.

On this project, due to the high spring forces that must be used to control the valvetrain at up to 7000+ rpm's, I would also groove the lifter bores to provide additional lube for the cam lobes. Some fellows will say this is over-thinking the project, but I like insurance and it does not cost that much more to groove the bores. Here is the tool from Comp to groove the bores....
https://www.summitracing.com/parts/cca-5003/overview/

Use an Edelbrock 7101 or Weiand 8150 intake manifold mounting a 750 vacuum secondaries or double pumper carb (a double pumper will work great with the loose converter). Use 1 5/8" long tube headers with either an X or and H pipe installed immediately after the collectors, then 2 1/2" pipe through mufflers of your choice to the rear of the vehicle. Terminating pipes under the vehicle makes the underneath sheet metal reverberate and will make you crazy after a short while. It also brands you as a Ricky Racer who doesn't know any better.

Use this tutorial that I wrote several years ago to do a successful flat tappet camshaft break-in and subsequent trouble-free operation....
http://www.crankshaftcoalition.com/wiki/Camshaft_install_tips_and_tricks

And finally, do not be fooled into buying any chemicals that claim to increase octane in gasoline. They will advertise that their product will raise the octane by one point, for instance from 91 to 92. It will not. It will raise it by one-tenth of a point, for instance from 91 to 91.1. The best answer to the whole problem would be to change everything in the fuel system over to use E85. A fellow could run 15:1 on the street using E85.

Pushrod length............................

.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #11 (Edited)
Would need to see lots of specs to really pick a cam. But the go to big cam for sbc is old school build is the comp 294s in my opinion.

12-224-4 - Magnumâ„¢ Mechanical Flat Tappet Camshafts


Its a flat tappet solid cam so not your normal cam choice but often perfect for street bruiser.

Are the heads ported its best to get in there and do a bit of work to the port for boost up the flow. Should be able to get some real power out of this setup with proper tuning. Be prepared to give up a bit down low and add some gear to make it jump and run. people will tell you that hump heads dont make much power but you can pull 400 plus hp out of them just as easily as most other oem heads. Often they are only down a few hp over much better heads. hump heads 292s are almost as good as any modern head the ports are larger and they flow very well. Its the chamber design that has gotten a lot better over the last few years. Of course 292s are next to impossible to find but others can be ported to work almost as good.

Now if your going to spend a lot on this build and trying to get all the power you can best to go roller and get better aluminum heads. Forget the vortecs they are good but who cares if your going to buy heads might as well buy something better than oem heads.

But good flat tops and humps with the 294s and at least 750 carb and good tall intake like the performer rpm or the victor jr. Along with good headers and dual's it should run well. get a good stall converter from freakshow converters and good gearing 373 to 411s should put the car down the track at a good clip.

Hope this helps.
Man that sounds good! would love to have that cam but are you sure it will work the way you described with my flat top pistons and 68 cc camel humps? 1.94 intake valves
 

·
Registered
Joined
·
12,338 Posts

start listening around 1 minute mark.
That cam fits the vortec heads almost perfectly


use 9.5:1 compression ratio

the second video did not give the cam part number.

You need to check retainer clearance if you use cast iron vortec heads,not required with the bump heads. The vortec heads with the low lift Z-25 cam is a very good match. Mild idle. Does not need as heavy of spring pressure as the other cams with over .500 lift. With the Z-25 pin the studs and go. The other cams mentioned I would use screw in studs. The Z-25 cam is a tight lash cam so you can use a lash loop successfully to match your engine needs. The "EDM" lifters should be used on any of the cams mentioned,Thank you Richard for reminding us.

Note: our shop used this same cam in a 327 4 speed car with both 3.36:1 gears and later with 4.11 gears. On street tires in the 1/4 mile the times were less than 1/10 difference. The 3.36 gears went back in. If you race and use racing tires then the steeper gears would help a lot.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #13
Its not going to be all that fast with those heads. I personally would use an Isky Z-27 and recommend an Isky Z-25 with "Vortec" heads. The vortec heads should have a split duration cam. I would kake it up with a very free flow exhaust system and a custom 780 double pumper Holley. I would not buy a flat tappet hydraulic cam.
You tube the Z-25 cam. Its not that lumpy at idle but it pulls very hard mid range and will easily take you to 6500 rpm
use a Z-28/edelbrock rpm intake. depending on heads 1 5/8 to 1 3/4" long primary tube headers.
Hope your car is set up for this type of power?

don't judge a cam by advertised duration
go by duration @ .050 valve lift

Im picking up some 5.7 vortec heads casting 10239906 from a guy who is selling them for 100 bucks! :D . They will get rebuilt and probably with better springs to stand higher lift. any suggestions?
 

·
Registered
Joined
·
12,338 Posts
you don't need higher lift. Check the retainers for fit with high lift cam if you use one. Check for cracks in the castings if they are used. If you go to a "hot" cam get the studs pinned.
 
1 - 15 of 15 Posts
Top