A mag did an article a while back on the new Vortec vs the old unmodified -292 Turbo head, if you will.. The -6 or whatever one GM is still selling, I think??

The Vortec came out on top, but the author said real clear that the old turbo head has way more potential in it then the Vortec does if you want ta start P&P'ing it!!! End of the story.. pdq67

 

hmmmmm that sounds incouraging PDQ 67
i may just do that the next time i pull the heads.

------------------
69 Camaro RS/SS 350.
GM 2.02 angle plug heads.
223 dur/480 lift hyd cam.
69 z/28 alum high rise.
69 z/28 780 vac sec holly carb.
4 bolt mains,steel crank,forged flat top pistons.
Turbo 350 2800 stall with shift kit.
3:73 12 bolt posi.
functional cowl induction & ZL2 hood

 

No. Period. There are a TON of aftermarket SBC heads out there that outflow the best production Vortec, Camel humps, etc that GM ever made. There are some VERY good aftermarket SBC heads out there - AFR, Canfield, Trick Flow, Edelbrock, Dart, World, Brodix, Jegs, Holley, Pro Topline, and on and on and on the list goes. Many of these guys have several different lines of SBC heads. 15 or 20 years ago this wasn't the case there just weren't that many, if any at all, aftermarket Chevy heads - kind of like Mopar is today.

Now look at the Mopar ranks . . . for the B/RB engines there are Indy heads, Edelbrock, and thats about it that I know of. there just isn't the aftermarket heads for the Mopar engines. Its economics - the big money is where the volume is. The are a bizzillion more Chevy engines out there on the road than Mopars.

Hope that puts it in perspective.

Just my opinion.

 

Yeah....what he said!!!

 

The turbo head wasn't an old fashioned double humper, but rather Chevy's SOTA race head back then!! But you had to make it what you wanted with respect to P&P'ing. I think that's why they still sell the suckers.

Sure, I know that technology has left them behind, but they are still good heads if you want to work them over and run them. Imho. pdq67

 

so guys......
i have a 223 dur intake @50 471 lift/231 dur exhaust @50 480 lift cam.......108 lobe seperation at center line. hydraulic cam......to go along with the rest of the goody's below.oh ya and 1 and 7/8 hooker headers too,with 2 1/2in exhaust and 2 chamber flow masters.

think its worth my while to p&p these heads now or do i need to upgrade the cam first?
think theres enough oomph in these parts to warrent getting the heads P&P now with out doing anything else to the motor??????

opinions please gentlemen [and i use that term loosely! LOL!]

------------------
69 Camaro RS/SS 350.
GM 2.02 angle plug heads.
223 dur/480 lift hyd cam.
69 z/28 alum high rise.
69 z/28 780 vac sec holly carb.
4 bolt mains,steel crank,forged flat top pistons.
Turbo 350 2800 stall with shift kit.
3:73 12 bolt posi.
functional cowl induction & ZL2 hood

[This message has been edited by z/27 camaro (edited 08-26-2002).]

[This message has been edited by z/27 camaro (edited 08-26-2002).]

 

The heads you have are good heads ...
i have seen camel hump heads support 550-600 hp. With your cam choice stick with the heads you have as they will handle a much bigger cam in the future. As everyone else has said, there are better heads available, but at the power level you're at the differences are not that much . You can realize bigger gains by porting. If you decide to port your heads stick to reworking the bowl area only. "porting" the intake and exhaust port will only enlarge the port, thereby decreasing the velocity.
The most return on your porting will be realized within the first inch below the valve.

 

I have a test of a 292 turbo head thats been modified quite a bit. It flowed 260 at about .7.

A second design bowtie was 220 out of the box and 285after a whole lot of work. (including sleeves in the headbolts).

Cast iron heads are very difficult to get good numbers out of (especially factory ones). Most current designs aftermarket aluminum heads will out flow modified cast heads from 6+ years ago

 

I'm not saying that your Camel hump heads are bad, they were among the best in their day and are a decent head now. A good pocket port and port match job would probably be worth about 20HP with no other changes to your engine.

1-7/8 headers are way too big and will KILL low end TQ, 1-5/8 would be a better fit IMO.

Depending on the gear ratio and stall, that cam might actually be a very good match now. It should have a power band from about 2200 up to about 5700 RPM in a 350.

 

Ditto Eric on the header size!

And no stock SB head was angle plugged, but only over-the-counter heads. And I really don't think Chevy made many of them?? pdq67

 

PDQ 67
yes they are 3991492 angle plug heads.
i didnt say stock did i?? LOL.
well your right..there were sold over the counter in 1970......so you think there rare??

eric 68
dont we want the exhaust to flow good, especialy if were going to run open headers at the strip and P&P the heads??

89rs 400
so are those good flow numbers??
sorry i dont no much about flow numbers per/say thats sort of why i'm fishing with this post.
it seems that there pretty good heads for what i'm using them for and if i P&P them next time around they should be a little better?

------------------
69 Camaro RS/SS 350.
GM 2.02 angle plug heads.
223 dur/480 lift hyd cam.
69 z/28 alum high rise.
69 z/28 780 vac sec holly carb.
4 bolt mains,steel crank,forged flat top pistons.
Turbo 350 2800 stall with shift kit.
3:73 12 bolt posi.
functional cowl induction & ZL2 hood

 

A properly prepared set of 292s will move good amount of air. I would check a couple of ports (most shops will do it for less than 30bucks per port) and see how close to 260 they are (the flowbench that was used for this test was pretty conservitive).

If you get a cam with close to 600" lift, they can make 500hp easy with a 350 and about 11 to 1.

 

thanks 89 rs 400.
what about you guys PDQ67 and eric 68??

 

Here is what a 1998 Super Chevy article said an old -461 head did with a P&P'd comp job.

Superflow 600 at 28" H20.
2.02"/1.60" valves.
Lift Intake Exhaust
.050" 32 27.3
.100" 63 55.6
.150" 95 80.7
.200" 123 106.5
.250" 152 126.3
.300" 178 139.9
.350" 199 155.8
.400" 217 168
.450" 231 178.8
.500" 242 189.4
.550" 231 195.2
.600" 234 201

So old heads really do OK, but not as well as modern heads! You can trade time for money if you are bucks down! Imho. pdq67

 

Keep one thing in mind. Technology had gotten a lot better in the last 22 years. 202's are good, Vortec is better, Aluminum is best. The question is, how fast can you afford?
Hope this helps.
joe

 

Yes we want the exhaust to flow good, but velocity is just as important for a header to work right. Smaller tubes create more velocity and better cylinder scavenging. If tubes are too small you create a restriction, if tubes are too big velocity is nil and you loose TQ.

Most recent magazine dyno tests show best results with 1-5/8" headers on most small blocks (including 383's BTW). 1-3/4" headers can be made to work well on large cube or high RPM engines (I run them on my 383), but 1-7/8" headers should be saved for the all-out 8,000 RPM race engine with 'glides and 5000 converters.

 

I will call your header test and raised you one.

Oct 98 carcraft
350 AFR195s vic jr and comp 292H cam
headers tested 1 5/8 all the way up to 2". (no mufflers). The 1 7/8 made 27more hp (at the same rpm 6700) as the 1 5/8s. They also made 3ft/lbs more torque.

The 1 7/8s were 5hp better than the 1 3/4 and only 1hp better than the 2". Average HP was better by 5 on the 7/8s than the 5/8s and only down by about 2 on the others.

October 2000 hotrod
355 with trick flows a comp magnum 286 and performer rpm.

headers tested (with mufflers) 1 5/8s to 1 7/8 and a set of step headers. 1 7/8 again produced more torque and about 14more hp.

And before anybody concludes that the smaller ones made more torque below the peak, let me dispell that notion. On both tests, the 7/8 had more torque at 3000 rpm on up.


One other little thing 292s are not doublehumps (bolt holes or not). They are a race casting from the late 70s. No heat crossover and angle plugs.

[This message has been edited by 89rs400 (edited 08-29-2002).]

 

<BLOCKQUOTE>quote:</font><HR>Originally posted by z/27 camaro:
been wondering.......does any one know for sure how they stack up against the newer performance heads? do they flow AS good?
<snip>
[This message has been edited by z/27 camaro (edited 08-25-2002).]<HR></BLOCKQUOTE>

I seem to recall that the old chevy 2.02 heads were also known as camel hump heads. I also seem to recall that the problem with the heads was valve strowding on the intake.

I have also seen information saying that Aluminum heads make less HP due to heat loss. However in recent years, the head castings were made thicker to retain heat and develop more power.

Aluminum, being easy to machine has lead to a lot of chamber and port designs that significantly improve performance. Can't say as I've seen that many aftermarket iron heads though. The key is finding an affordable deal.

-dnult

 

No.

Valve shrouding isn't a problem with a stock large valve double-hump head b/c the factory took a relief tool to the intake valve area and unshrouded the back side area! That is why a stock big valve double-hump head cc's at about 66 or so vs 62 to 64 generally with the medium intake valve and 1.5" exhaust...

My -461's cc'ed at 66+ a schosh!!, so have been there done that.

If I am not mistaken, you can up the thermal eff. of the aluminum heads by washing the water-jackets with waterglass and baking it til hard so that you in essence, put a thermal barrier on the inside of the head! At least, I think it was waterglass that they used?? (I.e., sodium silicate stuff).. pdq67

 

wow ..some good info here....thanks guys!!

the heads are 1970 3991492 castings angle plug with the double hump on the front.

thanks

 

z-27 Camaro, A few years back I was running a set of the 492`s on my 355 in my S-10 blazer, they were fully ported and flowed around 250@.600 lift. I cracked one and decided to change to a set of 200 cc sportsman 2`s. I did a port match and bowl blend and swapped in the valves out of my old heads with a fresh valve job and picked up 4 tenths in the 1/4 mile with no other changes. I won`t ever mess with another set of stock heads again. Good Luck, Brent

------------------
Prostreet 67 L-78 SS 396 project. Daily driven S-10 blazer: 355/700r4. 12.56 et. @ 108 mph.

 

89RS400,

All those tests you mention are long-cam motors revving to well over 6000 R's. Lets not compare apples to oranges here, Z/27 Camaro is running a cam with only 223*I/231*E. I don't know how you could say 1-7/8" headers could outperform smaller tubes at this build level. Come on.

And these aren't over-the-counter 292 GM heads either, they are 492's!

 

prostreet L78
so let me get this right.......you picked up 4/10's with the sportsman 2's....right?

what else were you running in your s/10 and what were your times??

how much did you pay for your sportsmans?

i dont want to change these heads i have,just trying to figure out what to do next with them and how do they stack up with newer heads.
my car does 13.3's in the quarter right now and is mostly used for street driving and car shows with the odd drag racing.
i like the fact that engine is all GM and looks realitively stock per say....but if i can get another 20 HP out of pocket porting the heads and port matching them ...then cool.

 

my bad about the 292. I thought at somepoint the discussion moved to that head but i guess not..

However, the second test I was reffering to was not a large cam motor.
Comp mag286 is a street cam.
Torque peak was at 4400 and hp was at 5900. About what an XE268 is.

Additionally, the first test was also done on two different motors. A 350 with vette heads, performer (not rpm) and comp HE252. The HP peak was at 4900.

Quoting from the article "the 1 5/8 made the highest overall peak torque, but the 1 7/8 recorded the highest average and peak hp numbers... The results lead us to question the big headers kill torque sermon"

there was only a separation of 5.7ft/lbs and 2.5 hp between the lowest and highest peaks. Additionally, at no speed below the torque peak did any header show a clear advantage any of the others. At some points the 1 7/8s exceeded the torque of the 1 5/8 and similarly for the 2" versus the others. ( I also question the logic of attempting to pump up the torque at rpm levels more than 1000 below the torque peak. Its not like the motor will see wide open throttle at 2400 rpm. Its not designed to operate in that manner)

Sounds like it can go either way. I think there are very few rules of thumb that can be applied to header tube sizes on smallblocks. Other tests I have seen put 1 3/4 over everything else until above 6500 rpm (smokie yunick)


[This message has been edited by 89rs400 (edited 08-30-2002).]

 

z-27, Yes, I picked up 4 tenths with only the head change. My combo is: 355 chevy with 64 cc Dart sportsman 2`s pocket porting only, Lunati solid roller cam 244@50, .555 lift, 1.6 rockers, short weiand team G single plane intake, 750 dp carb, 1-5/8 shorty sanderson headers, 700R4 with TCI super streetfighter convertor (about 3400 stall), 9" rear with 4.33 gears and 26" drag radials. Truck weighs 4000 Lbs with me in it, (I`m a big guy), Went from 13.2`s to 12.8`s with only the head change. I`ve picked up another 2.5- 3 tenths since then with a ram air setup and suspension changes. The sportsman`s didn`t cost a whole lot really, about $500 for the castings and a valve job, I reused my valves and other parts. I`m sure you could pick up some decent hp with a bowl blend and port matching, but it won`t be anywhere close to a good set of aftermarket heads.
Good Luck, Brent

------------------
Prostreet 67 L-78 SS 396 project. Daily driven S-10 blazer: 355/700r4. 12.56 et. @ 108 mph.