Stage 2 -street Cam -good Idle ?

My 67 GS does not like headers. Smash the hell out of them to install.
Stage 2 heads & headers comming soon....for better fit.
My C118 cam has me spoiled, so what stage 2 cam will get power and good idle?.

Looking at :

* 288-94 230-240 "Good idle... Sleeper type grind" 114 LC
Does this 230-240 cam have too much spread for stage 2 heads?

* 288-92 231-234 "Fair idle..... Car Craft Shoot Out Winner" 110 LC
I see "Pro Tour GSX" running 11.20"s with this cam, performer intake, Qjet!

* 290H 238-238 "Fair idle.....500HP ideal for stage 2" 112 LC

Which cam is best for street with maybe changing the lobe center and holding onto enough power to be a bad ass sneaky cam?

I'll be at 10.1 to 1 compression, stock rocker arms, B4B, Qjet.
My goal is mid 11's in the 1/4 mi. at 3800 lb.

 

Gary

The beauty of the Stage 2 head is, it doesn't needs as much exhaust duration to evacuate the exhaust.
The intake and exhaust duration can be the same or just have a small spread between them.
As a result the valve overlap is less for a given lobe separation angle, giving a better idle
The candidates would be:

TA310
TA288-92
TA290

The 310 and the 288-92 are on a 110 lobe center with a 284 and 288 advertised duration respectively.
The dynamic compression ratio is 7.8:1 and 7.7:1 with a 10:1 static compression ratio.
This is close to optimum and with the B4B manifold will give great low and midrange torque.
However they have 12 degrees more valve overlap than the C118 and the idle will not be as smooth.

If you want to trade low end torque for smoother idle, you could have the 310 or the 288-92 ground on a 116 lobe center.
The overlap will be near zero just like the C118 but the dynamic compression ratio will drop to 7.4 and 7.3.
At this point it would be a better match if the static compression ratio was 10.5:1.
Also as you increase the LSA and move the torque curve upward, the dual plane manifold will taper off
some of the upper end power that would have been gained.

If you want to compromise between low end torque and good idle, then go for a 113 lobe center

The TA290 will make big power but the power band above 4500 rpm will be attenuated by the dual plane manifold.
It is better to use a single plane manifold in order to take full advantage of the TA290.

The sleeper set-up for the TA290 is to have it on a 118 lobe center with 11:1 static compression ratio.
The Dynamic compression ratio ends up being 7.9:1
It will idle like the C118 but will make big power with a single plane manifold.
With the 11:1 SCR and a late closing intake valve, if an overdrive is used for low cruising rpm, the gas mileage will be very good on the highway.

Paul

 

Paul,
Thanks for the thorough answer. Dynamic compresion would have been my next question and you already covered it.

 

Not sure what the rest of his combo is but I did one for Mike Pesarchick on here. It was a 235/242 on a 114, he's in the 11's and it's easy on the valvetrain.

 

What lift did you use?

 

Mark

Do you have a listing with specs for available cams for the BBB for future reference?

Gary could use a 234/234 on a 114 with a 1.55 rocker lift of .500
Advertised duration around 286.

With an SP1 manifold should put him in the 11s

Gary

The B4B makes a lot more torque than the SP1 between 2000 and 3000 rpm but after 4000 rpm the SP1 will make a lot more power with the cams you are looking at.
That is what you need to get your car down the 1/4 mile.


Paul

 

I'll check but I think it was .520/.536 with 1.6 rockers.

Pmuller- yes I'd be happy to post some grinds, in what section should I do that? I have a 290 adv, 234 at .050 lobe with .325 lobe lift. X that by 1.55 and you''ll get around the .500 (actually .504) lift you're looking for.

FYI for all- I have fast ramp, although not as fast as the VooDoos, but not as noisy either, and moderate to slower ramp stuff as well. Tyler Northcutt got a 242/254, .568 lift from me last year. He put down over 550hp on the chassis dyno with a 100 shot of nitrous. His video is on here somewhere.

 

Jim Weise is the moderator of this forum, so I would check with him.

For now, if you have or can create an offsite location with the cam listings and just make reference or a link to it here, it would be greatly appreciated.

Thanks

Paul

 

Hi, I have a 1970 GS Stage 1 with Stage 2 heads, Ta310 cam, Ta roller rockers, headers, B4B, 10.3 compression, and 3.42 gears. I just took out a 2200 converter (worked great but drivability stinks and the cars surges, bucks, and sometimes stalls) and had a a TCI 240901 converter (2600-2800 stall) installed. I was told this would solve the "tightness" and thunk when I put the car in drive. I hate it even more now, car has to rev 1800 rpm (driving it like an old man) to get it to move. TCI recommended this swap to begin with and after the install, I called them about this. They said to send the converter back to do a swap out. I think I should go back to the 2200 converter and change cam to a TA 212 since I am willing to sacrifice some power to have a tolerable GS to enjoy. The only thing that has not been changed is the HEI distributor that was recurved at the time of the engine rebuild. When I crank the car up when it is warm, the engine revs to 1800 rpms and comes down slowly to 1300 rpm...always. I have had three rochester carbs and this did not cure the problem. The engine surges back and forth (have replaced intake gaskets twice to remove possible vacuum leak(s). I'm going to install another stock HEI distributor this weekend to see if that is the problem. Car is strong but is tempermental and cold natured (195 degree thermostat installed). Would anyone have an idea what might be wrong? Any info would be appreciated. All the Chevy guys say to put a Holley on it. Thank you, George

 

Do these things first:
* JW 3200 (minimum) stall 9.5" converter
* Qjet with Cliff Ruggles HP kit and use his books' 2nd recipe (using the biggest numbers) or 3rd recipe (using the smallest numbers). Set air valve at 3/4 turn to begin testing. Set air valve at 80 degrees opening (not 90 or straight down) Set rear throttle blades at a little over center at wide open throttle. (Bill Trovato says 90 degree angles always loose power) The idle speed set screw should not ingage more than one turn to keep good idle or nozzle drizzle will occur. Go back and open the air bypass if needed to do this. Best get an O2 meter to fine tune the carb from the beginning.
* Distributor with no more than 16 degrees of mechanical advance. This will equal 18 initial and 34 max, 16 initial and 32 max, or 14 initial and 30 Max, etc.

Note: Idle should not drop more than 100 rpm into drive from neutral. Carb and Dist must be set up really good to do this, and a stall converter will be needed. I don't see how a stiff converter could handle your engine no matter how you tune it.

 

TCI makes crappy converters.

 

Gary

Update?

Paul

 

Check your primary throttle plates shaft movement on your Quadrajet. If there is lateral movement up or down, left or right. there is your idling problem. Check on Gessler head porting web site for Quadrajet repair kits to fix this problem. Replace the carburetor gaskets between the carburetor and the manifold & tighten the bolts in small increments, careful not to wrap the aluminum carburetor base.

Next, your mechanical advance (springs may be too light) causing the idle to not return immediately. Try one light spring & one medium spring. The vacuum advance canister spring could be overcome with direct port vacuum coming from the carburetor. This can be solved by replacing the factory vacuum advance canister that has multiple internal adjustment settings to overcome the early vacuum signal.

Finally, replace all rubber vacuum hoses, there can be leaks in the old vacuum hoses. Also, check your intake manifold bolts to see if any are not tightened to proper torque specifications. Intake manifolds can leak air too.

 

Stage 2 heads flow 285 int & 215 ex @ .500" lift.
I really like a good idling cam. That ta 288-94 has 230-240 duration, 114 ls and about half inch lift.
How about getting the stage 2 intake flow up to 315. Now you have a head flow intake/exhaust ratio suited for a split duration cam
Just want all parts to work in harmony and good idle.
Any opinions?

 

Gary

You can go the other way and have TA grind a 288-92 on a 113 center.
That will give you the same overlap as the 288-94 and a little more valve lift.

Paul

 

If the 288-92 @ 113 would idle as good as the 288-94, that would be fine for stg2 head.
I may stick with this idea.

 

That 288 92 was a good cam with. A qjet and b4b i have 290h now an with a sp1 and holley 1000 and it is not much faste

 

[Update: I fixed the problem: the original torque converter that I bought (box was marked 2200 rpm stall) turned out to be a 1600 rpm stall..that explained the tightness. After taking the 2nd one out (TCI) and installing a 2200 rpm from Dacco...just right! Also the HEI distributor was recurved wrong so I installed a stock one and the car runs great and idles great! It now idles at 750 rpm in drive...rock steady. Amazing how the obivious was the problem. The only problem now is the cold drivability problem and after a call to TA Performance today, all I have to do is remove the allen plugs in the heads so water can flow through the intake and this will warm the engine faster. George:TU:

 

Paul,
You mentioned the TA sp1 manifold.
I have heard that the 1964-67 A-bodies have little clearance for an sp1 and must use an air cleaner with a lot of drop. However, this leaves the lid too close to the airhorn and blocks airflow.
I'd like to hear from someone with a SP1 equipped 67 that uses original height motor mounts.