From my mods in my sig, I had planned on a 3k stall TC or so. And some 2.02/1.6 heads with high compression. Is this an ok setup? For a non daily driver, I'm hopin to pull mid 12s, of course once I get my current situation figured out.

 

What'd that motor have for compression with the original heads? IMO the cams on the small side as well as the carb, my 355 has 9:3.1 compression, 2.02/1.60 valves, performer rpm intake, Lunati 292/292 .480/.480 cam, 3500 stall 350 tranny, and Holley 830 race DP with bigger squirters, headers and true dual exhaust with flowmaster mufflers, only 3.42 gears right now but best so far was a 1.82 60' & 13.69 E.T., car weighs 3280 with no gas in the tank or driver so figure on race day another 3558lbs full of fuel and driver, if I had your gear hopefully be in real low 13's. Once I get my 9" install and new 28" slicks I'll be stepping up to Lunati's 300/300 .515/.515 cam then she'll be in the 12's for sure. plus this winter it's going on a diet. Just compare what you have to mine and it'll give ya an idea.

 

I have 8.5:1 right now, that's why I want new heads. If I have to get a new carb eventually that's fine.

 

You might want to step up to the 294 comp if your going with a 3K stall, then when you get the new heads with 64cc chambers that ought to put you around a 9:5.1 compression which is perfect for street application, maybe get Fel-Pro's head gasket that's only 0.015 compressed as that will also kick up the compression a little more, maybe a 9:6 or 9:7.1. Since you have 3.73 gear you'll have to stick with a 26" tall slick if you go to the track, otherwise your not going to be using the full potential of the motor for the 1/4 mile. Right now with my set-up I'm losing out on 1600 rpm that my engine could pull, all because I'm under geared with the 3.42/26" slick, I'm only crossing the finish line at 4500rpm and I'd like it to be at least 6000-6500.

 

I was told that you want a stall "ideally" 500 rpms below peak tq and the 268 seems like a good match with a 3k stall I thought. I might get a 2800 stall or so, whatever is available, not goin to pay $600 for a TC.

 

Right, but I was going off your hopes of running in the 12's. I was the gunie pig of the group and bought the Jegs convertor, EVERYBOBY else runs custom made convertors made by BTE. Hell they're only about $400 built to your cars specs and if it is'nt right you can send it back and they'll loosen it up or tighten it depending on how it acts with your final set-up for free. But I paid $197.00 for the Jegs 3500+ stall and it works great. In town it's like a "normal convertor when I take my foot off the brake the car will idle forward on its own, then when cruising it'll go up to about 23-2400 rpm, but when I'm at the strip the convertor flashes right to 3600rpm and away we go. Looking at my timeslips the convertor is very consistent all the way down the track, all my numbers at every time tracked interval is almost the same each pass, the mph are the same, so who ever builds their convertors must be a reputable company-aside from the varying weather conditions. So unless you have a a real light weight car, the combo you have in mind for the motor just is'nt a 12 second combo, plain and simple. It takes quit a bit to haul a 32-3500lbs. car into that time frame. Cam spec are kinda generic in a way they always show a power range of 2500-6500, or 2000-6000, but talk to a experienced machine shop and there is really only a 3000 rpm band where the cam is producing maximum power, sure it'll still pull but the useful power range is all used up. You probably already know that a short block does'nt really mean squat, the cam and heads are where all the power is made, so if you have a small cam like 268 you might hit some mid to low 13's, but'll be hard pressed to see high 12's, a least step up to the 284 cause with either the 2800 or 3000 stall it'll put you in a better rpm range and you'll be crossing at a higher rpm than the 268 is rated for. If you want to make some serious power and it's not a daily driver, go solid cam with a good set of heads, right now that's another idea I'm toying with, the old talk about you have to adjust them alot is bunk, most guys I talk to set them once and they're done-if done correctly, and if you do have to reset them there is'nt any oil slinging cause the motor is off. They're a little noisiery than hydraulic, but make alot more power too.

 

Mark, when the xe268 was recomended, it was going to be a daily driver. IF you're wanting to run in the 12s, you should start with an entire differant engine. No flame here now. I don't believe you're going to get there with a 350 turning less than 6000 rpm, in a full bodied 3rd gen. I will tell you though, once you get there. you're going to want it to go faster. With what you have right now, it should just lite those tires on fire. My son-in-law almost got a ticket for doing a smoke show, at the local cruise in a couple weeks ago. I'm running more compression than you, but you should still have GREAT throttle responce. Make sure you don't have the valves too tight, timming set to 10/13 with a total of 34/36. Then it's carb time, if your secondarys are opening too fast it'll fall on its face, then slowly pick up. How much vaccume do you have at idle? Maybe a leak? Get what you have now running right, before you buy more.

 

I'll have to check the vacuum.

But, I don't see how 12s are out of my sights. RB83L69 said I should be able to hit 13.8 with my combo right now, of course that is just an estimate.

Add in a decent set of heads and a higher stall TC how can I not hit 12s?

How do I check the carb secondary situation?

Oh yeah, and I can HARDLY spin the tires, nothin that would cause smoke.

 

Mark, I don't know how often you go and run at the track, but with your combo in your sig. 13.8 is kinda far fetched, and even if that is the case and we'll say it would run a 13.8, dropping .8 of a second is HUGE to say the least, whenever you can pick up .1-.3 that is a great improvement believe it or not. I'm not trying to be a dick, but I've personally seen too many people, including myself, taking other peoples theories on "how fast it'll be" only to be hugely let down, like myself. When I first assembled my engine and gutted as much as practically possible in the car, everyone kept telling me, aw you'll be low 13's easy. It took all summer switching this and trying that before I even broke into the 13's consistently. Once I switch to the 4.11 gears that'll help alot, but even with my 3500 stall, 830 DP which by itself was a .3 increase, I don't think the cam I'm running is big enough yet, hence if I don't hit high 12's next year after rear end swap I'll install the Lunati 300/300 duration and .515/.515 lift cam, then I'm garunteed a spot in the 12's. That's if I stay hydrualic cam, the more I think about it, a solid would be better yet cause they are proven power makers, but then I'll need to swap the valve springs and all that, so I might just be content and put the money into my next car that will be strip only. You've seen my combo, if you want to talk about tire spinning, with my slicks on the street @14psi they'll make a turn or two then hook, but with my radials, I can hold 6 grand in first feathering it, then when I want to, hit second and hold to 6 grand feathering it, then if I'm really showing off hit 3 and spin and let out of it, with, a 3.42 gear. If you can't do that with your 3.73, your motor needs alot of mods, cause I'm only running 13.6 and that's what I can do. To me shreddin tires on the street don't mean a damn thing, but I'll say this, the track is a huge dissappoinment for guys with high hopes, let me tell ya. The heads are gonna help yes, but unless you got a big heart in that bitch, don't expect much.

 

Sorry I'm busy now, I'll read the above response fully later.

But, how can you not seeing me dropping 8/10ths with raising compression by 1.5 pts or so and goin from a stock TC to a 3k stall or so.? Just wonderin, I don't think you're bein a di(k, just statin your opinion.
Cause new heads will give me like at least 40hp and TCs have been shown to knock off up to 5/10ths, I'm not sayin I'll get 5/10ths though.

I respect your input though. I'm far from knowin it all.
I thought the Comp 268xe was a great cam at least good enough to run 12s with a proper setup all the wya around.

 

I just stating from my experience from racing and listening to other drivers and their input about things. I can't tell you how much my convertor picked me up cause I went from a 2800 stall in my race built 700r4, to a 3500 in a race preped TH350, all I know is that my times were the same after tranny swap, no better, no worse, which is kinda sayin alot cause the 700 has such a deeper first gear over the 350. But after I figured out the new launch technique for the new 350 tranny my short times actually got lower and so did overall E.T.'s, not much, but lower. Hey, whatever yoou decide to go with, I wish ya luck, cause as you know every car responds differently to mods, so maybe you'll be one of the lucky guys that somehow has the magic car with a real mild small block.
Case in point, buddies70 Chevelle has a mild rebuilt 396, the small BB heads, 4000 stall, 4.11 gear, 29" slicks TH400 runs consistent 12.68 and he weighs 4000lbs., Rob, the guy that we met out there this year runs a 72 Monte, 454, 10.5:1, big cam, 3500 stall, TH400, 4.11 with 28" slicks, runs consistent 13.2 and weighs 3800lbs.
Sometimes guys get lucky and just get that magic combo and everything works together, but it does take some tinkering and tuning.

 

You know, a 12 second car is a MIGHTY fast car!

I don't see the slightest bit of shame from a 350 running consistent 13s.

 

and to run 12s you are gonna need some serious traction and you will have to know how to properly launch the car for the best times. going from 13s to 12s takes alot of work and tuning and a combination of parts that works well together. hell getting to 13s takes alot of work. if i were you i would figure out why your car is running right and get it all tuned up (take it out to the test and tunes at the strip and actaully tune it) and see what it runs when it is running properly. then go from there. if i remember correctly you said right now tyour cars best time is 15.49 ; a 15.49 to 12s is quite a huge leap.

 

ill say it.

youd need afr 190cc heads with a 64cc chamber.

a cam with 230 duration @ 050 lift
would need to be a single pattern cam
a tight lda of 110 degrees.
figure on a total lift rocker arms included of roughly 540

should bring the comprsion up to 9.4:1 with the afr heads if my geuss about the piston shape is right on that gm goodrich motor. also a 3200 stall covnerter with that 3.73 gear would be better. you gotta come out of the hole alot harder. if you had 4.11 i would say a 3000 stall.

also you gonna need a 700cfm carb at least. the timing curve will need work. a total of 36 degress of adance in by 3000rpm with a base of 15 degress to make the thing idle.

getting to the twelves is gonna require killing some of the driveability of the thing. the diffrence in HP to go from 13.8 to 12.99 is about 75-85hp. becuase aside form acceleration your now fighting areodynamic drag on the big end as well.good luck.

have you considered Nitrous Oxide a 75 shot would get you there with alot less exspnse and the driveability wouldnt suffer as much.

 

I'm not really a naawwwwwzzzz kinda guy.

 

hey i wasnt critzing the motor only conecpt just saying that the car will lose alot of streetability. aways the combo i listed should get you into solid 12 no problem. need to be roughly 450hp to go that fast.