OK, how do I get my '72 Skylark from 12.20's to 11.80's?

OK guys, I need your help to beat my brother's 2008 Pontiac G8 GT. I had him until he went and got his heads ported and finally got drag radials. He went from running 12.40's last year to running 11.80's a couple weeks ago. My best run so far is 12.20@109.45. Here is what I'm working with:


1972 Skylark Custom 2-dr, full weight with A/C
'74 455 .030 over
Stock crank, .010 under, chamfered oil holes
Stock rods, resized with ARP bolts
Rod and main bearings have .002 clearance
TA Stage 2 SE heads, unported
TA 290H cam (.508 lift with stock rockers, 238 duration @ .050), 4 degrees advanced
Rhoads lifters (15" of vacuum at 750 RPM idle)
TA grooved cam bearings
TA SP1 intake
TA cast stock replacement pistons, .025 in the hole for approx. 10:1 compression with TA heads
TA timing cover with upgraded (not high volume) oil pump
TA 2" x 3.5" headers into 2.5" mandrel-bent exhaust with Dynomax Super Turbo mufflers
Quick Fuel 880 vacuum secondary carburetor, tuned for the highest MPH I could get out of it
Mallory magnetic breakerless distributor
RobbMc 550HP mechanical fuel pump with 8AN line from tank to pump and 6AN from pump to carb
RobbMc 1/2" fuel tank pickup tube
TH200-4R transmission with TSP 2800 stall lockup converter
3.23 rear gears with Auburn Gear limited slip differential
P275/60R15 Mickey Thompson drag radials


I was thinking of getting the heads ported and maybe going up to the TA 298H cam (.504 lift, 241 duration). If I get the heads ported, I need to decide between using the same local machine shop that did my block, crank, and rods (with whom I have been quite satisfied) or using one of the fine Buick builders on this site (like TSP or TA).


Questions:
1) Will porting the heads be enough to get me from 12.20 to 11.80 or so? I was also thinking of having them shaved to raise the compression to about 10.5:1
2) Is there any gain to be had in going from the 290H to the 298H? My cam options are somewhat limited as my pistons are not notched and the bottom end of this engine is not built for RPMs in excess of 5900
3) Can anyone suggest anything else I haven't thought of that will get me there without having to replace pistons?


Thanks! Now let's get to work beating that LS-powered Pontiac!

 

Couple of suggestions.

950cfm, or possibly 1050 cfm carb set up for car. Not with vacuum secondaries. Or a Quadrajet, had to say it!

What are your 60' times?

3.42 gear
4000 stall
Tires
You didn't mention suspension set up, but you may be able to get there with changes and not touch the engine.
No front sway bar
90/10 front shocks
Rear drag shocks
Rear sway bar, we use Spohn track bar
Battery in trunk

 

:gp:
I ran that time with almost the same setup but iron heads. Get the big Holly and it will explode when you nail it. You should be running 115 with those heads. Get an MSD Al-2 programmable. I think there is a ton of potential that everyone is missing by not being able to customize the timing curve.

Tell us more about the converter.

 

I would up the compression, you can get to 11-1 on good pump gas with aluminum heads, I personally think the exhaust is hurting you. go with a 3" system. Also you would benefit a bunch from a bigger carb Especially with those heads. Id run a minimum 1000 CFM carb. Getting the heads ported is also going to make a huge difference. As far as cams Get a hydraulic roller they can make a huge difference also.

 

I agree with what some are saying that there is more in your combo. Tuning is where you need to go. Bigger carb ,3.42-3.73 gears more convertor my guess is 34-3500 would really get that moving out of the hole. Get better rocker arms. The stock ones I'm sure are flexing some loosing some lift. Sounds like an 11.5-6 if you get your combo in sync better. Is it hooking well? Any rear traction devices? I like UMI lift bars myself. 3 in exhaust also.

 

Thanks for all the input so far! Let me address a few of the questions asked and suggestions made.


The torque converter is a Trishield Performance 2800 stall lockup converter. I really like this converter because it has great street manners. I'd rather not go too much higher on the stall if it can be avoided.


I have the HR Parts & Stuff rear bar. With the MT drag radials, the car hooks right up. Best 60' time is 1.74 with no wheelspin.


I don't think that going from a 3.23 gear to a 3.42 will make that much of a difference, but I'd like to hear other opinions on that. I imagine 3.73's would help, but I do like cruising down the highway at 75 MPH at 2400 RPMs too.


I agree the exhaust is holding me back some. I will try to make it back to the track once more before the season is over and run it with open headers to get a better idea of how much the 2.5" pipes are hurting me.


Does anyone else think the rockers are a problem? I thought I once saw a post from Jim Weise stating that for a flat tappet hydraulic cam with only .508" lift the roller rockers showed absolutely no gains over the stock rockers. I do have the heavy duty shafts from TA.

I forgot to mention timing in the first post. I'm running 8 degrees initial with 24 mechanical for a total of 32 degrees all in by 2500 RPM.


One last thing: I really want to keep this car as street friendly as possible. I have to believe a 462 cubic inch Buick V8 can run 11's and still be street friendly.

 

3in X with straight thru muffs will prob net a tenth MAYBE 2, 950hp or 1000cfm HP style carb WILL pick it up close to .2 potentially more depending on what I wants,run a Vac gauge and see what it tells you at WOT. A small increase In cam wont be noticeable, I myself would want some more lift but the xam you have isn't keeping you from running 11's but what is , is the rather weak 60 time, with the stout first gear of a 2004r you shouldn't need a steep gear as it will only aggravate wheel spin, but in your case since it is an overdrive with a 28in tire you could run a 410 and live with it altho it shouldn't be needed. Id un cork the exhaust and up the carb cfm and see where that gets you. But b4 I did a gear swap I would do converter swap and go non lockup otherwise you gonna start breaking/smoking the trans, a 3800 stall can be had and you never know its there till you call on it. Also initial timing means nothing as far as im concerned unplug the vac line and set total timing at 32 to 38 and let the initial timing fall where it wants, they like 12 to 20, if it will hot start then its fine

 

Don't be spending big money and changing things. Your already capable of your goal.
Put 18" collector extensions on and go back to the track with open exhaust ...OR
add an X pipe (3.5") and let the X suck the exhaust through, then reduce the diameter at the mufflers after the exhaust has shrunk from cooling.
Some combos absolutely hate reducers at the collector and loose unbelievable power just like stock fuel pumps and fuel lines.

Other suggestions:
Your 60 ft sucks for what you have (even at 12.20). Do not change gears, tires, etc. Check other stuff...
* Fuel air ratio... Low speed to high speed.
* Carb tuning...especially at the launch.
* Cam ...lobe damage, cam timming (killing low end), lifter preload (poor preload is a sneaky e.t. killer)
* Vacuum leak...intake gasket, carb gasket, etc
* Traction...put a white mark on your tire and make sure there is no tire slippage at launch.
* Exhaust...I repeat, no reduction at the collector. Extend the collector 18" to open air or into an X pipe.

 

What is your timing set at and total timing and how soon is it all in at? Your tuning carb for max mph but what about launch?. Is it sluggish? Hesitant? Got to tune everything.

 

That's crazy with TA Stage 2's and the rest of your parts.
I would think something is not right.
I would expect mid to low 11's with what you have.
I would dump the carb as mentioned above and go to a 3.73 or 4.10 gear since you have the OD trans.
With a 28" tire the 4.10's would put you at 90 mph at 3000 rpm. right now with your trans and gears you are at 3000rpm at 115 mph and at 5000rpm your are at 192 mph.....LOL

 

Converter and gears is keeping it from full potential, since its a street car I wouldn't sacrifice driveability. 100 shot, easiest to do plumbing is by getting a standalone 1 gallon fuel cell with the pump in it, and don't get greedy. I ran countless nitrous passes with my cast piston 455 and the person that bought it is still driving it. If you don't want him to know you have nitrous, purge it through the motor during the burnout.

 

Total timing is 32 degrees all in by 2500. So it's basically running 32 degrees all the way down the track as the car launches at about 2500.

The carburetor feels really good. There is no hesitation or bog of any kind at launch that I can feel. The Quick Fuel carb is wonderfully tunable with replaceable air bleeds and power valve channel restrictions, and adjustable vacuum secondaries. However, I will check the vacuum readings on it at WOT to make sure it isn't undersized for the engine as another poster suggested.

 

My experience with the stage 2 heads is they do not perform very well right out of the box. My original build stage 2 engine ran mid 12.20's. with a TA 310 cam 9.96:1 compression, Shorty headers with dumps. Sp1 intake with an 850 carb.

Chris Skaling took the initiative and ported the heads. Swapped out the original SP1 with the new version and put a 1000 cfm holly on it. Car then ran a best of 11.56 @ 117 mph.

Car has 373 gears, stock suspension with right side air bag. With my slicks and front runners mounted on aluminum rims the car with driver weighs 3850 lbs. 60 ft times are in the 1.60 to 1.70 range.

 

I run 3:73's, 200-4r, and 28" tires. It makes a great street combination. Get on the expressway, throw the lockup switch and cruise the big boy lane. Check your converter slip percentage. http://www.wallaceracing.com/converter-slip.php You should be much faster on the top end.

 

You can also fine tune your chassis to run faster too... not always more HP!

 

Thanks everyone for the responses. Unfortunately, as I was driving the car today to test the vacuum reading at WOT, my 200-4R transmission failed. I was quite surprised by this as the transmission is from a very reputable 200-4R builder and is supposed to be able to handle 750 HP/650 lb-ft. I'm quite certain my 455 isn't producing numbers like that, or I wouldn't be trying to figure out how to get it into the 11's. At any rate, it seems my first priority now is to get my transmission fixed, and then I can revisit the original issue. As I said, thanks for the ideas; I'll try some of them out once I get the transmission fixed.

 

That sucks. Any warranty?

 

Do you have a heavy duty trans cooler? Those trans need them .