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

What type of thermostat you running? Race type or your average street thermostat ? I ran the 160 race ones because they open exactly at 160 not some ten degrees higher like other ones. I ran the 160's because of high compression of 14.75:1 and very large roller cams exceeding .700 lift and adv. duration of 306 to 320 . But that was smc's not bbb's..

 

Thanks for the acronym education Larry.

Tomorrow I'm going to have another look at the timing and make sure I am indeed seeing the total timing correctly.

You're right about the tires. I wish I had gotten 275/50's instead. When it comes time to replace them I plan to go to the shorter tire.

 

Unless you run on a well prepped track a short.tire is only going to.irritate you , I could obliterate my 275 60 's at will.on.my local tracks with a 11.60 combo . So do your self a favor and either go 325 s or wrinkle walls . If its leaving soft enough to hook 275 s on test an tune tracks its leaving et on the table

 

Size of tire diameter is less important that composition if your tires are not hooking. Get sticker smaller diameter tires . dropping gear to 3.73 would even be better.

 

Sorry I'm getting back to this so late.

Larry's info on acronyms is correct.
I was using ECR as a somewhat intentional misnomer to draw you to the fact that weather and geographical conditions change what's actually trapped in the cylinder.
ECR is normally associated with supercharged applications, where the added mass of boost is calculated into the formula.

When I read posts showing the ability to tune carbs using air bleeds and track times I'm assuming one understands that what they can get away with in Colorado is very different than sea level.
So it goes without mention.
When using an online DCR calculator, there is an input (usually?) for altitude. Changing this value by a couple thousand feet might be worth a full point in trapped compression, more once weather changes are factored in...DA.
Therefore, what works at 2500 ft DA would need different tuning considerations than 600 ft DA.

***The one piece of information missing from this post regarding detonation, vastly more important than all the good guesses here (including my own) is what the spark plug is trying to tell you.
It will show you where the timing should be or if the heat range is close. If something is disproportionately off, it will tell you that too.***

GmcG is right about the thermostat. It CAN be a huge influence on what would be called octane tolerance. Equal or greater to that is the air temp into the cylinder.
4500 cfm fans and coated headers "should" suffice, but...
Remember, prior to ignition the compressed mix is heated to very near the auto-ignition point. All it takes is some incandescence or "end gasses" to light it off.
On a "chamber efficient" engine like a Buick ( meaning less timing required) there is more sensitivity for the simple fact that the piston is further up the cylinder (more compr. heat) prior to ignition.
When I'm street driving borderline combinations, I'll use the fans and elec. water pump to pull a heat soaked engine back down to 130* (?) before the next blast.

Simply put, you need every advantage available to maintain "octane tolerance".
Buick has many other advantages... I'm just isolating that one mechanical property, the distance the piston gets to in the cyl. prior to spark.

 

A few suggestions for track days along with your other changes:

• Octane booster for detonation resistance, more timing and ultimately more power
• Air bag in the RR spring at 20# or more for a more evenly loaded launch
• Plugs for track only (switch when you get there) with no general use glaze
• Air up the front tires to at least 40# for a smaller contact patch and less rolling resistance
• back off the brake adjusters so there is no contact friction
• A good alignment with less toe at track ride height
• Shallow stage for the appearance of less ET and more MPH

Cheryl

 

Latest update:

Purchased and installed a new TV cable to replace the one that was on the car prior to the transmission blowing up last November, as I found the old was was frayed and really never was quite long enough. The new one fits better and works perfectly. I did manage to spill a bunch of transmission fluid all over my nice clean engine while refilling the transmission after installing it. ou:

Also found that my 1-year old Griffin radiator was leaking on both sides where it attaches to the tanks near the top of the core. Fortunately a bottle of K-Seal seems to have fixed that problem, at least for now. The upper radiator hose wasn't holding any pressure before; now it is and there are no coolant spots under the car after it sits for awhile.

At the moment, the total timing is set at 32 degrees and that seems to have eliminated the detonation problem. As suggested by 8ad-f85, I'll check the spark plugs after I get some miles on them to see if I can get a better idea of what's going on with the combustion cycle.

Hopefully I can make a trip to the track in the next 3-4 weeks and we'll see where we're at. I think if the car hooks up it should certainly hit the 11's.

 

Any updates?

 

After doing all the above, neglecting this one problem can still spoil the fun.

WOW..........12.40's to 11.80's !!!! http://www.v8buick.com/showthread.p..."+or+2+1/2"+for+maximum+performance

AlaskaBuick posted this info back in 2008:

"I can tell you exactly what I gained on my Stage 2 wagon.....
Was running 3.5" collector necked down to 3" into an X pipe and 2.5" out of the x pipe. Went
12.4 at 107 best run.

Using the same headers I went from the 3.5" collector to a 3.5" X pipe in and 3" going out behind the X pipe all the way back thru race magnums:
11.8 @ 113mph."
Dennis

Get PYPES stainless steel 3.5" x pipe...... SKU: XVA14
This is like having extensions on headers, but permanently attached.
Reduce the diameter as far behind the X as possible, so the exhaust is cooled and contracted before going into any 2.5" or 3" mufflers or tailpipes.
....And, about that detonation, a cold air intake is good as raising octane.
Jet hot coating on the headers can greatly reduce under hood temps, if cold air intake is not in the plan (or add both!).

 

Now if I could only get traction I would be happier.
I put moog 5379s in the rear and factory fronts. The 6204s were just too tall for my liking.
90/10 shocks up front and nothing fancy rear shocks.
I have an HR bar with adjustable uppers and boxed lowers
295 MT drag radial
2.03 60' spinning through most of 1st gear.

http://www.v8buick.com/showthread.php?300616-Guess-what-it-will-run

 

Moog 6204 18.61 free height .609 dia wire....great traction
Moog 5230 18.25 free height .609 dia wire....lost traction (so, back to the "tall" 6204 for me)
....and yes, the 6204 is taller but will settle a little after a few months, and will never collapse in a year like Moroso springs.

Might try some cc501 Moogs on the back. Some guys have had good results with it. Seems the variable rate planted the tires better.

 

Working with a friend now so I am gonna be getting some new springs next year. maybe sooner.

 

Hi Brian,

Yes, I have an update, but it's not good - yet. I took the car to the track back in March - the first run felt like it was going to be a good one. The 1/8 mile went by in 7.62 - my best ever. But then the car started spark knocking something fierce and I had to let off, so my 1/4 mile time was only in the mid 12's at under 100 MPH. I backed the timing way off and ran again, but this time I missed a shift and over-revved the engine. Ran twice more and both times the car nosedived around mid-track. One time it even stalled at the lights. It was pretty warm and I seemed to be having vapor lock issues. Never did get a good run in. And to make matters worse, on the way home I noticed the oil pressure was down about 10 PSI from its normal spot.

I drove the car for another couple months with the low oil pressure, but I still had detonation issues. I noticed some pretty heavy blow-by one day when I had it running with the hood up and after that I parked it and pulled the engine. I found that number 7 piston had a crack between the 1st and 2nd ring landings - similar to how I broke #1 back in 2013. As for the oil pressure, that was caused by badly worn #2 main and #2 and #3 rod bearings. I'm guessing when I over-revved it I didn't have enough oil to the #2 main and that also starved the two rod bearings.

The good news is that two days ago I received my TSP 470 short block with roller cam. My son and I spent a number of hours today transferring the oil pan, heads, and timing cover from my other engine to the new block. We hope to have it running in a couple weeks and be ready for some racing in October.

 

Be sure to.sump the tank or get one of the Spectre Premium tanks the new one I received the other week was Baffled pretty well. But fuel starvation can.jack some parts up in a hurry

 

My convertible weighs about 200 lbs. or so more than yours as I have a/c also. Here's my setup.

462 cid, forged pistons, with true 10 to 1 compression. Stock bottom end otherwise.
SP1 intake
950 HP carb
stock distributor with an MSD box
430 heads, mildly ported
cam spec .491/.510 lift, 234/246 duration on a 113 centerline (Poston's old 113A cam)
headers with an x-pipe, 2.5" with very free-flowing mufflers
2800 stall converter from CKPerformance
200-4R trans with 3.73 rearend
stock suspension with airbags in the back at about 12-15 psi at the track on pass. side and 7-10 on driver's side
drag radials 325/50R15

Best to date was an 11.86 at 112 mph with 1/2 a tank of gas

And I leaned out #7 because I was using stock fuel lines and stage 1 fuel pump. I purchased RobbMC 1/2" pickup for the fuel tank and JW's mechanical fuel pump and am plumbing for all 1/2" fuel line from the tank to the carb. I'm also going to upgrade the distributor to an MSD unit with vacuum advance.