As you read this post please keep in mind I very much am an amateur at the drag racing "thing". My car is primarily a street weekend toy, but of course I want to eek out the max performance out of it.

OK, so over the winter I made some changes to the top-end of my 360 motor. Kept the same cam (hydraulic flat tappet, 238/244@0.050, .535/.540 lift, 108 LSA - Hughes HE3844AL) but bumped the static CR from 9.7 to 10.7 (head re-surface), my cranking compression went from 165 to 185-190 psi. Did some additional work on the heads, minimal really, removed the left-over (from original porting job) guide boss casting. This time I went back to running a Perfomer RPM intake instead of the Holley Strip Dominator single plane.

My ride is about 3600 lbs race weight, 360 motor, 4K stall converter, 727 trans, 3.91 gear on Nitto NT555R drag radials, Carter TQ 1-3/8" primary bore carb, 35deg total mech advance, 21 initial, all in by 2K RPM.

Now here is where I need your help. I did a few passes at Milan Dragway this past Wednesday and my times with the current combo are nearly identical to the old combo. What I am really floored by is that the Perfomer RPM intake did not seem to improve the 60' times (even though in normal city driving this intake is a clear winner as compared to the Holley). In addition, the bump 10.7:1 CR did not appear to improve anything either...I figured even a low end estimate of hp improvement due to higher CR would have been worth something.

Soooo....any guesses as to where I'm getting stuck with this?

Here are my run LOG contents for several runs:

REACTION - 60 FT - 330 FT - 1/8 ET - 1/8 MPH - 1000 FT - 1/4 ET - 1/4 MPH - TIRE PSI - LAUNCH RPM - COMMENTS

2014 Season runs (single plane Holley Strip Dominator intake with 9.6 CR)
0.460 - 2.006 - 5.580 - 8.571 - 80.65 - 11.262 - 13.533 - 99.62 - 32 - 3000
0.449 - 2.660 - 6.579 - 9.609 - 81.51 - 12.248 - 14.482 - 101.15 - 32 - 3000
0.603 - 2.333 - 6.119 - 9.132 - 81.96 - 11.749 - 13.966 - 102.08 - 32 - 3000
0.100 - 1.870 - 5.379 - 8.341 - 82.40 - 10.937 - 13.138 - 102.33 - 32 - 3000 - BEST TIME
0.153 - 1.973 - 5.519 - 8.473 - 83.17 - 11.056 - 13.254 - 102.54 - 32 - 3000

2016 Season runs (dual plane Performer RPM intake with 10.7 CR)
0.120 - 2.180 - 5.779 - 8.759 - 82.57 - 11.357 - 13.568 - 101.68 - 25 - 3000
0.520 - 2.356 - 6.386 - 9.450 - 80.89 - 12.081 - 14.314 - 100.99 - 25 - 3500
0.041 - 2.098 - 5.624 - 8.561 - xx.xx - xx.xxx - 13.316 - 102.75 - 19 - 3500
-0.126 - 2.034 - 5.515 - 8.440 - 83.76 - 11.006 - 13.188 - 102.98 - 19 - 3500 - RED LIGHTED
0.189 - 2.069 - 5.559 - 8.484 - 83.94 - 11.043 - 13.218 - 103.27 - 19 - 4000 - BEST TIME

Burnouts were good, lower tire PSI showed no tire spin at launch, shifted into 2nd @ 6500, 3rd @ 6300 and crossing the finish line around 5700 RPM.

Did I expect too much from this change?

If I am blatantly going wrong somewhere here by all means please tell me...I do not know how to interpret what the 1/4 mile slips tell me.

Thanks!

at 1st i would say tire spin you said no spin. 2nd your trans.
also are you doing every thing the same ie,, burn out and engine temp ect ect ??

Just my opinion but I would try swapping the intake back. I think you made lots of positive changes but the intake was a step back.

I'm in agreement with trying the old intake again. Also, how did you obtain a whole point of compression increase. That doesn't happen with a clean mill. Won't even happen with a .060" mill.

The 60 fts won't vary more than .01 unless you have tire spin, or a problem like no jet extensions, which can let air enter the rear jets. I agree on trying the other intake again. You have enough converter to make use of the upper end power, I believe.

Possibly the added work on the heads really netted next to nothing.

How much of an improvement were you expecting?

So really at the end of the day, you only cleaned the heads up to what you thought they should be, maybe swapped head gaskets and went with a semi similar intake, yes alot of work but for all that I might of just tried a bit different cam as well or the cam would of been the only change.

didnt think there would be a jet issue with a Carter TQ

You didn't mention what heads you have. If they are cast iron at 10.7 cr I would recommend mixing some 100 or 110 octane fuel with your 93 pump gas.
Also If you compare MPH @ the 1/8 and 1/4 you are slightly faster. Looks like you need to improve you 60' you ran almost the same et 13.138 vs 13.188 with a 1.87 vs 2.034 60. looks like some tire spin is in there.

Gary

Good to meet you, again! Very clean car you have there. The times are all over the place, so it will be a bit difficult to compare.

Do you happen to know the weather from the 2014 runs? The DA was 2000-2500' on Wednesday, so not great by any means, but average for Milan it seems.

A helpful link that will look up historical weather at the track you ran:
http://www.dragtimes.com/da-density-altitude-calculator.php

Sorry I didn't get much of a chance to chat, but the couple runs I witnessed (which you weren't driving) it seemed to kill the tires off the line. With that gear and converter you should be able to manage better short times if its hooking, easily along the lines of the 1.87 from 2014. For comparison, my Dart with a stock converter and 3.23's pulled 1.9 with similar ET.

Also, the track prep was typical Milan that night, i.e. no prep. I struggled with tire spin all night, and only managed a 1.63, with a worst of 1.73 (normal "dead hook" is 1.60).

I think you may still need to work on tire pressures. I'm not familiar with the Nittos, but a co-worker used to race for Nitto and helped with their early drag radial development, he indicated you could run the pressure much lower. I would start at 20psi and work down in 1 psi steps until it hooks, keeping everything else consistent. I think most radial guys end up in the 15-17 psi range.

Other tricks for the stock spring are clamping the front segment, unclamping the rear segment, ensuring you have adequate shock travel (not topping out the shock). Even single adjustable ranchos would be a good step up from stock replacement style.

The performer RPM should be a fine intake. That, the RPM AirGap and the LD340, are among the more well regarded street intakes. Is the divider cut down at all? It could want more plenum volume. Maybe you can fit a carb spacer and keep everything under the hood?

Good luck with it! Let me know if you plan to head out again and I can try to make it out myself.

Work on that sixty foot...you are losing a lot of ET there.

Different tire pressures, and try launching at different RPM's, or even off idle. It's harder when the track prep is little to non-existent.

Try different shift points too. I think you may be shifting too high.

Two things come into my mind, one is lack of consistency, work on fixing that first so yo can do some valid testing
Second thing is fuel delivery, can you jet that carb. up enough to slow the 1/4 mile per hour down? If not fix that next
Have you played with the squirter sizes yet? If not do that also

Shift points are too high IMHO. Buy a stand alone shift light set it for 6000 and start a base line.
Are you using SS springs? if so, take your pinion snubber off and toss it

Guys!

Thanks for the all feedback. I will provide some general responses in this post and will do a one-by-one specific post responses next.

Alright...so consistency...yeah, absolutely dismal, but that is party due to my complete lack of experience and party due to trying too many things in one session. I agree that next time out I need to focus on specific "configuration" and stick with it. Meanwhile, this outing was still a bit like throwing a dart in the dark. I tried a number of different things (given my previous 2014 session results, I tried to stay consistent there) with the goal of identifying a working combination.

Some of you pointed to shift-points. The motor seems to pull up to that 6300-6500 point. I am running my lifters with a zero pre-load, they are the HT2011R anti pump-up pieces. When I had put on a bit more pre-load (1/2 turn on the rocker adjuster screw) I could tell then the motor dropped about 200 RPM. But...excellent point, I will aim for a 6000 RPM shif-point next time out.

Tire spin, maybe I was over-optimistic in thinking I was free of this issue...LOL. There was a real difference going from the street 25 psi to 19 psi, and as the burnouts got better the tires got sticker. But I will start off with 18 psi next and watch this closely. Great advice re: 60ft times and the consistency that I should be after. Here is a question: for this type of a setup (street car after all) what would be considered a respectable 60 ft time?

Once again, thank you...appreciate all the responses. I have a set of custom pushrods (Smith Bros) coming to me so that I can try my Crane 1.6 ratio rocker arms...so hopefully a couple more test sessions still remain in this season.

Well, my heads are stock 596 castings. The chamber diameter is 4.075-4.100 one way (top to bottom) and 4.130 across the intake/exhaust valve centerline at the widest (side to side @ valve de-shrouding cut) point.

I started off with a 68 cc size...the head cut was 0.030" which got me down to a 61 cc camber (I actually cc'ed them).

Using these numbers I went from m previous baseline of 9.8 to the new number of 10.5 (not 10.7, thanks, I went back to my spreadsheet to re-calculate and realized the 10.7 number was coming from several of "what-if" scenarios I ran through).

I am running a Carter TQ 9800 series carb (electric choke) with the following setups:

PRIMARY JET = 98
SEC JET= 143
METERING ROD = 2004 (0.067,0.058, 0.040)
SEC AIR DOOR TENSION = 2 turns
SEC AIR DOOR OPENNING (back of throat) = .850"

For street manners the 98 primary jet and 2004 metering rods give me a very nice AFR reading of IDLE=14.2-5, CRUISE=13.7@110km/h, SEC_POWER=13.5.

Should I be aiming for a richer WOT reading?

I have been pretty lucky to assemble a great mix of jets and metering rods, so I can easily go up to something like 149 on secondary jets and play around with the sec air door openning.

Fair question...per the compression ratio change => hp/torque increase estimates the implied single point of static CR should equal to about 1.5% improvement (see David Vizard's " How to Port & Flow TestCylinder Heads" book).

I figured on my motor that woudl equal to approx 3-4hp increase...I agree, all math numbers, but that's all I got.

Yes, these are factory 596 castings, somewhat heavily re-worked (porting mostly, see this other post for some specifics) but with 2.02 and 1.60 valves. I never thought of going beyond the 94 octane if that octane level was not causing me detonation issues...wouldn't higher octane atually burn slower?

Likewise, I was very happy to see you there. Thanks for the great conversation and the tips regarding the tire pressure.



Nah, but I do have the specific dates, so I will try to a baseline the measurements using the link you provided.



Ahh..yes, those runs were made by my buddy who's been part of this Mopar project of mine for many years. To give him credit, both times he spun tires pretty badly, but he did mange to go from an initial 15 sec pass to a final of 14.1...so he was pretty happy with that!



My hands are pretty tied here. I am actually running a set of KONI adjustables all around (front & rear). They are set pretty stiff for minimal chassis movement. The car handles great with the HD sway bars both front and rear. So very little chassis weight shift to the back. The springs are replacement M-body 5 leaf setups, clamped in factory locations. I do not want to play around with this due to the road-handling characteristics.



Because I run a TQ on that intake (which is a square bore) I have a 3/4" adapter already in place. I did mill the divider wall in the intake itself down another 1/2"...but certainly nowhere as far as what MP books recommend. I would prefer to keep this dual plane since it does have great street manners.



Absolutely will do, as you can tell I certainly could use a pair of "supervisory eyes" on things...LOL!

I am running a 3/8" line from the tank, mechanical Carter M6902 high-volume pump through pressure adjuster (6 psi) to the carb.

Comment regarding slowing down the 1/4 mph...seems counter-intuitive? Do I not actually want to go faster?

I thought faster mph implied the motor is making more hp, so if I jet up and the mph picks up I am moving in the right direction, of course the caveat being my ET may suffer if I'm not hooking the tires properly.

The squirter I have is 0.037, but I do have a 0.040 available as well. Will try that out next. When I ran the 0.040 on the street the motor did not like it...maybe it was the small primary-bore TQ I am using?

No, not using SS springs, just replacement 5 leaf pack for M-body cars.

I do have an adjustable pinion snubber set up with about 1" movement. Haven't climbed under the car yet to see if I was getting any hits or not though.