Combo changed, but ET still the same?

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.

Put clamps on the front segment and remove the clamps on the rear segments and take off the snubber.

One of these will help with being consistent
https://www.summitracing.com/parts/pro-67005sc/overview/

Oh you guys...I have an adjustable shift-light on my tach...sorry...I've gotten used to it so much that I had actually completely neglected to mention it. So when superchuck posted the link to the shift-light product the proverbial lights finally went off in my head...LOL.

I pre-set my tach to have the light go off at 6300 RPM, so by the time I react and the shift is completed the tach pegs up to about 6500 RPM.

My son put together a little compilation of that day's events, you can find it on YouTube.

My suggestion to jet the carb. up richer until the MPH slows down in the 1/4 mile is to verify adequate fuel delivery (EDITED Once it starts to slow down jet it back to the best MPH )T.Q. carbs can make a hoop of HP when jetted correctly, jet it up and try opening the rear door some more until it slows down

Since you average MPH is up I'd say your power is up. poor track prep and more power lead to more tire spin so loses down low. and weather and wind can affect it too.
And if you say your seat dyno around town tells you it has more low end the gain was probably gone in tire spin.
work one thing at a time try to get 60" more consistent and quicker then try moving rpms at shift up and down.
do a log.

Could be that you do not spin at the hit and start spinning after 10 to 20 feet as you come into power band and carry that spin past 60'

you may be detonating but not hearing it over other noises. I had a similar combo with a 340, iron heads, quick advance, 10.4 cr, 175 psi cranking, would run fine, no audible knocking but at the track it would run .5 quick on a 50/50 mix. I think it's worth a try.
you do need to get your 60' nailed down but your MPH will tell you if it helps.

IMO, those 60' times are terrible for a combo like that with a 4k converter.
If you're sure it's not spinning, then either the motor is really soft down low or the converter is suspect.
I would put a white stripe on the tire and have someone video the rear tires on the launch and verify it's not spinning.
No reason a hi-12/low-13 second car shouldn't be dead hooking.

The speed also seems low to me for what the heads flow, cam size, cr, etc.
How do the converter slip numbers look?

Fwiw, I think you're shifting too high, but that's easy to sort out.

If that converter really stalls at 4000 RPM I think all the torque you added with the RPM intake is going out the window, thus your 60 times that haven't changed. You're just losing a little top end, which is probably offset by your head work.

The tight shocks, clamped springs and sway bar explain why the car looked "stiff". Very little movement front and rear. The video confirms this.

I've never had a good handling car that I've taken to the track, so I am not sure how to go about getting weight transfer and hook. If the shocks are easily adjusted, you could maybe loosen up the front rebound at the track, then tighten it back up for the drive home.

pump swill? If it's got any ethanol in it you are really lean is my guess.

Don't pay attention to the AF meter, look at the MPH on time slip. That will tell you what the engine likes. I rarely have any engine on pump swill that like AF readings higher than about 12.4 for best MPH. If you are that lean, there is a TON of HP trapped in the poor tune up.

Not sure on rear tire height, but, 5700 through the traps and only 101-103ish is very weak unless the tire is only 25" tall or less. The converter may be suspect with a lot of slip if tires are taller.

Get the jetting correct, fatten it up and see how it does.

I am somewhat convinced now (given the forum feedback) that I still probably have a pretty decent amount of time spin @ launch. I will do the white stripe on tire trick next time out to really get a good measure of this.

The converter is a custom built (for this car&combo) 9.5" Dynamic Converters piece that's spec'ed out to stall at 4K. I believe it flashes to around 4K@launch, but I have always staged @ 3000 or 3500 and only did the 4K launch once.


I also think this is a tad slow for the combo I built..LOL...but I always attributed that conclusion to my "wishful thinking".

Regarding the converter spli numbers...umm...help me out, how do I calculate this?

The Nitton NT555R drag radials I'm using are 27.75" tall. Paired up with my 3.91 SG rear end, am I looking at calculating the theoretical speed @ given RPM and comparing that to what my gauge is actually showing?

As I sat down logging the 1/4 numbers into my spreadsheet that is what I started to think.

The street manners feel I referrenced earlier is that the Performer PRM is a much more responsive intake. The Strip Dominator on the other hand is soft down low, however, the benefit last time out to the track with that single plane intake seemed to have been that even with the full 32 psi tire pressure I am pretty certain there was very little (maybe none?) tire spin.

So as you pointed out I am wondering whether now I have moved to a better torque output and with the additional head-work I provided for a tad more flow to "keep-up" with the higher RPM performance of the single plane??? Sorry...all theory at the moment and really I'm thinking out loud on this one.

Driveshaft is only turning about 4800 when you are at 5700, IMO, that's a lot of loss.

Never assume that the tire circumferences is accurate using a math formula If you don't have access to a seamstres tape buy one and measure both tire circumferences and use only that as your actual tire circumference Make sure and get the circumference within 1/4 inch of each other also, I use pressure to get them there
I've seen 3.5 inches differences in circumference on three different sets of the exact same size of new slicks at the races

Going off a 27.75" diameter, the moroso chart shows about 4880rpm for 103mph and 3.91 gears.
That's close to 16% slip, which IMO is way too high for a combo like that.
Should be well under 10%.
3600lbs, 103mph shows just a tick over 300hp on the moroso chart.
The motor combo should make an easy 400hp at the flywheel.
My experience is that if the car is working even remotely good, you should be able to run within 10% of the predicted ET for a given power/weight ratio.
In your case, 360hp(90% of 400), 3600lbs...... Shows 109mph.

I'm going to dig out some of my old VHS tapes and see if I can find some passes from my Dads old 79 Cordoba...... From around 1993.
The combo was .040 360 with some of the old flat top trw pistons for a 71 360 application(8.8:1 actual cr), home ported( by my dad) 1.88 360 heads(don't recall the numbers.... Might have been J heads) converted to 2.02(probably flowed a max of 225-230).
Torker II intake, 650dp Holley, crower solid cam(#31312)that was 250-254@ .050,108lsa, .540-.550ish lift, hooker 1 3/4 headers.
9" Fairbanks converter I bought at a swap meet, 4.56 gears, 10.5 x 28 slicks, 3900lbs race weight.
I'll double check this if I can find the videos, but as I recall it ran 12.60's and I think the speed was in the 106-108 range.
That shows about 365hp on the moroso chart, which would work out to 405hp if you figure a 10% loss for being in the car.
That motor was dyno tested prior to that with a mp509 cam in it instead and made right about 400hp.

For a comparison with another car with a known hp, that's also not set up for drag racing at all.....
I have a bone stock 2012 mustang gt. 6 speed, 3.31 gears, oem tires.
The only thing that's not as delivered is its had a few oil changes and I put in a pcv system catch can.
Horrible tire frying launches(2.10 best 60') and less than stellar shifting on my part netted a best of 13.42 at 109.8mph.
The car weighs 3500lbs + me, and I'm 240.
The moroso chart shows 380hp for 3740 and 109.8mph.... Motor is rated at 412hp.

IMO, you really seem to have two issues...... The 60' is off, and the speed seems pretty low.

On the other end of the spectrum, to show how good things can run without a bunch of fancy parts, when the car is purpose built to go down the drag strip.
1980 Dodge Mirada running in I/SA. Low comp 360, 308 heads with 1.88 valve and no porting.
Stock intake and a TQ carb. .420-ish lift cam, headers.
8" converter, drag shocks, slicks, 4.56's(I think).
Min weight is 3410....... It's gone 11.70's at 113-114.
That shows 385hp on the moroso chart.

(Quote) 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.(Quote)

I watched your video. The front end on your car does not move enough to transfer weight to the back tires. Until you get the front end to snap up you won't get the car to hook with any consistency. If I had to guess the front of the car is moving maybe 3" and it needs to move approximately 5.5" and quickly. I sniped 2 pics of your car from your video and at rest and at full extension. You can try to disconnect 1 side of the sway bar and loosen the adjustment on your Konis to help this and I'm sure your 60' times will be quicker and more consistent and you'll be able to reconnect the sway bar and readjust the shocks for the ride home. Until you can make the car hook consistently your really wasting your time trying other things.The only other thing I would try with your combo is to lower your shift points to no higher then 6200 RPM. Get the front to move first then work on the rear suspension and tire pressure then work on the rest of the combo. I would think this combo should be consistently in the high 1.70's to low 1.80's for a 60'. Good Luck!

All good advice to address the poor 60' issue..... But still need to find the missing 6mph.

I totally agree that this car is definitely missing MPH but getting the car to leave consistently will help to quantify other changes so you know if your losing ET/MPH due to tire spin or something else. If the car can't repeat how do you know if your making good changes or bad? Properly setup his combination at 3600 lbs. should be capable of going in the mid 12's at somewhere around 105-107. Of course Track elevation, barometer, density altitude, temp and humidity will be a factor.
One question for the OP. You mentioned that you have 1.6 rockers that you want to try. Do you know that there will be enough piston to valve clearance for the additional .035/.036 valve lift?

For sure, it needs to be verified if it's spinning or not as the first course of action.
If it's dead hooking and still only runs 1.9-2.0 60' times, to me that would be an indicator that perhaps the poor 60' times and low mph are related to power output.

Fwiw, my heap always worked better leaving at a much lower rpm than the op is.
I like to leave at the lowest rpm I can and not have any kind of bog...... Usually 1800-2200, which gives the motor a chance to get a run at the converter, and can often be worth another 1-200 in flash stall speed.

I think I should be OK, the readings (measured using play-dough imprint from piston top valve cut-outs and the heads/valve-train installed) with the current 1.5 ratio are:

INTAKE => 0.180
EXHAUST => 0.225

So that extra 0.035" lift should still give me a safe enough clearance.

I was a bit worried about the valve spring clearance actually. I am using the HughesEngines #1111, which is 155 lbs@1.800" and 330 lbs@1.250", so that gives me a spec'ed room of 0.550", but the published coil-bind comes in at 0.700" and when I originally ordered my cam Hughes had me upgrade from 1102 spring to 1111 given that I told them I'd like to run the 1.6 ratio rocker arm eventually.

To be sure, I did check the installed height of all the valve springs, they came in at 1.727-1.786 (actually, only 1 valve was 1.727 while the remainder were typically at 1.750).

the change in valve lift has almost no effects on valve to piston clearance.... it's the valve timing events, and you are barely changing those. I know that you know that you'll be ok but for the wrong reason.

OK, so I agree, the valve timing can potentially have the much bigger impact on this...but when the cam stays the same (as in my situation) eventually (if the lift change is significant enough) you might simply run-out of the existing "room" between the valve head and the piston/valve-cutout.

In this case I wanted to make sure I still have enough clearance left, because after all I shaved 0.030" from the head surface (static CR bump) and then increased the lift by 0.035", in effect that's equivalent to a 0.065" increase in lift, and if things were already tight before that change could cause a real problem.

Not an increase in lift as much as a decrease in P/V clearance.

I think the gist of it is...... Net valve lift has almost nothing to do with V/P clearance.
Full lift occurs at the cam C/L.
As an example, a 110lsa cam installed at 106 has peak valve lift at 106..... Or, 16deg after the piston is 1/2 way down the bore.
Duration has a much bigger impact on V/P clearance. Longer duration camshafts get the valves farther off the seat when the piston is near tdc..... Which is when the clearance gets tight.

Ahh...you guys, yeah, totally makes sense...duh...not sure why I wasn't seeing this. At or near the TDC is where this becomes an issue, the max lift on the intake side will not happen @ TDC, my cam has the intake valve openning at 13 deg BTC, so simply not enough lift @ TDC. Now the exhaust is a tad different, but again with my cam and the valve closing being 11 deg ATC, the max exhaust lift will occur well before the TDC.

Good stuff, thanks again!!!

To throw in another variable on P to V clearances, the lobe seperation angle and valve opending (timing) at TDC(valve opening overlap) can be change by advancing or retarding the cam or having the lobe seperation angle ground wider on another cam with the exact same lift and duration at .050 It is more noticeable on SB Mopars with the closer (102 to 108) LSA than on the BB Mopars with the wider LSA (110 to 114) Motors, so many variables
The more you learn the more you see that you need to learn more