Shooting for a new PB!

NET351 · 07-04-2010, 03:01 PM

In July last year I had a crack at drag racing for the first time...
The car was a 1969 XW falcon with recently dyno tuned 351 clevo. C4 auto with 4,000prm stall, 3.7:1 trutrac 9" diff.
I was hoping for a low 12 or high 11 second quarter...how wrong I was...

Long story short traction was a major issue. Although top gear burnouts were quite fun!

The first run I selected 'D' for Drag, took my right foot off the brake pedal, mashed the go pedal slowly to the floor and left it there. The result was a 14.01. Not too bad I thought for shifting at 5,200rpm and not stalling up the auto off the line... but would there be seconds in more revs?

As the night went on I experimented with tyre pressures, take off revs and gear shift rpm. The times dropped into the 13s and then I managed a few high 12s.

Car #688
As you can see by the 60ft time traction got worse and worse as street rubber was laid down over the course of the meet. I left happy that I got a 12 but somewhat disappointed that I could not get the potential out of the car. Here's a couple of videos - the first one having some fun warming the old hard tyres I had and the second is of one of the 13 second passes. You can hear how much it bogs down off the line due to the inability to bring the revs up on the brake.

Tonight I'm heading back to get a new PB. I've got brand new stickier rubber and the car is running well. The plan is to get the elusive 12.00 or even better an 11.90 something...

Cam · 07-04-2010, 05:14 PM

Good luck! What sort of power she making?

With the MPH a 11 should be possible, but it will be a stretch I think, unless you get some decent rubber on there!

She sounds pretty freaken tough!

FryXR · 07-04-2010, 05:18 PM

nice car mate, what sort of power is it putting out?

NET351 · 07-04-2010, 05:19 PM

Thanks! She's got about 450 HP the problem is getting everything spot on- traction, reaction, launch, gear changes and so on...just waiting in the staging lanes now...

Cam · 07-04-2010, 05:24 PM

Good luck! Some semi slicks might be a good investment!

let us know how u go..

By the way, dont worry about the reaction time, its not gonna change your ET! It's more about taking your time and getting things right when chasing ET!

FryXR · 07-04-2010, 09:07 PM

how'd ya go mate, get that 11?

NET351 · 07-04-2010, 10:38 PM

Well tonight was pretty disappointing...
First of all there were heaps of entrants which meant long waits and not many runs. My first pass was a disaster...
Old mate in the lane beside me left early and natural reaction kicked in and I followed, thus both of us not registering a time. Rookie mistake...

Second run was looking good until I got too excited with bringing up the revs on the brake and the car nudged forward just enough to break the beam and red light. And this was over 2 hours after it all started!
Long wait and then the 3rd run...pretty good traction but registered a slower time than I would have thought compared to how it felt from last time. A 13.28...fail. Main problem was bogging down as I nailed the gas. Was a fun run though chasing down the car beside me which got away quicker and was only about 1/2 a second slower ET wise.

Next run was much the same but a bit quicker at 13.10 as it cleared its throat a bit quicker to beat the Toyota ute running a V6 commodore engine beside me!

Final run of the night I had my a$s handed to me on a plate as a torana hatch passed the line 9.98 seconds after the green while I made a leisurely cruise in 13.13.

So I drove home a little confused as to why my ET was slower even though I had better traction and everything else was the same as last time. My 60ft times were slower too which is really strange.

I think the main area I can improve is the carby. At the moment I have a 650 spreadbore mechanical secondary and it really bogs down off the line. I think maybe a 750 squarebore would be better, either vacuum or mechanical secondaries. Also, I'm very suspicious of the auto: it likes to spew fluid out at high speed and do weird things. Like tonight on the way home it took to taking off in top gear quite a few times. Another factor is the weather - the last time I went was in winter and the air was dense. I might return in a few months when it's cooler with a different carby...

Work Horse · 08-04-2010, 07:15 AM

What 60ft and Mph did you get on each run?

Sounds like you have the power to go quicker. It would be extremely difficult to launch well with the power you are making and road tyres.

If your auto or converter are not spot on, I'd be chasing that problem before swapping carbs.

That said the right carb for your engine can make a huge difference. It's finding and tuning the right carb that's the challenge.

Keep at it mate, not many people get the best out of their car on the first couple of outings. And all the disappointment you feel now will seem worth it when it does go quicker.

Good luck, keep at it!

noukid · 08-04-2010, 02:12 PM

hey mate, any chance of getting some specs on the engine?

NET351 · 08-04-2010, 08:48 PM

Quote:

Originally Posted by Work Horse

What 60ft and Mph did you get on each run?

Sounds like you have the power to go quicker. It would be extremely difficult to launch well with the power you are making and road tyres.

If your auto or converter are not spot on, I'd be chasing that problem before swapping carbs.

That said the right carb for your engine can make a huge difference. It's finding and tuning the right carb that's the challenge.

Keep at it mate, not many people get the best out of their car on the first couple of outings. And all the disappointment you feel now will seem worth it when it does go quicker.

Good luck, keep at it!

Thanks for the reply and advice. Yes traction was certainly heaps better with the new tyres but more would certainly be better. One day I'll win lotto and buy a second set of rims so I can run slicks.
I'll definately be looking at the auto and converter seriously as there have been problems ever since the box was rebuilt. I'm sure it's costing me power...it will just have to wait a while though unfortunately as the garage I have at the moment is too small to be taking the gearbox out. Alsi, I think it might be easier to take the engine and gearbox out together with the extractors I have.

Here are the details from a couple of the runs. The questions I have are working out why the trap speed was down from last time and why the 20' time is still so slow...
#1
60' 2.122
330 5.695
1/8 8.624
MPH 84.13
KM/H 135.39
1000 11.146
1/4 13.286
MPH 105.38
KM/H 169.60

#2
60' 2.006
330 5.550
1/8 8.465
MPH 84.44
KM/H 135.89
1000 10.977
1/4 13.109
MPH 105.75
KM/H 170.20

NET351 · 08-04-2010, 08:56 PM

Quote:

Originally Posted by noukid

hey mate, any chance of getting some specs on the engine?

Hi, some specs for you:
351- 30 over
6" rods
Hypeuretic pistons
Balanced
Standard volume oil pump, blueprinted with 100lb spring
Large winged sump
2V heads- ported, severe duty valves, etc
Roller rockers
Solid cam - 292adv duration, 590" lift
Funnelweb intake
650cfm mechanical secondary carb
Pacemaker tuned length 4-1s, twin 2 1/2" system
Accel Distributor, Crane Hi-6 ignition and LX-92 coil

Made 333RWHP but was turning the tyres from 5,200rpm so it has a bit more than that at the wheels...

jcxr · 09-04-2010, 09:32 AM

Mate, you need a high stall badly. As you have mentioned, you are having a hard time bringing up the revs on the brake. With the high stall, it will whip around to the RPM's designed into the convertor. For a streeter, I use a 4200rpm stall and it is great.

NET351 · 09-04-2010, 11:00 AM

I have a 4,000rpm stall... It will spin above 3,000 on the track so I was holding the revs at about 3,000 while staging.

DBL15 · 09-04-2010, 04:03 PM

Quote:

Originally Posted by NET351

I have a 4,000rpm stall... It will spin above 3,000 on the track so I was holding the revs at about 3,000 while staging.

i am lost ?

if you have a 4000rpm stall , with your foot on the brake you should have no trouble at all going around to 3800 to 4000 rpm without the tyres wanting to turn ?

the quicker you get to 60 foot the better your times will be.

tweeked · 09-04-2010, 04:23 PM

Quote:

Originally Posted by DBL15

i am lost ?

if you have a 4000rpm stall , with your foot on the brake you should have no trouble at all going around to 3800 to 4000 rpm without the tyres wanting to turn ?

the quicker you get to 60 foot the better your times will be.

Think he is saying if he stalls it to above 3000 it goes up in smoke when the brake comes off Darren.

NET351 · 09-04-2010, 07:09 PM

Thanks Tweeked, that's exactly what I meant... There's no way I'd get it to full stall speed with the brake on without it turning the tyres either. The converter is quite progressive and not 'loose'. I'd need more runs to really know the limit of stall speed vs burnout but I'd say it would be between 3,000 and 3,500.
On the street it spins at around 2,500...

naughts · 09-04-2010, 07:50 PM

Quote:

Originally Posted by DBL15

i am lost ?

if you have a 4000rpm stall , with your foot on the brake you should have no trouble at all going around to 3800 to 4000 rpm without the tyres wanting to turn ?

the quicker you get to 60 foot the better your times will be.

No way. Lucky to get to 3000rpm on the brake for a true 4000 flash stall.
I have a 4800 stall and my car wants to push thru the beams anything over 3200. Saying that, my brakes are crap!!!!

xagsjoe · 09-04-2010, 07:59 PM

Get some caltraks or slapper bars under it and your 60's will improve, The converter should flash to nearly 4k if you get some good traction, A set of 90/10's don't take long to fit if you can be bothered and they will help too.

Some drag radials on some chaser rims if the pocket can let you and you will run 11s all day with traction. More than enough grunt in the old girl. Sound just like my old XY. Nice car Bud.

NET351 · 09-04-2010, 08:01 PM

Exactly! When I tried to get the revs over 3,000 the car pushed through the beam...Finding the right amount of revs is the key- some flash up to stall speed is good for inertia and to get the revs up quickly.

naughts · 09-04-2010, 08:05 PM

Mate, get some ET Streets under it and get you 60ft into the 1.7's or 1.8's and you will see some good times. You got plenty of HP, you just need to sort it.
60 ft is where it's all at.

NET351 · 09-04-2010, 08:23 PM

Quote:

Originally Posted by xagsjoe

Get some caltraks or slapper bars under it and your 60's will improve, The converter should flash to nearly 4k if you get some good traction, A set of 90/10's don't take long to fit if you can be bothered and they will help too.

Some drag radials on some chaser rims if the pocket can let you and you will run 11s all day with traction. More than enough grunt in the old girl. Sound just like my old XY. Nice car Bud.

Thanks mate! I appreciate the comments. I will definately make some serious changes before I go back to the track. First will be the auto, I'll also be looking into some other rims and slicks or drag radials. Good idea with the 90/10s I think they would be a big help because it leaves very flat. I also want to ditch the rubber mount between the diff saddle and spring to take the twist out. I'll start making a list...

xagsjoe · 09-04-2010, 09:41 PM

Taking out the rubbers is a good move too for sure. The big question is how much do you want to do to get the best out of it you can?

Remove front swaybar, Caltraks (or similar), 90/10s, 6cyl front springs, fit a stiff rear bar yada yada yada the list can grow but every little bit helps. Im no expert and have spoken to some smart racers while building my car to get some advice from blokes that run real quick and that basic list is universal to all of them.

This was how my old girl sounded. Still miss her.

Keep the improvements coming.

v gate · 10-04-2010, 04:28 AM

suspension is the key. your car doesnt seem to have much separation in the rear.
get someone to 4 corner scale the car with you in it. a set of slapper bars, shocks, springs (frount and back), set up your pinion angle maybe even extend your rear hangers. dont fall for the old wives tail about the rear needing squat its hard for some people to get their heads around that the rear should really be rising. when the rear squats what it is doing is the tyre is saying i dont like this and im running away. the only place for it to go is up hence squat (wheel spin). when the suspension is set for kill it fights back and drives the tyre down into the track. it is physics check my junka gt at l.a motor repairs and pay attention to the launch hope it helps

v gate · 10-04-2010, 04:39 AM

oh and separation is the gap between the lip of the gaurd and the top of the tyre

NET351 · 10-04-2010, 09:41 AM

Quote:

Originally Posted by xagsjoe

Taking out the rubbers is a good move too for sure. The big question is how much do you want to do to get the best out of it you can?

Remove front swaybar, Caltraks (or similar), 90/10s, 6cyl front springs, fit a stiff rear bar yada yada yada the list can grow but every little bit helps. Im no expert and have spoken to some smart racers while building my car to get some advice from blokes that run real quick and that basic list is universal to all of them.

This was how my old girl sounded. Still miss her.

Keep the improvements coming.

Awesome video man! You just can't beat the clevo sound...and you were playing with it...
Your comments re: how far to go with mods has always been in my mind because at the end if the day the XW is a street car and I won't make changes that will compromise it's safety, practicality or comfort on the street. What I've always had in mind is getting the best true street trim ET possible. So the big ticket items such as auto, carb, rear suspension rubbers will be done first. Once I'm happy with the performance for street trim I'll make some
more drastic changes and trailer it out. Like drop the tailpipes, carb spacer, different bonnet with scoop, race rubber, no engine fan, etc

pottery beige · 10-04-2010, 09:53 AM

All of the above is very good advice...
Here is a happy snap of my old bomb, it is just a baby cam combo torque monster all the same it use to leave the line as an 11sec car but run out of puff.. lol...

Front suspension... 6cyl spring's, 90/10 shock's, dis connect front sway bar, pizza cutter's...
Rear suspension... 35 yo std spring's, GT tramp rod's, 9'' slick's and wedge's between diff and spring pack for pinion angle..
Good luck and happy racing mate!!!!

NET351 · 10-04-2010, 12:36 PM

Thanks for all the replies!
V Gate: thanks for the advice and you're dead right-all the power is useless if it can't be put to the ground with the correct suspension.
Pottery Beige: your car looks super fast in that shot! How do you go about setting up the pinion angle? I've seen wedges used before but how do you actually work out the desired angle?

pottery beige · 10-04-2010, 02:20 PM

The wedge's.... damn i'm away with work so i can't help with pic's/ measurement's maybe someone can help us???
Now don't take me on this i maybe wrong i think mine were around 8mm to 2mm taper....
What your chasing is around 3-5deg pinion nose down...

v gate · 11-04-2010, 06:53 AM

sounds right to me be ready to spend a little more cash cause when you start to hook up it may show any weakness in your driveline and possibly fuel system converter/clutch blahblahblah. the joys of a bottemless money pit
but the satisfaction from going faster with less (money / horsepower) is a good feeling and has others scratching their heads and credit cards more often.
do yourself a huge favor and get it done properly at a shop save hassle and heartbreak.
before you do these mods dont expect the car to corner this is a straightline deal only
good luck