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Its slow! =( damn the vortecs
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RaG
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PostPosted: Sat Feb 28, 2004 6:02 pm    Post subject: Its slow! =( damn the vortecs Reply with quote

I expected a little more out of my combo, see the signature for motor specs.

Ran a 14.719 @ 86.54 mph
60' 2.142
R/T 0.569

This was my first 1/4 mile run ever. I just dropped it in drive, foot braked it and smashed down when the light changed, kept on it unit the end.

Only got to run 1 pass cause it was so crowded. Maybe its all in the timing? I have my timing @ 11 BTDC base, advance all in by 2800 rpm ( going by spring chart) . How much does the mech advance bring in? 24 0r 21 degrees? I gotta get some timing tape.

I have a stock stall and TH350 w/ shift kit. Has been used for over 2 years.

Figure it should pick up some when i swap in a TCI 350 trans and 2200-2400 stall. I didn't feel much wheel spin if any.

I think its time to sell the voretcs and get a blower like i originally intended. =( Have studded 2 bolt main, factory forged crank, H beam 5.7 rods, double keyway balancer, only hypt pistons though.

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96capriceMGR
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1996 Chevrolet Caprice

PostPosted: Sat Feb 28, 2004 6:39 pm    Post subject: Reply with quote

Is that intake Vortec specific, or did you redrill the heads?
Where is the track, any guess on elevation? Looking at the mph it looks real low, with my engine still stock I was trapping 92-3mph even in 90plus heat with high humidity and stock my engine is good for 260/330. The Vortec heads got the ports and chambers from the iron LT1 heads which is what I have, the flow numbers are proven good there has to be more too this problem.
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Hanz
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2003 Dodge Ram

PostPosted: Sat Feb 28, 2004 7:59 pm    Post subject: Reply with quote

I agree, you can't blame the heads when you have so many other unknowns and comprimised items.

Camshaft is not all that 'stout.'

Do you have a tach and know where the tranny was shifting? What was the rpm going through the traps and was it falling flat in the last few seconds?

You have to know timing at full advance, not just a guess.

Carb is marginal.

Your combo needs a little paying attention to what's going on, and tuning, maybe borrow a larger carb to try, maybe 1.6 rockers, and you might drop into the lower fourteens, but I wouldn't expect anything much lower than that. Not trying to discourage you, you just need to try little things ONE AT A TIME, and knock tenths off one or two at a time.

But don't blame the heads, people have ran much, much faster for years with much worse heads! Hanz

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cobblemaster
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PostPosted: Sat Feb 28, 2004 8:37 pm    Post subject: Reply with quote

When you run a big car, you have 2 options to go faster than that: big-block torque or winding the wee out of a small-block with really steep gears and loose converter.(or 4-speed) But that combo could probably use some jetting and timing research. What gears are you running?

That's not bad for the first time out of the box. You didn't even get to play with the tires and your reaction time.

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PostPosted: Sun Feb 29, 2004 1:36 am    Post subject: Re: Its slow! =( damn the vortecs Reply with quote

RaG wrote:
I expected a little more out of my combo, see the signature for motor specs.

Ran a 14.719 @ 86.54 mph
60' 2.142
R/T 0.569


What were the weather conditions? Air temp, pressure, relative humidity? What elevation is the track at? How much does the car weigh?

Something doesn't sound right, especially your trap speed. It seems really low. I plugged some guestimate numbers for weigh into the HP calc from MPH and using 3800 lbs and 87 mph trap speed the calculator came up with 170 RWHP. That's way too low for that combo, something is wrong. How's the transmission? is it slipping? compression test? leak down test?
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techinspector1
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PostPosted: Sun Feb 29, 2004 1:51 am    Post subject: Reply with quote

Pull all the plugs, wire the throttle blades open and do a compression test on all cylinders.
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tubbed67
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PostPosted: Sun Feb 29, 2004 8:03 am    Post subject: Reply with quote

I'm sure you'll have tons of things to look for next time you're out. Here are a couple others.

How much wheel spin did you have? Your tire pressure may have been too high.

I would suggest a steeper gear (4.11 or similar), get a tach and shift it manually this way the shift points are more consistent and you can hold it out longer to take advantage of your top end power.

It'll take you some experimenting to figure out what happened and what you can actually get it to run. Don't be discouraged, everyone makes a few runs and then wonders what went wrong. Don't write your combination off yet, it probably just needs some fine tuning.

What kind of times were you looking to run and what was your 60' time? A breakdown of your times and speeds may help discover your problem.
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BLK64SS
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PostPosted: Sun Feb 29, 2004 12:25 pm    Post subject: Reply with quote

Your trying to accelerate 4,000 lbs or so with a 10-1 355. Honestly I dont think it did that bad. I'm sure you will gain some with tuning, but I wouldnt expect a big change. Its one of those things, you have to decide what the cars main purpose is going to be and live with it.
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96capriceMGR
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1996 Chevrolet Caprice

PostPosted: Sun Feb 29, 2004 2:38 pm    Post subject: Reply with quote

Now granted I have sequential port injection but I think my Caprice is heavier and my cam is smaller, but roller, otherwise I have heads that flow about what his do and a 10-1 iron head 350(stock exept cam/springs/rockers, engine came out of a 95 Roadmaster). Last summer with a stock cam 191/195 and lift no higher than his, I had trap speeds over 90mph always actually I did trap at 89mph once not enough gas in the tank and terrible baffling will do that. That was a 1650 stall 2.93s and a 4L60E. I am only about 600-800ft. from sealevel which is still a question that needs answering.
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Hanz
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2003 Dodge Ram

PostPosted: Sun Feb 29, 2004 4:51 pm    Post subject: Reply with quote

BLK64SS wrote:
Your trying to accelerate 4,000 lbs or so with a 10-1 355. Honestly I dont think it did that bad. I'm sure you will gain some with tuning, but I wouldnt expect a big change. Its one of those things, you have to decide what the cars main purpose is going to be and live with it.


Very well said, (although it doesn't quite weigh 4000 lbs). Hanz

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tubbed67
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PostPosted: Sun Feb 29, 2004 9:56 pm    Post subject: Reply with quote

Whoops Embarassed ,
I forgot the 60' time was already listed, my mistake. I guess I spent too much time typing.
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jeep_406
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PostPosted: Mon Mar 01, 2004 10:32 am    Post subject: Reply with quote

Did you check to see that the carb is opening fully? You'd be suprised how many times that is overlooked.
Like the other guys said we need more info.
Did you pick a 600cfm vacuum secondary carb because that's what you had?
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BLK64SS
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PostPosted: Mon Mar 01, 2004 4:55 pm    Post subject: Reply with quote

3600 lbs maybe ? idea was understood tho ... One pass is no way to get a decent baseline anyways. Especially the 1st pass ever for car and driver.
Check and verify all the things people suggested timing, carb opening etc.
Then make a few more passes and start making changes in staging RPM
tire pressure, timing, jetting etc.
Be carefull tho .. you might get bit by the racing bug .... $$$$ ....

Have fun and keep us posted
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af2
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PostPosted: Wed Mar 17, 2004 9:57 pm    Post subject: Vortecs? Reply with quote

The heads are not the problem. They flow way better than the 461 heads I use to run. I had a 69 Chevelle with a 327 flat top .012 and .018 Duntov, Strip Dominator, 750 double pump and stock 461 heads with #120 lb springs, turbo 400 with a 10" Vega converter that stalled around 3000and a stock HEI. My first go at the track was a wapping 14.79 with 3.31 single spin. Shifting at 6800 I barely made it into 3rd when I crossed the line. I got home and finished the 4.11 posi and installed it the next weekend. I ran about 7 passes on the local highway before I lost #6 rod and never made it to the track. But let me tell you the car came alive with the combo. You talk about seat of the pants that pinned you in the seat. I could say 13s was right there. Combination is every thing and so is spring pressure and stall speed. Good luck
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RaG
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PostPosted: Thu Apr 15, 2004 12:49 pm    Post subject: Reply with quote

old post, but i know people search and read these old post for help with similiar problems,

The reason why it had to be so slow was because the secondaries were not opening up all the way, the diaphram inside the secondary housing was binding up. The secondaries could have only been opening just a little bit, maybe 20 degrees from idle position.

Also the increase in jetting from 66 pri to 68 in the primary made a noticable difference.

Gonna replace my stock cheap fuel pump with this GMPP mech fuel pump and give it a run tonight. Hopefully it will do something in the 13s.

I have god horrible wheel shake under wheel spin, but my suspension is junk.

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