need help getting the most out of my current set up

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oldpan
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need help getting the most out of my current set up

#1 Post by oldpan » Tue Apr 03, 2012 7:27 am

I have a 73' camaro with a 383. I have a holley 750 dp carb jetted 74-87. I had the fuel pressure set at 9psi when the car ran its best time of 12.45@105.73 mph on a 45° night. I was running lower fuel pressure befor and had about the same jets but was about 3mph slower. Am I on the right track here or should I turn down the fuel pressure and go with larger jets? Any suggestions on how to get the most out of this current setup would help. Not looking to change any parts looking to get the most out of what I have. Thanks
1973 camaro 383 turbo 350 chevy 12 bolt with 4:10 street strip car

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supernova
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Re: need help getting the most out of my current set up

#2 Post by supernova » Tue Apr 03, 2012 8:06 am

First off buy a Nova!!!! Hahahahaha :mrgreen: :mrgreen: :mrgreen:
2nd, the rule is fuel is mph and timing is et. With that said, your fuel pressure set that high with your jetting tells me you carb is wrong for your cam. What are the cam specs and is the carb set up for that cam and vacuum signal? It will make a difference.
I would think you should be at 6.5 - 7 psi and down size the jets if it's set up right.

I ran a 385 stroker motor years ago with a 750 road Demon that was up graded to a race Demon so it would see the vacuum signal and work with the cam. It ran 11.50's with .071- .078 jetting. That was with a good set of heads and a solid cam.
Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

oldpan
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Re: need help getting the most out of my current set up

#3 Post by oldpan » Tue Apr 03, 2012 8:24 am

Its a lunati with .532 in .552 ex lift. duration is 244 in 254 ex
1973 camaro 383 turbo 350 chevy 12 bolt with 4:10 street strip car

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Bruce69Camaro
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Re: need help getting the most out of my current set up

#4 Post by Bruce69Camaro » Tue Apr 03, 2012 11:09 am

I read somewhere that you want your pressure set around 6/6.5 psi and that you could take a chance of blowing the needle and seat out because they couldn't take much more then 9 psi.

As for the comment from Chris (SuperNova) about buying a Nova, just disreguard that, he has a mental issue that no therapy in this world can help.... :smt101
Those who think they know it all have no way of finding out they don't......... :scratch:

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supernova
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Re: need help getting the most out of my current set up

#5 Post by supernova » Tue Apr 03, 2012 1:40 pm

The duration may be a little high and cause the vacuum signal to be too low for your carb. I would give Peo Systems a call and see what they recommend doing with your carb. You might be leaving some et on the table.

Oh and Bruce thinks I'm mental!!!!!!! That's ok cause he might be right! :mrgreen: :mrgreen: :mrgreen:
Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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Bruce69Camaro
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Re: need help getting the most out of my current set up

#6 Post by Bruce69Camaro » Tue Apr 03, 2012 1:48 pm

Ok, thanks Chris but to be serious for a minute, I know he said he does not want to buy anything new, but do you think he might benefit more by using a 850 or is that too much?

I know there are other factors to consider but, look at my 396, Pro Systems calculated things out and I'm using a 850 that they setup?

He's not much more cubes away from me?
Those who think they know it all have no way of finding out they don't......... :scratch:

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supernova
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Re: need help getting the most out of my current set up

#7 Post by supernova » Tue Apr 03, 2012 2:14 pm

The 750 is a great carb for a 383 ci motor. His cam is not too big and I would bet the heads are not full race prept. I'v seen 750's work on a good 454 that 850's didn't work very well on.
The bigger jetting than normal and the high fuel pressure tell me that the motor has a low vacuum signal. Setting the carb up with this jetting is covering for the low vacuum. It may work like that but could it work better if it was set up right? That's the question........
Last edited by supernova on Tue Apr 03, 2012 4:55 pm, edited 1 time in total.
Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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wikd69
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Re: need help getting the most out of my current set up

#8 Post by wikd69 » Tue Apr 03, 2012 3:43 pm

oldpan wrote:I have a 73' camaro with a 383. I have a holley 750 dp carb jetted 74-87. I had the fuel pressure set at 9psi when the car ran its best time of 12.45@105.73 mph on a 45° night. I was running lower fuel pressure befor and had about the same jets but was about 3mph slower. Am I on the right track here or should I turn down the fuel pressure and go with larger jets? Any suggestions on how to get the most out of this current setup would help. Not looking to change any parts looking to get the most out of what I have. Thanks
Are you using power valves in that puppy ? If so, what are they rated, in inches ?

Based on what I've learned, PV's should be rated at 1/2 your idle vacuum. If you're pulling 7 inches of vacuum at idle, you'll want 3.5" PV's, etc. A lot of guys use PV's only on the primary side, and plug them on the secondary block.

Adopting the right PV's might help your off-idle transition as your throttle cracks and vacuum drops. Dunno if this make will a lot of difference for you, but it would certainly be something cheap to check.
1969 ProStreet Camaro RS Best 9.75@139 1.46 60'
Blown 427 BBC, TH400 w/Brake, Back-Half Ladderbar
Narrowed 12-Bolt, 4.10 Gears, Spool, Moser 33 Spline

http://www.marsh-racing.com/harrys_camaro-1.htm

oldpan
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Re: need help getting the most out of my current set up

#9 Post by oldpan » Tue Apr 03, 2012 7:22 pm

Thanks for the replies. I am running pv in the carb will have to check what size they are. Sure I would like to go faster if I could but if 12.40s is about all I can squeeze out hell that's fine by me. Just so you know I have a set of Brodix alum heads on the motor and know they have valve springs to match the cam. What would you or anyone else recommend as far as jetting and fuel pressure and timing?
1973 camaro 383 turbo 350 chevy 12 bolt with 4:10 street strip car

want-a-be
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Re: need help getting the most out of my current set up

#10 Post by want-a-be » Sun Apr 08, 2012 3:03 pm

oldpan wrote:I have a 73' camaro with a 383. I have a holley 750 dp carb jetted 74-87. I had the fuel pressure set at 9psi when the car ran its best time of 12.45@105.73 mph on a 45° night. I was running lower fuel pressure befor and had about the same jets but was about 3mph slower. Am I on the right track here or should I turn down the fuel pressure and go with larger jets? Any suggestions on how to get the most out of this current setup would help. Not looking to change any parts looking to get the most out of what I have. Thanks
The part of this that sticks out to me is that it ran it's best during a very cool night. Does no one think this may be a bit on the rich side?

What kind of timing are you running? Is the distributor locked out?

Bump the compression a point to a point and a half next time you have it down. What fuel are you running?

I do not like the power valve. But that's my opinion / experience.

There's no reason you can't look at an 850 for this combination.

Don

oldpan
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Re: need help getting the most out of my current set up

#11 Post by oldpan » Mon Apr 09, 2012 6:03 am

I have run my total timing from 34° to 38°. Not locked out. On the street pump gas at the track a mix of pump and 110. Right now compression is 11:1
1973 camaro 383 turbo 350 chevy 12 bolt with 4:10 street strip car

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spib
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Re: need help getting the most out of my current set up

#12 Post by spib » Mon Apr 09, 2012 10:44 am

what weight are you at? what convertor stall?
I think it should go faster then that, with that motor and cam

its the whole package though I went a best of 12.38 with a 355 bone stock with 470 lift cam,air gap and 650 dp carb, had 4:86 gears and 3500 vert with a turbo 350 it weighed 3200lbs with me in it then
http://www.youtube.com/user/spib43
10.56 @128 best to date


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oldpan
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Re: need help getting the most out of my current set up

#13 Post by oldpan » Tue Apr 10, 2012 6:24 am

The car has a 3500 stall in it. Im guessing it weighs about 3900-4000.
1973 camaro 383 turbo 350 chevy 12 bolt with 4:10 street strip car

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