Junkyard Carbed LQ408 Ran 10.920@124.82 on Motor
#41
10 Second Club
Thread Starter
Join Date: Nov 2010
Location: Shreveport La
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I was able to pick up 1 mph and a full tenth in the quarter mile. Very happy with that! FAST meter also showed a richer mix on topend, where as before it was getting a little lean.
#42
10 Second Club
Thread Starter
Join Date: Nov 2010
Location: Shreveport La
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Best time of the night was 10.848@125.32. She actually ran four 10.8x@125.x and I am now very satisfied with the tune. Thanks again guys for the "up-jet" suggestion.
#45
10 Second Club
iTrader: (6)
Join Date: Aug 2006
Location: Kearney, NE
Posts: 643
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Your backwards on the Power valve... You run Square jets WITH a Powervalve... Staggered Jets with the POWER VALVE BLOCKED!
The power valve adds the extra fuel so you so can run the jets square.
#47
Old School Heavy
iTrader: (16)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
There are two passages that feed the booster in the carburetors venturi. The main jet passage that is regulated by the main jet and the power valve enrichment circuit that is regulated by the power valve through the power valve restrictor orifices.
So, the power valve adds fuel through its own circuit, it cannot restrict fuel through the main jet circuit.
Furthermore, to avoid confusion, it is important to state that all Holley 4150 mechanical secondary carburetors (model 4779) have a power valve in the primary metering block. However, only some models have power valves in the secondary metering block. Most, but not all models have the secondary power valve port plugged from the factory. This is why you will see most 750 mechanical secondary holleys about a 71 jet in the front and a 80 jet in the rear.
http://www.holley.com/data/TechServi...%20Listing.pdf
It is only advisable to eliminate the power valve on the primary side in race only situation as the part throttle fuel mixture will be extremely rich. So much so that it is likely to foul the spark plugs during normal driving. The power valves purpose is to lean the mixture in part throttle situations, however it's actual function is to add fuel under heavy throttle and full throttle situations.
#48
10 Second Club
Thread Starter
Join Date: Nov 2010
Location: Shreveport La
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Demon 1000cfm 4150 Carb, Vic Jr, 240/244 613 598 109LSA cam...
LQ9 Regal vs 69 Firebird, KRPI Pro Street Finals 08-17-13 - YouTube
LQ9 Regal vs 69 Firebird, KRPI Pro Street Finals 08-17-13 - YouTube
Bryan
#52
10 Second Club
Thread Starter
Join Date: Nov 2010
Location: Shreveport La
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
She ran pretty good on just the 100 shot, I am happy with results. I am going to try next time to run the TR6s because she was really rich and fouled all plugs last pass. FAST read 9.5-10.5 at WOT last pass. First pass was 10.57@130 second was 10.30@133 third was 10.28@133 and last pass was 10.38@133. What a ride, all over the place out to 60'. Happy, happy, happy!
#54
Old School Heavy
iTrader: (16)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
She ran pretty good on just the 100 shot, I am happy with results. I am going to try next time to run the TR6s because she was really rich and fouled all plugs last pass. FAST read 9.5-10.5 at WOT last pass. First pass was 10.57@130 second was 10.30@133 third was 10.28@133 and last pass was 10.38@133. What a ride, all over the place out to 60'. Happy, happy, happy!
As for the running rich, plug selection and timing, lets talk that through.
In regards to the plugs, don't go hotter while running nitrous. I understand your thinking that a hotter play would stay cleaner, but that is not the right way to go about it. The hotter plug could spell doom for your expensive stroker motor. Let's fix the problem, which is a rich mixture.
What jets are in your nitrous plate?
Also, you had said previously that you're best N/A ETs are at 36 degrees timing, correct? You said above that you ran the nitrous at 28 degrees timing? If this is correct that it 8 degrees pulled for a 100 shot. That is way too much. The general rule of thumb is 2 degrees per 50 HP. You are leaving a ton on the table.
If you get that plate jetting cleaned up and get more timing in that thing, you just might run 9s without upping the nitrous jet.
#55
10 Second Club
Thread Starter
Join Date: Nov 2010
Location: Shreveport La
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Great pass! Starting to feel fast?
As for the running rich, plug selection and timing, lets talk that through.
In regards to the plugs, don't go hotter while running nitrous. I understand your thinking that a hotter play would stay cleaner, but that is not the right way to go about it. The hotter plug could spell doom for your expensive stroker motor. Let's fix the problem, which is a rich mixture.
What jets are in your nitrous plate?
Also, you had said previously that you're best N/A ETs are at 36 degrees timing, correct? You said above that you ran the nitrous at 28 degrees timing? If this is correct that it 8 degrees pulled for a 100 shot. That is way too much. The general rule of thumb is 2 degrees per 50 HP. You are leaving a ton on the table.
If you get that plate jetting cleaned up and get more timing in that thing, you just might run 9s without upping the nitrous jet.
As for the running rich, plug selection and timing, lets talk that through.
In regards to the plugs, don't go hotter while running nitrous. I understand your thinking that a hotter play would stay cleaner, but that is not the right way to go about it. The hotter plug could spell doom for your expensive stroker motor. Let's fix the problem, which is a rich mixture.
What jets are in your nitrous plate?
Also, you had said previously that you're best N/A ETs are at 36 degrees timing, correct? You said above that you ran the nitrous at 28 degrees timing? If this is correct that it 8 degrees pulled for a 100 shot. That is way too much. The general rule of thumb is 2 degrees per 50 HP. You are leaving a ton on the table.
If you get that plate jetting cleaned up and get more timing in that thing, you just might run 9s without upping the nitrous jet.
![Junkyard Carbed LQ408 Ran 10.920@124.82 on Motor-10.28-133.jpg](https://ls1tech.com/forums/attachments/carbureted-lsx-forum/417597d1469572003t-junkyard-carbed-lq408-ran-10-920-124-82-motor-10.28-133.jpg)
#56
Old School Heavy
iTrader: (16)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I agree totally, 34* is where it ran the best on motor so I pulled 4* plus 2* to be safe. Also i checked the fuel pressure to the nitrous plate and it was 1/2 pound high so I think i have the richness figured out. Next time out I will adjust the fuel pressure to the plate and and give her 2* timing with brand new plugs, 7s.
Attachment 417597
Attachment 417597
#57
TECH Enthusiast
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
great work.
just to clarify the power valve, it will introduce fuel based on vaccuum thru 2 small opening called power valve channel restrictors (drilled in basic blocks or tapped in custom metering blocks). generally jets would be staggered if power valve is right size ie engine vac /2; 13 /2 = 6.5 pv. only time i would guess if restrictors are too small or pv not right size.
just to clarify the power valve, it will introduce fuel based on vaccuum thru 2 small opening called power valve channel restrictors (drilled in basic blocks or tapped in custom metering blocks). generally jets would be staggered if power valve is right size ie engine vac /2; 13 /2 = 6.5 pv. only time i would guess if restrictors are too small or pv not right size.
#58
TECH Enthusiast
#59
10 Second Club
Thread Starter
Join Date: Nov 2010
Location: Shreveport La
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
#60
Old School Heavy
iTrader: (16)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
That right there is the biggest part of your problem. That is old school fat. Most guys are finding that their plugs don't start to clean up until they get in the neighborhood of a 10 jet-size spread on 5 1/2# to 6# of fuel pressure.
I have my 125 hp "street" jet tune in right now and that is 55n/43f on 6 1/4# of fuel pressure pulling 6 degrees (I could pull less). It yields a very clean plug and GREAT performance (1 full second and 10+MPH in the 1/4).
I am usually around 925# - 950# of bottle pressure.
I have my 125 hp "street" jet tune in right now and that is 55n/43f on 6 1/4# of fuel pressure pulling 6 degrees (I could pull less). It yields a very clean plug and GREAT performance (1 full second and 10+MPH in the 1/4).
I am usually around 925# - 950# of bottle pressure.