Slant Six Forum
https://slantsix.org/forum/

A new bullet
https://slantsix.org/forum/viewtopic.php?t=28649		 Page 1 of 20
Author:  turbo66valiant [ Mon Apr 28, 2008 8:40 pm ]
Post subject:  A new bullet
Here is my 66 Valiant project. This is the one I've been telling myself for years "I'm gunna race it" we, this weekend is it if I can get it running right. I'm having alittle trouble with full throttle perf. I keep jetting it up and it keeps running better and better but still no full throttle. Just evens out or slows down. Here is the specs:

170 ci
Mighty Demon 575 blow through
86 pri w/ power valve - 94 sec jet
T-60 turbo
25 degrees full timing
13psi boost
3.91 rear
4000 stall
Aeromotive A1000 pump w/ boost regulator
20 psi fuel pressure at 13psi boost
Av gas
727 w/ manual valve body
Stock cam

I can't believe it needs more jet than what I'm giving it. The throttle blades are not over opening. I can floor it and it does nothing but bring it back to 3/4 throttle and it takes off. Anyone have any experience in this. Thanks for your help.
Ryan
Image
Image
Image
Image
Author:  SV162 [ Mon Apr 28, 2008 9:33 pm ]
Post subject: 
Sorry I can't help you with your problem.........but let me just say something about your car.

WOW!!!!!!!
Author:  Joshie225 [ Mon Apr 28, 2008 9:36 pm ]
Post subject: 
If you're backing off to 3/4 throttle that should close the secondaries. Unless you have a pretty loose torque converter that's just too much carb to tolerate full throttle from a standstill.

Where is your fuel pressure regulator reference line? It should be on the carburetor hat along with the blow off valve.
Author:  turbo66valiant [ Mon Apr 28, 2008 9:40 pm ]
Post subject: 
Things I forgot to mention are:
1972 Cam degreed in at 106 degrees (factory degreed in at 110)
MP Orange box
Bowl porting with 1.70 / 1.44 valves
8.4 cr and forged pistons
NGK #? I'll have to check the #'s tomorrow, .032 gap
MSD Blaster 2 coil
Plugs have no soot around rim so I'm thinking it still is lean, but the jet size I have now is crazy. The rest of the plug looks lean. Later.
Ryan
Author:  turbo66valiant [ Mon Apr 28, 2008 9:45 pm ]
Post subject: 
Hey Joshie,
I disconnected the secondaries and it did the same thing. The problem exists all the way through the gears also. I did have the fuel reference into the elbow just before the intercooler but did't get enough fuel pressure. I moved it to under the carb and pressure went up under full boost.
Author:  Joshie225 [ Mon Apr 28, 2008 10:16 pm ]
Post subject: 
The fuel pressure reference line on a blow through carb setup has to be at the carb inlet. You had low fuel pressure before because of the pressure drop across the intercooler. With the fuel pressure reference below the throttle plate you won't have enough fuel pressure at part throttle and will starve the engine. You're setup so that you can have boost in the carb inlet and float bowls, but the fuel pressure won't rise to match and fuel flow into the carb will stop.

The carb is way too big for a 170. I would use a Holley 390 with mechanical secondaries. There just isn't enough air flow to get the fuel going.
Author:  dank10fenny [ Mon Apr 28, 2008 10:34 pm ]
Post subject: 
i love that ride, and hate you... ha jk
im almost ready to drag my slow ass valiant just so i can get into it, my boss does road racing and thinks im a big pussy for doin drag, but im not road racin that heavy beast. anyways, point is, dont wait till its "done" to race, cuz you know it will never be done
Author:  turbo66valiant [ Tue Apr 29, 2008 4:50 am ]
Post subject: 
Thanks Joshie,
I will put the fuel reference and BOV into the hat and see if it changes. I don't have a 390 Holley around here but wouldn't disconnecting the secondaries get me simular results? Later. Ryan
Author:  Dart270 [ Tue Apr 29, 2008 7:50 am ]
Post subject: 
Great car, Ryan. Welcome to the site!

Where are you located?

Lou
Author:  Shaker223 [ Tue Apr 29, 2008 9:43 am ]
Post subject: 
The carb is fine for your application, I have a 600 DP Holley on my 225. Your plug gap is to wide. Close it up to .025. I'm not sure of the heat range of your plugs but they should be on the colder side (I use RN9YC).
Back your 25* timing down a little to start. I ended at 19*. The problem could also be with your enrichment from the power valve. It could be getting confused under boost conditions. You may have to boost reference it to the hat. Has the carb been modified for a blow thru application? I don't remember but do you have a wide band?

You may have to much gear as well. My 225 is done at 4500 and had to put in a 2.94 to make it to the end of the qtr.
Author:  turbo66valiant [ Tue Apr 29, 2008 10:26 am ]
Post subject: 
Hey,
I'm located in central South Dakota. Pretty much on the edge of the earth! Matter of fact, the races were called off this coming weekend because of the SNOW forcasted for Sat and Sun. Crazy. At least I have another week to figure it out.

The carb is a New Blow Through Demon. It has the special metering blocks to increase fuel as boost rises. I took the power valve out and it didn't make a difference. I even added jet of compensate for the blocked PV. I will decrease my gap size. I had thought maybe the extra air was disrupting the spark but .032 I thought was conservative. I'll try the .025. The plugs are NGK R BR5ES. Supposivly the same as a RBL11Y. Thats what Car Quest told me at least. Should I get colder ones? I had a feeling my gear is to deep. It does like to rev though. My tach stopped working the other day so I need to fix that tonight a see what rpm it's turning. I don't have a wide band on this car. I have one on my 72 Charger I could maybe steal though. The convertor is out of the 72 Charger. That would launch at 4000 rpm all day but it had a 440. I'm thinking I can only get about 3000 out of it with this motor.
Do you think I have my stock cam advanced to much?
Later
Author:  turbo66valiant [ Tue Apr 29, 2008 10:34 am ]
Post subject: 
Shaker,
What jets, PV and squirters do you run? I'm assuming your rear PV is blocked.
Later
Author:  Shaker223 [ Tue Apr 29, 2008 10:54 am ]
Post subject: 
Rear PV is blocked and the front is boost referenced to the hat. That helped full throttle AFR a lot. I used a spring off of a 6.5. I'll have to look on the squirter when I get home but it was one of the larger ones. I enlarged the Power valve channel restriction as well for additional fuel flow under WOT/part throttle. I want to say it is in the .070-.080" range. Jets are 72 front and 79 rear. I run around 11:1 afr. It sounds like your regulator is referenced peoperly but it should be off of the bonnet.

Also try Turbomustangs.com Loads of good info for blow thru apps.
Author:  Shaker223 [ Tue Apr 29, 2008 1:05 pm ]
Post subject: 
I just noticed your jet sizes...something is up...that seems way to fat.
Author:  turbo66valiant [ Tue Apr 29, 2008 1:18 pm ]
Post subject: 
Tell Me about it! I don't know why it keeps getting better the more jet I put in. Vacuum at idle is 13-14" and there are no vacuum leaks. Is this normal vacuum?
Page 1 of 20 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/