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Author
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Topic: Can't get any more mph!
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rustang@home
Gearhead Posts: 134
From: Clarion, PA
Registered: Jan 2004
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posted 08-13-2005 11:20 PM
  
I've tried several different things this season, and no matter what, this 347 runs 117mph. I've tried 4.71's (7600 thru the traps), 4.33's (6900 thru the traps), 8" converter, 10" converter, higher ratio rockers, cold air to the carb, vic jr intake, funnelweb intake (big disappointment with it!) timing, jets, etc. I'd think after all this, I would see a swing one way or another somewhere along the line. Could it be valvesprings? Running out of fuel? exhaust system? Not sure where to try next. 
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capri man
Gearhead Posts: 7249
From: doerun, ga.
Registered: Nov 2000
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posted 08-13-2005 11:29 PM
is your et changing?? that is really all that matters!!  ------------------
mike r
racing is real
everything else is just a game.
81 capri-302-7.25 @93mph 1/8
1.54 60ft 50 % of the fun dragracing is meeting people who will give you the shirt off their back to wipe the grease off your hands.
M&M member #839 http://perfectrun.com/ipw-web/bulletin/bb/images/smiles/icon_5usaribbon.gif
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Butch Jennings
Gearhead Posts: 632
From: No. California
Registered: Apr 2000
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posted 08-14-2005 09:57 AM
My first thought is that it's running out of fuel. Larry and I once picked up almost 4 mph on a friend's car by ugrading the fuel pump and supply line. Butch
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rustang@home
Gearhead Posts: 134
From: Clarion, PA
Registered: Jan 2004
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posted 08-14-2005 09:03 PM
Yeah, I guess I'm confused that I've changed around some significant stuff, and to see no change in mph just seems a little fishy to me. Is there a sure way to verify if it's fuel? What kind of fuel pressure should I expect to see at the end of a run? Some other things I'm mulling over...tonight I'm checking valve springs, and I'm kind of suspicious of my exhaust. I'm running an xpipe with 3" exhaust. The one pipe takes kind of a wicked bend right out the left header collector. Plus I just wonder if an xpipe might not be the best thing at 7500rpm?
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Butch Jennings
Gearhead Posts: 632
From: No. California
Registered: Apr 2000
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posted 08-14-2005 10:10 PM
I think a general rule of thumb is you should be able to fill a gallon jug in under 1 minute at the carb inlet. Butch
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Mark T 7724
Gearhead Posts: 240
From: Palmdale, CA
Registered: Nov 2000
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posted 08-14-2005 11:05 PM
Butch: for a car over 400 HP it should be 1 gallon in 30 seconds. A good way to see what's going on with jetting is a Pyrometer with leads in 1 and 8. If your making jet changes and you can't make much affect on the EGT you probably have a fuel problem. By the way I sell these and they have been a very valuable tool for diagnosing problems. Click on my Website below ------------------
1964-1/2 Mustang SS/L 289 4-Speed, 10.537 @ 124.83. West Coast Money Maker Racing Team Member, tallentracing.com
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Rustang
Gearhead Posts: 805
From: Clarion PA
Registered: Nov 2000
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posted 08-15-2005 02:43 PM
I'm going to hook up a fuel gauge I can watch going down-track. Right now I'm running a new holley blue pump, 3/8" aluminum line, fram HP filter, and older holley blue regulator. I've never been a fan of the blue regulator. I have one of those larger volumax regulators I'm thinking about putting on. thoughts?
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Mark T 7724
Gearhead Posts: 240
From: Palmdale, CA
Registered: Nov 2000
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posted 08-15-2005 07:01 PM
You should really do the fuel volume test, You can see pressure on the guage and still be running out of fuel. The older Holley blue regulators were good the new ones are not, The Barry Grant I had was good untill I started pumping twice the volume (Over a Gollon in 30 Seconds) at 6-1/4 psi. Now I have the Aeromotive and it works great.------------------
1964-1/2 Mustang SS/L 289 4-Speed, 10.537 @ 124.83. West Coast Money Maker Racing Team Member, http//www.tallentracing.com
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 08-15-2005 07:53 PM
What's the easiest thing to do first?
Unless you are running a class where exhuast is mandated, I would be inclinded first to drop the mufflers and see what it did. At the shop, we have seen cars pick up as much as 30 hp by uncorking the exhuast. As for fuel delivery, I really REALLY dislike the blue pumps. If I remember correctly, my single blue pump ran out of steam at around 115 mph, and that was with 1/2" line. After that I started running 2 of them till I got tired of the un-reliability of them and switched to one big pump. Just as an FYI, a buddy of mine back in Iowa runs 10 ohs at 135 mph with a Carter mechanical pump (the one that requires a regulator) on his 408W.
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zepheracer
Journeyman Posts: 33
From: Butte, Mt.
Registered: Jan 2003
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posted 08-15-2005 08:58 PM
I'm using a single Holley blue pump, No. 8 line from pump to standard Holley regulator. Using No. 6 to carb. Running 10.60's @ 126 with a 408.
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Mark T 7724
Gearhead Posts: 240
From: Palmdale, CA
Registered: Nov 2000
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posted 08-15-2005 09:22 PM
Easiest thing is to verify what fuel flow you have going to the carb, Disconnect the fuel line at the carb put in a 2 gallon jug and see what you get in 30 seconds.------------------
1964-1/2 Mustang SS/L 289 4-Speed, 10.537 @ 124.83. West Coast Money Maker Racing Team Member, http//www.tallentracing.com
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rustang@home
Gearhead Posts: 134
From: Clarion, PA
Registered: Jan 2004
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posted 08-15-2005 10:03 PM
with my old motor, I've been 10.90's at 125 with this fuel line, regulator, etc. Mark, one time I did try the fuel flow test like you're saying. I did it with the float bowls in a pan, then measured what came out. From what I recall it was more than adequate. But that was 5-6 years ago. I'm going to check again KV, I do require mufflers for my class (NMCA Mean Street). But at the next T&T I'm going to drop the exhaust and see what happens. Another thing I discovered last night. I checked a couple valve springs, I noticed that my new rockers (Erson 1.7's) are all very stiff. When you hold them by the shaft and try rotating them, you can barely turn them. When I take them and tap the fulcrum back to center, they loosen up. When you look at them closer you can see where the snap ring's wearing on the needle bearing cage from this side force. I've run 1.6 comp cam rockers on this motor and no problems whatsoever. Maybe this is causing some funky dynamics at hi r's?
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Mark T 7724
Gearhead Posts: 240
From: Palmdale, CA
Registered: Nov 2000
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posted 08-15-2005 10:30 PM
rustang: The fuel check is basic Supply and Demand, If the motor demands it you better supply it. The next thing I hear is you went from 1.6 rockers to 1.7, did you check for "Coil Bind" as you have increased the opening of the valve. This may be why your 1.7 rockers are going bad. ------------------
1964-1/2 Mustang SS/L 289 4-Speed, 10.537 @ 124.83. West Coast Money Maker Racing Team Member, http//www.tallentracing.com
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Rustang
Gearhead Posts: 805
From: Clarion PA
Registered: Nov 2000
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posted 08-16-2005 06:40 AM
quote:
Originally posted by Mark T 7724:
rustang: The fuel check is basic Supply and Demand, If the motor demands it you better supply it. The next thing I hear is you went from 1.6 rockers to 1.7, did you check for "Coil Bind" as you have increased the opening of the valve. This may be why your 1.7 rockers are going bad.
Good point, it merits checking but I think I looked at that when I put it together. Lift is only .548 with the 1.7 rocker. I'll check it tonight. What is considered adequate clearance before coil bind starts becoming a problem?
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Mario428
Journeyman Posts: 82
From: Charlottetown, PEI, Canada
Registered: Nov 2001
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posted 08-16-2005 07:23 AM
quote:
Originally posted by Mark T 7724:
You should really do the fuel volume test, You can see pressure on the guage and still be running out of fuel. The older Holley blue regulators were good the new ones are not, The Barry Grant I had was good untill I started pumping twice the volume (Over a Gollon in 30 Seconds) at 6-1/4 psi. Now I have the Aeromotive and it works great.
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Mario428
Journeyman Posts: 82
From: Charlottetown, PEI, Canada
Registered: Nov 2001
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posted 08-16-2005 07:26 AM
quote:
Originally posted by Mark T 7724:
You should really do the fuel volume test, You can see pressure on the guage and still be running out of fuel.
Simply untrue, Barry Grant brainwashed so many people in the early 80's with that hogwash it is ridiculous.
If you want 6 PSI at the carb and your pressure gauge shows 6 PSI thru the whole run you have enough pump.
I go 127 MPH with a 3000 lb Fairmont and the pressure gauge stays pegged at 6 PSI with a single Holley Black pump that is 3 years old.
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 08-16-2005 08:56 PM
The longer rocker ratio may be creating some weird harmonics in the springs now causing it to hit a brick wall. We had one customer bring us his car after they took the 1.6 rockers off and stuck 1.7's on, and it was down 40 hp. He went home and stuck the 1.6's back on, and the power came right back. The only thing we could think of since the srpings weren't coil binding and his piston to valve was good, was it created some bad harmonics that caused the power to drop.
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rustang@home
Gearhead Posts: 134
From: Clarion, PA
Registered: Jan 2004
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posted 08-16-2005 08:58 PM
Just did the fuel flow test. 3-1/2 quart at 30 seconds. (.75 gallon/30 seconds, or
1-1/2gpm)So do I need more pump? BTW no valve spring coil bind
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steve'66
Gearhead Posts: 9489
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-16-2005 09:01 PM
quote:
Originally posted by Mario428:
Simply untrue, Barry Grant brainwashed so many people in the early 80's with that hogwash it is ridiculous.
If you want 6 PSI at the carb and your pressure gauge shows 6 PSI thru the whole run you have enough pump.
I go 127 MPH with a 3000 lb Fairmont and the pressure gauge stays pegged at 6 PSI with a single Holley Black pump that is 3 years old.
I'm with Mario on this one. Too many overkill fuel systems out there that will fuel a fire big time.  Mel's '66 is a Holley Red, 3/8" line to a Mechanical pump at the engine, AN6 to the carb. My low 11 second ride is 3/8 line to a Holley mechanical pump. SteveW
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rustang@home
Gearhead Posts: 134
From: Clarion, PA
Registered: Jan 2004
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posted 08-16-2005 10:34 PM
By the way, that fuel flow was measured after the regulator.
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 08-17-2005 07:20 AM
quote:
Originally posted by rustang@home:
Just did the fuel flow test. 3-1/2 quart at 30 seconds. (.75 gallon/30 seconds, or
1-1/2gpm)So do I need more pump? BTW no valve spring coil bind
I hate the blue pumps and would change it in a heartbeat. I would much rather overkill a fuel system then chase my tail trying to diagnose one that's too small. You don't have to have coil bind to get bad valvespring harmonics.
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Rustang
Gearhead Posts: 805
From: Clarion PA
Registered: Nov 2000
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posted 08-17-2005 09:00 AM
I have a volumax fuel pump and regulator laying around. I don't remember the part number but I think it's the bigger of the two volumax pumps holley used to offer. I think before I change anything fuel system-wise, I'm going to T&T tomorrow night. With the fuel pressure gauge installed I'm going to monitor pressure down-track for the first time (I'm going to video it so I don't have to watch it!)and see if I need to change stuff. As far as the valvespring harmonics, those stupid rockers freezing up I'm sure will cause some funky harmonics. I'm getting some different rockers, and Erson wants me to send my "sticky" ones back to them so they can get a peek at them. ------------------
'68 mustang 351 clevor- 10.92@124
'67 Stang, 351W -11.18@118
'69 351C Torino-14.90@100
'78 Pickup 351W-15.56@88
'79 Pickup 460 ET=??
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