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7/19/2021 12:56 PM  #26


Re: What is the correct sparkplug?

OK Doug, remind us what carb do you have? I think all the cars got a 3/8" line by sometime in 68. 

If you haven't had the sending unit out in 50 years, it might be worth taking a look at the fuel sock. 


John  -- 67 Mustang Coupe 390 5 speed
 

7/19/2021 8:35 PM  #27


Re: What is the correct sparkplug?

TKO & 6sally6
I regapped the distributor rotor / stator gap and drove it. There was no change I think mainly because I forgot to regap the sparkplugs. During the drive I took off the gas cap, there was no change. I'll do it again.
TKO
I looked at fuel lines for the Boss 429 and Ford uses the same one from the 250 six cylinder on up. Fuel line for cars is sold by outside diameter. By that it is 3/8 but the ID is 5/16. In order to get 3/8 ID I need to buy 1/2 OD. To buy 1/2 fuel line there is no way the fittings will fit into the anything. Such as the fuel sender outlet the fuel pump or the carb. 
Bolted to Floor
The carb is a Edelbrock 750 cfm 1411 model 


Sometimes ya just gotta fly low.     70 convertible 76B model, L code out of the box. 416W stroker now.
     Thread Starter
 

7/19/2021 10:27 PM  #28


Re: What is the correct sparkplug?

Gap 'em about 40 if you have an MSD box(or equivalent).  If not try about 34-36.
I doubt that will make a dif.
IF..........like Bolted sez.........its the stock sock on the  sending unit........might be the next 'rock-to-look-under' for the problem.
6sally6


Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
 

7/20/2021 5:35 AM  #29


Re: What is the correct sparkplug?

I wouldn't put much stock in what Ford did.  Their goal was to be cheap, not effective.  The Boss429 wasn't meant to be fast, and frankly, it wasn't.  The goal of the Boss429 was to homologate the 429 engine for use in the Torino in NASCAR competition.  I knew a guy in college who had one that he had raced extensively.  Off the showroom floor he said the thing was a dog compared to other car's he'd owned like a '68 428CJ.  It took a lot of effort to get the engine running near its peak potential.  Despite its size it was meant for high RPM use and wasn't well suited to the street.

Before you spend the time and money to convert the fuel line over I would get a fuel pressure gauge on it and see what it does under load.  This isn't going to tell you the whole story, but its a start.  What kind of fuel pump are you running? 

 

7/20/2021 7:39 AM  #30


Re: What is the correct sparkplug?

TKOPerformance wrote:

Before you spend the time and money to convert the fuel line over I would get a fuel pressure gauge on it and see what it does under load.  This isn't going to tell you the whole story, but its a start.  What kind of fuel pump are you running? 

I agree with checking the fuel pressure inder load. (suggest using the temporary Road Kill 'zip-tie' method)  Just realize if there is a pressure drop under load, it does not mean the pump is bad.  I would still suspect some restriction in the fuel line.
 


65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
 

7/20/2021 8:39 PM  #31


Re: What is the correct sparkplug?

BobE wrote:

TKOPerformance wrote:

Before you spend the time and money to convert the fuel line over I would get a fuel pressure gauge on it and see what it does under load.  This isn't going to tell you the whole story, but its a start.  What kind of fuel pump are you running? 

I agree with checking the fuel pressure inder load. (suggest using the temporary Road Kill 'zip-tie' method)  Just realize if there is a pressure drop under load, it does not mean the pump is bad.  I would still suspect some restriction in the fuel line.
 

I have the stock engine driven fuel pump and an Edelbrock electric fuel pump. The electric is switched, used to prime the carb without using the starter to do so. Turning it on doesn't prevent it from running out of gas. It's supposed to be a 6 psi pump. Im not familiar the Road Kill zip-tie method.
 


Sometimes ya just gotta fly low.     70 convertible 76B model, L code out of the box. 416W stroker now.
     Thread Starter
 

7/21/2021 8:21 PM  #32


Re: What is the correct sparkplug?

I drove it today. Big difference after adjusting the plug gap. I think regapping the rotor to stator and the plugs is what fixed it. It still has a slight miss at 4500 RPM. And the carb still runs out of gas. If I drive it like a grandma it is OK, but who drives a Mustang like a grandma?


Sometimes ya just gotta fly low.     70 convertible 76B model, L code out of the box. 416W stroker now.
     Thread Starter
 

7/21/2021 11:36 PM  #33


Re: What is the correct sparkplug?

I can't remember, did you change to bigger jets?


Bob. 69 Mach 1, 393W, SMOD Toploader, Armstrong  steering.
 

7/22/2021 7:59 AM  #34


Re: What is the correct sparkplug?

HudginJ3 wrote:

BobE wrote:

TKOPerformance wrote:

Before you spend the time and money to convert the fuel line over I would get a fuel pressure gauge on it and see what it does under load.  This isn't going to tell you the whole story, but its a start.  What kind of fuel pump are you running? 

I agree with checking the fuel pressure inder load. (suggest using the temporary Road Kill 'zip-tie' method)  Just realize if there is a pressure drop under load, it does not mean the pump is bad.  I would still suspect some restriction in the fuel line.
 

I have the stock engine driven fuel pump and an Edelbrock electric fuel pump. The electric is switched, used to prime the carb without using the starter to do so. Turning it on doesn't prevent it from running out of gas. It's supposed to be a 6 psi pump. Im not familiar the Road Kill zip-tie method.
 

Road Kill is a TV show on the Motor Trend network.  With tongue-in-cheek, they provide different ways to use tie-wraps.  What I meant was to 'jury rig', using zip-ties, a fuel presure gauge that you can see while driving.  The typical fuel pressure gauge uses 1/8" tubing that one can fit through the gap in the hood to cowl, or fender, and zip-tie it to the the cowl grill as a temporary installation. 
 


65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
 

7/22/2021 6:54 PM  #35


Re: What is the correct sparkplug?

Bearing Bob wrote:

I can't remember, did you change to bigger jets?

        Before I ever started this build it I was told to get the 750 Edelbrock and that it would be to big for the engine. The reason for the Edelbrock was they are easy to work on and it would need to be de-tuned for the engine size. When I first started to drive it, it was real rich. 7 miles to the gallon rich, but it ran out of gas even then. I leaned it out to 15 mpg's and then got the bright idea to install the roller cam. At that point it was running rich again. I couldn't figure out how to richen it up and have it still run right so I put it back to the factory settings. It runs better and now is at 11 mpg's. I bought the AFR gage but am not sure it is work correctly. It shows a consistent 13.2 to .5. I leaned to to show 14.2 but it ran terrible like it is to lean so I put it back to factory specs.

Bob E     LOL well now you know what I don't watch. I've used the Road-Kill tie-wrap method with out knowing it. I guess it would be called the Air-Kill tie-wrap method.  
 


Sometimes ya just gotta fly low.     70 convertible 76B model, L code out of the box. 416W stroker now.
     Thread Starter
 

7/23/2021 5:22 AM  #36


Re: What is the correct sparkplug?

What AFR gauge are you using?

I'd say the issue is with fuel supply. 

 

7/23/2021 11:55 AM  #37


Re: What is the correct sparkplug?

Glad to hear it's doing better, but I'm still curious why it's running out of fuel. Do you have any idea what the capabilities are for the mechanical fuel pump?

What are the GPH and PSI rating for the electric fuel pump you added? I did see one on Summits site rated at 2-3.5 PSI and 30 GPH. 

I installed a Carter Street Super Mechanical fuel pump on the FE. It's rated for 7 psi and 120 GPH. It has never staved for fuel. Been thinking about calling it Thirsty!! Our engines are different, but both have stroker cranks and come with about 15 CI of each other. 

I think its boiling down to the fuel:
can't get out of the tank
can't get through the line
or the pumps can't get enough volume to the carb.
 
 


John  -- 67 Mustang Coupe 390 5 speed
 

7/23/2021 2:03 PM  #38


Re: What is the correct sparkplug?

I'm with Bolted on this one. 

 

7/23/2021 6:25 PM  #39


Re: What is the correct sparkplug?

snap-snap!!.....(fingers snapping!)   I got it!!!
Using a gas can... suck directly from the gas can (using the electric pump) into the carb.
IF it does NOT go empty..... its the sock and/or fuel line.
Only way I can think of to try and pin point one area.
IF it stills goes dry...................................you're-on-your-on!!
Give it a try.
6sally6


Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
 

7/24/2021 6:44 PM  #40


Re: What is the correct sparkplug?

TKOPerformance wrote:

What AFR gauge are you using?

I'd say the issue is with fuel supply. 

 It's an AEM brand.

Bolted to Floor
It's an Edelbrock 1791. It's rated at 6 psi and 120 gph.

6sally6
That's to much work. It's quicker to drain the tank and pull the sending unit. I've got to jack up the car any ways for other issues. I'll let y'all know.


Sometimes ya just gotta fly low.     70 convertible 76B model, L code out of the box. 416W stroker now.
     Thread Starter
 

7/26/2021 5:29 AM  #41


Re: What is the correct sparkplug?

AEM gauges are typically very reliable and accurate.  Where is the sensor located?

So I understand this fuel system correctly: there is an electric pump feeding the mechanical pump which then feeds the carb, correct? 

 

7/26/2021 9:04 PM  #42


Re: What is the correct sparkplug?

TKOPerformance wrote:

AEM gauges are typically very reliable and accurate.  Where is the sensor located?

So I understand this fuel system correctly: there is an electric pump feeding the mechanical pump which then feeds the carb, correct? 

 
The sensor is located aft of the short header coupling on the right side at about a 45º angle. 


Your are correct on the fuel pump set up. I have an on off switch on it also. I installed to prime the fill the carb bowls because they dry up after letting it sit for weeks at a time before starting it again. The more I think about it, it has to be the fuel pick up sock. Right now I'm swamped with airplanes so it is sitting till I can get to it.


Sometimes ya just gotta fly low.     70 convertible 76B model, L code out of the box. 416W stroker now.
     Thread Starter
 

7/27/2021 5:58 AM  #43


Re: What is the correct sparkplug?

Here's the real question: how much power is the engine supposed to make?  I'm guessing you are in the 500HP range.

 

7/27/2021 9:23 PM  #44


Re: What is the correct sparkplug?

When I ordered the kit they thought 430 to 435 HP. It feels/ acts like a like more now with the conversion from the flat cam to the roller cam.


Sometimes ya just gotta fly low.     70 convertible 76B model, L code out of the box. 416W stroker now.
     Thread Starter
 

7/28/2021 5:59 AM  #45


Re: What is the correct sparkplug?

So I'm guessing its a low RPM torque monster then, because with that many cubes hitting 500 should be pretty easy.  HP isn't something you feel anyway.  Torque is what you feel, and the swap to a roller bolsters average torque and area under the curve, which is why they are so effective on the street.

I await hearing what's going on in the tank, but my guess is that a stock type replacement mechanical fuel pump simply can't deliver enough volume to feed an engine like that. 

 

7/28/2021 5:54 PM  #46


Re: What is the correct sparkplug?

Im going to check the sock before I do anything else. What do you think about EFI, like a FiTech vs Holley Sniper? Those kits come with electric furel pumps that are supposed to support over 500 HP. I read the negatives about both of them and think it is mostly people that dont follow directions or know much about cars. I aint no expert by any means but Im sure I can handle it. I know the mechanics I can. Might have a little trouble with the adjustments. I'd run a return line instead of another gas tank under the hood.  Just thinking

Last edited by HudginJ3 (7/28/2021 6:25 PM)


Sometimes ya just gotta fly low.     70 convertible 76B model, L code out of the box. 416W stroker now.
     Thread Starter
 

7/28/2021 6:38 PM  #47


Re: What is the correct sparkplug?

I have my doubts about a parts house replacement mechanical pump keeping up with your motor too. Your electric fuel pump should be more than capable though.  

I'm wondering about the sock in the tank if the rest of the lines are in good shape. 

A buddy bought a Sniper kit for his 80 Vette LS conversion. I think I favor it more than the FI Tech at this point for the Blue Thunder 2x4 Medium Riser intake I have hiding out in the garage!! I could be fickle though. https://cdn.boardhost.com/emoticons/blooper.png


John  -- 67 Mustang Coupe 390 5 speed
 

7/28/2021 9:01 PM  #48


Re: What is the correct sparkplug?

Bolted to Floor wrote:

I have my doubts about a parts house replacement mechanical pump keeping up with your motor too. Your electric fuel pump should be more than capable though.  

I'm wondering about the sock in the tank if the rest of the lines are in good shape. 

A buddy bought a Sniper kit for his 80 Vette LS conversion. I think I favor it more than the FI Tech at this point for the Blue Thunder 2x4 Medium Riser intake I have hiding out in the garage!! I could be fickle though. https://cdn.boardhost.com/emoticons/blooper.png

I really hope it is the sock. I replaced the fuel line this past year and kept the original one to use as a return line if I decide to go with EFI. Im really feeling the same as Bullet Bob as to fiddling with it so much. I've let it go ever since I did the original install but figured it was time to get serious. It is refreshing to see it come together.  


Sometimes ya just gotta fly low.     70 convertible 76B model, L code out of the box. 416W stroker now.
     Thread Starter
 

7/29/2021 5:29 AM  #49


Re: What is the correct sparkplug?

My thoughts on EFI are: get it running right with a carb before going to EFI.  Do I like EFI for its functionality?  Absolutely.  BUT, I think trying to escape what's likely a relatively minor issue by undertaking a major conversion is a recipe for disaster.

On any engine I've used that's supposed to make significantly more than stock I always at least consider modifications to the fuel system.  For your setup I would have used either a high volume mechanical or electric pump running to an adjustable regulator with a return.  All lines would be 3/8" or AN-6.  However, if you are going to EFI a 5/16" line will be fine, even if its too small for a carb.  EFI uses significantly more pressure so a 5/16" line can get you in the 550-600HP range. 

I think your current problem is the pump more than anything, especially if the fuel pickup looks fine. 

 

7/29/2021 9:09 AM  #50


Re: What is the correct sparkplug?

HudginJ3 wrote:

TKOPerformance wrote:

AEM gauges are typically very reliable and accurate.  Where is the sensor located?

So I understand this fuel system correctly: there is an electric pump feeding the mechanical pump which then feeds the carb, correct? 

 
The sensor is located aft of the short header coupling on the right side at about a 45º angle. 


Your are correct on the fuel pump set up. I have an on off switch on it also. I installed to prime the fill the carb bowls because they dry up after letting it sit for weeks at a time before starting it again. The more I think about it, it has to be the fuel pick up sock. Right now I'm swamped with airplanes so it is sitting till I can get to it.

Do you leave electric pump on while it’s normally running?


Dan - Never a Yooper! Eh?
 

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