What should fuel pressure be?

[rdorman]

Sounds as though you are getting close. Idle air bleeds are usually a last resort. 7 psi is MAX. Turn it down a bit. Under normal cersumstances, set the float level at the middle mark on the window, often the lower mark on the front works well. Main jets some times have an effect on the idle system because of more fuel in the main well. Pop when you let off usually means the idle system is not properly tuned. Check the position of the throttle plates at idle to be sure they are correct. A little carbon around the rim of the plug is from the rich idle mixture. 12 initial may be a little low. Set the idle timing for maximum vacuum, re-adjusting idle speed to be the same for each setting and take ready. Recurve to get the max you found on the dyno. Sounds like to me you only have to get the idle and initial timing worked out and you are good. The Victor will have cylinders that run hot and cold though. When tuning with temperatures it is possible to have high temps and be to rich, not to lean. Temp alone don't tell all the story but it does sound as though you have pull throttle correct.

Happy tuning!

Rick

[blykins]

You know it's funny...on Barry Grant's troubleshooting part of his website, it lists rich idle and popping through exhaust both as a result of high fuel pressure.....it lists some other items, but it seems like high fuel pressure is a common denominator. Since I am pushing close to 8psi, I think I'm gonna order a regulator (the Holley Red fuel pump I have should be regulated at 7, but apparently it's not) and see what that does.

[Bill Wells]

blykens..maybe the holley red is at 7 psi like it is supposed to be, and your other gauge is off ? bill

[blykins]

Always a possibility I guess.....it's a brand new Autometer fuel pressure gauge mounted on my fuel log.

[blykins]

OK....Update.

Plugs are Champion C59YC. Rick Parker told me that he saw them on the chart...they're next to the lowest for being cold.

Put a regulator on the fuel line. Running at 6 psi now.

Got another problem now....I mentioned it in another post....Alternator pulley is too big to let the alternator charge at idle. Battery has basically been getting drained (down to 56% according to my battery charger) while idling and low throttle operation....i.e. tuning carb....checking for fuel leaks, etc. MSD hasn't had enough spark to thoroughly make things happen efficiently...so I had a little miss and now the plugs are sooty.

So now I have to see if I can find a smaller pulley so the battery will charge 24-7. Will probably change plugs now.....so just wondering if I should buy a hotter plug while I'm at it.

[Bruce Edwards]

Most older cars will not charge at idle. The alt is just not strong enough. If you are running the coolest plugs for your model you may want to start in the middle of the heat range and adjust from that point.
Installing a smaller pulley on your alt will get it to charge more at idle but in real time how much idle time will the car see? If you make it to small the other problem is the alt turns to fast and sometimes they will fail due to the high internal speeds. The Ford Mustang Cobra came with a very large alt pulley to slow it down so it would not have that problem at high speed.
I would stop playing with it till you can get some road time. Things will be different on the road than in the garage.
How close are you to road time?

[blykins]

It's roadworthy now.....Being road legal is another thing.....no headlights, taillights, signals, etc.

It seems like I have to do a lot of tinkering with the engine running though....adjusting fuel pressure....rejetting....changing air bleeds.....

I mean how can you do this stuff without running the engine? And most of the time it's idling while checking fuel pressure, air bleeds, etc....So it's not charging the battery. Therefore it's not getting a hot blast from the plugs....which in turn soots the plugs, makes it have a miss, and it doesn't start as quick as it did.

So here I am having to put another set of plugs in it and making sure the battery's at 100%......

[Bruce Edwards]

We set our engines up on paper first and that makes getting them tuned easier. Plus I use a list of parts I know will give me the HP wanted by the customer. Having built engines for a long time I know what it will take to fine tune one of my engines. In most cases since it is all thought out before any parts are bought or machine work done I do not run into many surprises.
Like the 351W in Bill's ERA 289 FIA that we fired up the other day. Once I got the timing set it fired right up and sounded good with only a minor adjustment to one rocker and a small turn of the mix screws. That is all I will do to it till we get the wheels on it and road test it. Then I will mess with the timing and check the fuel mix by how the plugs look and the way the car acts under load. In most cases they burn the back tires off from the get go and have good overall performance. Just comes from years of doing it I guess.
The big think is not over thinking it till you get it on the road. Everything changes under load and with different air temps. Finding the best balace is the key.

[blykins]

So what plugs should I use with my Edelbrock Vic Jr heads, Bruce?

Do you like a certain brand better? I thought I was using a C59YC plug...but I can't find anything to back that up right now....I'm 2.5 hours from the car....

Edelbrock's site only mentions a RC12YC.

I'm worried about clearance if I don't use the right plug....and I'd like to have a little hotter plug right now....

[blykins]

OK...I checked some records I have here on the computer....looks like I'm using C59Y plugs...14mm x 3/4" reach.

[Bruce Edwards]

When I use the Edelbrock heads I use what they show in the instruction sheet and change it from that point when needed.
I install Champions in Edelbrock head engines. Never had a failure and that is a big thing with me. I stay away from all the "fancy" plugs and use Champions, Autolite, and AC depending on the engine. Not a big fan of Bosh, NGK, split fires and the like. Also if you are not running fuel injection stay away from platimum tip plugs. You need more surface area with a carb engine to keep the plug clean. The small tip plugs tend to fowl out easy the extra fuel carb engines use at start up.
Install the RC12YC's and see how it does. That is what is in Dave's 351W with 425HP andhe has been driving it for over 2 years now and the plugs still look like the day I put them in. That is also what is in Bill's ERA 289 FIA.
Like I have said I tend to stick with what works.

[Excaliber]

Comp cams listed installed valve height at about 1.890, but Gessford (Neil, engine assembly man) said he prefers about 1.850. Thats quite a difference. I set mine at 1.850 with shims.

[Bruce Edwards]

I am not sure why he would go against the cam maker as to spring load. The shorter you make the spring the higher the seat pressure. The other problem you get into is you may run out of spring before you get coil spring stack. This is what happens when you do not have enough spring for the lift and the spring "stacks" up on it's self. Very bad for spring life. Tends to break them then the retainers fall out and the valves fall into the combustion area and well...........
Did you get the heads bare or did they come set up with Edelbrock springs? If you got them bare and bought a cam spring and lifter kit from Comp cams I would have set it to what they recommend for their spring and cam after all they made it and should know it's limits.
Did you ever say what it is you plan on doing with the engine? Street engines do not need to be set up like race cars. That is unless you like the constant tuning and overhaul work that goes with a highly modified engine.
Me, I just like to drive fast and put in gas.

[blykins]

Hey Bruce.....what's a symptom of low fuel volume? Fuel pressure is now at 6 psi. Anything I should watch for now? Seems to take the gas well when I get into it a little....

[392cobra]

Brent,
Do you have a liquid or air filled fuel pressure gauge on your fuel log ?

The reason I ask is that you seem to be adjusting fuel pressure a lot.

A liquid filled can give you false readings the warmer/hotter it gets.It will show a lower pressure as the gauge warms up.

I changed over to air filled and I get consistant readings no matter the ambient tempt. now.

[blykins]

It's air filled....it's an Auto Meter gauge.

I haven't been adjusting a lot.....it was too high, I put a regulator on it and set it at 6. Now just wondering if I set it too low....and how would I know if it's too low....

[392cobra]

I run 6 - 6.5 with a Holley Blue pump.Have run the Black pump as well.

Just my opinion,with 425" I'm not sure if you have enough capacity with a Red pump for anything more than tooling around and short bursts.

[Bruce Edwards]

The easy way to tell if you do not have enough volume is the car will tend to die out with a long blast on the gas. If the pump can not keep up the engine will fade away as it starves for fuel.
I do not think you will have a problem with that. Check your GPH rate as listed for the pump you are using.

[blykins]

OK...one more question....

Could a lean idle mixture cause some popping through the exhaust when cold....and a slight miss with a little sluggishness on throttle response?

[Bruce Edwards]

When the engine is cold the choke over rides the idle system. Are you running a choke or have you taken it off the carb?
If it will help you any give me a call and maybe we can work it out faster that way.
407-857-8587 is my shop number and I am here from 9:00-5:00