Minimum electric fuel pump pressure

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plumkrazee70

plumkrazee70

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Hello all. I have a 70 dart with the following motor:

68 340 .040 over
Keith black hypers 9.5 compression
Big valve j heads
Rpm air gap
Comp cam: .454 lift duration @.050 218 lobe:110
Edelbrock 650 Thunder AVS

I have a carb spacer on it now, but still getting the dreaded hot start situation (have to hold the throttle down a quarter, when cranking for it to start after it gets warm) Temps are at 195 all day, in traffic, on the road, etc. I can't add a return easily (no vapor line)

I want to either add or solely use an electric fuel pump for quick starts. Will this one fit the bill for my mild ride? http://www.summitracing.com/parts/crt-p60504

The psi says 4, wasn't sure if that was going to be too low. I am also following this article for install: http://www.how-to-build-hotrods.com/electric-fuel-pump.html

Thanks again for any opinions.
 
If your having to hold the throttle open to get it to start, it could be a flooded, or rich condition, in which case more fuel pressure probally wont help. You have one of the worst carbs for heat soak/boiling issues. A thick plastic spacer would perhaps help. The problem is compounded by the sorry excuse for fuel they sell us now days.
 
what material is your carb spacer made of, and how thick? I hope not aluminum, I use the 1/4" thick edelbrock gasket. like replica said-more fuel is probably not the answer, the fuel bowls are not boiling over completely, test this by removing air cleaner and pump carb a few times, it will probably squirt and take even more air to fire up. and just for info, that carter pump would be good enough for your mild combo
 
Try this test: Drive the car the way you usually would. Immediately after shut-off, open the hood, remove the air cleaner allowing an open view of the carb throats. Watch and wait, generally only 2-3 minutes. If there is percolation, you will see fuel bubbling up and into the throats. This will flood the engine for the next start. I suggest a phenolic carb spacer, also called heat soak spacer. Search Ebay for one to fit your carb. Good luck.
 
replicaracer43 said:
The problem is compounded by the sorry excuse for fuel they sell us now days.
Click to expand...

This!!! I was having all kinds of problems earlier in the year with "winter blend" fuels when it was really nice here and was getting into the 80's. If you even looked at the fuel, it would bubble up and vaporize. It really sucked.
 
340fourspeedDuster said:
Try this test: Drive the car the way you usually would. Immediately after shut-off, open the hood, remove the air cleaner allowing an open view of the carb throats. Watch and wait, generally only 2-3 minutes. If there is percolation, you will see fuel bubbling up and into the throats. This will flood the engine for the next start. I suggest a phenolic carb spacer, also called heat soak spacer. Search Ebay for one to fit your carb. Good luck.
Click to expand...

I appreciate all of the replies. I do have a spacer, it is less than 1/2" thick. It is made of phenolic wood, I think. If it is indeed flooding what is the remedy?
 
1) Are your Transfer and Idle ports synced up?
2) Are your secondaries shut up tight,yet not sticking-tight?
3) Are you running fresh,cold air to the carb?
4) Or is she sucking that hot underhood air?
5) What are you running for timings, and idle rpm?
6) What do you have available for fuel in your neighborhood, and what fuel are you using?
7) Is your PCV hooked up?

The stock 340 pump can put out close to 7 psi.It ran the AVSs and the TQ.
The stock teener pump can do at least 4 to 5, into a 2bbl.
 
AJ/FormS said:
1) Are your Transfer and Idle ports synced up?
2) Are your secondaries shut up tight,yet not sticking-tight?
3) Are you running fresh,cold air to the carb?
4) Or is she sucking that hot underhood air?
5) What are you running for timings, and idle rpm?
6) What do you have available for fuel in your neighborhood, and what fuel are you using?
7) Is your PCV hooked up?

The stock 340 pump can put out close to 7 psi.It ran the AVSs and the TQ.
The stock teener pump can do at least 4 to 5, into a 2bbl.
Click to expand...

1) I am not to versed on carbs, but am willing to learn. (Can you walk me through checking this)
2)Same
3)I would imagine so, it is just an edelbrock air cleaner with K&N filter. I have a six-pack hood so it gets fresh air there
4) See (3)
5) Timing is 18 initial; 36 Total all in by 3k
6) I have 92 ethanol free and 92 10% ethanol
7) Yes; passenger side valve cover to front of carb.

The fuel pump is an edelbrock performer listed as 6 psi 110 gph
 
I've said this before, There is such a thing as too much idle timing. It may not be too much for the engine, just too much for the low-speed circuit sync. And then you get into tuning issues. And 18 is too much for your 218 cam.And heres the reason why: the Throttle blades get to be too far closed and port sync suffers to the point that you have to crack the throttle to wake them up. And in fact the transfer port can run dry and become an idle air bypass.

So The first thing you have got to do is check that sync. Take the carb off drain it by tipping it upside down over a cakepan or something. Dispose of the gas or collect it and put it into a closed container--Safety first!
Now flip it back right side up, and make absolutely sure that the choke is off and the curb idle screw is firmly against its stop. Hold it there and flip it upside down again. So you are looking at the butterflies.Find the front two. Orient them so they are the furthest from you. Now find the points of the mixture screws where they are sticking into those bores.Next find ,immediately beside them, the transfer slots. They are slots, running vertically up the bores. They are about a half a millimeter wide and maybe 3 or so, mm long. These are the ports we need to sync up.If you cracked the butterflies to find them, check the curb idle screw to make sure it goes back to the stop.
Ok so now you know what ports we're talking about. The one thats slotted concerns us. With the throttle closed that slot should appear as a very small rectangle, about 1.5 times as long as it is wide. On your engine it can be a little shorter; perhaps 1.25 times as long as it is wide. Make it so. Use the curb idle screw against its stop.Remember about the choke; You do not want to have the fast idle cam engaged. From now on do NOT adjust that screw. Ok so thats done.
Next flip the carb right side up. Again choke off.Check the secondary throttle blade opening. They should be as closed as possible, without sticking closed, and both should be the same closed.
Next, set your idle mixture screws to 1.5 turns from lightly seated. Lightly seated.Lightly.
Thats it we're done. put her back on. Fill the bowls through the vents and start her up. Warm it it up to operating temp.
Theres a good chance she will be idling fast.Do not be tempted to back out the speed screw.Instead bring the idle timing down a little at a time,to as low as 12* but no lower.Once the idle speed is down around 700 to 800, readjust the mixture screws as may be required, per Rustys method. If you have to screw them out much past 3 turns, we'll have to do something about that.Remember up to this point we have NOT adjusted the curb idle screw.
Alright I'll leave you to get that done. Then we'll continue.
Which fuel is in your tank?
More to come
 
AJ/FormS said:
I've said this before, There is such a thing as too much idle timing. And 18 is too much for your 218 cam.
Click to expand...

Oh Ok. I was going by the "kick back method" on the starter and then backing off a few degrees. What should I set the initial to? It fires right up cold.
 
plumkrazee70 said:
Oh Ok. I was going by the "kick back method" on the starter and then backing off a few degrees. What should I set the initial to? It fires right up cold.
Click to expand...

Thats ok,
You we're just doing what is preached on here all the time. Mostly that works on bigger cams, and loose convertors.

Heres my formula for a suggested initial timing;

Take your cam size as measured at .050. In your case 223. Drop the 1st digit, so thats now 23. take 40% of that; that would be 9. Add that to a basic 5 , and the result is 14. So 14 degrees is the target for your set up.See post #14

If you had a 240 cam, it would be 19*. A 250 cam would be 25*. These are targets.
 
AJ/FormS said:
I've said this before, There is such a thing as too much idle timing. It may not be too much for the engine, just too much for the low-speed circuit sync. And then you get into tuning issues. And 18 is too much for your 218 cam.And heres the reason why: the Throttle blades get to be too far closed and port sync suffers to the point that you have to crack the throttle to wake them up. And in fact the transfer port can run dry and become an idle air bypass.

So The first thing you have got to do is check that sync. Take the carb off drain it by tipping it upside down over a cakepan or something. Dispose of the gas or collect it and put it into a closed container--Safety first!
Now flip it back right side up, and make absolutely sure that the choke is off and the curb idle screw is firmly against its stop. Hold it there and flip it upside down again. So you are looking at the butterflies.Find the front two. Orient them so they are the furthest from you. Now find the points of the mixture screws where they are sticking into those bores.Next find ,immediately beside them, the transfer slots. They are slots, running vertically up the bores. They are about a half a millimeter wide and maybe 3 or so, mm long. These are the ports we need to sync up.If you cracked the butterflies to find them, check the curb idle screw to make sure it goes back to the stop.
Ok so now you know what ports we're talking about. The one thats slotted concerns us. With the throttle closed that slot should appear as a very small rectangle, about 1.5 times as long as it is wide. On your engine it can be a little shorter; perhaps 1.25 times as long as it is wide. Make it so. Use the curb idle screw against its stop.Remember about the choke; You do not want to have the fast idle cam engaged. From now on do NOT adjust that screw. Ok so thats done.
Next flip the carb right side up. Again choke off.Check the secondary throttle blade opening. They should be as closed as possible, without sticking closed, and both should be the same closed.
Next, set your idle mixture screws to 1.5 turns from lightly seated. Lightly seated.Lightly.
Thats it we're done. put her back on. Fill the bowls through the vents and start her up. Warm it it up to operating temp.
Theres a good chance she will be idling fast.Do not be tempted to back out the speed screw.Instead bring the idle timing down a little at a time,to as low as 12* but no lower.Once the idle speed is down around 700 to 800, readjust the mixture screws as may be required, per Rustys method. If you have to screw them out much past 3 turns, we'll have to do something about that.Remember up to this point we have NOT adjusted the curb idle screw.
Alright I'll leave you to get that done. Then we'll continue.
Which fuel is in your tank?
More to come
Click to expand...

This is absolutely brilliant. I just filled it with about 13 gallons of 92 ethanol free, there was about 3 gallons of 92 10% ethanol, when I filled.

I will do as described in this post and report back with any questions. I will see if I can find the time to get out there this weekend. Very much appreciated. I see what you are saying about the timing, make sense.
 
If, after all of that worthwhile work is done and it still has hot start issues I'll suggest one of the plate type isolators. They're under-appreciated here and pretty much everywhere else, BUT my AFB couldn't have cared less about the spacer isolator that I tried first. Still had hard hot starting. In the summer I could smell the fuel!

The plate isolator works as a heat shield. In the case of the AFB's the fuel bowls are hanging off the side of the carb. RIGHT over any heat riser in the intake manifold. Put an aluminum plate between them and it will deflect most of the radiated heat trying to reach the fuel bowls. I made mine from a piece of 1/8" aluminum. It spanned rocker cover to rocker and was almost as long as the intake itself. I did cut various clearance holes in it.
 
Just realized my gas tank is leaking I ordered a replacement should be here next week sometime. I will report back when this goes in and I can follow the instructions above.
 
plumkrazee70 said:
Just realized my gas tank is leaking I ordered a replacement should be here next week sometime. I will report back when this goes in and I can follow the instructions above.
Click to expand...

Make sure you keep the old lock ring and re-use it if for some reason you swap out the sending unit.
 
AJ/FormS said:
I've said this before, There is such a thing as too much idle timing. It may not be too much for the engine, just too much for the low-speed circuit sync. And then you get into tuning issues. And 18 is too much for your 218 cam.And heres the reason why: the Throttle blades get to be too far closed and port sync suffers to the point that you have to crack the throttle to wake them up. And in fact the transfer port can run dry and become an idle air bypass.

So The first thing you have got to do is check that sync. Take the carb off drain it by tipping it upside down over a cakepan or something. Dispose of the gas or collect it and put it into a closed container--Safety first!
Now flip it back right side up, and make absolutely sure that the choke is off and the curb idle screw is firmly against its stop. Hold it there and flip it upside down again. So you are looking at the butterflies.Find the front two. Orient them so they are the furthest from you. Now find the points of the mixture screws where they are sticking into those bores.Next find ,immediately beside them, the transfer slots. They are slots, running vertically up the bores. They are about a half a millimeter wide and maybe 3 or so, mm long. These are the ports we need to sync up.If you cracked the butterflies to find them, check the curb idle screw to make sure it goes back to the stop.
Ok so now you know what ports we're talking about. The one thats slotted concerns us. With the throttle closed that slot should appear as a very small rectangle, about 1.5 times as long as it is wide. On your engine it can be a little shorter; perhaps 1.25 times as long as it is wide. Make it so. Use the curb idle screw against its stop.Remember about the choke; You do not want to have the fast idle cam engaged. From now on do NOT adjust that screw. Ok so thats done.
Next flip the carb right side up. Again choke off.Check the secondary throttle blade opening. They should be as closed as possible, without sticking closed, and both should be the same closed.
Next, set your idle mixture screws to 1.5 turns from lightly seated. Lightly seated.Lightly.
Thats it we're done. put her back on. Fill the bowls through the vents and start her up. Warm it it up to operating temp.
Theres a good chance she will be idling fast.Do not be tempted to back out the speed screw.Instead bring the idle timing down a little at a time,to as low as 12* but no lower.Once the idle speed is down around 700 to 800, readjust the mixture screws as may be required, per Rustys method. If you have to screw them out much past 3 turns, we'll have to do something about that.Remember up to this point we have NOT adjusted the curb idle screw.
Alright I'll leave you to get that done. Then we'll continue.
Which fuel is in your tank?
More to come
Click to expand...

Sorry for late late reply. Found out my gas tank was leaking so I got a new one and life got in the way.

I had time this last weekend to set the transfer slots and the secondaries like you said. Attached is a picture of how they came out. They needed very little adjustment as it looked really good when I checked them. I also adjusted the Air/Fuel screws in lightly seated and turned them out 1.5 turns. I put the carb back on and the after it was warmed up (choke open) the car was idling at 500 rpm. I thought it was going to be higher like you stated. I couldn't turn down the timing without killing it.

Thoughts?
 

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You might benefit from some of the DEI or other brand of fuel line insulation in the entire engine compartment, from carb all the way around to the area of the firewall.
 
abody said:
You might benefit from some of the DEI or other brand of fuel line insulation in the entire engine compartment, from carb all the way around to the area of the firewall.
Click to expand...

Thanks for the input. I want to get the timing and the carb setup right first. Then I will tackle the next thing. I am convinced the problem may go away once the carb and timing are set right.

It seems I have a flooding or rich condition (because I have to hold throttle at half to get it to start)
 
Hey, hi there. Yeah that sync looks pretty close. And yes the low idle is odd.
1)Are you running a PCV system? The 218 cam will want it.
2)Have you verified the damper TDC mark?
3)Are the metering rods stuck down at idle, and are they staying down.
4)Is that spacer a 4-hole, or at least devided?
5)What are your day-time temps there?
The AVS carbs usually like a bit more idle mixture, try turning them out more, perhaps as much as 2.5 turns out. Set them for best quality of idle.
-If TDC is true, and the PCV is functioning, and there are NO vacuum leaks,then we need the engine to tell us if its rich or lean. The way to do that is to pass a shop-rag over the primaries, without choking it to a stall. But first, stuff the rag in the secondary side; it should make little-to-no difference in idle speed.Yank it back out! Back to the primaries;If the rpm goes up, its getting too much air. If the rpm goes down, it wants more air.
If it wants more air, you crack the secondary open a bit and retest.
If it wants less air, that really means;Why? Go back and make absolutely sure its not drawing air from somewhere it shouldnt be.When thats done and no source is found, then you will have to prove that the fuel level is on spec.
-The electric pump may be too much.With the engine warmed up and running, shut the pump off. Wait a minute or three. If the idle speed rises before it falls,then the fuel level is too high. If the idle speed drops continuously to a stall, the fuel level is too low.If the idle remains the same for about a half a minute before dropping, then its pretty close.This assumes the mixture screws are optimized between 1.5 and 2.5 or so.
-Oh yeah, I'm assuming that when you are setting the timing that the vacuum advance system is defeated, and that later, you are connecting it to the spark-port.
-Do all the above tests with a stable idle speed of 650 to 700, using timing to get it, not primary cracking.
Ok so, have at her.

Thanks for the wake-up call.
 
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