Stock fuel pump

[OregonNed]

What is the average fuel pressure number for a stock fuel pump on a small block? I don't have a regulator on my line, but considering it. Thanks!

[Stocker]

I checked mine not too long ago while chasing a problem.... not sure but it seems like it was around 6 psi. Maybe a bit higher but not much.

[cherokeejohn]

I switched to elect pump last year once I discovered that the lobe that pushes the push-rod for the mechanical pump was wore down just enough that my pump wasn't pushing enough fuel. Anyhow after researching it I found that a stock SB350 mech pump pushes 7PSI. I bought one off Ebay for around $12, wired it up to a hidden toggle switch and works great, just don't forget and leave it on. On a positive note, It acts as a sort of anti-theft device

[OregonNed]

Thanks for the responses!

[geezer#99]

Originally Posted by OregonNed

What is the average fuel pressure number for a stock fuel pump on a small block? I don't have a regulator on my line, but considering it. Thanks!

Normally around 7 psi but some have been up to 9 psi.
What carb do you have?

[OregonNed]

On my 327 I have an Edelbrock 600 cfm. Thinking about switching to a 500 cfm. Might even go with an Edelbrock fuel pump.

[geezer#99]

Why switch?
600 works.
Even with a eddy pump rated at 5.5 to 6 psi you might need a regulator.

[Myoldtruck]

Im using a stock a/c delco pump with a regulator to my edelbrock carb. I have regulator set to 5psi. They dont like much more pressure than that I found out.

[OregonNed]

I think in the end I will put in a regulator. I have the Edelbrock fuel line kit with the metal line and banjo connector that travels mid intake into a Edelbrock filter with AN fittings on each side. From there it goes to the pump with a braided fuel line. Hopefully I can just install it right at the filter - before or after depending on which way is correct.

[Fbks_Cruiser]

I too am running an Edelbrock carb and have been considering adding a regulator when I re-plumb the fuel line. What regulator are folks using?

[geezer#99]

I like ones that max at 5.5.
Easier to control.
Some are cheap, some not.
https://www.summitracing.com/int/sea...illocation=int

[davepl]

Regulator can't hurt, but GM built about 100,000,000 vehicles without them. Why would a mechanical pump need it?

[gvw5400]

Just a thought, but how did all the dual quad mopar HEMI's run without pressure regulators? A buddy in high school had a 65 impala with a 327 and a AFB carb stock.
Also didn't 409 dual quad chevys run AFB carbs?
What is different now? How could all these engines run without pressure regulators and now it is unthinkable?
All The best, Dirk

[geezer#99]

Originally Posted by gvw5400

Just a thought, but how did all the dual quad mopar HEMI's run without pressure regulators? A buddy in high school had a 65 impala with a 327 and a AFB carb stock.
Also didn't 409 dual quad chevys run AFB carbs?
What is different now? How could all these engines run without pressure regulators and now it is unthinkable?
All The best, Dirk

Fuel line size plays a big part.
Small (5/16) tubing and several 90 degree bends reduced the pressure.
THat's what worked for me with the dual quad I experimented with.

[gvw5400]

Geezer, that makes some sense, If you used smaller tubing with success do you think we could add a restriction to a 3/8" line to reduce fuel pressure?
Does anyone know the fuel line size of a stock 1965 Impala 327 equipped with a Carter
AFB carb? OR the fuel line size of a dual quad 409?
All the best, Dirk

[Gromit]

This is to propose what I believe is a fatal disadvantage to the stock style fuel pump that no-one else has mentioned so far in this post.

Actually I hope I am wrong because I myself am running a stock pump.. but nervously. In my case it is a brand new pump with less than 100 miles on it and the 350 Small-Block motor.

As far as I know, (and I am no expert) if the stock-type fuel pump diaphragm ever happens to spring a leak, it will pump gasoline directly into your crankcase oil; and thereby dilute your engine oil and cause it to produce a milkshake-like foam made of the mixture of gas and oil; which will cause your oil pump to then begin to cavitate, and at the very least cause the motor to overheat due to insufficient oil pressure since the pump cannot push the foam as efficiently as it can push the pure oil.

Hopefully someone will correct me if I am wrong here.. I have it on my list to eventually replace my stock pump with an electric and its accompanying regulator; but so far I drive very few miles so I just take comfort in knowing everything is in new condition at the moment so I still have time to plan.

Definitely it is good to check oil at every fuel fill for the dreaded milkshake..

[ratty69]

Originally Posted by gvw5400

Does anyone know the fuel line size of a stock 1965 Impala 327 equipped with a Carter

Can't answer that, but the fuel pump for that application ( ACdelco 40018, also fits a gazillion 58-66 Chevys ) happens to be the same one I used on my engine. The edelbrock used to flood with the q-jet pump that was on there before. Runs fine now.

[gvw5400]

Ratty Thanks that good info!

[geezer#99]

Originally Posted by Gromit

This is to propose what I believe is a fatal disadvantage to the stock style fuel pump that no-one else has mentioned so far in this post.

Actually I hope I am wrong because I myself am running a stock pump.. but nervously. In my case it is a brand new pump with less than 100 miles on it and the 350 Small-Block motor.

As far as I know, (and I am no expert) if the stock-type fuel pump diaphragm ever happens to spring a leak, it will pump gasoline directly into your crankcase oil; and thereby dilute your engine oil and cause it to produce a milkshake-like foam made of the mixture of gas and oil; which will cause your oil pump to then begin to cavitate, and at the very least cause the motor to overheat due to insufficient oil pressure since the pump cannot push the foam as efficiently as it can push the pure oil.

Hopefully someone will correct me if I am wrong here.. I have it on my list to eventually replace my stock pump with an electric and its accompanying regulator; but so far I drive very few miles so I just take comfort in knowing everything is in new condition at the moment so I still have time to plan.

Definitely it is good to check oil at every fuel fill for the dreaded milkshake..

A couple things come to mind.
Sure it could put fuel into the oil and dilute it lowering the viscosity but it would take a lot of fuel leakage.
The pump can't cavitate. It's a positive displacement pump. THey don't cavitate.
The fuel vapors could be a bigger hazard. Heat plus vapors makes a boom.
Likely your biggest contributor of gas in the oil is from a flooding or rich carb. Plus fuel wash scores your piston walls.
Along with your electric pump are you gonna replace your carb too?
Mechanical fuel pumps and carbs have run for millions of miles.