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#1 |
Registered User
![]() Join Date: Dec 2012
Location: Vancouver, Washington
Posts: 1,644
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Stock fuel pump
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!
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1968 Chevrolet C/10 LWB - 327, TH350 - 4/5 Drop |
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#2 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,621
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Re: Stock fuel pump
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.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#3 |
Registered User
Join Date: Aug 2013
Location: Wasteminster, Maryland
Posts: 409
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Re: Stock fuel pump
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
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72 C/10, LWB, 5.7, Auto, with A/C ![]() F.B.I = Full Blood Indian Appalachia/Eastern Cherokee,"Tsalagi" |
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#4 |
Registered User
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Location: Vancouver, Washington
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Re: Stock fuel pump
Thanks for the responses!
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1968 Chevrolet C/10 LWB - 327, TH350 - 4/5 Drop |
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#5 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: Stock fuel pump
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#6 |
Registered User
![]() Join Date: Dec 2012
Location: Vancouver, Washington
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Re: Stock fuel pump
On my 327 I have an Edelbrock 600 cfm. Thinking about switching to a 500 cfm. Might even go with an Edelbrock fuel pump.
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1968 Chevrolet C/10 LWB - 327, TH350 - 4/5 Drop |
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#7 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: Stock fuel pump
Why switch?
600 works. Even with a eddy pump rated at 5.5 to 6 psi you might need a regulator. |
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#8 |
Registered User
![]() Join Date: Sep 2015
Location: Mohnton pa.
Posts: 208
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Re: Stock fuel pump
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.
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#9 |
Registered User
![]() Join Date: Dec 2012
Location: Vancouver, Washington
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Re: Stock fuel pump
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.
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1968 Chevrolet C/10 LWB - 327, TH350 - 4/5 Drop |
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#10 |
Senior Member
![]() Join Date: Apr 2016
Location: Fairbanks, AK
Posts: 334
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Re: Stock fuel pump
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?
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1972 GMC K2500 Super Custom Matt |
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#11 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: Stock fuel pump
I like ones that max at 5.5.
Easier to control. Some are cheap, some not. https://www.summitracing.com/int/sea...illocation=int |
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#12 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: Stock fuel pump
Regulator can't hurt, but GM built about 100,000,000 vehicles without them. Why would a mechanical pump need it?
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#13 |
Registered User
Join Date: May 2013
Location: Colorado Rocky Mountains
Posts: 263
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Re: Stock fuel pump
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 |
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#14 | |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: Stock fuel pump
Quote:
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. |
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#15 |
Registered User
Join Date: May 2013
Location: Colorado Rocky Mountains
Posts: 263
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Re: Stock fuel pump
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 |
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#16 |
Registered User
Join Date: Jul 2015
Location: Central Coast, CA
Posts: 500
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Re: Stock fuel pump
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.. |
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#17 | |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: Stock fuel pump
Quote:
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. |
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#18 |
Registered User
Join Date: Jun 2016
Location: Vancouver B.C.
Posts: 206
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Re: Stock fuel pump
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.
Last edited by ratty69; 04-08-2017 at 11:35 PM. |
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#19 |
Registered User
Join Date: May 2013
Location: Colorado Rocky Mountains
Posts: 263
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Re: Stock fuel pump
Ratty Thanks that good info!
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