I'm curious if I need a bigger fuel pump for the 350 in my Chevelle. I don't know anything about the one that is currently on there, it does say made in USA on it but thats it. From what I know it could be the pump from my original motor when I had the crate motor installed, some parts from my original motor were swaped onto the crate motor when it was installed. I was thinking about getting a Carter street pump, it says it flows 120 gallons per hour at 6psi. has anyone used this pump or have any others to reccomend?

Heres the spec sheet on my 350 http://jasperengines.com/performance/classii3.pdf I'm using an Edelbrock performer intake, a Holley 650cfm double pumper, a complete MSD ignition and a good high flow exhaust. My main problem with wanting to change the fuel pump is that I think the engine is not getting enough fuel. I can literally put the pedal to the floor and until I get to 40mph and around 2500rpm does it start to really move, from a dead stop it doesn't really have any pep and from all the bolt ons I have added the fuel pump is the only thing I have not changed, could this be the problem?

No compression,small cam,no gears it would be lucky to turn the tires over. You can bump your initial timing up to 10-12* and might help a little, according to the engine specs the motor is built more for economy and not performance. The Carter pump is a good one,just don't think it will help much.

• Operating range of 2000-4800 rpm
• Good Midrange torque and response:
2400-3200 rpm range

It looks like it is in the operating range that is was built for.

It should run a bit better than a stock engine. It does say 3.73's are suggested, this would help.

It's just a tuning issue. If the pump was shot or on it's way out your performance would worsen as the rpms climb. Instead you say that it is flat until 2500 rpm. Tune your spark and fuel curves and I bet it will be just fine. Run 87 octane gas only. Disconnect the secondaries on the carb so the primaries can be tuned alone. A vacume secondary carb would probably much more responsive on your car, 600 cfm would be more than adequate. Your initial timing should be somewhere between 10 nd 18 degrees- only through trial and error will you find what the combo likes. Make sure the total timing doesn't exceed 40 degrees. Get your idle mixture setting tuned in then tune the main jets and primary valve/enrichment circuit. Tune your accelerator pump rate and amount for the best full throttle launch.

How about converter. You probably need a 10" converter that stalls somewhere at least 2500 and maybe even 3000 for a street/strip setup to get the thing up into its torque curve. Have you checked the cam installation to make sure it is degreed in correctly? How about trans shift points. Is the trans shifting out of first to quick at WOT (can adjust on the governor to help with this), or does it do this even in manual mode?

Keep in mind these cars weigh in excess of 3800 lbs in street trim and this is a pretty mild 350 with no compression. Hence the reason I am thinking more converter to get up into the torque curve to get this thing moving, but I don't know what you have now. Also more gear, but depends on how much highway driving you do and what you are willing to live with.

Keep in mind also that the out of the box setup on most Holleys when matched with the correct size engine is pretty dead on for the street. A 650 is probably about right for your 350 although a 600 might be a little more responsive. Might be able to play with accelerator pump nozzles and cams, and timing to help dial the thing in.

BTW- a pump problem would have you running out of fuel at higher rpm's not at the hit of the throttle and then the thing starts pulling.

I have pondered the fuel pump thing for several years. I keep coming back with this. The stock Fuel pump is fine for all but the most radical engines (read mostly RACE USE). My logic us that if you ever research tune up specs they will give you a volume spec for 30 seconds of cranking. usually a pint. If you do the math based upon max card size and then take the fuel mixture ratio need for max power. The stock pump is more than adequate. IMO It kinda falls with the HV oil pump thing. again IMO.

Milan

Dump the double pumper! Based on the PDF you linked, Jasper recommends either a 2BBL or the STOCK 4 BBL. Very few chevy small blocks had mechanical secondary carbs stock. I have a feeling that if you find a Q-Jet from a 327 or 350 automatic car, you will be amazed at how well your car runs right off the line. A Holley Spreadbore w/ vac secondaries would be a good choice as well. Your engine will respond great to small primaries and vacuum seconds.

I have pondered the fuel pump thing for several years. I keep coming back with this. The stock Fuel pump is fine for all but the most radical engines (read mostly RACE USE). My logic us that if you ever research tune up specs they will give you a volume spec for 30 seconds of cranking. usually a pint. If you do the math based upon max card size and then take the fuel mixture ratio need for max power. The stock pump is more than adequate. IMO It kinda falls with the HV oil pump thing. again IMO.

Milan Milan who??? :D How the heck are you?? Haven't seen you here in a while..

Scott

Hey Scott!!! Not to Hijack post graemlins/waving.gif

Crazy busy.... it was wierd having the time to post.
drop me a line

Milan

Thanks for all the responses guys, I now have a few leads on some things to check. I do realize my 350 is pretty blah but it should have a little more pep, but with some adjusting and tuning I think it can be improved. It sucks about the double pumper I have because I just bought it a month ago. :mad: I originaly ran this same size and type carburetor when the engine was installed six years ago but this year it started leaking and running rough and I had it rebuilt and still leaked and ran rough so instead of feeding money into the old carb I replaced it with a new one.

For gears I'm running 3.42's in a 12 bolt with an eaton posi and 28" tires, the trans is a TH350 with a transgo shift kit and what I was told a step above stock convertor (2000 stall?). So another carb might help? I know it won't make more power but if it had just a little more off the line acceleration I would be very happy, I don't race my Chevelle but when I get the chance to lay into it I like for it respond well. This comment may ruffle some feathers but when I was driving my Fathers 95 Ford Lightning today it seemed to have more getty up and go than my Chevelle did redface.gif I hope I can change that, but like I said I have some things to tune and adjust now and I will see what happens, thanks.

The lightning should feel peppier..it is FI and super charged and can run low 13s. I doubt your combo as itis will run low 13's. Good luck

BK72SS,

28" tall tires can't be helping the situation either.