NEHA

At the tail end of okemo 2 I was having what felt like fuel delivery issues. I replaced the filter and I am looking to replace the electric pump as well, Roy Spaulding had remarked that it sounded sick and tired. The current pump is only about 72gphfrom the info I can find. From the research I've done that seems like its cutting it kinda close when you consider its running a 500ish HP v8 at 6500 rpm. My fuel issue only showed up at full throttle and high rpm for extended periods like by check 4 and toward finish. What would be a good flow rating to shoot for in a new pump? Would it be good to go with a pump with a higher rating? Also would a summit racing or kegs brand pump be fine(I'm on a budget) or are there other brands that would be better quality. The current pump is a carter P/N 152-875 also known a a carter p4594 I think. As always thanks for your input.

Luke,

Fuel pump was never a problem although, it could be tired. Check your spark plugs first before you go for a new fuel pump.

Smokey

Thanks smokey, I'll replace those first.

Luke - FWIW - there is a little strainer screen in the inlet of the Carter pump that may have some crap in it, or one of the vanes could be stuck. Left dry long enough, they will lock up, because the carbon shaft seal needs to be wet - but when carefully unstuck, they go right back to working OK.

The fuel delivery numbers: 500 hp x .5 lb BSFC (hp/hr)x gas @6.5 lb/gallon = 38.5 gph @ 100% duty cycle. IIRC (and I use the same pump, in tandem), given that 72 GPH is a free flow rating (on a NEW pump), which makes the 6 psi rate something like 55, it is indeed kinda marginal. One possibility is that you are not getting full voltage at the pump, particularly if there is no alternator on the car. Don't bother with Summit's plastic pumps - Junk is too kind a word. A 2nd Carter like you have is $3 more than the JEGS special.

However, I would defer to Smoke on the "most likely" problem. IMHO, he was running too hot a plug in the car, due to issues with the magneto he used to use. The Crane boxes ( I use one, so does Kevin) will actually tolerate a pretty cold plug, due to the multistrilke capability at lower engine speeds. I would look at an Autolite AR-3923 or AR133, depending on which ones fit your heads. Your regular Autolite guy can order these race plugs, or Jegs has 'em. You MAY have to go to a non-projected nose styl plug if projected tip ones hit the pistons - Play-doh may be of help to verify.

The forums I read suggest a pump closer to 130 gph is suggested for an engine with that output at full throttle / top RPM. What I read also indicates it is a pusher type pump and should be mounted low near the fuel cell.

It is worthwhile ensuring the full battery voltage is at the pump when its running. Relays and connections do go bad.


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Good info, thanks guys. The plugs I currently have are autolite r135's I believe. So I I'll buy a set of each from 133-135 and try em out. I see what I can do with the pump, they are cheap enough on amazon I may just order a new one.

Something tells me this is the problem
http://db.tt/3eYWv83z

More pictures of the clogged pump screen before and after cleaning
http://db.tt/T8argKVF
http://db.tt/H193YIxS
http://db.tt/lUOM5qfW
http://db.tt/52hfLgqB

Looks like wood chips, what was clogging it?

There were some wood chips, rocks, and just general greasy grime. Also some sort of fiberous material.