[hp 400 dave]

I need a new fuel pump. I have a mildly modified 389 tri power with a 4 speed and 3.42 rear. What would be the best mechanical fuel pump for this application? Is any replacement pump fine?

[Tom Vaught]

The best mechanical fuel pump (in my opinion) would be a 6 valve Chevrolet lower section
added to a Pontiac upper lever/housing with the mods done by Ken Crocie.

If I remember correctly, Ken did the mod on several Pontiac engines over the years.
Then you have a great flowing street fuel pump.

Tom V.

[tom s]

I have used the Carter street pump for years on my421s and 455s.Tom

[421mike]

X2 Mike

[hp 400 dave]

Thanks guys. Looks like I will get the Carter street pump.

[Kenth]

25+ years ago i found i was leaving a lot of power at top end on the table using a mech. fuel pump for my 1966 Tripower GTO.
Also had problems with fuel percolating at engine shut-off.
Since then i´m using a Carter P4070 electric pump as a replacement for the mech.
Not looking back.....

[chrisp]

Carter HP m6907 mech pump is perfect / my 461 with 66 trips 500 hp has been flawless now for years 3/8 pick-up & line .

[Dick Boneske]

Just remember, about 6 psi is all the Rochester carbs can tolerate. that is plenty to get adequate flow through three needle/seats.

[John Milner]

I used an AC 40373 pump on my tripower engine. It works just fine. I initially tried one that was for a late 70's 400 and it overpowered the needle and seat on the carbs at idle and when you'd shut the engine off it would leak down. I ran a regulator for a while and cranked it down to 6 psi. It did better. However, I didn't want to run a regulator. The AC 40373 Pump took care of the problem. The carbs just won't tolerate much over 6 psi of pressure.

[hp 400 dave]

I was concerned about too much pressure, that's why I asked what others used. Thanks everyone for your input. Going to install the new Carter street pump tonight.

[lust4speed]

I posted quite awhile ago that a new Airtex mechanical pump we purchased was pushing 10 PSI, and it turned the carbs into bubbling fountains. We hid a 1-4 PSI Holley 12-804 regulator just above the pump and solved the issue.

[MrArt2u]

Bringing back an old(ish) thread because my 22 year old Carter M6907 pump finally died. I called Carter for a rebuild kit and they sent me to Then and Now Automotive in Weymouth, MA. They manufacture rebuild kits here in America and have a kit listed online (CK6907) but I called in to ask a couple of questions. I spoke to Tom, he was very knowledgeable and asked me a few questions about my pump (most important-is it USA or China made and what is the casting number.) It turns out they can send you different springs for the diaphragm to adjust the fuel pressure. Stock Carter M907 is a minimum of 6 1/2 psi (he figured even more.) He sent me springs to go higher (not what I wanted for my tri power) or lower, closer to 4 or 5 psi, which is what I wanted to achieve with a new regulator. I'll be doing the rebuild over the next couple of days and will report back with the results.

You can look up Then and Now Automotive on youtube to see the rebuild process for a Carter fuel pump. No reason to not DIY.

[chrisp]

Originally Posted by MrArt2u

Bringing back an old(ish) thread because my 22 year old Carter M6907 pump finally died. I called Carter for a rebuild kit and they sent me to Then and Now Automotive in Weymouth, MA. They manufacture rebuild kits here in America and have a kit listed online (CK6907) but I called in to ask a couple of questions. I spoke to Tom, he was very knowledgeable and asked me a few questions about my pump (most important-is it USA or China made and what is the casting number.) It turns out they can send you different springs for the diaphragm to adjust the fuel pressure. Stock Carter M907 is a minimum of 6 1/2 psi (he figured even more.) He sent me springs to go higher (not what I wanted for my tri power) or lower, closer to 4 or 5 psi, which is what I wanted to achieve with a new regulator. I'll be doing the rebuild over the next couple of days and will report back with the results.

You can look up Then and Now Automotive on youtube to see the rebuild process for a Carter fuel pump. No reason to not DIY.

Excellent lead on the rebuild kits .

[grivera]

Originally Posted by MrArt2u

Bringing back an old(ish) thread because my 22 year old Carter M6907 pump finally died. I called Carter for a rebuild kit and they sent me to Then and Now Automotive in Weymouth, MA. They manufacture rebuild kits here in America and have a kit listed online (CK6907) but I called in to ask a couple of questions. I spoke to Tom, he was very knowledgeable and asked me a few questions about my pump (most important-is it USA or China made and what is the casting number.) It turns out they can send you different springs for the diaphragm to adjust the fuel pressure. Stock Carter M907 is a minimum of 6 1/2 psi (he figured even more.) He sent me springs to go higher (not what I wanted for my tri power) or lower, closer to 4 or 5 psi, which is what I wanted to achieve with a new regulator. I'll be doing the rebuild over the next couple of days and will report back with the results.

You can look up Then and Now Automotive on youtube to see the rebuild process for a Carter fuel pump. No reason to not DIY.

How did your rebuild work out?

[Dick Boneske]

Is there a reasonable source for the spring that regulates fuel pressure in these pumps? During the past five years, I've had more than a dozen Tri-Power owners with flooding issues due to too much pressure. Several claimed they bought the low pressure pump from Ames Performance, and saw more than 8 psi at the carbs.

I don't believe there is a reliable source of Pontiac fuel pumps that deliver less than 6 psi.

[61-63]

I just looked the Carter M6907 pump on Summit's website and it says it puts out 6psi. May not be right but that's what it says.

[Tom Vaught]

Originally Posted by Dick Boneske

Is there a reasonable source for the spring that regulates fuel pressure in these pumps? During the past five years, I've had more than a dozen Tri-Power owners with flooding issues due to too much pressure. Several claimed they bought the low pressure pump from Ames Performance, and saw more than 8 psi at the carbs.

I don't believe there is a reliable source of Pontiac fuel pumps that deliver less than 6 psi.

Agree Dick. Have seen several mechanical fuel pumps over the years (when a accurate fuel gage was installed), show 8-9 psi fuel pressure. Chinee crap!!

Tom V.

[chrisp]

Originally Posted by 61-63

I just looked the Carter M6907 pump on Summit's website and it says it puts out 6psi. May not be right but that's what it says.

Have used the 6907 for years on multiple tripowers trouble free , standard needle & seat , not the flapper disc style , never had any issues .

[Dick Boneske]

Is there a source for rebuild kits for the ‘65 and earlier pumps? I’ve got six NORS pumps that could be rebuilt if I had the parts. I would get them dichromated for NOS appearance and ethanol-proof with new diaphragm.

[carbking]

Dick - try "Then and Now" in the Boston area.

Jon