Intake manifold choices

canyncarvr said
Yes. The Mallory is noted as being no longer available from the two retailers I found that had it listed. I have a
Holley 12-887 on my 'list-of-stuff' for a return line if that ends up being the direction this is headed. That part would fit my real estate situation better.

All of this has got me thinking about the Holley fuel pump I use. Rated at 7psi and installation said to not require a regulator, I wonder if the latter of that is not the best choice. 7psi is a bit much for a Holley carb I think. I would prefer 4-5psi. I had a regulator installed years ago when I took this car to the track, but removed it for the current build in the car.

I did order a Trick Flow style (carb mounted) throttle cable holder that is built to accept a Mopar style cable. That will get me away from the angle problems of a raised/spaced DC style 'high' bracket I have now AND away from the in-the-way style (imo) of the Mancini bracket. Foremost, it will get my 1/2" phenolic spacer in place.

I have yet to determine if replacing the carb seats helped at all. This last flood was different from every previous situation in that the fuel was NOT percolating in the bowls, it was not that hot a day, but I do know that heat-soaks do 'stack' in this car. A .001" diameter difference between the brass and the o-ring in the original pieces has to be less-than-good. I have not touched my 4779 except for idle adjustments since it was new and just back from a local builder's set-up. That's been 20 years.

Thanks to all for good points and input. I appreciate it.

The Mallory part number is 29388. Far better than that holley regulator. Any time you see a bypass regulator that has the fuel enter the regulator backwards from a dead head regulator know that that design was used because it was cheap to get to market.

Holley was way behind on bypass regulators and had to get something out there and that was what they did.

I actually saw one up close, in my hand about a month and a half ago. The ports were pretty small. Bypass area was at best enough to handle a Holley blue pump. Much more than that and the regulator doesn’t look like it can bypass enough fuel at low demand (like idle and cruise) and then you end up with pressure creep and the very real chance of pushing fuel past the needle and seat.

Also, return line size is pretty important. You want the line big enough that it’s not the restriction because if it is, it will do the same thing as a restrictive bypass.

Of course, there are exceptions to this. One I remember was a Barry Grant pump. On that one system the return line was what controlled fuel pressure. Between the return line and the regulator was how he designed that system to work. So if you had the return line too small you couldn’t get the regulator to drop the pressure enough. If the return line was too big you couldn’t get the fuel pressure up because it was all going to the tank.

I forget if that was a street/strip system or a drag only system. But if you didn’t plumb it exactly as the directions said, it wouldn’t work.