j9fd3s

iTrader: (3)

ive done some fuel system testing, and the short answer is that you want no regulator.

the regulator you do not want is the holley, it kills fuel flow and pressure is all over the place

the stock pump, flows quite well, and pressure is rock solid at 2.75psi.

if you must change stuff, i like the mallory pump, it fits the car well, and has a regulator in it that actually works

t_g_farrell

iTrader: (1)

J9 good info as always. Which Mallory is that?

Jeff20B

iTrader: (13)

I think he's talking about this Mallory pump. Mallory/MSD 4070M Fuel Pump for RX7 1975-1985 - Racing Beat

I like the Mallory 4309 fpr they sell. Mallory/MSD 4309 Fuel Pressure Regulator for RX7 1975-1985 - Racing Beat

Carter Dial

Carter Dial

Carter Dial

Qingdao

iTrader: (3)

I'd pull the vent solenoid out and cut the plunger off of it. At least that's what I did to my carb.... Seems asinine to power something that will cause your carb to fail to restrict fuel; when its original purpose for existence is no longer there.

BUT if it works hey why not slap it back in and turn the key.

Carter Dial

Maxwedge

iTrader: (1)

Carter, the wire you circled in black is the richer solenoid and is not needed if you've already removed the emissions junk. Have you stripped wiring and emissions from the engine, or is it still there?. The solenoid on the fuel side (driver's side) is the air vent solenoid I was speaking about. If it is in there it needs power or your carb floods. This is all in the carb stripping guide I linked a few posts back. When I did mine I didn't want to do any irreversible damage, so I just powered it as the guide suggested. To remove it you have to break it out and I didn't want that.

Qingdao

iTrader: (3)

Hook it up if you desire. That can confirm that this is your problem. I think it is, and also in combination with maladjusted/new floats.

I never followed a "stripping guide". I'm sure its helpful, but I just went through the carb and took "unnecessary bits" off. Unfortunately that means I can't tell you 100% what I disconnected. However I can say that if I ran into a solenoid that caused flooding I can guarantee I "solved" the problem; this typically means I cut the plunger off the valve on the inside of the part.

Jeff20B

iTrader: (13)

I've done just about everything you can do to these carbs and I do remove the float bowl vent solenoid on most of them for reduction of things that could go wrong.

j9fd3s

iTrader: (3)

yeah that one. if you had a stock engine though i see no reason to change the pump at all, it flows plenty

j9fd3s

iTrader: (3)

no idea, you'd have to test it.

test 1 is easy, its just volume. so find a container with some kind of measurements on the side, mine is for juice and its labeled in Milliliters. Mazda's spec is cc/minute so this is nice. take the fuel link off the carb, put it in the container, and run the fuel pump for 30 seconds. Mazda's spec is 1400cc/minute or more.

test 2 is to put a pressure gauge on it, but you need a 0-5psi one and the bigger the better. those little 0-15psi ones lack resolution. stock pump does 2.75psi and its steady as a rock.

Carter Dial

Qingdao

iTrader: (3)

Jerry can will fix the no fuel issue.

chuyler1

iTrader: (1)

Very interesting. I am working on an EFI upgrade with a DCOE style throttle body. I was actually thinking of working the dashpot into the linkage for a smoother off throttle experience. Not sure I can fit it, but I'm going to try.

Jeff20B

iTrader: (13)

I never use the dashpot and things run fine.

midnight mechanic

a stupid question>>>-->Do carburetors wear out? A mazda dealer mechanic told me such.

Qingdao

iTrader: (3)

The shafts can. They will make a vacuum leak.

Benjamin4456

Any reason to omit the dashpot? Is it a just a choice for simplification? Not trying to thread-jack, just curious since I'm doing a full carb build and I'm looking at simplifying (improving) everything possible. Does removing it not cause issues with the throttle snapping shut and such, or does it simply require more finesse?

Qingdao

iTrader: (3)

Gotta be honest I had to google search what a dash pot was... Nope, apparently its unnecessary cause I've never had any issues without it.

Benjamin4456

Awesome, one less thing to clean up and install on my stripped carb. I had never tested without it before and seeing how it's there in the first place, I'd say it's reasonable to have figured it had some purpose to serve. Nice to know it's not necessary.

Thanks

chuyler1

iTrader: (1)

If you look it up some say it was to prevent stalling, others will say it was specifically emissions related (despite them existing before emissions was an issue). I think it would likely be most useful in traffic, cruising at 10-15 mph in 2nd gear. Lifting off the throttle as you try to modulate speed without it may cause a slight shutter and bucking, while having it will produce a smoother deceleration transition. So you can remove it...but why?

GSLSEforme

Benjamin4456

Yeah, that does make sense. I've seen people who say to remove it and those who don't. I would agree that it has little to do with emissions, as I can't see how closing the throttle plates slower would affect that.

Perhaps once I get the carb installed I'll do some testing with and without it. I had wondered about slow traffic throttle work (going between brake and gas more often than normal at low speeds), so I can see where that might cause some issues. Again, I didn't want to thread-jack, but thanks to everyone who replied to my comment.