The accelerator pump arms on my QF850 hit Performer RPM manifold and I had to use a 1/4" phelonic spacer to get it to fit.

Sooo...a probable 1/4" phenolic spacer (open bore or 4 bores at ? Bore Size), a plate type throttle cable bracket, 3 gaskets (?), the $77 QFT fuel connection kit for 2 feeds, Quick Fuel m-850 (or m-800), and new longer carb studs. Yikes.

Question: What max rpm do you run your boat? I have no intention to run over 4800 (just to keep my goals in perspective).

I've yet to pull the trigger on the QFT, now knowing of the necessary supporting cast. If it was simple carb swap and test run, great. Its not the $800...I'll be saving that with the boat sitting next to my garage. The auto parts store has the 1480 calibration kit waiting for me ($65)...I could give the recalibration a shot 1st, even avoiding the higher rpms through the rest of the season if needed. Then do the new carb off season. At that point I think I'd dump
the air gap and do an hp500 Carb/Intake package from CP Performance (Hardin Marine manifold, QFT 800 btw, and gaskets). For about the same $.

Im running 5200. Summit has a fun little calculator that would get you in the ballpark. I'd only bother with the racing numbers estimate as the torque loads on a boat are too heavy to be considered cruising.

https://www.summitracing.com/experta...cfm-calculator

Before I'd do anything install a wideband monitor before anything else because you should still have it with any new carb as well. I neede one to dial in my carb as well.

https://m.summitracing.com/parts/inn...FUWUfgodMFEAkw

I don't remember what exhaust you have but Wags engineering most likely makes a plate that slips into your riser joint for the O2 sensor.

I think it's real close to being enough carb, otherwise I think I would have also experience it through the prop...it would be nice to have the wideband. Wags site is down, do you space both manifolds or just one. My exhaust was the older wet joint EMI Thunder that I welded up to convert to dry joint with bypass hoses.

You can also send the riser to EMI and they'll weld in a bung. I had someone local weld a bung into my headers which was the easiest way to handle it. Throw the calibration kit into your current carb and see if it makes you happy. Fwiw, my engine ran fine but I put the wideband on it and found that the wide open mixture was good but right at my cruise speed it was lean, and over time may of melted the bugger.

wouldnt welding in a bung be in the "wet" zone?

http://www.offshoreonly.com/forums/g...sor-bungs.html

Results are mixed. Some folks run a few seasons with no problems and others struggle to get a few months out of an O2 sensor. I put an innovate bung extender on mine and ran all of last season with issues. Some people use them just long enough to get a good tune and then forget about it.

Yo Baja Chicken...where should he get those bungs welded in?

F**k if I know. I'm just trying to help the guy out. He should go talk to someone that's qualified.

you already told hin. post 126. send them to EMI. that way if they eff em up, they have the spares right there to replace them with.

The Wags Engineering o2 spacer for the dry joint should work... Baja turned me on to that info ;)

http://i690.photobucket.com/albums/v...7/IMG_2672.jpg

http://i690.photobucket.com/albums/v...IMG_2671_1.jpg

^^^Like^^^

I wonder if they make them with a slight wedge shape to them. Cuz you're raising the whole Riser up a good inch. But if the back was only up three quarters of an inch the outlet of the Riser would be sloped pretty much back down to where it belongs to connect up with all your exhaust plumbing.

Just a heads up that if you plan to mount the monitor on the dash you'll need the extension cable.

I got no response from wags but this is on ebay: https://www.ebay.com/itm/322489451597

I've messaged them about fitting the EMI Thunder...

Wags' website, classified ads, and Ebay items have been gone for a bit now.
The "Performance Fuel Injection Systems" guys may be able to help. They offer a few different style plates.
Dennis Moore Performance also has O2 plates. MOORE PERFORMANCE BOAT ENGINE PARTS REPLACEMENT / HIGH PERFORMANCE
There is a big difference between manifolds with short cast risers and headers with stainless risers(like Eddies picture thread).
The O2 plates recommended by Baja Chicken Nuggets are for wet stock Mercruiser manifolds. The bolt hole differences
are only 1/8" on the width and 1 1/4" on the length compared to your EMI's. Nothing a rat tail file, Form-A-Gasket,
and duct tape couldn't handle.
You really don't need O2 plates anyway. Just get the correct carburetor and proper tune and you should be good to go.

What's your method of getting a tune without a wideband?

Go on youtube. Put in the name of the tune. It's free!!!

This is a not issue for most as the 4" exhaust hose has enough flex. I've run both the Wags engineering piece and the Moore Performance piece on stock Merc risers and GLM manifolds.

The only issue I've witnessed with the Wags spacer is there are no thru passages for cooling in either side of the sensor. Not a cooling issue but the riser has provisions for these coolant passage ways and what ends up happening is water is then trapped on the top side of the spacer and it will slowly pit the spacer material at that spot. Using a gasket without the rear coolant passage holes would prevent top side water contact and corrosion issues.

Wot? No O2 sensors? We're doomed.

How did we survive the past 100 years tuning our engines without O2 sensors?

Reading spark plugs and tweaking carburetors may be a lost art but it does work.

If 92cobalt243 wants to incur the added expense of a wideband/O2 set-up then he should do it. When
properly used it will give the information needed to tune his engine to perfection. Provided of course
that he knows how to use that information. It might even jump out of the engine compartment and tell
him his carburetor is too small. :lolhit:

I was really thinking of capt call-type situations where there is little to no wiggle room...literally.

I almost forgot that I had to Yamabond the studs that had somewhat stripped which are at the riser gasket joint...along with a "one off" EMI Thunder spacer being upwards of $200...I'm going to keep it simple. Like my motor guy said "tweak it pig rich until it doesn't run so good and lean it back a bit". Then I'll go buy a bigger carb 😂

Just to wrap up...the Edelbrock 1410 is big enough, just not with the stock rod/jet calibration. Went 1 stage richer (4%) in both power and cruise modes and the boat runs great...hesitation/miss is gone and the calibration kit #1480 has parts to get me to 3 stages rich (12%). I'll keep checking the plugs and make adjustments as needed. Currently on adjustment #10...
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Thanks.