Exhaust gas smoke

bobg · Post by **bobg** » Mon May 03, 2010 10:04 pm

My 12M aft cabin has Crusader 454s and I have noticed the starboard engine is smoking a bit even running at full temp - gas, not oil. Listening carefully it seems to be misfiring a little bit although it is hard to hear with the way the Internationals muffle the exhaust through the hull.

I plan to start looking for this issue this coming weekend and wanted to see if you guys have any additional suggestions on what to look for.

I have already re-timed both engines. I plan to start with the choke as this seems to be the most likely culprit. If that looks OK, then back to the ignition system. Starting with examining the plugs for fouling and gap. Then wires, cap, rotor, and coil.

You guys have any suggestions or other ideas?

alexander38 · Post by **alexander38** » Mon May 03, 2010 10:15 pm

those are good places to start, look thur old post you'll find a lot of different reasons for it. last year I had one doing it, did the tune up thing and most of it went a way. then found a bad fuel pump that was leaning her out on the top end. Are you running corn gas ? if so how long ?

bobg · Post by **bobg** » Mon May 03, 2010 10:24 pm

The previous owner said that he ran non-ethanol gas and de-tuned the engines to run 87 octane. My marina has 89 but it does contain ethanol. I just filled up the back tank but I am still running on the reserve tanks which he filled (only had the boat for a month).

I hadn't thought of the fuel pump, but it seems to do it at all engine speeds.

bobg · Post by **bobg** » Mon May 03, 2010 10:37 pm

After you mentioned the fuel pump I thought of something else - float/needle-valve. It's been a while since I pulled apart a carburator and this one will be a pain to work on due to location - may have to pull it off.

Do you guys know which carb Crusader used I haven't checked. Is it a Quadrajet?

alexander38 · Post by **alexander38** » Tue May 04, 2010 5:31 am

most likely a Q-jet, but start with the simple things first.

rossjo · Post by **rossjo** » Tue May 04, 2010 10:19 am

Doubt its a Qjet (could be though) - probably a Carter AFB ... what year?

Unless you've rebuilt your carb with Viton float needle seals, they will deteriorate with the ethanol. Not sure how long, but it will happen. I just put a new set of Viton seals in my Qjet - and it runs good now - we'll see if it lasts (supposed to).

bobg · Post by **bobg** » Tue May 04, 2010 5:41 pm

alexander38 wrote:most likely a Q-jet, but start with the simple things first.

I agree with starting with the simple stuff, I am simply coming up with a checklist.

After crawling around in an engine compartment for hours and bruising a few knuckles, my mood will start to deteriorate (along with my vocabulary) and I won't be thinking clearly

. A checklist helps me to remember all the things to look for. I hate getting home - hour drive - and thinking "I forgot to check for that"

bobg · Post by **bobg** » Tue May 04, 2010 5:43 pm

rossjo wrote:Doubt its a Qjet (could be though) - probably a Carter AFB ... what year?

Unless you've rebuilt your carb with Viton float needle seals, they will deteriorate with the ethanol. Not sure how long, but it will happen. I just put a new set of Viton seals in my Qjet - and it runs good now - we'll see if it lasts (supposed to).

Boat is 88 model. Thanks for the needle valve tip. I will look into that. Would the Viton be typically available at local marine parts dealers?

Jerry · Post by **Jerry** » Wed May 05, 2010 7:25 am

bobg wrote:[ Would the Viton be typically available at local marine parts dealers?

Yes they are and at most Automotive parts stores also. Just get the carb number off of yours and call around. Just about all of the kits that I have seen lately come with the Viton.

rossjo · Post by **rossjo** » Wed May 05, 2010 10:24 am

Be careful - my Qjet rebuild kit from NAPA last year was NOT Viton. I had to special order (http://www.cliffshighperformance.com) the Viton seals and Accel pump. NAPA has a lot of old stock, and I'm sure the others do as well.

I would not count on the counter guy at the Auto (not Marine) parts store knowing if its Viton or not. Talking to Cliff (above), he says there are about 5 generations of Viton now, and the latest gen is the best ...

Why chance it? Its cheap - and the cost is your time doing 2 carbs ... (I do mine right on the engine, but use hemostats to make sure I don't drop screws in the carbs).

What carbs do you have? Are the square-bore (same size in all four bores) or spread-bore (smaller bore in front, larger in rear)?

bobg · Post by **bobg** » Wed May 05, 2010 1:16 pm

rossjo wrote:Be careful - my Qjet rebuild kit from NAPA last year was NOT Viton. I had to special order (http://www.cliffshighperformance.com) the Viton seals and Accel pump. NAPA has a lot of old stock, and I'm sure the others do as well.

I would not count on the counter guy at the Auto (not Marine) parts store knowing if its Viton or not. Talking to Cliff (above), he says there are about 5 generations of Viton now, and the latest gen is the best ...

Why chance it? Its cheap - and the cost is your time doing 2 carbs ... (I do mine right on the engine, but use hemostats to make sure I don't drop screws in the carbs).

What carbs do you have? Are the square-bore (same size in all four bores) or spread-bore (smaller bore in front, larger in rear)?

I am not sure yet what carbs are on it yet. Plan to check this weekend when I go to the marina. I don't think I have enough room above the carb to be able to see what I am doing to leave it on the engine while I rebuild it. The salon deck above it is too close.

Is there a way to visually tell if the parts are Viton so I can check it before I buy a kit?

Rodman · Post by **Rodman** » Wed May 05, 2010 2:31 pm

bobg wrote:
rossjo wrote:Be careful - my Qjet rebuild kit from NAPA last year was NOT Viton. I had to special order (http://www.cliffshighperformance.com) the Viton seals and Accel pump. NAPA has a lot of old stock, and I'm sure the others do as well.

I would not count on the counter guy at the Auto (not Marine) parts store knowing if its Viton or not. Talking to Cliff (above), he says there are about 5 generations of Viton now, and the latest gen is the best ...

Why chance it? Its cheap - and the cost is your time doing 2 carbs ... (I do mine right on the engine, but use hemostats to make sure I don't drop screws in the carbs).

What carbs do you have? Are the square-bore (same size in all four bores) or spread-bore (smaller bore in front, larger in rear)?
I am not sure yet what carbs are on it yet. Plan to check this weekend when I go to the marina. I don't think I have enough room above the carb to be able to see what I am doing to leave it on the engine while I rebuild it. The salon deck above it is too close.

Is there a way to visually tell if the parts are Viton so I can check it before I buy a kit?

No way you want to rebuild it on the engine. There is a ball bearing and springs inside. If you drop one those in the intake. Its a lot more trouble, then you will have to remove the intake to get that stuff out.

bobg · Post by **bobg** » Sun May 09, 2010 4:25 pm

Thanks everyone for all your help. I am at the boat and here is the latest. Choke appears to be fine - carb is a quadrajet. I started pulling plugs down the inboard side of the engine. 1,3, and 5 look good - minor carbon fouling. But 7 is badly gas fouled. So this should isolate the problem to wires, cap, or rotor.

I am trying to figure out what distributor I have to get the right cap and rotor. Service manual says engine came with Prestolite, Mallory, or Delco distributors. Prestolite and Mallory were conventional while Delco was electronic. These distributors are Prestolite, but I can't find any points in there. So I assume these engines got an electronic conversion at some point. If that is the case, would the part number on the outside of the distributor be enough to get the right parts? Or would the internals of the original distributor have been changed such that I now need to get more information off the internal parts of the distributor?

bobg · Post by **bobg** » Mon May 10, 2010 8:33 pm

BTW rossjo, the quadrajet was spread bore.

rossjo · Post by **rossjo** » Mon May 10, 2010 10:54 pm

Right - Qjets (later mfgd by Edelbrock) are the only spread bore 4BBL.

If its a square bore 4BBL, its a Holley, Motorcraft or Carter AFB.

I'm not sure on the distributor for a Crusader - have a Mercruiser myself - someone else here will know ... good luck!