'92 5.8 Pro Boss(Carbed) Intake Vacuum Port
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Boat Maintenance
Forum Discription: Discuss maintenance of your Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=30449
Printed Date: November-18-2024 at 5:33am
Topic: '92 5.8 Pro Boss(Carbed) Intake Vacuum Port
Posted By: Airfooter
Subject: '92 5.8 Pro Boss(Carbed) Intake Vacuum Port
Date Posted: June-26-2013 at 1:30am
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Can someone please tell me what the vacuum port size is in the rear of the intake manifold on a 5.8 Pro Boss? Possibly 1/4" NPT? I recently rebuilt my carb and I want to hook up a vacuum gauge. I read on here that the port in the rear of the intake manifold is the best spot to hook a gauge up to, but I forgot to verify the port size before I left the boat this weekend and I want to purchase the fitting this week. Also, how about a hand held tach? I've been looking at them on Amazon. Any thoughts on the http://www.amazon.com/Electronic-Specialties-328-Tach-Plus/dp/B002Z32OHW/ref=sr_1_10?ie=UTF8&qid=1372216875&sr=8-10&keywords=hand+held+tach" rel="nofollow - 328 EZ Tach Plus versus a http://www.amazon.com/CyberTech-Digital-Photo-Tachometer-Contact/dp/B001N4QY66/ref=sr_1_2?ie=UTF8&qid=1372216587&sr=8-2&keywords=hand+held+tach" rel="nofollow - Lazer Tach , or any others? I don't want to spend anymore than $50-$60. Thanks! Adam ------------- 1992 Nautique Excel |
Replies:
Posted By: 89Martinique
Date Posted: June-26-2013 at 1:47am
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I dont know the size but be sure to use a "T" when hooking up you vacuum gauge. My idle changes on both boats if I block the pcv. ------------- Current Boats: 1992 Supra Comp-TS6M PCM 351w HO Pro Boss Pro-Tec Ignition - Full Composite (no wood stingers!) 1989 (3rd Gen) Correct Craft Martinique B/R PCM 351w Power Plus 1984 E-Scow Keuka Lake, |
Posted By: TX Foilhead
Date Posted: June-26-2013 at 2:22am
| I'm going to guess bigger, maybe 3/8. If you'll bump this tommorow about dark I'll be in the garage and can measure it. |
Posted By: Airfooter
Date Posted: June-26-2013 at 11:44pm
That's good to know. I was curious about that prior to finding out that there is a plugged port towards the rear of the intake manifold that can be used for a gauge. My plan is to use it now and not touch the PCV line. ------------- 1992 Nautique Excel |
89Martinique wrote:Posted By: Airfooter
Date Posted: June-26-2013 at 11:47pm
Bump - thanks in advance. ------------- 1992 Nautique Excel |
Posted By: TX Foilhead
Date Posted: June-27-2013 at 1:18am
| On my stock manifold it measures out to 5/8. The port on the plate under the carb isn't the best place from what I've heard, but if you have a new carb there should be a port on the carb itself. |
Posted By: Airfooter
Date Posted: June-27-2013 at 1:39am
Good deal. That should be 3/8" NPT then. I'm going to use the port in the manifold (as shown below - pic taken from another post), not in the port plate. I have a 4010 carb and didn't see a port or connection anywhere besides the barb that the clear tubing from the top of the fuel pump runs to.  ------------- 1992 Nautique Excel |
Posted By: 89Martinique
Date Posted: June-27-2013 at 2:50am
Ah, the 4010. Gotta love em'. Beat any other 600 cfm, or should. But can be real hard to keep consistent. (on the road) Marine conditions vary less than road conditions so its easier to keep them tuned in.  ------------- Current Boats: 1992 Supra Comp-TS6M PCM 351w HO Pro Boss Pro-Tec Ignition - Full Composite (no wood stingers!) 1989 (3rd Gen) Correct Craft Martinique B/R PCM 351w Power Plus 1984 E-Scow Keuka Lake, |
Posted By: 89Martinique
Date Posted: June-27-2013 at 2:54am
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Which side of the carb is the vacuum port on? Obviously the 2 mixture screw control 4 separate cylinders. So, how do get the vacuum of both sides of the carb? I just set the jets by turning in until motor starts to run differently (lean) then back out 1/4 turn. I do this to each side several times. So far, so good. ------------- Current Boats: 1992 Supra Comp-TS6M PCM 351w HO Pro Boss Pro-Tec Ignition - Full Composite (no wood stingers!) 1989 (3rd Gen) Correct Craft Martinique B/R PCM 351w Power Plus 1984 E-Scow Keuka Lake, |
Posted By: Airfooter
Date Posted: June-27-2013 at 11:04am
There is no vacuum port on the carb itself that I see. Since I'm using the port in the intake manifold as shown in the above picture, my understanding is that I'll be able to adjust one side of the carb with the boat in gear (in the water) and then adjust the other side the same amount. After that I'll adjust the idle if needed and re-adjust the mixture screws again until I see the highest vacuum reading at 550-600 RPM with the boat in gear. This is my first carb rebuild and my first time tuning a carb therefore please correct me if I'm going about this wrong! As for adjusting the mixture screws and listening to the engine, I tried this. The engine didn't start to stumble until the screw was lightly seated (I was adjusting one side at a time). I read on CCF that if the idle is set too high, and the butterfly is open too far, the boat will not be running on the idle circuit. The engine was idling at 600 RPM on the boat tach so I'm purchasing a hand held tach to see if the boat tach is off. My plan is to back the idle off a bit more prior to adjusting the mixture screws again. ------------- 1992 Nautique Excel |
Posted By: TRBenj
Date Posted: June-27-2013 at 11:16am
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You want to set the idle for 650 in gear, not 550-600. You need to adjust both idle circuits simultaneously- not one and then the other. Start at 1-1/2 turns out on both and adjust them in 1/4 turn increments (both together). ------------- |
Posted By: Airfooter
Date Posted: June-27-2013 at 11:34am
Right there lies my problem. I will bump up the idle as well. Thanks for your input! ------------- 1992 Nautique Excel |
Posted By: 89Martinique
Date Posted: June-27-2013 at 12:37pm
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Hmmm. I dont think you will be able to get your low idle. I should have the same motor: I can have a 600rpm neutral idle no prob when its cold. ~500rom in gear. Fully warmed up. Can't get anything below 800 for the life of me! Right now it idles 800~900 rpm. (Depends on how hard you just ran it) And if I back the idle screw out even an 1/8th of a turn, it starts surging and wants to die. As soon as I put it in gear it will die unless returned to the slightly higher idle. When in gear ~750 rpm. A little too fast for me. Now my CC. That thing idles around ~500 rpm and ~250 rpm in gear. Beautiful slow idle. ------------- Current Boats: 1992 Supra Comp-TS6M PCM 351w HO Pro Boss Pro-Tec Ignition - Full Composite (no wood stingers!) 1989 (3rd Gen) Correct Craft Martinique B/R PCM 351w Power Plus 1984 E-Scow Keuka Lake, |
Posted By: TRBenj
Date Posted: June-27-2013 at 12:54pm
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That low of an idle is very hard on your damper... which is why 650rpm is recommended. A 250rpm drop when going from neutral to in gear is also quite excessive... might want to check your alignment to make sure youre not all bound up. A 50rpm drop is more typical if the boat is dialed in. 800-900rpm idle is high. If you cant get it to idle any lower, then you may have a vacuum leak. Or, your butterflies are open. Or, youre idling off the transition circuits (in which case the idle mixture screws wont have much effect). If it only does this when returning to idle after a hard run, also check to make sure the secondaries arent being held open. Its also possible that your dist advance weights arent returning all the way, in which case a shut down and restart will usually reset them. Whatever the case is, something isnt quite right! ------------- |
Posted By: Airfooter
Date Posted: June-27-2013 at 4:37pm
Right now the engine is idling at 600 RPM just fine. I spent about a 1hr and a 1/2 cruising the lake at various speeds, stopping, idling some more, etc, and didn't have any problems. Last year was a different story. I had to have the idle set 750-800 RPM which is why I rebuilt the carb. I am still going to increase the idle to the recommended 650 RPM in gear. ------------- 1992 Nautique Excel |
Posted By: 89Martinique
Date Posted: June-28-2013 at 12:32pm
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Its been that way for a long time. No dizzy weights. Pro Tec takes care of that. The secondaries do close. I will tinker with over 4th of July weekend when it joins the CC in the water. Thats my only grip. Other than that it runs fantastic. I do have to replace my floats. The primary float bowl sunk over winter due ethanol eating the plastic weld seem! My uncle has a pair of after market metal floats waiting for me, just got get em shipped. Now for the alignment. What thread do I go to again to check my alignment. I have always felt that my CC isn't fully lined up. Has a slight vibration under 1,000 rpm. ------------- Current Boats: 1992 Supra Comp-TS6M PCM 351w HO Pro Boss Pro-Tec Ignition - Full Composite (no wood stingers!) 1989 (3rd Gen) Correct Craft Martinique B/R PCM 351w Power Plus 1984 E-Scow Keuka Lake, |
Posted By: Airfooter
Date Posted: June-28-2013 at 12:48pm
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=21279&title=shaft-strut-alignment-video" rel="nofollow - Here is the alignment video. http://correctcraftfan.com/forum/forum_posts.asp?TID=6037&KW=alignment&title=span-classhighlightalignment-span" rel="nofollow - Here is another helpful/popular thread. ------------- 1992 Nautique Excel |