81 351 stall when engaging F or R
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=34714
Printed Date: April-28-2024 at 4:35am
Topic: 81 351 stall when engaging F or R
Posted By: kthackwray
Subject: 81 351 stall when engaging F or R
Date Posted: October-01-2014 at 1:23pm
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Just took my new - rebuilt 81 tique for it's maiden voyage after a engine rebuild I bought it stripped down so no real reference point regarding how it was before So a couple of problems - starter is hit and miss See earlier post And engine stalls when I put her into forward or reverse at idle If I engage quickly and gas her she gets going. I have to say that the timing may not be perfect but she fires up ok and settles to an idle with a slight tappet noise which also needs to be sorted by the engine rebuild guy Anything I should check before trying to get the engine tuned ? |
Replies:
Posted By: GottaSki
Date Posted: October-01-2014 at 1:51pm
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Likely Vacuum leak, or the primary metering block has clogged idle fuel orifices. Is the engine responsive to the the idle mix ajusters? ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: backfoot100
Date Posted: October-01-2014 at 2:07pm
So you're saying that you haven't timed it yet? ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
kthackwray wrote:Posted By: TRBenj
Date Posted: October-01-2014 at 2:21pm
No. Tune it first. |
Posted By: kthackwray
Date Posted: November-10-2014 at 2:42pm
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Just a quick update - and possibly another question So in the mean time I have had the engine rebuild guy have a look and we had to adjust the hydraulic rockers - tappet noise is gone - we then adjusted the timing and she is sounding much smoother. He set the idle a bit up because the motor is still tight and has to be run in. Got her out on the water this weekend and had to gas it once I put it gear (or else the motor stalls ) Ran a couple of laps around the dam and the motor seems to getting better and better Then I tried some adjustments to the carb - basically set the idle screw to as low as I could get it to idle - around 1000 rpm - then adjusted the 2 idle mixture screws 1 1/2 turns out from closed (from the PCM manual ) - settled on anothe 1/2 turn out on each for best throttle response result I then tried to lower the idle a bit more but she won't drop below 1000 rpm which seems quite high for engaging the gearbox (and definitely too fast for a no wake zone ) Throttle response seems good though So to the previous question - Is the engine responsive to the the idle mix adjusters? - Yes Should I still be looking for a leak ? I have not had the carb rebuilt - only put in a new carb gasket so far I have jotted all the carb numbers down and will try source a carb kit next - then probably take it to a carb shop for testing |
Posted By: phatsat67
Date Posted: November-10-2014 at 3:13pm
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What is the initial timing set at?? Not being able to idle the engine below 1000 rpms and a stall when going into gear points towards a big Vacuum leak. Verify timing is within the correct range then start looking for vacuum leaks anywhere and everywhere. Were the heads milled? Did the machinist mill the intake manifold to match the milled heads? Also, you say it is responsive to the idle mixture screws. You should be able to kill the engine with one screw turned close to or all the way in. If you can't do that and the butterfly idle screw is all the way backed out you have a massive vacuum leak. ------------- |
Posted By: Gary S
Date Posted: November-10-2014 at 4:16pm
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You could take off the throttle cable from the carb to make sure that's not the cause of the high idle ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: TRBenj
Date Posted: November-10-2014 at 4:21pm
| Maybe we should take a step back. I think we're all under the assumption that the cam has been broken in at a minimum. I also would not be dinking around with the idle too much before setting the rings. Maybe you can elaborate a bit on exactly where you are in the post-rebuild break in process before we continue. |
Posted By: Gary S
Date Posted: November-10-2014 at 6:01pm
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If you take one step back,you could fall in ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: kthackwray
Date Posted: November-11-2014 at 6:19am
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Thanks for the help The heads were fine but I have a new block - so not sure if this would affect the manifolds sealing. Post Build break in - the motor has probably run for 1 hrs max since rebuild The rebuild guy suggested 2 - 3 hours at a constant 2000 rpm without hard acceleration for starters - and as I said - it fells better and better. Timing - old school guy - so - adjust the point gap -turn the dizzy till she purrs and achieves the best throttle response. At this stage I am still weighing up my options for when I get it out on the water again.I want to have a few things to try before I start stripping the carb etc. I will run her on the trailer with a big tub of water and see if I can kill the engine by screwing in the idle mixture screws - this makes sense to me and quite an easy check to see if I have a vacuum leak I also pulled the numbers off the Holley Carb - 9776 comes up on the Holley site as INSTALLATION & ADJUSTMENT INSTRUCTIONS 199R8407-2 Is this the same as the 4150 or 4160 ? It has no electric choke ? is this original ? Sorry for all the questions but I bought the SN with the motor in 1000 pieces Hey - What a forum ! - thanks for all the help |
Posted By: 8122pbrainard
Date Posted: November-11-2014 at 9:23am
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Yes, your carb needs an electric choke. I also suggest getting a timing light. The "old school" method worked but that was on vintage low RPM engines. A dwell meter wouldn't hurt ether. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: kthackwray
Date Posted: November-11-2014 at 9:40am
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OK - so it looks like the 9776 is not the original marine carb - just a generic replacement 4 barrel Holley for automotive use - Hmmmm Guy at the carb shop will see if it has the necessary bits for a marine application - looks like we are heading down another expensive upgrade ! |
Posted By: Orlando76
Date Posted: November-11-2014 at 9:45am
| I wouldn't fool with trying to convert an auto carb to a marine. I don't think it can be done and if your carb guy says it can, I'd look for a new carb guy. If nothing else is bite the bullet and buy a marine 4160 from the mass rebuild company in Jacksonville FL. Not certain their name but several here used them. |
Posted By: 8122pbrainard
Date Posted: November-11-2014 at 9:47am
Get the proper carb. An obvious clue to it being an automotive is the lack of J tubes above the carb throat. How did you end up with the auto carb? Your "carb guy" at the carb shop? If so, he sure needs some educating!  ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Hollywood
Date Posted: November-11-2014 at 11:03am
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I wouldn't classify buying the proper marine 4160 carb an "upgrade". More like a cost of doing business. ------------- |
Posted By: phatsat67
Date Posted: November-11-2014 at 1:18pm
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+1^^^ ------------- |
Posted By: kthackwray
Date Posted: November-17-2014 at 4:22am
| I managed to source a refurbished 4160 in country from a hot rod shop who happened to have one - should get it this week and go from there ! |
Posted By: 8122pbrainard
Date Posted: November-17-2014 at 10:08am
Make sure it's the marine version. The 4160 comes in several forms. Which one did you get? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: kthackwray
Date Posted: November-17-2014 at 12:07pm
| Definitely a marine version ! |
Posted By: kthackwray
Date Posted: January-26-2015 at 4:53pm
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So my refurbished Marine carb arrived and I wanted to install it and it has 2inlet pipes So I starts to see what else I may need to change and noticed the Vacuum pipe on the inlet manifold and start to wonder what this is for And then bingo the penny dropped I blocked it with my finger and presto the beast is tamed A few more adjustments and she is idling at 600 rpm and crisp throttle response etc Now the dilemma Do I replace what looks like a new 450 cfm automotive carb with a really old looking 600 cfm marine carb and which looks like it has a pile of additional mechanical parts to worry about concidering the expected increase in fuel consumption etc Gonna run it on the water this weekend and see how she goes before making a final decision |
Posted By: Orlando76
Date Posted: January-26-2015 at 4:58pm
Automotive carb!? Whoa you are going to get heat from this forum  If I follow your post correctly: Honestly yes, dump the auto carb. There shouldn't be any extra parts on the marine, actually the marine should have less. Fuel consumption increase? Probably going to be opposite. |
Posted By: CrazyCanuck
Date Posted: January-26-2015 at 5:03pm
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I'm no expert, but the higher max cfm doesn't mean you will burn more fuel. Not in normal cruising anyway. Unless I have it wrong. I don't think anyone will say its okay to run an automotive carb at all. I had one on my 78, and bought an Autoline carb. The Cm-702 is a reman of a Holley 4160 and worked great right out of the box at about half the price. So far I am very pleased at how much fuel the SN burns.... ------------- https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcRtW3vJrMHLdqBzndt9VX3oOpBuRopGlzKq9Ea7pAO7wnTuoD8E8g |
Posted By: seacamper
Date Posted: January-26-2015 at 5:15pm
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Hey Kenny The guys are trying to tell you that the auto carb could kill you and anyone in your boat. The marine carb is made to keep gas and sparks back in the engine so that you don't blow up from fumes or burn up due to an out of control fire. The auto carb is a non starter. ------------- 1980 Ski Nautique Boat Bar 1988 Mastercraft Tristar Open Bow 1988 Mastercraft Tristar Closed Bow 1969 Seacamper Houseboat 1986 Harris Pontoon 2004 Seadoo GTX SC + Flydive Xboard 1999 Adventurecraft |
Posted By: 8122pbrainard
Date Posted: January-26-2015 at 6:00pm
At least South Africa is far away from me so when it blows I'm still safe!  Stick with marine!------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: kthackwray
Date Posted: January-27-2015 at 4:45am
| OK - Got it - Africa is not a place for sissy's ! |
Posted By: SNobsessed
Date Posted: January-27-2015 at 11:45am
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All size carbs meter fuel at the correct A/F ratio. The engine only pulls the air it's displacement pumps (minus deficiencies). Bigger carbs don't drink more fuel for a given engine, they just allow more air flow. The downside is that big venturies are less responsive to low air flow, so a big carb does't work well on a small engine. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |