Forums
NautiqueParts.comNautiqueSkins.com - Correct Craft Upholstery and Part
  New Posts New Posts RSS Feed - Bad gas?
  FAQ FAQ  Forum Search   Register Register  Login Login

Bad gas?

 Post Reply Post Reply Page    <12
Author
KENO View Drop Down
Grand Poobah
Grand Poobah


Joined: June-05-2004
Location: United States
Status: Offline
Points: 3478
Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: February-08-2018 at 8:32pm
Originally posted by Gary S Gary S wrote:

Originally posted by KENO KENO wrote:

Also there is talk about what spark plugs to use in the thread.


Now Ken,depending on what oil I use,what make filter I choose,how often I change my impeller or what type of rag I remove wax with- whats the best brand plug to use?


Your favorite brand of course
Back to Top
jblocal View Drop Down
Senior Member
Senior Member
Avatar

Joined: September-06-2010
Location: Stuart, Florida
Status: Offline
Points: 177
Post Options Post Options   Thanks (0) Thanks(0)   Quote jblocal Quote  Post ReplyReply Direct Link To This Post Posted: February-20-2018 at 7:50pm
Got it all put back together with the gt40p heads and new exhaust, Started right up and sounds great in the driveway. Hopefully going put it in the water tomorrow after work. I’ll report back with results.
Back to Top
MrMcD View Drop Down
Platinum Member
Platinum Member
Avatar

Joined: January-28-2014
Location: Folsom, CA
Status: Offline
Points: 1562
Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: February-21-2018 at 2:11am
It will have more horsepower and torque with your new heads. A good move on your part.
Glad you got it back running again. Since you now have more compression you will want to verify how much timing you have at 3,000 to 4,000 RPM.   You need to know the amount at this RPM so you know the engine is safe to run hard.
Each head design has unique known timing constraints, some can only accept 28 degrees while others need 40 degrees for max performance. The 351W heads I believe are happy at 35-36 degrees but I will let others with more Ford knowledge advise you.
A set back or dial back timing light helps to determine how much centrifugal advance your distributor has and if it advances smoothly without sticking.   Once you know your advance you can set your timing at idle to allow the right amount at 3,000.
Most want your centrifugal advance fully in by 3,000 for best performance.
If you find your distributor allows 24 degrees of advance and you want 36 total timing at 3,000 you would set idle to 12 and your good to go.   It is just math.
If the distributor does not advance properly this is the right time to fix it.
Proper timing makes a huge difference in performance and economy. Hope this helps.
!
Back to Top
jblocal View Drop Down
Senior Member
Senior Member
Avatar

Joined: September-06-2010
Location: Stuart, Florida
Status: Offline
Points: 177
Post Options Post Options   Thanks (0) Thanks(0)   Quote jblocal Quote  Post ReplyReply Direct Link To This Post Posted: February-21-2018 at 8:43pm
Great! Thanks! Going have to look into that. Boat ran great today on the water. Throttle was lot more responsive even at higher rpm. I only brought it up to 3500 for a second. Cruised around at 3150 for while and was doing 26knot which feels a little faster. The exhaust even sounds better. Going to check my timing and open her up next time.
Back to Top
tryathlete View Drop Down
Platinum Member
Platinum Member
Avatar

Joined: April-19-2013
Location: Lake Villa, IL
Status: Offline
Points: 1235
Post Options Post Options   Thanks (0) Thanks(0)   Quote tryathlete Quote  Post ReplyReply Direct Link To This Post Posted: February-21-2018 at 8:56pm
Originally posted by MrMcD MrMcD wrote:

It will have more horsepower and torque with your new heads. A good move on your part.
Glad you got it back running again. Since you now have more compression you will want to verify how much timing you have at 3,000 to 4,000 RPM.   You need to know the amount at this RPM so you know the engine is safe to run hard.
Each head design has unique known timing constraints, some can only accept 28 degrees while others need 40 degrees for max performance. The 351W heads I believe are happy at 35-36 degrees but I will let others with more Ford knowledge advise you.
A set back or dial back timing light helps to determine how much centrifugal advance your distributor has and if it advances smoothly without sticking.   Once you know your advance you can set your timing at idle to allow the right amount at 3,000.
Most want your centrifugal advance fully in by 3,000 for best performance.
If you find your distributor allows 24 degrees of advance and you want 36 total timing at 3,000 you would set idle to 12 and your good to go.   It is just math.
If the distributor does not advance properly this is the right time to fix it.
Proper timing makes a huge difference in performance and economy. Hope this helps.


How are you determining when detonation occurs? Are you going by ear? Dangerous territory! Are you using 87 octane as your base fuel?
Back to Top
MrMcD View Drop Down
Platinum Member
Platinum Member
Avatar

Joined: January-28-2014
Location: Folsom, CA
Status: Offline
Points: 1562
Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: February-21-2018 at 10:40pm
If working on a boat I always assume 87octane. Many times it is all you can find on the water.
I like to stay conservative on timing since I have seen many detonation damaged engines in my career . Adding an extra 2 degrees timing can offer a couple more horsepower but in my book it's not worth the risk.
You are correct that serious detonation can be silent. You just feel the engine start to lay down on power. I have seen fractured rings, broken pistons, blown head gaskets and pounded out rod bearings from detonation.
Most of those guys say the engine was running the best it ever had right before they blew up.
I would stay with a known safe total advance number for a 351w with the P heads and with a carburetor. As stated I think he would be OK at 35 or 36 but I don't know so I'll let the Ford experts advise.
If it pings at lower RPMs the timing curve is a little fast and it can be slowed down.
!
Back to Top
jblocal View Drop Down
Senior Member
Senior Member
Avatar

Joined: September-06-2010
Location: Stuart, Florida
Status: Offline
Points: 177
Post Options Post Options   Thanks (0) Thanks(0)   Quote jblocal Quote  Post ReplyReply Direct Link To This Post Posted: February-22-2018 at 9:00am
I had to put a timing tape on my harmonic balancer and Mark new lines last time I set timing. Marks are gone now I need to remark it. I didn’t hear any pinging running. Going to check it after work today.
Back to Top
tryathlete View Drop Down
Platinum Member
Platinum Member
Avatar

Joined: April-19-2013
Location: Lake Villa, IL
Status: Offline
Points: 1235
Post Options Post Options   Thanks (0) Thanks(0)   Quote tryathlete Quote  Post ReplyReply Direct Link To This Post Posted: February-22-2018 at 10:56am
We don’t need vacuum advanc e discussed in the attached link, because our engines are always loaded by the prop (there’s no light load at higher rpm to take advantage of vacuum advance). I really liked this link on the subject of ignition timing.

Importance of ignition timing
Back to Top
MrMcD View Drop Down
Platinum Member
Platinum Member
Avatar

Joined: January-28-2014
Location: Folsom, CA
Status: Offline
Points: 1562
Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: February-22-2018 at 8:35pm
I did a little forum searching and it is stated that the GT40P Heads have the fast burn chambers so max total timing recommended with a good fuel mix is 32.   The GM 1996 and newer Vortec heads are similar in needing less timing than the older head designs for max performance. As hard as boat engines work you might want to start with 30 total timing and tune from there to avoid any detonation issues. Sorry to mislead stating 35 or 36 should be safe.   With the old heads that would have been safe but not with the GT40P heads. I run a 1995 GT40 with P heads but it is computer controlled so I have not needed to check timing but thanks to your engine now I know.
!
Back to Top
TRBenj View Drop Down
Grand Poobah
Grand Poobah
Avatar

Joined: June-29-2005
Location: NWCT
Status: Offline
Points: 19650
Post Options Post Options   Thanks (0) Thanks(0)   Quote TRBenj Quote  Post ReplyReply Direct Link To This Post Posted: February-23-2018 at 4:27am
Gt40 has gt40 heads... not gt40p (unless you swapped them).
Back to Top
MrMcD View Drop Down
Platinum Member
Platinum Member
Avatar

Joined: January-28-2014
Location: Folsom, CA
Status: Offline
Points: 1562
Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: February-23-2018 at 2:29pm
Thanks Tim.   I know Chevy's, My Nautique has the Ford. Still learning.
!
Back to Top
jblocal View Drop Down
Senior Member
Senior Member
Avatar

Joined: September-06-2010
Location: Stuart, Florida
Status: Offline
Points: 177
Post Options Post Options   Thanks (0) Thanks(0)   Quote jblocal Quote  Post ReplyReply Direct Link To This Post Posted: March-13-2018 at 9:01pm
I still havnt got everything 100%. Can’t get my idle circuit to function properly. Idle screws all the way in makes engine idle better. Can’t find any vac leaks. Don’t see any fuel dripping. Pulled the carb cleaned it and checked powervalve. Vac is 14 at idle and compression was 120 on one side 118-119 other. 10 degree initial turning. Thinking either i need rebuild my carb which is pretty new or redo my valve adjustment. Especially after reading recent post on here. Can you tell from those numbers if valve isn’t adjust properly? And if they could have anything to do with idle circuit? Engine starts, runs fine, no noise, even idles damn good but rich.
Back to Top
MrMcD View Drop Down
Platinum Member
Platinum Member
Avatar

Joined: January-28-2014
Location: Folsom, CA
Status: Offline
Points: 1562
Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: March-14-2018 at 3:00am
I'm not a carb guru but if your throttle plates don't close far enough it causes the idle circuit problems.
If you can close the throttle more the idle circuit may start functioning better.
When they are not closed properly the carb will pull fuel ignoring the idle circuit.
If memory serves me correctly the screws on the side of the Holley adjust fuel flow. Screwing them in is supposed to reduce fuel.
Look down the primary / front barrels a slot should be exposed with the throttle closed.
Open the throttle all the way and look with a flashlight to see the full slot.
Do a little reading and you will get dialed in how to set up your throttle plate setting.
!
Back to Top
KENO View Drop Down
Grand Poobah
Grand Poobah


Joined: June-05-2004
Location: United States
Status: Offline
Points: 3478
Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: March-14-2018 at 4:28pm
Originally posted by jblocal jblocal wrote:

I still havnt got everything 100%. Can’t get my idle circuit to function properly. Idle screws all the way in makes engine idle better. Can’t find any vac leaks. Don’t see any fuel dripping. Pulled the carb cleaned it and checked powervalve. Vac is 14 at idle and compression was 120 on one side 118-119 other. 10 degree initial turning. Thinking either i need rebuild my carb which is pretty new or redo my valve adjustment. Especially after reading recent post on here. Can you tell from those numbers if valve isn’t adjust properly? And if they could have anything to do with idle circuit? Engine starts, runs fine, no noise, even idles damn good but rich.


Is that 14 in vacuum at idle in neutral or idling in gear

Here are some representative numbers from a post last year

Had 20 in idling in neutral at about 700 rpm

Originally posted by KENO KENO wrote:


A lot of people aren't gonna want to believe what I'm about to say, but if that's the case they can verify some readings for themselves.

You always hear that boats run under constant load and then when a power valve discussion pops up, somebody will say that when you punch it from a dead stop, vacuum goes to zero and quickly recovers.

It don't happen that way though

If you give it full throttle vacuum drops to zero and stays there till you back off the throttle.

If you run the boat at a steady 4000 rpm's vacuum stays steady, it never recovers to a higher vacuum till you back off the throttle.

Same thing at any RPM in a boat that's operating under a constant load.

Here are some representative numbers on a good running 351 that I wrote down a couple of years ago and verified again with a quick boat ride tonight

Full throttle     zero

4000 rpm        2.5 inches vacuum

3000 rpm        7 inches

2000 rpm        9.5 inches

1000 rpm in gear   13 inches

idling in neutral 20 inches

This particular boat has a 6.5 power valve so it's open whenever the boat is going over about 3300 rpm

All these numbers can vary some from what I have depending on engine loading, hull efficiency etc but they'll be steady at whatever reading you have till you move the throttle. It's the concept we're after here. And remember it ain't a car.

Back to Top
jblocal View Drop Down
Senior Member
Senior Member
Avatar

Joined: September-06-2010
Location: Stuart, Florida
Status: Offline
Points: 177
Post Options Post Options   Thanks (0) Thanks(0)   Quote jblocal Quote  Post ReplyReply Direct Link To This Post Posted: March-14-2018 at 7:58pm
This is just idle on the trailer. I might be mistaking but I’m pretty sure I gave it some gas and vac actually increased to 20. I ordered some shims and Holley rebuild kit. Going go back thru valve adjustment one more time. Read great post yesterday on here gave me better idea. Think I’m also going drain tank and start fresh with rec 90. I’m about wore out working on it. Seems I’m stuck and going over things multiple times.
Back to Top
MrMcD View Drop Down
Platinum Member
Platinum Member
Avatar

Joined: January-28-2014
Location: Folsom, CA
Status: Offline
Points: 1562
Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: March-14-2018 at 10:33pm
In neutral/no load vacuum will increase above idle. When you add load is when vacuum goes away or falls off.
The higher the load the less vacuum you have when in gear accelerating.
As Keno showed with partial throttle opening your vacuum will vary depending on RPM.
In a boat engine is always under load if in gear unlike a passenger car.
In a boat at 30 MPH your throttle plates are probably 30% open so you still create a little vacuum, floor it and vacuum will be zero.
!
Back to Top
KENO View Drop Down
Grand Poobah
Grand Poobah


Joined: June-05-2004
Location: United States
Status: Offline
Points: 3478
Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: March-15-2018 at 6:27pm
14 inches is kinda low and 120 is too with the 40P heads unless your gauge(s) are off.

You've probably read about different causes which is probably why you're buying shims.

You're probably referring to the link I posted the other day with Shep 72's method, it can't hurt to check. It works good.

I'd guess you won't need the shims and that the valves are OK, but you'll know soon.
Back to Top
jblocal View Drop Down
Senior Member
Senior Member
Avatar

Joined: September-06-2010
Location: Stuart, Florida
Status: Offline
Points: 177
Post Options Post Options   Thanks (0) Thanks(0)   Quote jblocal Quote  Post ReplyReply Direct Link To This Post Posted: April-01-2018 at 9:24pm
Update: I ended up needing to shim most of the rockers. Drained tank, rebuilt carb, and fresh plugs. 1 screw is responding now on idle/air mix. Other doesn’t seem to do much. Got the vac at 16 nice and smooth. Took the boat out today and performance wise has done better than ever. The gt40p head seems to have more power and huge improvement over the stock heads.
Back to Top
KENO View Drop Down
Grand Poobah
Grand Poobah


Joined: June-05-2004
Location: United States
Status: Offline
Points: 3478
Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: April-02-2018 at 2:55pm
So how's your compression after the shimming?
Back to Top
MrMcD View Drop Down
Platinum Member
Platinum Member
Avatar

Joined: January-28-2014
Location: Folsom, CA
Status: Offline
Points: 1562
Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: April-02-2018 at 3:00pm
Good news, sounds like you got it finally.
!
Back to Top
 Post Reply Post Reply Page    <12
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Copyright 2018 | Bagley Productions, LLC