Welcome to Carver Yachts Owners Forum

We are a boating forum for owners of Carver Yachts to enthusiastically discuss all aspects of Carver Boat ownership. Whether you are looking for your first Carver or currently own one, you are sure to feel at home on CarverYachtOwners.com

You are currently viewing our board as a guest which gives you limited access to view most discussions, articles and access our other FREE features. By joining our free community you will have access to searching the forum topics, post topics, communicate privately with other members (PM), respond to polls, upload your own photos and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

454 TBI XL Recommended Spark Plugs and Timing

GAS engine, transmission and generator repair and maintenance discussion forum.
User avatar

Topic author United States of America
390Express
First Mate
First Mate
Posts: 155
Joined: April 6th, 2018, 2:15 pm
Vessel Info: 1996 390 Trojan Express
Location: Michigan
Has thanked: 95 times
Been thanked: 8 times

454 TBI XL Recommended Spark Plugs and Timing

Postby 390Express » November 8th, 2018, 1:14 am

Changed the plugs at the beginning of the year, but the mechanic thinks I may have fouled them out running that bad gas through the motor. I installed RV8C's, copper plus, marine plugs, mostly because they came with the boat. I'll probably use an NGK plug next year, after I get my issues worked out. Pulling a plug from either motor shows that they're both running a bit rich. I have them gapped at 0.040. Recommendations online range from RV8C to RV12C for my motors, 0.035 gap. Wondering if I should go to a hotter plug, or leave it a little rich. Plug isn't wet, just a little black and sooty.

Fairly confident that my issue isn't fuel related at this point, unless its in the throttle body (possibly a plugged injector). The left injector has a slightly different spray pattern and an occasional "drip" vs mist, but it seems to be getting enough fuel, if not a bit rich.

I checked the timing, the port motor reads 14 degrees at idle (around 750), the STBD motor reads 18. When you swap the timing plug to set timing the boat idles slower (around 500) and timing goes down to around 10-12 for the port motor, and is around 14-16 for the STBD motor. The STBD motor is the motor that's giving me trouble (popping through the carb under load, and at random). The rotator/top side of the distributor (forgot the name of the gear looking piece at the top that usually wears out) does not have any play. The dist. gear and/or thrust washer at the bottom of the distributor has a small amount of play. As a result timing varies +/- 2 degrees on the starboard motor, but mechanic says it shouldn't be enough to give us the issue we're having. The advance for the Port motor goes up to around 36 degrees full advance, but the Starboard motor goes up to around 45. Seems way high. (changed the cap and rotor as well, rotor had a mild amount of corrosion)

Any idea as to why, or how to correct it?
Last edited by 390Express on November 8th, 2018, 1:17 am, edited 1 time in total.

User avatar

Topic author United States of America
390Express
First Mate
First Mate
Posts: 155
Joined: April 6th, 2018, 2:15 pm
Vessel Info: 1996 390 Trojan Express
Location: Michigan
Has thanked: 95 times
Been thanked: 8 times

Re: 454 TBI XL Recommended Spark Plugs and Timing

Postby 390Express » November 8th, 2018, 1:16 am

.....
User avatar

Canada
bud37
Admiral
Admiral
Posts: 1628
Joined: April 23rd, 2015, 10:22 pm
Has thanked: 225 times
Been thanked: 335 times

Re: 454 TBI XL Recommended Spark Plugs and Timing

Postby bud37 » November 8th, 2018, 8:32 am

Two questions, do these engines have ECU 's controlling things, what is the idle in gear advance timing spec. The second one , how are you getting these total advance numbers ( procedure ), cause those numbers seem a bit odd, but may be seen if you just blip the throttle.
Ok a third question, do you have knock sensors ?
User avatar

United States of America
km1125
Admiral
Admiral
Posts: 718
Joined: February 28th, 2017, 6:04 pm
Been thanked: 170 times

Re: 454 TBI XL Recommended Spark Plugs and Timing

Postby km1125 » November 8th, 2018, 9:19 am

Is there a mechanical advance on the distributors or is the advance electronic?

The starboard sounds way too advanced, especially at full advance. If it's using mechanical advance, it's solely dependent on engine RPM and should be limited by the mechanical mechanism. That can get bent or worn and springs rust. If it's mechanical I would thoroughly inspect it to make sure it's operating correctly. I don't know anyone local who still has a distributor machine, but that would be cool if you could find one to validate/calibrate the distributors. The amount of mechanical advance is the exact same regardless of initial timing.

If it's electronic advance, then the pickup could be an issue. As the parts rotate faster there's a sharper 'pulse' to detect the cylinder which gives and earlier indication of timing, which would trigger a slightly earlier (more advanced) spark. ALSO, it can differ based on initial timing. As the electronic system is based on TIME instead of actual RPM, it depends on whether it's using a crank based sensor or a cam (distributor) based sensor. Having more base timing causes more "mechanical" advance, as it's based on a percentage of the base timing.

Gapping the plugs too much (not sure if 14% is "too much" though) would cause some misfires especially at high load. This unburnt gas could then be giving the impression of the plugs being "too rich".
User avatar

Canada
bud37
Admiral
Admiral
Posts: 1628
Joined: April 23rd, 2015, 10:22 pm
Has thanked: 225 times
Been thanked: 335 times

Re: 454 TBI XL Recommended Spark Plugs and Timing

Postby bud37 » November 8th, 2018, 9:38 am

While we are getting updated, something else occurs to me.....how are the plug wires, are they new..... sometimes wire routing can create odd firing issues, try to make sure they are kept away from engine ground posts, not pinched in looms etc. Worth a look, its free.
User avatar

Topic author United States of America
390Express
First Mate
First Mate
Posts: 155
Joined: April 6th, 2018, 2:15 pm
Vessel Info: 1996 390 Trojan Express
Location: Michigan
Has thanked: 95 times
Been thanked: 8 times

Re: 454 TBI XL Recommended Spark Plugs and Timing

Postby 390Express » November 8th, 2018, 10:26 am

It’s my understanding that my distributor is the AC Delco 1104060, and it’s the same distributor as most of the TBI/MPI distributors for Merc and Crusader, ECU controlled timing).

Plug wires are new this year, routed the same as factory. I was checking the timing in neutral, looking at the time at idle (750), off idle around 1500, then near the full advance mark of 2800. Engine was slowly brought up to RPM and monitored through acceleration to see if it was jumping around a ton. Nothing out of the ordinary, just seemed unusually high at full advance.
User avatar

United States of America
mjk1040
Admiral
Admiral
Posts: 1118
Joined: July 30th, 2015, 8:15 am
Vessel Info: 1998 355 AC/MY "Deja Vu"
Location: Savannah, NY
Has thanked: 6 times
Been thanked: 146 times

Re: 454 TBI XL Recommended Spark Plugs and Timing

Postby mjk1040 » November 8th, 2018, 2:53 pm

It may just be fouled plugs from the shitty gas issue you had earlier. My Crusaders call for AC Delco MR43lts plugs? Its stamped on the MP intake housing.
Mike :down:
I'd Rather Be Boating!
1989 Sea Ray Seville
1986 Carver Mariner 32'
1990's Thompson 22' Cuddy Cabin
1990's 4Winns 245 Vista Cruiser
1980's Thompson 19' Open Bow
User avatar

United States of America
SplashyLady
First Mate
First Mate
Posts: 181
Joined: January 5th, 2016, 10:02 am
Vessel Info: Carver 3227 Sedan Convertible
1986 - 260 Mercruisers - Kohler 5E
Location: Lake Norman, NC
Has thanked: 19 times
Been thanked: 51 times

Re: 454 TBI XL Recommended Spark Plugs and Timing

Postby SplashyLady » November 8th, 2018, 4:49 pm

Good info on TBI troubleshooting here: http://tbichips.com/?page_id=351
Captain John
Past Commodore, Peninsula Yacht Club
Lake Norman, NC
Carver 3227 - "Splashy Lady"
Aquasport 222CCP - "Gone Fission"
User avatar

Topic author United States of America
390Express
First Mate
First Mate
Posts: 155
Joined: April 6th, 2018, 2:15 pm
Vessel Info: 1996 390 Trojan Express
Location: Michigan
Has thanked: 95 times
Been thanked: 8 times

Re: 454 TBI XL Recommended Spark Plugs and Timing

Postby 390Express » November 8th, 2018, 4:51 pm

It very well could be MK. It’s the solution that makes the most sense to me right now. If the plugs were filed out, an incomplete burn would make the cylinder run rich and make the motor sputter. Once it’s rich and supporting, it can’t recover, stalls. It runs great for 2-3 min, then the check engine light comes on, then it runs like hell, then stalls.


Side note - what does the knock sensor look like, where is it located, and how do I determine if it’s bad?
User avatar

Canada
bud37
Admiral
Admiral
Posts: 1628
Joined: April 23rd, 2015, 10:22 pm
Has thanked: 225 times
Been thanked: 335 times

Re: 454 TBI XL Recommended Spark Plugs and Timing

Postby bud37 » November 8th, 2018, 4:59 pm

390Express wrote:Source of the post It’s my understanding that my distributor is the AC Delco 1104060, and it’s the same distributor as most of the TBI/MPI distributors for Merc and Crusader, ECU controlled timing).

Plug wires are new this year, routed the same as factory. I was checking the timing in neutral, looking at the time at idle (750), off idle around 1500, then near the full advance mark of 2800. Engine was slowly brought up to RPM and monitored through acceleration to see if it was jumping around a ton. Nothing out of the ordinary, just seemed unusually high at full advance.

Just cause wires are routed factory doesn't mean all is ok,...... I still cant figure how you are getting such high timing numbers on both engines......at idle maybe around 8 btdc and maybe full in around 32, I say maybe because I dont know what the spec actually is. It is possible to get higher numbers with a knock sensor to help control things under acceleration. Something is fishy here.
Do these engines run hot ? What does your mechanic say about the timing , he must have some opinion on those numbers....

Return to “Gas Engines/Transmissions”



Who is online

Users browsing this forum: No registered users and 3 guests