Hey gang, I know from researching that base timing for a 454 should be somewhere around 8-10 degrees and the thunderbolt module adds another 24 to get to a total timing number of 32-34. My question to the experts out there is what would happen if initial timing was only set to zero? I think a ****up was made by my mechanic. initially boat was idling great and sounded good. This was a fresh rebuild, we broke in cam at 2000-2500 rpm on the trailer backed down the ramp but discovered water coming in somewhere so we didn't run it that day. They took drive off and double checked bellows and couldn't find anything, They tried a couple fixes for that and finally we decided to say screw it and try to run the boat. So we started out and the motor seemed to be running good but after about 20 minutes we got a temp alarm and then the boat wouldn't idle properly. Very high idle. We did get the motor to cool down enough to idle back to the dock but the idle stayed really high. They did some tinkering and kinda sorta maybe found a vaccumn leak when they sprayed some carb cleaner around some different areas though it didn't seem real distinct. Also important to note that when the temp alarm went off and we shut it down it was dieseling big time. The following day at the shop we started it up and again it was idling high right out of the gate and dieseling upon shutdown. Today, my mechanic informed me that the tech that worked on the boat and set the initial timing said he set it to zero which my mechanic knew was incorrect and part of the problem. I like my mechanic, but he's a younger guy and I don't think he is as knowledgeable with old school carburated stuff. The tech he had working on it is a nice enough guy but this isn't the first thing hes ****ed up. After this failed attempt we found more water in the bilge and finally were able to pinpoint it to the recently replaced steering pin. They installed a new gimple ring using the jr marine method. They took it apart this week and discovered the seal between the bushings was missing. This tech did that work too. So again, I like my mechanic, he has apologized and made it clear to me that the steering pin correction is on his dime and he is doing everything to make this right. He has worked dilligently on this boat but without a doubt hes struggling to hire good experienced talent and hes trying his best to oversee, run ashop and not totally babysit everyone. my concern now is that we messed something up running it as much as we did with the timing out of wack. I'm hoping maybe just soemthing with the carb but i suspect simply getting the timing set properly isn't going to resolve this issue because it was running okay and then suddenly now it's not. Would the dieseling and backfiring have done something to damage the carb? BTW, carb was freshly rebuilt as part of the engine rebuild process and worked fine on the motor the brief time it was used before motor blew up.

Sorry, thats all a mouthful. I'm starting to lose my patience and just want to get this damn thing figured out and on the water.

Engine may have overheated due to timing being slow, or maybe something else going on. Not sure 10 deg slow would make it overheat that quick, depends on how hard you were running it. If you have a Holley carb the power valve is probably ruptured from the “dieseling “
That will make it run rich though not lean. Hope it didn’t get hot enough to damage anything.

We had opened her up a good bit and briefly were up at 5k rpm so we weren't holding back.too much. We were able to get her cooled down pretty quickly and while idling back to the dock she stayed plenty cool.
It is a Weber carb, not a Holley if that makes a difference.

Hard to believe it idled well and ran up to 5000rpms with the timing 10* retarded.

I am a novice with this stuff but if I hadn't seen it and heard it with my own eyes I'd be questioning it. Iv never run this boat before ; I bought it as a fun project to possibly flip or maybe use for a year or 2 then sell. Scored it cheap from a friend that owned it for close to 20 years and had it sitting with a blown engine. Reason I give you this back story is just to say that I couldn't really speak to the performance numbers I was seeing because I didn't have a benchmark from previous use.

I'm just deathly scared that something like a cam lobe got flattened and we will have to pull motor again.

Would be pretty low on power, and wouldn't want to start easily being 10 deg retarded. Also, dieseling is normally caused by a "hot spot" in the engine burning the fuel or highly advanced timing, not retarded. It shouldn't have caused any long term issues but not sure what you have going on.

I’d have that mechanic check to make sure that distributor is in proper and it is set pointing toward number 1 cylinder at TDC before he goes checking the timing.

Let’s see some pics of this schit show. Frt of engine 1st.

Many variations of ‘rebuilt’ engine. Give us a parts and machine work rundown.

Do a compression test.

Bored 30 over. 18cc icon forged dome pistons, comp cams Xtreme marine 262h cam kit, peanut port heads. Bought motor used last year, when we sorted through all the. It's and got it running, it blew up first trip out. Tear down by revuilder found evidence of serious water in one of the cylinders the amount of rust was why it had to be bored 30 over. Looks like the rust are up the rings and made it lose compression on that hole. Machine work was done here in Tampa by united speed world, a well regarded shop that's been around quite awhile. Motor rebuilt by local engine rebuild shop also with good reputation and plenty of experience with marine engines. Since it's a gen 5 flat tappet motor I made the decision to do the mild cam upgrade and forged domes to boost power. New manifolds and risers were put on our of an abundance of caution inspite of the ones that came off looking like they were in good shape.
link to cam https://www.summitracing.com/parts/cca-k11-232-3

This should be my 10th post hopefully I can post pics now but pretty basic gen v 454 . Do I dare tell you guys that it's in a sea ray sundancer, not a go fast boat lol