Jayl13

Im sure you all are getting tired of me posting questions up but need to know with these engines, what to set the timing to?

I dont have a merc book or a chevy book on hand so im relying on you guys here to get me the right timing for this.
I did not look at the cam cards so I dont know if it is on there or not.

454 standard roatation engine with 110 lsa cam.
Any suggestions?
Thanks
Jason

mxz800

just curious did your engine builder give you an idea to start with?? i am thinking 30degrees total would be a conservative place to start off with.

Jayl13

no he did not say anything but I am going down there after work to drop off the new dip stick tube I had to buy since one of my original ones was rusted through and broke in his hands.
Ill ask him but he does not have the merc book either but he has computer information for the cooling systems and tolerances.
Maybe he does have somthing Ill find out.
Just trying to get an idea from the marine community to see if it differs from the auto industry (my guess would be yes since cars have transmissions and are not under load like marine engines are)
Jason

kaamacat

Jay13. I know everyone always talks about total, but, the initial still needs to be considered for starting-and-such. I would think that 10-12 is fine for starters, but nothing below 8. (and 12 on the upper side).



Bob

NObaja

My stock 454 was 34 total advance 12 at idle. the stock module for a 454mag gives 22 deg of total advance. I would still check the total around 3000 rpm to be sure not to go over.

Turbojack

I run 540 BBC with total 30 locked in. This means motor starts with 30 & motor has no problem starting.

FloridianSon

The only way to find out what she runs the best at is on a dyno or the water test if you have a thunderbolt IV system! Take her out and bring up the timming a little at time and see if you can get from 30- 32-34 to 36 and if she still is makeing power after each increase .she might run best at 36 but then there is the river fuel issue and if you have the stock thunderbolt IV 24* moduel your base timming will also increased to 12*at 36* total. Use timming light to conferm you total timming!!!I would think that 34* is with in reason for most of the fuel that you can find on the water.

blue thunder

8 degrees base is what my manual says. Anymore on startup of new engines and you are foolish. Work the advance out later. Nuff to worry about without that at startup. Focus on the important stuff.

My .02

BT

FloridianSon

Well since we are there! The contents of The book say after you have found the total timming that the motor likes you then find Inital timming by water testing if you have the thunderbolt IV system .Idle the engine in gear install good tac. and vacuum gage,rotate dis. untill the smoothest idle and highest vacuum.Constantly reset the idle speed and air-fuel untill at 750rpm and the highest vacuum with the least amount of throttle opening.The idle screw should not be turned out so far that the throttle blades are resting in the throttle bores and sticking.For instance ,suppose that the engine idles best at 12*initial and makes the most rpm at high speeds with 32* total the ignition module you use is the one with 20*advance.20* plus 12*=32* On a modified motor the initial could be as much as 24*If a module is not available with a small enough amount of advance then the initial advance will have to be lowered down to match the best module attainable and the carb adjusted to the best idle possible at that point.There are 7 different modules.The V-6 which will only give you 6-10*when used on a V8.The V8-20R at 20*The V8-HPat 20*The V8-22 at 22*the V8 -22A at 20*The V8 -24 at 24* and the V8-24S at 24*.Some of these modules will advance faster the the outhers so understand them.For the most part the correct initial timming will be between 8-12*and total of 30-34* above 3000rpm and the timming should advance very smoothly between idle and 3000rpm!

CheckmateF1

I was recently told that on a stock Thunderbolt V ignition system, like my 97 HP500 carb, that the Merc manual says to check total advance right AT 3200rpm. No more no less. Apparently the knock sensor system does some weird stuff with timing after 3200rpm. Thus giving a false reading of accurate total advance if your revving the motor past that.

Before I got this info I was checking total advance with rpm up to 3500-3800rpm. I would have my wife on the throttle going up through 3000 to 3500 or 3800. Once the advance stopped moving, that was my total setting.

Well I guess that's the wrong procedure. Im gonna use the "correct" procedure tomorrow and hope I get better results.

Can anyone confirm that this is the correct procedure? Anybody have a shop manual for 97 and up carb HP motors?

Thanks, Eric