One more...carb opening vs timing advance

[cocacola]

Recently, I replied to this post (http://forums.screamandfly.com/forums/showthread.php?t=175159)and understand that my timing is off abd does not come in at the right time.

Need to know how to properly adjust linkage to have timing come in at right time. Carbs are opening before timing changes...

Help!!!

[Raceman]

Carbs opening first will make it REAL boggy/lazy down low. If you get a service manual it will tell you how to set the pickups. It's pretty hard to get the timing in too quick unless it makes the engine idle too fast to shift right. The F1 engines with the Speedmasters (non shiftable gearcases) run the timing at full advance locked, so it's all in when the engine starts.

[cocacola]

Thanks Raceman.
I have a 2.5 service manual, but this is a 2.4.
Would adjustments be the same?




Carbs opening first will make it REAL boggy/lazy down low. If you get a service manual it will tell you how to set the pickups. It's pretty hard to get the timing in too quick unless it makes the engine idle too fast to shift right. The F1 engines with the Speedmasters (non shiftable gearcases) run the timing at full advance locked, so it's all in when the engine starts.

[T-REX]

They have quite a few diffrent cams for carbs, and they all advance the time'in at diffrent rated...U need to find the one that fully advances tha time'in before the carb shafts move(early 2liters)...U have to make ya own linkage because tha Vert fronts had diffrent linkage than horz fronts

[cocacola]

my "cam" is touching the roller on carb linkage when there is no throttle applied...so any movement starts opening carbs.

is that right?

Since I probably won't make my own linkage, I have to assume I need to adjust linkage so timing is being advanced BEFORE cam touches roller.

How does that sound?



They have quite a few diffrent cams for carbs, and they all advance the time'in at diffrent rated...U need to find the one that fully advances tha time'in before the carb shafts move(early 2liters)...U have to make ya own linkage because tha Vert fronts had diffrent linkage than horz fronts

[Jay Smith]

Lets see if my memory is clicking tonight from my old carb days ! I think the line on the cam should be lined up to the center of the carb linkage roller... To be set correctly.

But as Rex said there are many different cams that open the carbs and advance the timing in different ratios throttle verses timing advance...

Good luck,
Jay

[Jay Smith]

You CAN give the motor MORE lead timing ( I always do , they hit harder out of the hole , ever EFI motors done like that ) but you may have to work on the idle as advancing the lead timing can sometimes increase idle speed..


Jay

[cocacola]

Thanks guys. Right now, it's adjusted exactly as Jay says. I will have to start hunting around.


Lets see if my memory is clicking tonight from my old carb days ! I think the line on the cam should be lined up to the center of the carb linkage roller... To be set correctly.

But as Rex said there are many different cams that open the carbs and advance the timing in different ratios throttle verses timing advance...

Good luck,
Jay

[T-REX]

early 2liters let tha time'in advance before tha carbs even move...that iz tha cam ya want!!!....I have made cams outta aluminium to make the carb/time'in do what I want for differnt tess...U kan also grind exsisting cams to allow the time'in to advance first....I also kan cheet tha cam by putt'in sum clearance between the cam and the roller...az pee wee sayz, tha time'in set about splitcase alwayz leeves good, but ya may have to adjust it a lil lower to git the idle down(split case don't allow runn'in shifts too good)...

Oh, do ya final idle adjustments in the water, the backpressure of the water makes quite a differnce with idle...in and out ov geer!!

[1BadAction]

Rex, does the XR2 have that cam?

[T-REX]

It haz one ov 3!!!....But tha vert reed one iz one ov tha ones to look for:thumbsup:

[cocacola]

T-Rex,
I "cheated" the cam as you mentioned this weekend (gap between cam and roller so timing advance before carbs start to open). Holeshot and lower rpm running MUCH better. Remember...I am no outboard mechanic. Is there any harm in all the timing being in BEFORE carbs move? That's not how mine is set, but it looks possible and wondered if I could get it better. Mostly, I tow my daughter around on the tube. Much easier to keep engine speed where I want it to stay on plane. Until this weekend, I did not know just how damn good 200 horsepower felt out of the hole. The way it ran yesterday reminded me of how good my old 115 inline 6 use to tow the tube going slow.

[Mark75H]

I am not an expert on the 2.4, but most motors are easier on the starter and battery if the spark is not full on before the carbs move. Your idle speed may be a little fast, too.

[cocacola]

I am not an expert on the 2.4, but most motors are easier on the starter and battery if the spark is not full on before the carbs move. Your idle speed may be a little fast, too.

I understand that, but I don't have to touch throttle to start it. Well...that's not totally true, but yersterday, it started much easier when I slightly advance throttle once it started to fire. I attribute this to the way spark was setup.

[T-REX]

Starter will take A lil mo ov a jolt when ya start with advanced time'in, but if it iz tuned rite, U should never heer tha starter....A bump ov tha switch, ya heer tha bendix hit tha flywheel, and it's runn'in....I run most all my river motas(even on my center console) around 6 to 8* BTDC....If ya run them any higher, it git's hard to shift...

I start my lil F-1 wit 10* time'in, and 300# compression...I have started it with full 29* time'in, but it haz to be on 24 volts!!:eek: