Thunderbolt IV timing advance

[KEESEY]

So I spent a healthy amount of money building a 388 stroker to put in my boat, issue I am having is timing. I don’t think the stock thunderbolt IV has enough built in advance to keep it running efficiently, after 2k the engine breaks up and performance is reduced, I have done some searching in here and cannot find what the stock system has for a total advance and what my idle timing should be, any help would be greatly appreciate I can list all the parts for the engine build if needed

 

[alldodge]

There are some numbers on the module it should be V8-(two numbers). These two numbers tells you how much advance the module has

 

[Scott Danforth]

If its the V8-24 module, its all in by 3700 RPM

If your breaking up by 2000 RPM, you have another issue.

 

[KEESEY]

I am going to check what my advance is at 3500 this weekend, was just curious about the advance, so if I am not getting what it is suppose to be putting out then I can replace it and if it is working properly I can move on to the next issue, I know I am running a little rich currently but don’t want to lean it out too much and burn up some parts, don’t think it’s too rich as it starts right up and idles fine, it’s a brand new 650 quick fuel marine carb, appreciate the help with the numbers and advance I will do some more digging this weekend

 

[Scott Danforth]

Here you go

 

[Bondo]

Ayuh,...... Welcome Aboard,.... I donno that carb, but to see what's goin' on, take it out, 'n test run it, then quickly shut it down, 'n check the spark plug colors,......

Could be the hi-speed circuit is floodin' the motor, or goin' lean,.....

Either way, the spark plugs will tell ya,....

 

[KEESEY]

So is there any particular way to set base advance, I know some have wires you use to take the advance out but I don’t see anything on this module that would allow that, right now when I hit the damper with the timing light at 800-900 rpm I am at 9degrees

 

[Bondo]

So is there any particular way to set base advance, I know some have wires you use to take the advance out but I don’t see anything on this module that would allow that, right now when I hit the damper with the timing light at 800-900 rpm I am at 9degrees

Ayuh,..... The T-Bolt IV is 'bout the simplest reliable marine ignition, Ever,..... It'll work til it don't,....
'n I've never had that happen, yet anyways,....

Yer at 9*,.... It's point, 'n shoot,..... no wire jumpin',....

Idle is alittle high,... oughta be 650/ 700 rpms,....

 

[alldodge]

The TB-IV is a point and shoot, no base timing mode. Are you at 9 BTDC or ATDC, should be Before?

 

[KEESEY]

Ok just snuck out of class and fired it up again, I was at 9 BTDC and plugs where black, I have the v8-22A I spun the motor up to 3700 and adjusted till I had 35-36* and let it come back down, then adjusted idle to 700rpm and then leaned it out till it about stalled and went back half turn, it snaps up a lot better and idles way better, also starts easier, going to see how it does on Saturday under a load, hit it at idle and it’s at 14-15* now so I hope that does it, thanks for the fast replies and info it was really helpful

 

[KEESEY]

I also must add that this motor is a beast when it runs right
350 .60 over 4bolt
internal balance 383 stroker kit
eagle forged crank
eagle forged H beam rods
mahle forged +16cc pistons
studded mains and heads
62cc custom aluminum heads 2.08 intake valves 1.6
exhaust 210cc cnc runners
stainless steel roller rockers
comp cans exterme marine roller cam
high rise dual plane aluminum intake
quick fuel 650 cfm marine carb
hardin marine aluminum seaward series manifolds and stainless risers

 

[Scott Danforth]

Ok just snuck out of class and fired it up again, I was at 9 BTDC and plugs where black, I have the v8-22A I spun the motor up to 3700 and adjusted till I had 35-36* and let it come back down, then adjusted idle to 700rpm and then leaned it out till it about stalled and went back half turn, it snaps up a lot better and idles way better, also starts easier, going to see how it does on Saturday under a load, hit it at idle and it’s at 14-15* now so I hope that does it, thanks for the fast replies and info it was really helpful

your a little advanced on your base timing. I would back off to max of 12.

 

[KEESEY]

your a little advanced on your base timing. I would back off to max of 12.

will do going to take the tools with me to the lake Saturday and do some adjustments and see where things are at under load

 

[Scott Danforth]

what cam do you have in the motor?

 

[KEESEY]

what cam do you have in the motor?

Running 1.7-1 roller rockers

 

[Scott Danforth]

Did you clearance the valve guides and check clearances. The 1.7:1 rockers may have valves and piston trying to be one

 

[KEESEY]

Yeah it’s clearanced, the heads where set up to run up to .700 lift and the pistons have a large pocket

 

[KEESEY]

Update: the timing fixed part of it, I also just notice that at idle my fuel pressure is 3-4psi and at 2500rpm it’s down to 2psi so it will be getting an electric pump this week get rid of the mechanical pump

 

[Bondo]

Ayuh,.... Is the boat side of the fuel system up to snuff,..??

Clean fresh filter,..??
No crud in the anti-siphon valve,..??
Dip-tube clear,..??

A fuel pump can't build pressure or pump volume if it can't suck fuel,.....

If ya do go electric, ya need an oil pressure switch to kill the fuel pump if the motor ain't runnin',.....

 

[KEESEY]

Ayuh,.... Is the boat side of the fuel system up to snuff,..??

Clean fresh filter,..??
No crud in the anti-siphon valve,..??
Dip-tube clear,..??

A fuel pump can't build pressure or pump volume if it can't suck fuel,.....

If ya do go electric, ya need an oil pressure switch to kill the fuel pump if the motor ain't runnin',.....

Dip tube to carb was replaced all AN fittings and -6 line only thing not was the pump, I have a spot for a switch should be easy