another thunderbolt ign ?

stratcat88

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i have the thunderbolt 4 ignition. do i have to jump things out like the 5, or do i point and turn dest? also theirs no timing tab on engine but their is a mark. could anybody give me some info on timing this 350 small block mercruiser. no #s and its old. probable 70s early 80s. thanks. tim
 

Bt Doctur

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Aug 29, 2004
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19,290
Re: another thunderbolt ign ?

Go to your local auto and ask for a replacement timing tab, there cheap.Install it using 2 of the timing cover bolts
TB-IV is point and shoot
Basically: You determine Top Dead Center of piston number 1 ,harmoninc balancer should have a line on it. install some type of pointer using this line as 0
Timing pointer will have graduated marks or notches indicating 4,6,8,etc degrees before TDC.
http://t2.gstatic.com/images?q=tbn:ANd9GcRb8Naqk-5rp_kTKGnFRudfo_Y0krvwyIYsTwJmM8FPYhvsyo_jGlkEdQ
http://t1.gstatic.com/images?q=tbn:ANd9GcSPYnw3mHIaP6bToUwE9Zz5OcBw9paf9HaMc_E3lqwAc_XBUwLPyQzioiI
 
Last edited:

stratcat88

Petty Officer 2nd Class
Joined
Nov 16, 2009
Messages
174
Re: another thunderbolt ign ?

Go to your local auto and ask for a replacement timing tab, there cheap.Install it using 2 of the timing cover bolts
TB-IV is point and shoot
Basically: You determine Top Dead Center of piston number 1 ,harmoninc balancer should have a line on it. install some type of pointer using this line as 0
Timing pointer will have graduated marks or notches indicating 4,6,8,etc degrees before TDC.
http://t2.gstatic.com/images?q=tbn:ANd9GcRb8Naqk-5rp_kTKGnFRudfo_Y0krvwyIYsTwJmM8FPYhvsyo_jGlkEdQ
http://t1.gstatic.com/images?q=tbn:ANd9GcSPYnw3mHIaP6bToUwE9Zz5OcBw9paf9HaMc_E3lqwAc_XBUwLPyQzioiI
thanks doc. so after reading about 5 lbs. of info on timing this engine, the idle is set at 750 and then you advance the throttle to 2500 and set the dest. to the same mark ? thanks again.
 

Bondo

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Staff member
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Messages
70,939
Re: another thunderbolt ign ?

Ayuh,..... Or use a digital timin' light, 'n dial it in to 0?, 'n line up Tdc,...

T-Bolt IV is the Greatest ignition there ever was,... Point, 'n shoot,... what ya see is what it is,...

I use a paint-pen to mark Tdc,... easy to see,...
 

Bondo

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Re: another thunderbolt ign ?

thanks doc. so after reading about 5 lbs. of info on timing this engine, the idle is set at 750 and then you advance the throttle to 2500 and set the dest. to the same mark ? thanks again.

Nope,.... Not Right,... Timin' is set at Idle,....

Idle is 650/ 750 rpms, in the water, in gear,....
 

stratcat88

Petty Officer 2nd Class
Joined
Nov 16, 2009
Messages
174
Re: another thunderbolt ign ?

Nope,.... Not Right,... Timin' is set at Idle,....

Idle is 650/ 750 rpms, in the water, in gear,....
thanks bono.so i cant do it on the trailer,ok so after i get the idle set i dont have to worry about raising the rpm ? well wait, hjeres my problem. after getting the roch 4 barrel rebuilt, new fuel lines,fuel water separator,spark plugs,gaped at 35,wirers, i have to pump the throttle 5 times to get it to start and then it konks out and i got to pump it again. this goes on for about 20 min. then the only way it stays running is leaving the throttle at 1500 rpms for another 10 min. then i can bring it down to 1000 and thats where it idles.
 

Bondo

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Re: another thunderbolt ign ?

thanks bono.so i cant do it on the trailer,ok so after i get the idle set i dont have to worry about raising the rpm ? well wait, hjeres my problem. after getting the roch 4 barrel rebuilt, new fuel lines,fuel water separator,spark plugs,gaped at 35,wirers, i have to pump the throttle 5 times to get it to start and then it konks out and i got to pump it again. this goes on for about 20 min. then the only way it stays running is leaving the throttle at 1500 rpms for another 10 min. then i can bring it down to 1000 and thats where it idles.

Ayuh,.... Then you've got a fuel delivery issue,.... Probably the Carb,....
Is the carb gettin' Good gas,..??

Once that's fixed, set the idle to 650/ 750,rpms, 'n set the timin',...
 

stratcat88

Petty Officer 2nd Class
Joined
Nov 16, 2009
Messages
174
Re: another thunderbolt ign ?

Ayuh,.... Then you've got a fuel delivery issue,.... Probably the Carb,....
Is the carb gettin' Good gas,..??

Once that's fixed, set the idle to 650/ 750,rpms, 'n set the timin',...
well bond-o, i pulled the deck up, 12 screws, and pulled fuel sender and looked down in the tank and you are right. a lot of garbage floating around in there. most likely clogging up the pickup and thats why i have to pump the throttle 50 times. there is no way to pull this big tank, all foamed in, without it becoming a major event.maybe i should so i can check the bulheads and stringers in that section. what am i going to do with 80 gallons of gas and how am i going to clean the tank with only that small hole? thanks again.
 

stratcat88

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Messages
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Re: another thunderbolt ign ?

oh i forgot, the flu doesn't smell like varnish,2 months ago i put 50 gallons in the tank.
 

Bondo

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Re: another thunderbolt ign ?

well bond-o, i pulled the deck up, 12 screws, and pulled fuel sender and looked down in the tank and you are right. a lot of garbage floating around in there. most likely clogging up the pickup and thats why i have to pump the throttle 50 times. there is no way to pull this big tank, all foamed in, without it becoming a major event.maybe i should so i can check the bulheads and stringers in that section. what am i going to do with 80 gallons of gas and how am i going to clean the tank with only that small hole? thanks again.
oh i forgot, the flu doesn't smell like varnish,2 months ago i put 50 gallons in the tank.

Ayuh,.... What I did in that situation is got a Huge fuel filter, a 2ndary Mack full filter, holds 'bout 1/2 gallon,...
'n an electric fuel pump,...

I rigged to to pull from the tank's dip tube after I pulled the anti-siphon valve, into the Huge filter, to the electric pump, to a white 55 gallon drum,...

After it was the drum, I pump it out, 'n run it in my wood splitter, lawn mowers, 'n the ole lady's car(my pickup is diesel),...
So long as what I suck out is from the Top of the gas, 'n still smells like gas, it runs just Fine,...
Any water, 'n crud is gonna be at the bottom of the drum, just like in yer tank now,...

Another option I've done when dealin' with water in the tank is, run my transfer/ filterin' system, 'n skip the drum, pump it right back into the tank,...
That's the Beauty of the Huge Mack filter,.... ;)
It could be done with the regular canister type boat fuel filter, but ya might go through a couple of filters, to get the job done,...
Water, Will pass through a canister filter, it's limited by it's volume capacity,... Once Full, it passes water,...
 

stratcat88

Petty Officer 2nd Class
Joined
Nov 16, 2009
Messages
174
Re: another thunderbolt ign ?

Ayuh,.... What I did in that situation is got a Huge fuel filter, a 2ndary Mack full filter, holds 'bout 1/2 gallon,...
'n an electric fuel pump,...

I rigged to to pull from the tank's dip tube after I pulled the anti-siphon valve, into the Huge filter, to the electric pump, to a white 55 gallon drum,...

After it was the drum, I pump it out, 'n run it in my wood splitter, lawn mowers, 'n the ole lady's car(my pickup is diesel),...
So long as what I suck out is from the Top of the gas, 'n still smells like gas, it runs just Fine,...
Any water, 'n crud is gonna be at the bottom of the drum, just like in yer tank now,...

Another option I've done when dealin' with water in the tank is, run my transfer/ filterin' system, 'n skip the drum, pump it right back into the tank,...
That's the Beauty of the Huge Mack filter,.... ;)
It could be done with the regular canister type boat fuel filter, but ya might go through a couple of filters, to get the job done,...
Water, Will pass through a canister filter, it's limited by it's volume capacity,... Once Full, it passes water,...
sounds like you've got a farm. cool. plenty of room to work on things. thats what im gonna do bond-o. thanks.
 
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