My 540 lost some power...need some advice.
06-25-2008, 07:18 AM
#11
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depending on the dist. you may even be able to lock the dist advance and see how it starts, should not be running any more than 8-1 comp at that boost, and 28 max timing..no wonder you took out a piston, a goos water/alchol injection setup would help. the only way to know your compression is to know what pistons and head cc's you have, whoever did the engine should know, at this point the pin has been pulled !
have you done a plug check ? what heat range ? feel free to give me a call if you wish, 540-786-8111, Rob
have you done a plug check ? what heat range ? feel free to give me a call if you wish, 540-786-8111, Rob
06-25-2008, 07:50 AM
#12
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Thread Starter
06-25-2008, 07:58 AM
#13
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Thread Starter
Thanks for all the input guys! I talked to the guy who freshened up the motors and told him about all the repsonses on here. We are going to back the timing to 28-30 at full advance.
If i lock the timing will it crank at 28? I was told that it would make it very difficult to crank but did read about a MSD crank retard kit that brings the timing down on the start only.
Blowers have 160hrs on them.
thanks again for all ur help!
If i lock the timing will it crank at 28? I was told that it would make it very difficult to crank but did read about a MSD crank retard kit that brings the timing down on the start only.
Blowers have 160hrs on them.
thanks again for all ur help!
06-25-2008, 05:01 PM
#15
Registered User
Check out allot more pics here! 
http://www.offshoreonly.com/forums/s...d.php?t=165627
http://www.offshoreonly.com/forums/s...d.php?t=165627Holy $hit. I'll be right down to get you boat running like a Swiss watch.
Unfortunately, they'd probably be polite enough to call me "sir".
06-25-2008, 06:30 PM
#17
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Great pics for sure !!!! anyway....what was i saying.....oh yea...at 28 deg and low compression I don't think you will have a issue starting, running more compression and timing in my race car and it's a MSD and is locked @ 36 so you should be fine, still need to do some plug checks to make sure the jetting is ok....lean blower =$$$$$$$$$$$$$$$$$$$$
06-25-2008, 09:39 PM
#18
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I had run lock timing for a number of years before I went efi. No problem starting and engine idles great. I would set timing at 30 max if you have alum. heads and 28 if iron. You may now have a valve, piston, and/or piston ring problems after running that much timing & 8lbs of boost. Detonation will distroy an engine quickly. Do you have intercoolers? Backing your timing down would give you less HP unless the motors are detonatioin so bad with all of the timing.
I would start with a compression test, easy to do and gives you a starting point. Not as good as leakdown but easier to do. If compression test shows all the same then you should know you have not damaged engines when you were running that much timing. First cylinders to go are #5 or #7 since they fire right after each other.
Give us a time frame as to all of these events, and results. I think you lost a drive first, then replace drives. Did you lose any rpm or speed then?
When you lost a motor did you redue both at the same time? Did motor go back the same or did you make changes? We need more details.
I would start with a compression test, easy to do and gives you a starting point. Not as good as leakdown but easier to do. If compression test shows all the same then you should know you have not damaged engines when you were running that much timing. First cylinders to go are #5 or #7 since they fire right after each other.
Give us a time frame as to all of these events, and results. I think you lost a drive first, then replace drives. Did you lose any rpm or speed then?
When you lost a motor did you redue both at the same time? Did motor go back the same or did you make changes? We need more details.
06-26-2008, 09:30 AM
#19
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Thread Starter
I had run lock timing for a number of years before I went efi. No problem starting and engine idles great. I would set timing at 30 max if you have alum. heads and 28 if iron. You may now have a valve, piston, and/or piston ring problems after running that much timing & 8lbs of boost. Detonation will distroy an engine quickly. Do you have intercoolers? Backing your timing down would give you less HP unless the motors are detonatioin so bad with all of the timing.
I would start with a compression test, easy to do and gives you a starting point. Not as good as leakdown but easier to do. If compression test shows all the same then you should know you have not damaged engines when you were running that much timing. First cylinders to go are #5 or #7 since they fire right after each other.
Give us a time frame as to all of these events, and results. I think you lost a drive first, then replace drives. Did you lose any rpm or speed then?
When you lost a motor did you redue both at the same time? Did motor go back the same or did you make changes? We need more details.
I would start with a compression test, easy to do and gives you a starting point. Not as good as leakdown but easier to do. If compression test shows all the same then you should know you have not damaged engines when you were running that much timing. First cylinders to go are #5 or #7 since they fire right after each other.
Give us a time frame as to all of these events, and results. I think you lost a drive first, then replace drives. Did you lose any rpm or speed then?
When you lost a motor did you redue both at the same time? Did motor go back the same or did you make changes? We need more details.
1. Last year (april) running 5800-5900 rpms...broke a xr upper. Replaced both uppers w XR new style upper. Still turning the same rpms after this change.
2. Put less than 93 octane in boat.burnt up piston n one motor. Replaced 2 pistons and freshened up motor..no changes at all done to motor. Other motor was still running fine so I did nothing. This was in august. Set timing on freshened motor to 32 to match motor that did not burn a piston. Was turning about 5400 rpms w both motors at the end of last year.
3. This past winter i freshened up the other motor. All pistons were fine. Freshened up motor and made no changes.
4. Replaced both distributors caps w new ones (same ones just new)
5. We set the timing at 32 @ 3000 rpm. But after a few runs this year, the timing has creeped up to 36 @ 3000 rpms. Very hard to idle, crank and surge(which I need to put into gear) Acts like the carbs are loading up badly. When the motor is hot, I have to give the throttle to almost halfway for it to fire up. Pain in the butt.
Checked the plugs...very black w some sort of deposit build up on them.
No intercoolers.
Throttle linkage is fine.
I'm going to take all of your advices and lock the timing at 30. Also, going to adjust the carbs again after we set the timing. I will let you know my results.
