SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: nolongergreen on May 28, 2014, 07:28:10 PM
-
Im about to tear the motor down since it has a bad vibration in it just all of a sudden. If my crank has gotten damaged i was wondering that if I do end up having to change the crankshaft, Is there a different one I can put in like a small stroker type crank without having to change the rods and larger pistons?
-
Im about to tear the motor down since it has a bad vibration in it just all of a sudden. If my crank has gotten damaged i was wondering that if I do end up having to change the crankshaft, Is there a different one I can put in like a small stroker type crank without having to change the rods and larger pistons?
Excuse the ignorant question but what motor do you have?
-beerjet-
-
If you change the stroke, you will need to change the pistons. That requires a different pin height.
-
Can I have the junk crank if it is BBC?
Sent from my SCH-I535 using SoCalJetBoats mobile app
-
Not trying to move in on your action el mojado, but... If your crank is at all usable, for bad @$$ crank work, check out:
Castillo's Crankshaft
14654 Firestone Blvd
La Mirada, CA 90638
(714) 523-0321
Also, Lunati Cams and Cranks is back to using their old crank shop since the Holley thing. I had a few cranks shot peened, ground, knife edged, and nitrided by them and they came back flawless every time. http://www.lunatipower.com (http://www.lunatipower.com)
-
I need a junk crank to set up my rail kit.
Sent from my SCH-I535 using SoCalJetBoats mobile app
-
460
Sent from my SAMSUNG-SGH-I337 using SoCal Jet Boats mobile app
-
Im about to tear the motor down since it has a bad vibration in it just all of a sudden. If my crank has gotten damaged i was wondering that if I do end up having to change the crankshaft, Is there a different one I can put in like a small stroker type crank without having to change the rods and larger pistons?
In a word... no.
You change the crank stroke, rods and/or pistons are going to have to change as well.
What makes you believe it's the crank? Have you tried running the engine with the drive line unhooked to see if it may be the pump or drive shaft before narrowing it down to the engine?
-
Yes its unhooked and that's what I thought it was so i rebuilt the pump with the master rebuild kit since i sucked gravel into the pump but it was all fine but rebuilt it anyway to be sure.
Its completely disconnected from the coupler now and is still there.
160 psi on all cylinders and the top end is all good.
Dampner has not spun because t.d.c. still lines up perfectly.
Somethings making it dance around........... My cam is not that freakin big...
The intake had been leaking water into the intake ports being it had a rusted looking trail going into a few cylinders so im assuming it might have drawn in enough to cause a problem when it tried to compress. However it did not stall the motor or make any obvious signs of it, being as the higher the rpms the more water pump the pump moves it would have let the most water in at max rpms it might not have shown as much as if it were at idle taking that much in.
Hoping for as a last ditch effort to replace a few plug wires but thats highly unlikely since they are new with very little run time.
-
Yes its unhooked and that's what I thought it was so i rebuilt the pump with the master rebuild kit since i sucked gravel into the pump but it was all fine but rebuilt it anyway to be sure.
Its completely disconnected from the coupler now and is still there.
160 psi on all cylinders and the top end is all good.
Dampner has not spun because t.d.c. still lines up perfectly.
Somethings making it dance around........... My cam is not that freakin big...
The intake had been leaking water into the intake ports being it had a rusted looking trail going into a few cylinders so im assuming it might have drawn in enough to cause a problem when it tried to compress. However it did not stall the motor or make any obvious signs of it, being as the higher the rpms the more water pump the pump moves it would have let the most water in at max rpms it might not have shown as much as if it were at idle taking that much in.
Hoping for as a last ditch effort to replace a few plug wires but thats highly unlikely since they are new with very little run time.
Is it a vibration or more of a shake? Reason I ask is, if it was a vibration... it would be really weird that it would go out of balance all of a sudden... I mean unless you have a knocking noise like a bearing or something... or perhaps lost the weight on the flex plate if it is a 1979 and later 460... Crankshafts themselves do not go out of balance. If it was more of a shake... you may have something more along the lines of a misfire and that causing it to shake, rattle, and roll.
Did you change flex plates or balancer spacer before this vibration occurred? There are internal and external flywheels/flexplates and counterweighted and non counterweighted balancer spacers... their use depends on what year crankshaft you have (early or late).
-
It's a 79 up but I'd have to search my posts for where I posted the numbers on the block to be certain.
I don't see any weights on the flywheel but it is externally balanced on the crank in the front.
Sent from my SAMSUNG-SGH-I337 using SoCal Jet Boats mobile app
-
If it is external balance up front... then it's gonna have to be external in the back. If you do not find any weights welded to the flexplate... then I'm sure you have your culprit. THOSE I have seen go out of balance as I have seen where the weights come off and then cause the engine to vibrate something fierce.
-
So if its externally balanced in the front , they are always externally balanced on the flexplate?
-
So if its externally balanced in the front , they are always externally balanced on the flexplate?
I'd say 99% of the time, yes. Did you replace the flex plate at some point? If not, remove the old one, and see if you can see where the old one had a weight... chances are, if it had a weight on it and it came off, you'll see where it once was and should be able to find the weight somewhere in the boat.
-
Well I will look again but we just had the motor out to do the pump and would thing it would have been laying somewhere in the bottom. I have not changed the flexplate. I also just picked up a spark tester so I can test and make sure that it's getting a strong spark on everyone of the plugs. I have noticed from time to time I would look at the tach and it would be reading about 1/2 the rpms that it should and kinda bouncing around
Sent from my SAMSUNG-SGH-I337 using SoCal Jet Boats mobile app
-
Maybe a loose connection or bad ignition system? It's all new but that doesn't always mean it's not broken.
Sent from my SAMSUNG-SGH-I337 using SoCal Jet Boats mobile app
-
Changed flex plate runs smoother than ever now onto the carb
Sent from my SAMSUNG-SGH-I337 using SoCal Jet Boats mobile app
-
Changed flex plate runs smoother than ever now onto the carb
Sent from my SAMSUNG-SGH-I337 using SoCal Jet Boats mobile app
Cool... nice inexpensive fix... :thumbup:
-
Thank god, now if can get the carbs tuned in I'm good to go.
Sent from my SAMSUNG-SGH-I337 using SoCal Jet Boats mobile app