vibration in new engine

cop-coupe · 01-01-2005, 05:07 PM

my new 306 has a very odd vibration 2800 and above and gets worse the higher the rpm upto 4500 (that is the highest Ive let the rpms go) it does it free rev or driving, I have also swaped in a c-4 with the 50 oz flexplate the crank # shows to be out of an 87 truck, any pointers please, would anything ignition wise or fuel systeme cause this.... looking for somthing simple preferably.....I can wish right.

Jeff Chambers · 01-01-2005, 05:12 PM

Was the rotating assembly balanced at assembly, including with the balancer and flexplate? Was your converter balanced? Has the balancer slipped? Just a few things to check, but it definitely sounds like a balancing issue. '87 truck...might this have been a 28 in-oz crank?

cop-coupe · 01-01-2005, 05:28 PM

I thought all post 87 cranks were 50 oz balanced. The rotating assembly was not balanced together. I bought the short block from a builder in Indy, then finished it off with my parts. The only thing I did not take into consideration was the converter. It came with the trany. Is it possible to have the converter balanced seperately, I know this probably would not be ideal for your application but for just a hobby car for shows and occasional strip time would this be sufficient

Jeff Chambers · 01-01-2005, 09:38 PM

Check your PM. Since its an Indy Performance shortblock, I'd bet the problem is in the rotating assembly itself.

Ieatcamaros · 01-02-2005, 02:35 PM

FWIW, 87 trucks did have the 50 oz setup.

Ackbar00 · 01-04-2005, 05:00 PM

I was having the same issue. I am not completely sure it is fixed ( 2 feet of snow will do that) but I put new Romac balancer on mine and I can tell a big difference right away. Plus, my old one was really fucked up. I would check into this route. The Romac can be had for $200 on ebay. That is where I got mine.

01-01-2005, 05:07 PM	#1
cop-coupe Registered Member Join Date: Apr 1999 Location: belleville IL. Posts: 60	vibration in new engine my new 306 has a very odd vibration 2800 and above and gets worse the higher the rpm upto 4500 (that is the highest Ive let the rpms go) it does it free rev or driving, I have also swaped in a c-4 with the 50 oz flexplate the crank # shows to be out of an 87 truck, any pointers please, would anything ignition wise or fuel systeme cause this.... looking for somthing simple preferably.....I can wish right.

01-01-2005, 05:12 PM	#2
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Re: vibration in new engine Was the rotating assembly balanced at assembly, including with the balancer and flexplate? Was your converter balanced? Has the balancer slipped? Just a few things to check, but it definitely sounds like a balancing issue. '87 truck...might this have been a 28 in-oz crank? __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

01-01-2005, 05:28 PM	#3
cop-coupe Registered Member Join Date: Apr 1999 Location: belleville IL. Posts: 60	Re: vibration in new engine I thought all post 87 cranks were 50 oz balanced. The rotating assembly was not balanced together. I bought the short block from a builder in Indy, then finished it off with my parts. The only thing I did not take into consideration was the converter. It came with the trany. Is it possible to have the converter balanced seperately, I know this probably would not be ideal for your application but for just a hobby car for shows and occasional strip time would this be sufficient

01-01-2005, 09:38 PM	#4
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Re: vibration in new engine Check your PM. Since its an Indy Performance shortblock, I'd bet the problem is in the rotating assembly itself. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

01-02-2005, 02:35 PM	#5
Ieatcamaros Domestic Rice really sucks! Join Date: Apr 2002 Location: KY Posts: 973	Re: vibration in new engine FWIW, 87 trucks did have the 50 oz setup. __________________ The sig says it all.

01-04-2005, 05:00 PM	#6
Ackbar00 Rebel Fleet Commander Join Date: Oct 2001 Location: Huber Heights, OH Posts: 1,003	Re: vibration in new engine I was having the same issue. I am not completely sure it is fixed ( 2 feet of snow will do that) but I put new Romac balancer on mine and I can tell a big difference right away. Plus, my old one was really fucked up. I would check into this route. The Romac can be had for $200 on ebay. That is where I got mine. __________________ 1993 Mustang GT, PTK w/ T-64 - My Cardomain Webpage 11.25@123.5 on only 8 psi. 10.84@121 on only 1 headgasket "The Truth is, Your the Weak, and I am the Tyranny of Evil Men!"

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