rocking engine

nielsmobers · 07-16-2002, 05:04 AM

Hey,

I have a rocking engine in my 1972 grandé 302cu , I've already replaced the vibration damper which took away have of the vibration. When I drive about 50mph the engine vibrates like this: rrrrRRRRRrrrrr rrrrrRRRRRrrrrr rrrrrrRRRRRrrrrrr rrrrrRRRRrrrr. I'm 100% sure it's the engine, could it be that they gave me the wrong damper, it's an universal damper for all ford small block engines. At first I was told that it had to be a damper from exactly the same engine and year as the car, but they gave me an universal damper. Does someone also have vibration problems with his/her car, I don't know what to look for, any information can help. This Saturday I'm going to Antwerp (Belgium) to a mustang day there I will also try to find some answers.
Thank in advanced

Niels

PKRWUD · 07-16-2002, 04:39 PM

The dampner is the same across the board for your year. They didn't become specific until 1982.

Have you checked your motor mounts?

Take care,
-Chris

Jeff65 · 07-17-2002, 03:52 PM

Its not vibrations its engine surging! Chances are the power valve in your carburetor is bad or you have a vaccuum leak. What's happening is your engine is alternately running rich then starving for fuel and this is why it goes...rrrrrRRRRRrrrrrr. You need to find the cause of the surging and I've given you a couple things to check...Good luck!

jwboner · 07-18-2002, 01:44 AM

If it is a vibration while you are in neutral it will be the engine or clutch. But when going down the road it could be anywhere in the driveline. I have had bad luck with ram pressure plates breaking and throwing off the entire balance of the engine, it could also be the drive shaft or even a little ujoint.

nielsmobers · 07-18-2002, 05:19 AM

First, thanks for the replies this is really helping me.

I've checked the motor mount, these are very porous. I'm gonna replace them.

Engine surging, I think I know what it means, but I'm really sure.
The reply on that: I have two fuel systems, LPG and normal gasoline, on both fuel systems the virbration starts at the same rpm. The LPG is injected in the inlet after the carburetor, do you think that makes a difference looking for engine surging. A vaccuum leak is a possibility, I will check that. If I measure the Co emission will I than know it if I have carburetor problems??

The virbration is there in neutral, but then I have to accelerate to a higher rpm, I think it's around 3000rpm. Does an automatic transmission also use pressure plates, I thought it used a trorque converter?? If this could happen to an automatic transmission, is there a possibility to check this without removing the engine.

The englisch is with a dutch accent that's why some sentences look strange.

Thanks in advanced. Niels

zach0 · 07-18-2002, 07:31 AM

If you have an automatic it could be the balance weight on your flywheel. I don't know how much of a vibration that would cause though.

Jeff65 · 07-18-2002, 01:32 PM

If the car is stationary, with hood open, and you operating the throttle linkage, does it surge at 3000 rpm?

nielsmobers · 07-19-2002, 06:32 AM

Yes, the surging occurs the way you describe, it could be that I guest a little high in rpm's. Just to be sure that I know what surging is, does it mean that the engine runs irregular (It's hard to find a corresponding translation in dutch).
I ask this because the engine sounds normal when it runs idle and when you accelerate, or do you need a trained ear to hear the surge. Tomorrow I'll go to the Mustang meating in antwerp, there I will check other Grandé's how they vibrate and I'll check there vaccuum lines to compare them with mine.
Thanks.

Niels

Rev · 07-19-2002, 06:13 PM

Surging usually occurs at idle and goes away at higher RPM's. It's always caused by a lean condition, usually a vacuum leak, or a very lean idle. At least that's my experience.

Not really too sure that this sounds like surging. Not too sure it sounds like imbalance vibration either. Wish I knew exactly what it is.

Rev

J&MStang · 07-19-2002, 11:10 PM

If your motor mounts are gone, the engine flexes more than usual and this can activate your accelerator linkage. As it rocks back and forth, the engine surges in sympathy. Get those mounts changed with something solid like Lakewood Muscle motor mounts.

07-16-2002, 05:04 AM	#1
nielsmobers Registered Member Join Date: Jul 2002 Location: Holland Posts: 28	rocking engine Hey, I have a rocking engine in my 1972 grandé 302cu , I've already replaced the vibration damper which took away have of the vibration. When I drive about 50mph the engine vibrates like this: rrrrRRRRRrrrrr rrrrrRRRRRrrrrr rrrrrrRRRRRrrrrrr rrrrrRRRRrrrr. I'm 100% sure it's the engine, could it be that they gave me the wrong damper, it's an universal damper for all ford small block engines. At first I was told that it had to be a damper from exactly the same engine and year as the car, but they gave me an universal damper. Does someone also have vibration problems with his/her car, I don't know what to look for, any information can help. This Saturday I'm going to Antwerp (Belgium) to a mustang day there I will also try to find some answers. Thank in advanced Niels

07-16-2002, 04:39 PM	#2
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	The dampner is the same across the board for your year. They didn't become specific until 1982. Have you checked your motor mounts? Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-18-2002, 01:44 AM	#4
jwboner Registered Member Join Date: Jun 2001 Location: Under the hood Posts: 164	If it is a vibration while you are in neutral it will be the engine or clutch. But when going down the road it could be anywhere in the driveline. I have had bad luck with ram pressure plates breaking and throwing off the entire balance of the engine, it could also be the drive shaft or even a little ujoint. __________________ 65 fastback 347 DFI injected w/vic jr, TFS heads, MSD, cable clutch TKO, 3.70 9", tc subframe conns, custom traction bars, griffen alum radiator, armored fuel cell, and torq thrust D's Retrofitted Prelude seats. Vintage Air underdash kit. Fiberglass here and there too More on the way all the time.

07-18-2002, 05:19 AM	#5
nielsmobers Registered Member Join Date: Jul 2002 Location: Holland Posts: 28	reply on your replies First, thanks for the replies this is really helping me. I've checked the motor mount, these are very porous. I'm gonna replace them. Engine surging, I think I know what it means, but I'm really sure. The reply on that: I have two fuel systems, LPG and normal gasoline, on both fuel systems the virbration starts at the same rpm. The LPG is injected in the inlet after the carburetor, do you think that makes a difference looking for engine surging. A vaccuum leak is a possibility, I will check that. If I measure the Co emission will I than know it if I have carburetor problems?? The virbration is there in neutral, but then I have to accelerate to a higher rpm, I think it's around 3000rpm. Does an automatic transmission also use pressure plates, I thought it used a trorque converter?? If this could happen to an automatic transmission, is there a possibility to check this without removing the engine. The englisch is with a dutch accent that's why some sentences look strange. Thanks in advanced. Niels

07-18-2002, 07:31 AM	#6
zach0 Registered Member Join Date: Apr 2001 Location: Hampton, Virginia Posts: 227	If you have an automatic it could be the balance weight on your flywheel. I don't know how much of a vibration that would cause though. __________________ 1980 RX7 with 289 Ford V-8 bored .030 over, Very radical cam, Torker 2 high rise intake, Holley 650 Carb, MSD Nascar 6ALN ignition, MSD coil and distributor, Headers with dual open side exhaust. Over 300 horse. 1966 Mustang still in progress

07-17-2002, 03:52 PM	#3
Jeff65 Registered Member Join Date: Jul 2002 Location: Oklahoma City Posts: 208	Its not vibrations its engine surging! Chances are the power valve in your carburetor is bad or you have a vaccuum leak. What's happening is your engine is alternately running rich then starving for fuel and this is why it goes...rrrrrRRRRRrrrrrr. You need to find the cause of the surging and I've given you a couple things to check...Good luck!

07-18-2002, 01:32 PM	#7
Jeff65 Registered Member Join Date: Jul 2002 Location: Oklahoma City Posts: 208	If the car is stationary, with hood open, and you operating the throttle linkage, does it surge at 3000 rpm?

07-19-2002, 06:32 AM	#8
nielsmobers Registered Member Join Date: Jul 2002 Location: Holland Posts: 28	surge reply Yes, the surging occurs the way you describe, it could be that I guest a little high in rpm's. Just to be sure that I know what surging is, does it mean that the engine runs irregular (It's hard to find a corresponding translation in dutch). I ask this because the engine sounds normal when it runs idle and when you accelerate, or do you need a trained ear to hear the surge. Tomorrow I'll go to the Mustang meating in antwerp, there I will check other Grandé's how they vibrate and I'll check there vaccuum lines to compare them with mine. Thanks. Niels

07-19-2002, 06:13 PM	#9
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Surging? Surging usually occurs at idle and goes away at higher RPM's. It's always caused by a lean condition, usually a vacuum leak, or a very lean idle. At least that's my experience. Not really too sure that this sounds like surging. Not too sure it sounds like imbalance vibration either. Wish I knew exactly what it is. Rev __________________ '66 Coupe, 306, 350-375 HP, C-4, 13.07 e.t., 104.8 mph, 1/4 mi. O.B.C. #2 '66 coupe

07-19-2002, 11:10 PM	#10
J&MStang Registered Member Join Date: May 2002 Location: Moore, OK Posts: 25	If your motor mounts are gone, the engine flexes more than usual and this can activate your accelerator linkage. As it rocks back and forth, the engine surges in sympathy. Get those mounts changed with something solid like Lakewood Muscle motor mounts.

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