Engine Romac Balancer question

Justin87

Active Member
Aug 7, 2017
146
44
48
Hello all,

Put in some garage time this weekend on my “inherited” 306 motor and could use some of this forums sage advice.

Assembled the bottom and front end of the motor and ran into a bit of a snag with my harmonic balancer.

The motor came with a Romac steel 50oz balancer. The paperwork from DSS Racing said that it should use a 50oz balancer and a 50oz counterweight on the flywheel.

Using an installer tool, I put it on, but it was a tight. Holy smokes it was tight. The balancer instructions called it a “partial interference” part and it warned me that it would be tight and to use a lot of oil, or even heat it up in the oven.

My questions are:

1. Are Romac parts no longer made? Finding information about them online has been difficult. This one was still new in box because it came with my motor, but the motor was originally ordered from DSS in like 2009. It seems like they aren't readily available.

2. Is their an established method to knowing that it’s on all the way? The stock balancer has a hard machined lip on the shaft of the balancer but this one is curved. (See attached pictures)

Basically, I’m ask if their is a danger in letting the crank bolt finish the job since I’ve gotten it so close.

3. How much is this going to suck if for reason I need to take it off. Anyone have experience with one of these? I did oil it, but it was a beast getting it on.

I’ve read a few threads on here with people discussing the pros and cons of buying them, but anyone pulled one off recently?
 

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Deleted member 215073

I'm not sure about Romac, but my Power Bond balancer said you may need to remove some material from the balancer with a fine sandpaper to get the correct fit. They also recommended anti seize instead of oil.
 

08GT500

Active Member
Jul 12, 2018
904
140
53
Hi Justin, LTNS.
Well, you got pretty far! I’m guessing this isn’t running a twin broached crank(dual alignment keys?). I usually verify the supplied key/keys fit’s the balancer’s Key way width, and enough height remains for the key to clear the keyway within the balancer, correct dimensions & Hospital clean, heat, never-seize on crank & install.
ROMAC is now a NORMDA subsidiary, here is their site:
https://www.norndaautomotive.com.au/romac.html.
Have a borescope to view if Steel is rolling up behind the balancer? Key is sitting flat?
Fords have long nosed balancers, gets tighter the further it pulls in.
This is an interference fit, not just a press fit.
The Balancer will stop when it bumps the Cam Gear, then it’s home. More radiuses are used throughout balancer for strength, if you’re almost there, noting more resistance, is normal. With no heat it’ll surely fight. Lube the hel* out of it wit pb blaster/light oil & it’ll come.
If you’re bending a good Mfg’s install tool, then I’d rethink pulling it & finding out why.
DSS = another opinion, utilize it & ROMAC if you hit that point.
You can still remove it, debur the shaft, check clearances, key, heat it up per Mfg.in an oven & once done-pull it home, but this sounds relatively normal
-If Mfg allows open flame (ask them) first- heat carefully, not more than 15-20 seconds, circular motion with a propane torch, carefully & evenly, doesn’t take much, an inch+ out from the crank using a piece of plate so you don’t strike the motor. It will transfer quick to the neoprene elastomer (bad), then crank, and the absorbing so you need have your game face on once done, ready to pull it home.
If the tight fit from Crank to Balancer wasn’t present, it would shear the key & throw the balance off.
Some are very tight, I’ve snapped a few. An interference fit Coming apart will be a bitch, removal is not quite as bad as the install.
You can pull it in with the bolt, or assist with, IF a new crank bolt & it’s almost homed & you’re NOT exceeding its it’s 90-100Ft/Lb finished Torque, gear lock on block Bolt/ring gear in back to prevent rotation. Until then, i’d stick more to the Tool. Don’t want to shear that bolt. Can be repaired, a headache you don’t need if your fighting it w/no movement.
View the values below as a reference. If you need to utilize them, there they are. An 0.0005 interference fit is difficult, may be as high as a thousandth, or more- very tight!!
Best way is like fitting a piston pin to a connecting rod. HEAT. Then no steel rolls, galling, etc.Next time you’ll know.

For Information purposes & usage if needed.
Dimensions below are as follows:
1.376/1.375 is your Crank diameter.
1.374/1.375 is your Internal Balancer diameter.
1.462 Maximum Key in Crank height shown.
1.467/1.477 Max. installed Crank key way depth.
-Most do not have Micrometers 1 to 2”, much less ones that read in tenths (.0001), identified by the lengthwise lines (0-9) running atop the Micrometer, yet most decent local machine shops will.
Crank external measurement, preferably using a 1-2” external Micrometer designed for measuring tolerances within one tenth(.0001).These are identified by the lines running across the top of the Micrometer. Dial Calipers are only good for less accurate tolerances (+/- .005). Yet used carefully, should be capable of reading your installed key height & keyway height & width.
1570441560972.jpeg

Below is the Balancer and it’s bore, Key way height. Take it to a machine shop & ask them to measure the dimensions listed. Otherwise, You’ll need a telescoping gauge & the 1-2” Micrometer above that reads in tenths. Dial Calipers would only be useful here in measuring keyway height, width, since their tolerances are generally +/- .005. It’s just as easy to compare by using a new key, trying its fit, comparing NAPA, Advanced, etc should have one. Stock size is used.
1570441621486.jpeg
So, if it’s moving & tool’s holding up, keep it clean, lubed, pull it in. If something’s drastically wrong, pull it & verify why. Think you’ll be OK.
Best of luck,
 

Justin87

Active Member
Aug 7, 2017
146
44
48
I'm not sure about Romac, but my Power Bond balancer said you may need to remove some material from the balancer with a fine sandpaper to get the correct fit. They also recommended anti seize instead of oil.

This one did not say anything should be removed, it just said it was machined to an:

“interference fit with a bore matching factory diameter with a plus tolerance of .0005”

And then it said to use an install tool and that it would be noticeably tight but should slip on, which it did.

It did suggest oil or anti-seize, I had oil handy so I used that, but perhaps I should pull it just to use anti-seize.

It was honestly just kind of surprising considering I’ve replaced the factory balancer on the various fox bodies I’ve had over the years and they usually aren’t that tight.

This is the first aftermarket balancer I’ve ever used because this is the first “built” motor I’ve ever worked with. All
My other foxes were basic bolt-on cars.
 

Justin87

Active Member
Aug 7, 2017
146
44
48
Hi Justin, LTNS.
Well, you got pretty far! I’m guessing this isn’t running a twin broached crank(dual alignment keys?). I usually verify the supplied key/keys fit’s the balancer’s Key way width, and enough height remains for the key to clear the keyway within the balancer, correct dimensions & Hospital clean, heat, never-seize on crank & install.
ROMAC is now a NORMDA subsidiary, here is their site:
https://www.norndaautomotive.com.au/romac.html.
Have a borescope to view if Steel is rolling up behind the balancer? Key is sitting flat?
Fords have long nosed balancers, gets tighter the further it pulls in.
This is an interference fit, not just a press fit.
The Balancer will stop when it bumps the Cam Gear, then it’s home. More radiuses are used throughout balancer for strength, if you’re almost there, noting more resistance, is normal. With no heat it’ll surely fight. Lube the hel* out of it wit pb blaster/light oil & it’ll come.
If you’re bending a good Mfg’s install tool, then I’d rethink pulling it & finding out why.
DSS = another opinion, utilize it & ROMAC if you hit that point.
You can still remove it, debur the shaft, check clearances, key, heat it up per Mfg.in an oven & once done-pull it home, but this sounds relatively normal
-If Mfg allows open flame (ask them) first- heat carefully, not more than 15-20 seconds, circular motion with a propane torch, carefully & evenly, doesn’t take much, an inch+ out from the crank using a piece of plate so you don’t strike the motor. It will transfer quick to the neoprene elastomer (bad), then crank, and the absorbing so you need have your game face on once done, ready to pull it home.
If the tight fit from Crank to Balancer wasn’t present, it would shear the key & throw the balance off.
Some are very tight, I’ve snapped a few. An interference fit Coming apart will be a bitch, removal is not quite as bad as the install.
You can pull it in with the bolt, or assist with, IF a new crank bolt & it’s almost homed & you’re NOT exceeding its it’s 90-100Ft/Lb finished Torque, gear lock on block Bolt/ring gear in back to prevent rotation. Until then, i’d stick more to the Tool. Don’t want to shear that bolt. Can be repaired, a headache you don’t need if your fighting it w/no movement.
View the values below as a reference. If you need to utilize them, there they are. An 0.0005 interference fit is difficult, may be as high as a thousandth, or more- very tight!!
Best way is like fitting a piston pin to a connecting rod. HEAT. Then no steel rolls, galling, etc.Next time you’ll know.

For Information purposes & usage if needed.
Dimensions below are as follows:
1.376/1.375 is your Crank diameter.
1.374/1.375 is your Internal Balancer diameter.
1.462 Maximum Key in Crank height shown.
1.467/1.477 Max. installed Crank key way depth.
-Most do not have Micrometers 1 to 2”, much less ones that read in tenths (.0001), identified by the lengthwise lines (0-9) running atop the Micrometer, yet most decent local machine shops will.
Crank external measurement, preferably using a 1-2” external Micrometer designed for measuring tolerances within one tenth(.0001).These are identified by the lines running across the top of the Micrometer. Dial Calipers are only good for less accurate tolerances (+/- .005). Yet used carefully, should be capable of reading your installed key height & keyway height & width.
1570441560972.jpeg

Below is the Balancer and it’s bore, Key way height. Take it to a machine shop & ask them to measure the dimensions listed. Otherwise, You’ll need a telescoping gauge & the 1-2” Micrometer above that reads in tenths. Dial Calipers would only be useful here in measuring keyway height, width, since their tolerances are generally +/- .005. It’s just as easy to compare by using a new key, trying its fit, comparing NAPA, Advanced, etc should have one. Stock size is used.
1570441621486.jpeg
So, if it’s moving & tool’s holding up, keep it clean, lubed, pull it in. If something’s drastically wrong, pull it & verify why. Think you’ll be OK.
Best of luck,

Once again, your wealth of technical expertise is highly appreciated!

As I mentioned before this is the most “built” of a motor that I’ve ever dealt with having only done basic “bolt-ons” to all my previous foxbodies.

Going into a couple things you mentioned:

1. I did check with DSS and sent them a picture of the balancer and they said it matched the paperwork for the motor. They also warned me that Romacs are notoriously tight.

2. The crank and balancer are both a single key way design. I did try to verify their same size before the install just with a tape measurer (not as precise I know) and they at least appeared to be the same general size.

3. I used a Blue Point Harmonic Balancer installer to install. As I said, it was tight, but it did work.

4. I do have a new ARP crank bolt.

Eventually it seemed like I was stripping the jam-nut on the thrust bearing, which is what lead me to believe it was fully installed.

As I installed it, I did stop multiple times, checking the crank to see if their was any metal flaking or rolling as you put it.

I THINK my only mistake might have been using oil and not anti-seize. So perhaps it’ll be worth while to pull it off just to do that.
 
Last edited:

08GT500

Active Member
Jul 12, 2018
904
140
53
Hi Justin,
It certainly wouldn’t hurt anything by pulling it, but I don’t think it’s necessary. Agree w/ DSS, hard installs are commonplace for many of the performance balancers, theory is tighter clearances help balancer concentricity remain stable at higher rpm’s.
The bore on the balancer is made to the factory crankshaft diameter size of 1.3750 & they added a +.0005 tolerance.
Machinists generally stay in the middle of that, say 1.3752 -just to be safe. The crank is dead accurate at 1.375, generally.
Tolerance of .0005 (in) is 0.00127(mm)..pretty small- about half of a single human hair. Now split that 1/2 hair in (2), .00025 (in) that’s the clearance you have on each side of the crank inserted into the Balancer.
When tolerances are that tight, any little nicks or burrs or even a tight key can drive anyone crazy. I’d not be concerned if it’s near homed now, use the Crank bolt to pull it the rest of the way in, torque to spec’s (90lbs, but double check).
Zooming your motors image, balancer is deeper in than originally thought, note if it moves in further when you tighten crank bolt to spec’s. Take your pulley, Mount it on the balancer, same with Water Pump. Double check your alignment with a long straightedge.

Good to hear from you, Justin
- Best!
John