Rollmaster CS3031 timing set and fuel pump eccentric

[Oldtimer]

I am installing a ROLLMASTER CS3031 timing set in my 351W, from a 75 E-250.

The original engine had a two piece fuel pump eccentric that is not compatible with the Rollmaster cam gear.

The engine is carburated.
I need some options.
Will a one piece eccentric work?
Is there an aftermarket option?
Do I need a different timing set?
Do I go to electric fuel pump?

Thanks

 

[jamesroney]

I am installing a ROLLMASTER CS3031 timing set in my 351W, from a 75 E-250.
View attachment 944382

The original engine had a two piece fuel pump eccentric that is not compatible with the Rollmaster cam gear.
View attachment 944381

The engine is carburated.
I need some options.
Will a one piece eccentric work?
Is there an aftermarket option?
Do I need a different timing set?
Do I go to electric fuel pump?

Thanks

The one piece is thicker. You don’t want it.
The eccentric you have will work, but you have to shorten the cam dowel, or run a later 5.0 dowel.
Electric fuel pumps are horrid and have no business on a Bronco. Unless they are submerged in the tank.

You might need to machine the face of the cam sprocket if the eccentric hits the timing cover. It doesn’t take much.

 

[Oldtimer]

The Ford cam gear has an offset step so eccentric outer sleeve can spin.

The Rolmaster has no offset step.

 

[Oldtimer]

Here are a couple of DIY options from

, but I will wait and see what Rollmaster recommends.

 

[jamesroney]

Yuck. I see it now.

Can you measure the distance between the timing cover and the front of the sprocket to see if a 1 piece will fit?

If so, I have a couple of extra ones. Otherwise, we can face the sprocket and run the 1 pc. I can check how hard the 1 pc eccentric is, and if it is mild...I can cut one down for you.

But it all starts with the cover to sprocket space.

 

[ntsqd]

My surface grinder won't care how hard it is, but I am ~300 miles south of y'all.

Seems like it would be easy to put a relief in the cam gear.

 

[Broncobowsher]

Carter P4070 has replaced all my mechanical fuel pumps for decades.

 

[Oldtimer]

@jamesroney, how tall are 1 pc eccentrics?

Timing cover is 1.760" deep.
Cam gear is .775" proud of cover mounting surface.
Difference is .985" (+gasket).
Aerospace tells me eccentric shoul be less than .975" tall.
Reality says it needs to be less than 7/8", and 3/4" would be better.

Not sure the above Ford Truck Enthusiasts hack would be a good idea, it would have outer steel eccentric rotating against a aluminum gear.

 

[jamesroney]

The stock one piece measures .940. The stock two piece is .748

The one piece is hard. Like Rockwell 60 hard. Harder than carbide wants to cut.

So I Ground one for you. It finished at .748 (19mm). No charge.

 

[Oldtimer]

Thank you is all I can say, and that is nowhere near enough.

 

[EPB72]

Last two customers cars a mustang in December and a bronco last July ,, took 7 pumps to get 2 good ones. , the bronco already had a new one , Napa the first one Carter bad check valve ACDelco pump worked the mustang 3 pumps different brand but looked identical all put out 21 psi the lat one amplify brand from summit looked identical , there was a date stamp on it for 2020worked good at 6,5 psi ,, lost faith in current mechanical pumps.

 

[Oldtimer]

Follow up on cam eccentric to timing chain cover clearance.

Ford Performance M-6287-B302 eccentric is .930” tall and
gives .040” measured clearance to cover.
Not near enough clearance in my opinion.

A used 1 piece eccentric ground .749” tall
gives .250” measured clearance to cover.
It may be too much clearance, but will work.

Fuel pump arm contacts each eccentric at same distance from cam gear.

Note:
The new Carter M6558 fuel pump arm did not contact eccentric all the way around, which may cause low fuel delivery.
The 30 year old AC 41119 fuel pump arm made contact all the way around eccentric.

The fuel pump arms have different shapes, as seen in their profiles when mounted in timing chain cover.

PS. Since nobody lists dimensions of Ford Performance parts,
and AMAZON makes it super simple to order and return parts,
thats what I did

 

[ntsqd]

Are there different diameter, different eccentricity, or both fuel pump eccentrics?

 

[Oldtimer]

Eccentricity is same for all, controlled by bolt hole to dowel pin hole spacing in cam.
Diamaters are close (+/- .035")
1 piece .940" tall, 2.516” OD, from James garage
1 piece .930” tall, 2.520” OD, FMS M-6287-B302
2 piece .833” tall, 2.550” OD, from 351W- 75 E250

2 piece effective OD is 2.449" (inner piece OD of 2.385 + .064 wall thickness of outer piece)

 

[ntsqd]

You just blew a perfectly good theory and potential internet rumor right out of the water.


I doubt they'd answer, but maybe ask Carter what eccentric their M6558 pump is supposed to work with?

 

[jamesroney]

Thank you is all I can say, and that is no where near enough.

If you wanted a taller one, I could have ground it taller a lot faster...

Be wary of the earlier FE eccentrics. They are dimensionally identical, except the bolt hole is 7/16 thru, instead of 3/8 thru. (nominal)

The fuel pump arm is pretty easy to notch and weld in the correct position. you and @ntsqd might have discovered why there have been a rash of fuel pump failures recently. I don't remember why I was cutting / welding fuel pump arms...but it was about 5 years ago, and wasn't for a Bronco.

 

[jamesroney]

Eccentricity is same for all, controlled by bolt hole to dowel pin hole spacing in cam.
Diamaters are close (+/- .035")
1 piece .940" tall, 2.516” OD, from James garage
1 piece .930” tall, 2.520” OD, FMS M-6287-B302
2 piece .833” tall, 2.550” OD, from 351W- 75 E250

2 piece effective OD is 2.449" (inner piece OD of 2.385 + .064 wall thickness of outer piece)

You sure about this?

Eccentricity is controlled by mounting bolt concentricity to OD. bolt to dowel pin spacing is irrelevant. (I only know this, because I was going to grind yours between centers...and realized there is no hole in the center of the eccentric.)

Pretty sure the one you got from me finished at 3/4 inch nominal height.

We are kinda splitting hairs on OD. They are all 2-1/2 inch nominal, with maybe +.025 on the radius. That Carter pump arm is out about a foot...

Nice work and I appreciate the write up. Might save some poor slob in the future.

If I were you...I'd consider facing the hub on that cam sprocket. I don't like that the cam gear is too thick. Mostly because you can't get good protrusion of the timing pin if the sprocket is thick. As much as we are focusing on timing cover clearance, there is also the back side of the eccentric to consider. The 2 piece uses a short dowel, and an tab. Early cam uses an extra long dowel, and drives on the hole. The SBF engine turns clockwise, so the eccentric wants to unscrew the cam bolt. It should either be left hand thread, or it must be pinned. Don't even think of using thread glue.

 

[Oldtimer]

The ROLLMASTER CS3031 timing set comes with two dowel pins.
1-1/8 and 1-3/8 inches long.

They list the timing set for "pre EFI engine". My assumption would be mechanical fuel pump.

The 1-1/8 pin is short enough that the tab on 2 piece eccentric will engage hole in cam gear, BUT cam gear does not have step to allow outer eccentric to rotate. See below photo of resulting carnage.

The 1-3/8 pin is long enough to engage 1 piece eccentric and short enough to not interfer with washer under bolt head, BUT gear is too thick to allow reasonable clearance between timing chain cover and any available "off the shelf" 1 piece eccentric.

Rollmaster USA has no phone # and won't answer e-mails.
Rollmaster Australia won't answer e-mails, and not sure I want place international phone call.

All the eccentrics I have in hand have the same mounting bolt hole offset to OD.

And YES, the one you ground is .749" tall.

Also note: If no eccentric is used, ARP cam gear bolt (#: 254-1001) will bottom out about the time you contact the ARP washer. Gear may not be tight.

 

[ntsqd]

Time to look at a different vendor's product?

 

[Oldtimer]

I have a soulution that will work (thanks James), but if I were to do this again, I don't think I would go this brand timing set even though recommended by Ed @ FTI.