Need some help on a BBF cam/dist interference...

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blykins
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Need some help on a BBF cam/dist interference...

Post by blykins » Tue Mar 13, 2018 7:47 pm

I'm building a BBF truck pulling engine. Using an Eliminator Premier block with a 60mm camshaft.

I do a lot of FE's, so I'm used to checking distributor clearance at various points during the build, especially with aftermarket blocks. I did the same checks with this block and found the distributor gear hitting the front cam bearing, so I had to clearance the bearing.

Put all the galley plugs in after washing the block and installing the camshaft with thrust plate and decided to check distributor fitment once more because I will be buttoning up the front end here shortly. Glad I checked it one last time...

With the cam in, the distributor is noticeably harder to seat all the way. Once seated, the camshaft and distributor are locked tight. Neither will turn and it's nearly impossible to get the distributor back out.

Here's what I've checked so far:

1. Distributor gear is at correct installation measurement, 3.045" with end play taken up.
2. Distributor falls in and rotates without camshaft in block.
3. Distributor gear is correct 351C/460 gear, I checked the diameter and pitch against other distributors I have in stock.

The cam and distributor lock up solid when the distributor is seated. I can put the cam bolt in the cam and use a 1/2" drive ratchet and it just won't spin. However, I can spin the camshaft backwards and it will spit the distributor up and out.

I'm at a loss here. I've emailed Comp to make sure that they didn't use a special gear on the camshaft......Windsor gear?????

Any ideas or anyone think of anything I can check? Obviously I'm stuck at this point.
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Re: Need some help on a BBF cam/dist interference...

Post by R.Olds » Tue Mar 13, 2018 8:32 pm

Either the cam gear is a bit to large, which I ran into on a windsor build one time. I had other cams to install and they all had proper gear clearance, but the cam I had custom ground was so tight it would lock up. Everyone said I was crazy until I sent the cam back so they could double check it....they found it was out of spec and sent me a new cam which fit perfect.
I also had a world windsor alum block that had the lower dist shaft hole machined to close to the cam, it would bind up as well. the same cam and dist fit a brand new Ford Racing block I had with no issues so it was definitely a screwed up block from world. There is a thread somewhere in here on that cluster F**k.... I just happen'd to have a few misc gears laying around and found one that was a bit smaller in dia that gave me good clearance.
Do you have any spare 385 series cams or distributors laying around, you can try process of elimination. You probably would have already, but its the only thing I can think of..... :D

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Re: Need some help on a BBF cam/dist interference...

Post by JonKaase » Tue Mar 13, 2018 8:37 pm

Last time I did one like that I had to turn about .080 off of the OD of the dist gear. I think we didn't grind the cam bearing enough. Or the front main on the cam hit the gear because of the bigger diameter. But it still worked and didn't wear out driving the oil pump... Kaase

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Re: Need some help on a BBF cam/dist interference...

Post by blykins » Tue Mar 13, 2018 8:45 pm

Thank you both for the input.

Jon, I would have thought it was bearing interference too, but the dist drops in and spins perfectly without the camshaft in the block.

You may have something though about the dist gear hitting the front journal.

This is a dry sump engine with a crank trigger so this really should be stupid easy.....but it's always something.

Gonna wait on the reply from my Comp rep just to make sure they didn’t do something wonky with the cam gear.
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Re: Need some help on a BBF cam/dist interference...

Post by cjperformance » Tue Mar 13, 2018 8:50 pm

JonKaase wrote:
Tue Mar 13, 2018 8:37 pm
Last time I did one like that I had to turn about .080 off of the OD of the dist gear. I think we didn't grind the cam bearing enough. Or the front main on the cam hit the gear because of the bigger diameter. But it still worked and didn't wear out driving the oil pump... Kaase
Yep exactly. ^^ put some light bearing blue on the gear OR diff gear paint etc, fit the dissy, if its tight to turn i wouldnt reccomend tyrning it over but just sliding the dissy up and down a few times will leave a witness as to where the interference is. You may need to m/c a little off of the cam gear as well and re chamfer the teeth.
Craig.

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Re: Need some help on a BBF cam/dist interference...

Post by blykins » Wed Mar 14, 2018 6:52 am

My only fear is that something else is amiss, since I don't trust small quantity runs of aftermarket parts. Could the hole in the block be off?

Here's a pic of how the gears interface. The distributor gear is pretty deep into the cam gear. I'd like to be able to just cut some off the dist gear and roll with it. Wouldn't worry me as much with a dry sump system.

Image
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Re: Need some help on a BBF cam/dist interference...

Post by cjperformance » Wed Mar 14, 2018 7:10 am

Is the pan on? Maybe bolt up a stock oil pump and drive shaft to get another point of reference for dissy alignment.

Have you compared cam gear OD and gear teeth base diameter to another cam?

Clean and spray paint a spot on the dissy gear, fit it then turn cam backward to spit dissy out and find exactly what part of the teeth is binding.

Pain in the A but got to check stuff while waiting for comp to get back.
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Re: Need some help on a BBF cam/dist interference...

Post by blykins » Wed Mar 14, 2018 7:41 am

Mostly SBF's and FE's come out of my shop, so I don't have any spare 385 series parts laying around. No pumps or pump shafts......and no spare cams.

Got another MSD distributor coming, just for a quick stab in the dark. By looking at the picture though, it looks like if I cut the distributor gear, it wouldn't do me any good. Looks like the teeth on the cam gear are getting hard into the root of the distributor gear.

Belt drive distributor looking better and better every second....
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Re: Need some help on a BBF cam/dist interference...

Post by blykins » Wed Mar 14, 2018 8:29 am

BTW, the distributor gear does not contact the front cam journal that I can see.
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Re: Need some help on a BBF cam/dist interference...

Post by R.Olds » Wed Mar 14, 2018 11:10 am

when I was dealing with the same scenario I was fortunate enough to have 6 or so different gears from Crane, DUI, MSD, Mallery and so on, it was a junk Procomp dist that had a gear close to .020 smaller in dia. I did have to machine it to fit my MSD dist though....
Of course the manufacturers of the parts I had problems with had never seen anything like it before..... :^o

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Re: Need some help on a BBF cam/dist interference...

Post by Walter R. Malik » Wed Mar 14, 2018 1:11 pm

Check to be sure that the O.D. of the teeth, (either on the cam or the distributor gear), are not binding in the root of the opposing gear.
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Re: Need some help on a BBF cam/dist interference...

Post by piston guy » Wed Mar 14, 2018 1:15 pm

Brent,
From "my eye" it looks like the cam gear OD it too big and the gear is bottoming out in the dist gear. The OD should be the same as a C cam. Also do you have a "used" C bronze gear (or dist) to check with?
Randy

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Re: Need some help on a BBF cam/dist interference...

Post by blykins » Wed Mar 14, 2018 1:49 pm

Randy (and Randy)....

That's what I think is happening. I'm waiting on Comp to give me a spec of that gear OD. I don't think I have any Cleveland camshafts on the shelf right now. I also don't have any bronze gears as I don't use them.

I've got another distributor coming, but I'm 100% sure it's gonna be the same way. It looks like the cam gear teeth are in the root of the dist gear teeth.
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Re: Need some help on a BBF cam/dist interference...

Post by grant6395 » Wed Mar 14, 2018 2:01 pm

Walter R. Malik wrote:
Wed Mar 14, 2018 1:11 pm
Check to be sure that the O.D. of the teeth, (either on the cam or the distributor gear), are not binding in the root of the opposing gear.
This^^
I had a sbf I just finished that this happened to .
Tried 2 different gears. I just took .020 off the gear and it was fine. The dist gear was binding in the root of the cam. Also a dry sump application

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Re: Need some help on a BBF cam/dist interference...

Post by blykins » Wed Mar 14, 2018 5:52 pm

The plot thickens....

I did have another cam here for a BBF. I measured the OD and the width and compared it to the one that's in the Eliminator block. Exact same specs.

At this point, I'm just gonna whack some off of the distributor gear for giggles. If that doesn't work, then I'm gonna go belt drive.
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