DUI Distributor issue

Hello Fellow Correct Craft Fans,

I’m a new member of your group, but I have been lurking here for the last 6 years, gathering all of your sage advice and recommendations. Your site was recommended by a childhood buddy whom is in the boating industry, and has used the info to rebuild his beautiful 72’ Ski Nautique. Your: “what to look for when buying an older Nautique” guide is invaluable. We have had our 2001 for the last 5 years, and during that time we have replaced the stringers, installed electronic ignition, rebuilt the 4-barrel Holly, replaced all of the hoses/belts/fuel filter-water separator, and cleaned/flushed out the fuel tank. The boat had developed some issues with the transmission cooler leaking water into the bell housing, and was fixed along with replacing the transmission components. During the last two seasons, the boat runs ok below 3000 RPM, but when we try to ski nearer to 34-36 MPH (~3400 RPM), the engine starts cutting out. I had replaced the distributor cap and rotor (ensuring the cap was snug, as I kept the old rubber seal from the old one-the new ones have a crappy, thin cork seal). No change to the performance. I replaced the carb with a brand new Holly 4160 from Summit Racing, and the engine started/idled and ran wonderfully up to 3000 RPM. After reading the wonderful narrative about swapping over to the DUI distributor, I sucked it up and bought one (along with the RR gear). I wanted it to “go on correctly” so enlisted our mechanic to swap/install and do the fine timing/tuning. Some problems arose when at first the DUI was rotating in an oscillatory manner, then as the RPM were increased it settled down and ran really well up above 3000+ RPM. Then noticed the oil pressure going to zero and cut the ignition. Pulled the distributor and noticed the female end of the DUI dizzy shaft (the hexagon) was stripped smooth. UGH! Used a magnet and recovered the metal filings and using a bore-scope noticed that the oil pump shaft is ok. Putting a speed bit on the pump, it spun up and pumped oil, effortlessly. We contacted Performance Distributors and ordered a new shaft. We received one that was not drilled put to receive the drive gear cotter pin, so sent the entire lower part, with the stripped shaft back to then so Scott (their technical expert) could discern the problem. Looking at the stripped segment on the drive shaft depicts not much of (1/4” or so) is engaging the oil pump. Do any of you know how much it should engage?

Thanks in advance, Very Respectfully, Ted Rutherford

Ps the top photo is the stripped DUI shaft, and the bottom shows the old distributor.

Thanks for the response sir. I will do as you say Todd, and check that it is seated all way. Performance Distributor just called and said "it might be a heat issue, or binding" he replaced the lower piece and is shipping it back. As far as engaging the oil pump 1/4" is plenty according to Scott (the tech advisor at P.D.).

Hollywood wrote: Sure is easy to bash the mechanic who is not here.... I have not heard of anyone having engagement issues with their DUI or anyone not seating their distributor either.

It's clearly too soft of a metal from DUI or compentcy issues elsewhere. If it's on DUI's end surely there's reports elsewhere online and DUI would know about it. My concern is everyone's a mechanic, and there's no difference in a boat motor than a car motor says the same mechanic.

I just did a DUI swap and there is a specific note in the instrucitons about not using a high volume oil pump ... you don't have one of those do you?   

Is the length of the shaft from where it seats in the block
to the gear end the same as the old dissy ?
Is the new one seated in the block correctly ?

I had an old 4 cyl nova that the oil pump was driven by dizzy thru a roll pin. Left me stranded several times cause it was sludged up & had excessive oil pump load so it sheared the roll pin. . What weight oil are you using?   What oil pressure are you getting?

351w oil pump is driven by a 5/16 hex key.
Can you get the hex key out of the oil pump.
It "should" have a slot for an e-clip to keep the hex from
dropping to far down into the oil pump. I know it can be
twisted but much, much stronger than the Chevy roll pin.
You can even buy a heavy duty, hardened hex oil pump drive key

Waterdog wrote: 351w oil pump is driven by a 5/16 hex key. Can you get the hex key out of the oil pump. It "should" have a slot for an e-clip to keep the hex from dropping to far down into the oil pump. I know it can be twisted but much, much stronger than the Chevy roll pin. You can even buy a heavy duty, hardened hex oil pump drive key

That clip you're talking about Waterdog goes on the shaft before you install the shaft and the pump from below.

It's there to keep the shaft from being able to be removed when pulling the distributor. If you didn't have that clip the shaft could come up enough to come out of the oil pump and then fall down into the oil pan.

Some info for Ted

I took a distributor out of a 351W and took some measurements and Ted's 5 inch measurement from flange to the end of the shaft agreed with mine.

From the same flange to the bottom of the gear is about 4 inches.

From the seating surface for the flange on the engine block down to the top of the oil pump shaft was 4 7/16 inches which means the shaft sticks 9/16 of an inch into the distributor shaft BUT..................the top roughly 1/4 inch of the oil pump shaft is tapered for the distributor to slide over it easier so that leaves about 5/16 of an inch of the oil pump shaft in contact with the inside the distributor shaft with my "not.terribly precise measurements" since the 1/4 inch tapered part is not in contact.

This might be kinda hard to visualize but what it tells me is that your distributor shaft engagement of about 1/4 inch with the oil pump shaft sounds right just like DUI said.

The oil pump shaft is hardened steel, I don't know what the distributor shaft is but I bet it's not as hard as the oil pump shaft.

So I think like somebody said, either an inferior quality distributor shaft from DUI or your oil pump has issues

All my numbers here are rounded off slightly but the end result of about 1/4 to 5/16 inch of engagement between the 2 shafts holds true.

When I installed my DUI, it took a fair amount of effort to get the oil pump and dizzy shaft aligned. Once it dropped in, it was golden, but it was not without a fair amount of effort. I assumed it was because the dizzy shaft was so new.

Duane, the replacement shaft was not drilled, and we did not want to mess it up, so sent it (the whole dizzy) back to P.D. to check/drill and remount gear, so they could determine all was well with no issues...

AlphaDon, one of the things i had asked Scott at Performance Distributors was if it was ok to put a bit of lithium grease in the hex opening, either that or some other type, that would not foul up the oil, if it mixed... He said he saw no problem with doing that...

Again, thanks folks for your kind help. Very Respectfully, Ted

I wonder if the difference between the 7k and 10k DUI is a harder shaft (hehe) which could also turn a high volume pump?

Orlando76 wrote: Guessing the distributor wasn't seated all the way which I would grill your mechanic over, then find a new mechanic..

re: sheared drive,      I would venture to say that 90 + % of the drag racers are running high volume, high pressure pumps in their Fords. Never heard any complaints. Interesting thought though.

TedR wrote: Hey Folks, thanks again for the help and insight. The problem is solved! The remounted dizzy shaft came back with the drive gear mounted slightly higher than before, so that the hex engages more of the oil pump drive shaft (length does matter) just idling the engine, with a some powerful magnets on the oil filter trying to capture any ferrous fillings that might be left after using cleaning out the "dizzy hole". Then oil change and try out on the water. Thanks again Gentle Correct Craft Fans. Very Respectfully, Ted

May be too late too ask but how much is slightly higher?

Just curious because Ford has some pretty tight tolerances on the distance from the bottom of the seating flange to the bottom of the gear, see the link below

dist gear installation

Sounds like a DUI screwup on the original shaft

KenO