DUI Distributor issue
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=39645
Printed Date: May-08-2024 at 6:00pm
Topic: DUI Distributor issue
Posted By: TedR
Subject: DUI Distributor issue
Date Posted: August-11-2016 at 4:49pm
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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.  
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Replies:
Posted By: Orlando76
Date Posted: August-11-2016 at 5:05pm
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Guessing the distributor wasn't seated all the way which I would grill your mechanic over, then find a new mechanic. I'm not sure how much the shaft engages, your old shaft should give a good indication. Sorry to hear about the troubles, we've all been there. ------------- Please support The Cystic Fibrosis Foundation 1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
Posted By: TedR
Date Posted: August-11-2016 at 5:24pm
| 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.). |
Posted By: Hollywood
Date Posted: August-11-2016 at 5:32pm
| 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. |
Posted By: Orlando76
Date Posted: August-11-2016 at 5:41pm
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. ------------- Please support The Cystic Fibrosis Foundation 1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
Hollywood wrote:Posted By: TedR
Date Posted: August-11-2016 at 5:58pm
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He's a real "mechanic" (I am not). and the owner of boat yard/Marine repair shop up here in Minnesota, which has an outstanding reputation. He has never seen this happen as well... Maybe the oil pump temporarily seized, shearing the inside of the shaft?! The oil pump works now and spins easy. I'll give you folks an up date when we try again. |
Posted By: Dreaming
Date Posted: August-11-2016 at 6:10pm
| 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? |
Posted By: TedR
Date Posted: August-11-2016 at 9:30pm
I do not know, but will find out sir. I do remember seeing that note, thanks |
Posted By: Waterdog
Date Posted: August-12-2016 at 9:00am
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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 ? ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: TedR
Date Posted: August-12-2016 at 10:48am
Thanks for the reply Waterdog. Yes the length is identical (5" from tip to end of shaft to the base of the distributor that seats on the engine block). when the dizzy is installed it looks "correctly" seated. |
Posted By: SNobsessed
Date Posted: August-12-2016 at 11:08am
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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? ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: TedR
Date Posted: August-12-2016 at 11:45am
From the Performance Distributor website: Topic 2: Excessive Distributor Gear Wear on Ford Worn Ford GearExcessive distributor gear wear can be a problem with Ford engines. Most of the time, the problem is a result from the use of a high volume oil pump. High volume oil pumps put a lot of stress on the distributor and cam gears. A high volume oil pump is not necessary on a street driven engine that turns no more than 7000 rpms. Only extreme racing engines require the high volume pump. If you use the high volume oil pump the following precautions will save your distributor gear from early destruction.(1) Drill a .030″ hole in the lifter/oil galley plug behind the distributor. This will allow additional lubrication on the distributor and cam gears. (2) Install a deeper oil pan. High volume pumps will pull all of the oil out of a stock pan creating a lack of lubrication. (3) Ford oil pump mounting brackets have elongated holes. Due to this, the distributor shaft and oil pump shaft should be aligned so that the distributor turns freely before tightening the mounting bracket bolts. Failure to do this will cause a binding situation, thus damaging the gear. (4) Stock Ford hex oil pump drive shafts are known to vary in length which could cause a bottoming or binding situation. (5) Brass distributor gears can be used to avoid damaging the cam gear. Brass gears are softer and can wear out quicker than the cast gear, but will not cause damage to the cam gear. If using a brass gear, check it occasionally for wear. Talking to Scott (the Performance Distributor Tech Advisor), he said that he had never seen this happen yet either; he was helpful answered many of my layman's questions. |
Posted By: Waterdog
Date Posted: August-12-2016 at 11:45am
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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 - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: TedR
Date Posted: August-12-2016 at 11:52am
We were not able to get the hex key out. Thanks for the info Waterdog; I will relay this to the gentleman helping me. I sure appreciate all of the input from y'all. |
Posted By: KENO
Date Posted: August-12-2016 at 12:18pm
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. |
Posted By: Waterdog
Date Posted: August-12-2016 at 2:42pm
I lent out my "How to Rebuild Small Block Fords" book - Damn ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: KENO
Date Posted: August-12-2016 at 10:33pm
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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. |
Posted By: Duane in Indy
Date Posted: August-12-2016 at 10:48pm
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KenO, The shaft has to be soft enough to drill the cross hole in it. I have seen them shear off, that's why I think they are probably dead soft. Another reason that I like to turn the gear 90 degrees and redrill the gear only when mounting it. Two holes in the shaft would weaken it too much. For some reason there is no "universal" location for the cross hole. They just slap them on and pin them. A lot of new gears don't have any cross hole in them when new. ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: AlfaDon
Date Posted: August-13-2016 at 12:24am
| 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. |
Posted By: TedR
Date Posted: August-13-2016 at 3:07pm
Dear Keno, thanks for taking all that time to remove your distributor and take those measurements, that does concur with what i saw and what Performance Distributors reported to be normal. You are exactly right sir: the pump shaft is tapered, and does not engage the entire dizzy shaft. When i receive back the "fixed" DUI distributor, i will carefully attempt to reseat. V/R ted |
Posted By: TedR
Date Posted: August-13-2016 at 3:13pm
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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 |
Posted By: KENO
Date Posted: August-13-2016 at 4:25pm
Aw Shucks Ted it was nothing.  Actually the amount of engagement between the shafts is one of those things you don't give much though to and my curiosity got the better of me and I just had to know. KenO |
Posted By: Orlando76
Date Posted: August-13-2016 at 5:01pm
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I wonder if the difference between the 7k and 10k DUI is a harder shaft (hehe) which could also turn a high volume pump? ------------- Please support The Cystic Fibrosis Foundation 1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
Posted By: TedR
Date Posted: August-17-2016 at 11:50am
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 |
Posted By: 8122pbrainard
Date Posted: August-17-2016 at 12:15pm
------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Gary S
Date Posted: August-17-2016 at 1:26pm
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I think that's pretty harsh especially if DUI determined that the gear mounting was questionable. I'm sure Robert Yates has lost an engine or two over the years would you fire him too? Joe had 408 troubles,I would not hesitate for him to touch any of my engines. I'll never know,but my dad had his Ski Supreme's 351 rebuilt and right after that it split the distributor drive. I wonder now if a high volume pump had been put in. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: Duane in Indy
Date Posted: August-17-2016 at 1:33pm
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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. ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: TRBenj
Date Posted: August-17-2016 at 1:41pm
| Hv pumps are definitely harder on dizzy shafts and therefore cam gears. The Windsor oil pump drive and smallish dizzy shaft diameter can be problematic with HV/HP pumps, apparently. Bow tie stuff is much larger and not an issue per the folks I spoke with from Milidon and Melling... I just went through this on my BBC. |
Posted By: KENO
Date Posted: August-17-2016 at 1:47pm
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 https://performanceparts.ford.com/download/pdfs/DistributorGearInstallation.pdf" rel="nofollow - dist gear installation Sounds like a DUI screwup on the original shaft KenO |
Posted By: halfnelly
Date Posted: August-17-2016 at 1:56pm
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I've always been taught not to run a high volume pump in a Windsor, simply because they don't really need one. The rationale I was always given was "It ain't a small block Chevy, don't build it like one!" They can pump the pan dry at high RPM and cause a lot of wear on the distributor gear or twist the pump driveshaft, plus they cost more HP to run. I've seen a lot of guys use a blueprinted stock pump instead of HV in their Windsor builds. |
Posted By: 8122pbrainard
Date Posted: August-17-2016 at 2:07pm
The "harshness" was directed to whoever installed the distributor not noticing it wasn't seated and not to DUI's gear placement possible mistake ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Gary S
Date Posted: August-17-2016 at 3:20pm
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I understand that but we have know way of knowing if it was fully seated or not do we, we were not there. If it was not fully seated would there not be unusual wear on the gear too? Remember it's that gear that turns the distributor first, any forces that sheared the oil pump drive would also be concentrated on those gear teeth first, the OP never mentioned the gear being damaged. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: 8122pbrainard
Date Posted: August-17-2016 at 3:24pm
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Gary, There wouldn't be any wear on the gear since they are straight cut bevels. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Gary S
Date Posted: August-17-2016 at 4:32pm
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But if not fully seated the gears would be running out farther on their tips instead of the full width of the teeth? The pressures would have to be that much greater ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: TedR
Date Posted: August-17-2016 at 6:20pm
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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 https://performanceparts.ford.com/download/pdfs/DistributorGearInstallation.pdf" rel="nofollow - dist gear installation Sounds like a DUI screwup on the original shaft KenO[/QUOTE] KenO, not sure how much higher ~1/16" to 1/8" at max... I did not get a good enough picture, that "Ford Racing" guide had some good info, thanks. I have not called DUI yet to give them a constructive debrief. I'm so dang happy that my boat works. I put on the new 3 blade Acme 540 and i ran it up to almost WOT. 44 mph (not GPS certified) @ ~ 3900-4000 RPM. The only hitch is that there is a new "whine" when the boat is engaged in forward. It does not happen in reverse. The alignment still looks ok. I pulled it out of the water and ran it, and no whine... no binding, all sounds and looks ok. Again, so thankful to no longer be "boat-free" |
Posted By: TedR
Date Posted: August-17-2016 at 6:23pm
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BTW the new 3 blade prop creates a much less turbulent wake than the 4 blade. Smoother hole shot too. |
Posted By: Air206
Date Posted: August-17-2016 at 7:13pm
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So, I replaced the Pro Tec with a DUI in a 454. When I dropped it in place, it is not possible to tell how much of the shaft is engaged. If it bottoms out, you can tell ...... but engaging 1/4 inch vs 3/8 inch vs 1/2 inch.... how would you know? Maybe mine isn't engaged enough...I wouldn't know. I have never heard of anyone measuring the distance prior to install. Is that done? How can you tell during install since you don't see anything and it would "feel" the same. Stupid question from a simple guy............. ------------- https://tinyurl.com/y6t5e3bu" rel="nofollow - 04 Air206 http://tinyurl.com/9urzgls" rel="nofollow - 91 Barefoot 78 SkiTiq |
Posted By: KENO
Date Posted: August-17-2016 at 8:24pm
Here's a good Chevy explanation of setting distributor height and the article has input from Steve Davis of DUI. Right now I'm too simple minded to make the link work for whatever reason http://www.hotrod.com/articles/ctrp-0606-proper-distributor-installation-practices/ KenO |
Posted By: Air206
Date Posted: August-17-2016 at 8:43pm
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Keno- His directions are exactly what I did and what I am referring to. You can assess too much engagement (bottoming out) but it is not possible - by the means in that description - to assess too little engagement. Hard to throw anyone under the prop if you can't assess marginal engagement. Using the old dizzy shaft setup would be the only practical way I would see to compare placement... and that assumes proper initial setup. Are there fancy ways to assess marginal engagement, Pete? ------------- https://tinyurl.com/y6t5e3bu" rel="nofollow - 04 Air206 http://tinyurl.com/9urzgls" rel="nofollow - 91 Barefoot 78 SkiTiq |
Posted By: KENO
Date Posted: August-17-2016 at 9:19pm
If you go back to page 1 of this thread you can see how I checked a 351 engagement that came out the same as what the broken DUI had (about 1/4 to 5/16 of an inch). This particular engine has been running for 40 years with this distributor so the engagement must be OK.. It would be taking the same basic measurements on a Chevy and doing some math. I think it would be a little harder to get all the measurements on a Chevy but it can be done. |
Posted By: Air206
Date Posted: August-17-2016 at 9:46pm
That's exactly what I am saying - The "checking upon installation process" doesn't assess minimal engagement only bottoming out. The only way to do it is to measure the old dizzy and hope the setup doesn't change (intake manifold change, etc.). In your write up, you give measurements and use the term "about". The DUI install discussion says to seat and wiggle to assess 100ths of inch wiggle. That's my point.... "wiggling to assess 100ths of an inch" is best guess process given what's known. It isn't a process that separates the "hack", as Pete calls, them from the Engine Gurus. ------------- https://tinyurl.com/y6t5e3bu" rel="nofollow - 04 Air206 http://tinyurl.com/9urzgls" rel="nofollow - 91 Barefoot 78 SkiTiq |
Posted By: JPASS
Date Posted: August-17-2016 at 10:10pm
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Couldn't you measure the gear engagement the same way you would on a rear differential? I've seen where they use a bright white or yellow paint and brush it on the ring gear, then spin the pinion and see how the teeth mesh by the transfer of the paint. ------------- '92 Correctcraft Ski Nautique |
Posted By: KENO
Date Posted: August-17-2016 at 10:14pm
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It worked for me with a Ford distributor. I was curious what I had for engagement since I hadn't really thought about it before this thread and I'll guess neither had you. Now I know. what mine is. I didn't have any "instructions" on how to do this, just thought about it logically and started measuring things. The "about" was rounding off a few thousandth's at the most to get the concept across and keep things easy to read. You can take measurements of the new distributor just as easily as you can the old one and figure out how much engagement you have when you know how deep in the engine the top of the oil pump shaft is. You can have faith that DUI or any other outfit did it right or you can measure. You probably did a quick comparison of the new and old before installation right? |
Posted By: Air206
Date Posted: August-18-2016 at 12:50am
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Yup - Found out I had the wrong gear rotation! Like I said - Simple guy...... LOL! http://i.imgur.com/hqb1m6W.jpg%20" rel="nofollow">  http://i.imgur.com/hqb1m6W.jpg%20" rel="nofollow"> ------------- https://tinyurl.com/y6t5e3bu" rel="nofollow - 04 Air206 http://tinyurl.com/9urzgls" rel="nofollow - 91 Barefoot 78 SkiTiq |
Posted By: KENO
Date Posted: August-18-2016 at 9:39am
I remember that. Good write up you did about it back then From another simple guy PS When I should have been getting my beauty rest last night I think I thought of a simple way of checking the engagement depth on a Chevy but I'd rather try it first to see if it actually works. |
Posted By: 8122pbrainard
Date Posted: August-18-2016 at 11:04am
The OD shoulders on the main shank of the distributor body that are in the block maintain the proper gear engagement depth no matter how far the distributor is inserted into the block. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Gary S
Date Posted: August-18-2016 at 12:02pm
Stealing Steves picture for a minute Pete are you saying for example,that if the gear is running half engaged that the forces on those teeth are not increased? If they are not then why not cut the gears in half to cut friction losses? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: Hollywood
Date Posted: August-18-2016 at 12:34pm
| Am I confused or does the cam gear have nothing to do with distributor seating? Couldn't you just twist it right through completely if there was no distributor shaft shoulder or oil pump? |
Posted By: KENO
Date Posted: August-18-2016 at 9:47pm
Pete Could you put this into some language that can actually be understood and makes sense too? |
Posted By: 8122pbrainard
Date Posted: August-18-2016 at 9:57pm
The distributor can't move outward from it's axis. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: KENO
Date Posted: August-18-2016 at 10:34pm
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I did a little looking at Chevy distributor shafts and oil pump intermediate shafts today and from my "simple" measurements there is about 4/10 of an inch of engagement when the distributor shaft is bottomed out in the oil pump shaft Since all the installation instructions tell how to make sure it's not bottomed out and say nothing about engagement, it's probably because you have plenty of engagement and you use shims where the distributor sits on the manifold to reduce engagement if you're bottoming out in the oil pump shaft. The location of the mounting pin hole in the distributor shaft makes it pretty much impossible to screw up the gear mounting because you can't really drill a new hole anywhere. You can't mount the gear too high and you can't mount the gear too low either   The first picture shows the distributor shaft with the gear off and you can see the mounting hole. You can't redrill a hole closer to the distributor body or you'll be drilling thru the gear to put a pin in it. There's no room to drill closer to the oil pump end without breaking off the tang at the end of the shaft. And you can't go 90 degrees without drilling into the tang also. You also can't drill the hole in the gear at a different height and have it fit and mate with the existing hole in the shaft. The second picture shows how much engagement there is when bottomed out against each other. (The piece of wire is just sneaking in to do a little photobombing) I didn't take a picture of the distributor itself with the gear on it but there are a million or so on the internet to look at. So........lot of words to explain at least to myself why nobody seems to worry about lack of engagement on a Chevy distributor. |
Posted By: Gary S
Date Posted: August-19-2016 at 12:06am
Pete I'm not talking about it not meshing correctly. I thought we were discussing the distributor not being fully seated. If it's not fully seated and say only half of each gear were meshing would not the forces on those gear teeth be that much greater? Ken I have only owned 2 Chevy's in my life,none were apart but small Honda motorcycles used the same drive as well as VW and MG. Interesting they all use a similar method ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: 8122pbrainard
Date Posted: August-19-2016 at 7:51am
Gary, I searched for a picture that would explain it better than I can in words but didn't find any so, I'll try again. The technical description of the distributor gearing is a crossed helical gear set. These gears have straight cut gears so when they mesh, there's only a single point contact. This single point contact can be anywhere on the gear face.so depth of engagement of one gear to the other can be anywhere on that face. IE: the point contact doesn't need to be centered on the face. Where's the new member who's the gear engineer for Chrysler? Maybe he could explain it better than I can? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |