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Do I have to use a steel distributor gear
in my 331 which has a hydraulic roller cam (Comp Cam 280 H)? I was looking at MSD distributors and they make one for Ford 289/302 engines with hydraulic cam only problem it has no vaccum for my Holley carb (vacuum secondaries). I thought I read somewhere that an iron gear would be eaten up by a hydraulic cam. Should I buy a MSD distributor that has vacuum advance and change out the gear to a steel one??? **)
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My opnion on vaccum advance is that street cars should use them.
You should use a dist drive gear recommended by the cam manufacturer for your cam. In this case, you probably will want a steel gear ( I'm not a fan of bronze) for the roller cam but check with Comp Cams to be sure. So if it were me, I'd buy the vacuum adv dist and change the gear. Larry |
Comp Cams have done most of the development (with another company) on polymer gears for the distributor drive. I suggest you check with them to see which material they recommend for the cam you intend to use. Badger
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The answer to your question is yes. Comp cam has them. You can get one from summit racing for about $60. dollars.
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Keith Craft installed one of the polymer gears on the MSD dizzy for my new 331.
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Steel.. I wanted the vaccum advance/steel gear MSD also (not avail with MSD as a standard item).
The local speed shop told me it was easy to swap the gears and agreed to do it for me while I waited.......after an hour they gave up. Went with the mech advance unit and have been very satisfied. The vaccum advance might be nice on a daily driver but most cobras are play cars. John |
Changing a gear from iron to steel is not as easy as you may think. When you get the steel gear, you would think, all I have to do is remove the pin and switch gears. Maybe in some cases it is that easy but MSD gives instructions for doing the new gear. In the gear I did, the pin holes were off and a new hole had to be drilled through the shaft. You now have to worry about disrtibutor shaft end play length and of course two holes through the shaft cannot help strength. MSD will put that steel gear on any of their distributors, if you have your dealer order that way! You have to pay for the steel gear and I believe about a $40 charge to mount it at time of construction of the distributor. I had this done just recently for a second engine. You can order your vacuum distributor with the steel gear. Have your supplier call MSD and confirm and get the details of what they, the distributor has to do to order it this way. The only drawback is you will have to order via a local distributor not a Jegs or Summitt.
Bill K |
I have heard more than a few times that when changing the gear, install a chevy (notice it's not capitalized!) drive pin. Larger and stronger I'm told, so less chance of shearing.
I don't have any first-hand experience at it though. Thoughts? Larry |
It couldn't hurt to have a stronger pin but the pin shouldn't come into play, if it does that's because the fit of the gear over the shaft was too loose. The press fit of the gear on the shaft is the critical fit that prevents the gear from slipping, if it's not a tight press fit there will likely be problems sooner or later even with a stronger pin.
BTW, Comp Cam's hydraulic rollers are a material that works well with distributor gears. You could use the gear that comes on an MSD or you could add the steel gear, there's no need for anything exotic. It's solid roller cams made from alloy steel that are cause for concern, not a "hydraulic roller", at least not the Comp ones. |
Hi , comp cams solid and hydraulic rollers are made of Austempered cores and can use a std Iron gear, a specially ordered billet steel roller needs the bronze , or the new ultra-poly gear, Im pretty sure you can use that on anything.When I was in the USA last year I went to Mc Master Car , think thats a nation wide engineering supply place ,They sell a heavy duty roll pin 1/8 th The same design as MSD use , that sort or of roll pin will out last the hardened tension pin .
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The biggest reason for distributor gear failure is a high volume oil pump, are you using one?
If you are in the process of building your engine now you will be better served by a stock pump. Scott S |
I agree with Scott about the high volume pumps.........they put a lot of stress on the dist. gear especially with cold heavy oil on start up and you'd be surprised how long it takes to warm up 8 or more quarts of oil!!!!!!!!!!!!.......I use a Melling HP series oil pump in my race car and love it.......they are standard volume and the pressure can be adjusted and they are blue printed from Melling, if memory serves me right, it was about 42 bucks..............best money I spent........
running anything from 15/40 conven. oil to 20/50 Mobil 1, it idles at 60 psi cold and 40 psi hot, once the oil is 200 degrees or more, anyhting over 1500prms gets me 55 psi.......... David |
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http://www.compcams.com/technical/Ca...106-07/235.pdf If ordering a custom grind hydraulic roller, I know that Comp will press an iron gear on the cam in place of a steel one if you ask. |
distributor gear
Whatever comp cams tells you do NOT use a standard cast iron gear with the Comp Cams retro roller cam. Mine chewed up the distributor gear in a hundred miles. Using a steel go with no issues.
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Hi 69 MACH 1 , ring your COMP CAMPs Tech line. And as I wrote steel Billet cams require a bronze gear or the ultra -poly , Comps Extreme energy std cataloge ordered, (XR) cams are Austempererd cores (cast steel), allways use the gear they recommend.
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That would be interesting to know. Since the gear is behind and smaller than the bearing surface the cam would have to be "assembled" and I am unaware of any, other than OEM style,cams like that. Maybe he was describing the complete cam material as opposed to just the gear.
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They're pressing iron gears on Chevy cams by replacing the gear and the last journal. Since the gear is on the front I didn't think they could do it with Fords.?
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