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| 74mm crank? http://woodsbuggy.com/phpBB3/viewtopic.php?f=3&t=16097 |
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| Author: | hpfreak [ Wed Oct 02, 2013 11:25 am ] |
| Post subject: | 74mm crank? |
Thinking about going to a 74mm crank as red Barron has suggested in previous posts. I originally just wanted to get this thing back together but my wife has told me its to close to Christmas to be buying any buggy parts:evil: well now she's gonna pay for that and I'm gonna want more expensive parts:twisted: I have a couple questions about the switch. All the parts I have now are brand new minus 3 rides so I don't want to replace anything I don't need to. Do I need the shims or would going without increase my compression to much? Being that I'm running a c35 cam I'm sure my geometry is off as it stands would running the stock size push rods bring it closer or take it to far the other way? Do I need adjustable push rod tubes or can I stretch my stock ones out a little bit? Last but not least is this small increase in displacement truly worth the cost and agrevation? Posted using the WoodsBuggy Mobile App |
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| Author: | WayneJ [ Wed Oct 02, 2013 1:58 pm ] |
| Post subject: | Re: 74mm crank? |
A 2054 makes a nice little engine and with the right combination of heads and carburation you'll be pleased with the performance. It's not so much the increase in CC's that you'll notice, but the quicker rod ratio will make for a more responsive low end. Going from a 1915 to a 2054 with no other changes will raise your compression about .58 ( a little over 1/2 a point). So... if you were at 8.5 to 1 with the 1915, you could expect to end up around 9.1 to 1 with the 2074. Not too big of a deal in a light weight buggy and running good fuel. IMO, regardless of engine size / combination, it would definitely be a good idea to step up to cut to length chromoly pushrods and solid rocker shafts and dial in your valvetrain geometry. You'll be fine with stock pushrod tubes as long as your running stock 1.1 to 1 rockers. Also, I'm down here in Portsmouth....if you decide to back up and run a stock crank I probably have one laying around here that would get you going. |
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| Author: | hpfreak [ Wed Oct 02, 2013 2:43 pm ] |
| Post subject: | Re: 74mm crank? |
I am running solid rocker shafts and 1.1/1 rockers. When I bought my engine kit I was told it would be real close to .060 deck height. I'm running cb 044 magnums which are supposed to be a 55cc combustion chamber. From my calculations I'm somewhere in the neighborhood of 9.5/1 cr. From what your telling me I would be around 10/1 cr without shims. what octane would I have to run with that cr? Sent from my AT100 using WoodsBuggy mobile app |
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| Author: | hpfreak [ Wed Oct 02, 2013 2:54 pm ] |
| Post subject: | Re: 74mm crank? |
After a little bit of math I realize my pistons would protrude from the top of my barrels without shims so never mind the shim question:mrgreen: Posted using the WoodsBuggy Mobile App |
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| Author: | WayneJ [ Wed Oct 02, 2013 3:01 pm ] |
| Post subject: | Re: 74mm crank? |
So you have no shims at all right now? If that's the case I'd just figure on running .100 solid barrel shims, that should bring your deck back close to .060 The CB heads are usually pretty close to spec on the cc's, but I'd definitely check the assembled deck height just so you know for sure where your at. There are a lot of variables and tolerance stack up to consider when it comes to cases / cylinders/ etc. I've actually seen one case that was .020 off center on the crank centerline. |
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| Author: | hpfreak [ Wed Oct 02, 2013 3:26 pm ] |
| Post subject: | Re: 74mm crank? |
I do plan on being a lot more precise this time around. I also plan on cleaning up my combustion chambers a bit so my cc's will probably be a bit closer to 60. I really didn't want to have to do cut to fit push rods cause I don't feel comfortable doing so as I've never done it before. Does anyone sell push rods that are just 2.5 mm longer? Posted using the WoodsBuggy Mobile App |
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| Author: | WayneJ [ Wed Oct 02, 2013 5:12 pm ] |
| Post subject: | Re: 74mm crank? |
There are some places that will cut the pushrods and assemble them to a requested length for a fee, or your can order high quality one piece pushrods in .025 increments from Trend Performance. Problem is, In theory one would think that if your adding an additional 2.5mm of width that you need a 2.5mm longer pushrod, but it doesn't always work out that way. Some 94mm barrels are slightly longer than stock, cylinder shims add length, not to mention whether or not the case has been decked, etc. I like to use custom pushrods even on a stock width engine build. Setting up the correct geometry really isn't that big of a deal, it just takes a little time and attention to detail. All you need is a good Sharpie, an adjustable pushrod (which you can either buy or booty fab one) a caliper to measure with (even if it's just a cheapo Harbor Freight piece), and a couple soft valve springs (worn out stockers will work). You can cut the pushrods with a cheap hardware store tubing cutter and debur them with a countersink or even a decent drill bit. You can press the ends in with a little bit of heat, a sturdy workbench, a hammer, and two old lifters.....or you can measure for the correct length that you need and order a set. All is takes is a decent mechanical aptitude. Other than that, if you've got the stuff to get it done, a couple hrs to put into it, and a case of beer, Hell your good! |
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| Author: | hpfreak [ Wed Oct 02, 2013 5:24 pm ] |
| Post subject: | Re: 74mm crank? |
Thanks Wayne I appreciate all your help. It seems custom fitting push rods is something I better learn if I'm gonna stick with this sport. What's the worst that could happen my geometry could be off (I'm sure it already is). I believe I'm gonna go ahead and build a 2054 I just hope Santa is generous this year. I guess there goes the wheels I was hoping for 
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| Author: | WayneJ [ Wed Oct 02, 2013 5:34 pm ] |
| Post subject: | Re: 74mm crank? |
No problem man....I started messing with AC VW's when I was a kid back in the 80's. Damn things are expensive to build, but I still have a fondness for them. HP per Dollar?....yeah, a Ecotech or Suby will win every time...but there's something about the sound of a healthy AC VW screaming it's balls off that just can't be beat. I'm not on here much but I'll PM you my e-mail and Facebook info. When you get into it hit me up, or if nothing else I'm only about 90mi away. |
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| Author: | Red Barron [ Wed Oct 02, 2013 7:09 pm ] |
| Post subject: | Re: 74mm crank? |
hpfreak wrote: Thanks Wayne I appreciate all your help. It seems custom fitting push rods is something I better learn if I'm gonna stick with this sport. What's the worst that could happen my geometry could be off (I'm sure it already is). I believe I'm gonna go ahead and build a 2054 I just hope Santa is generous this year. I guess there goes the wheels I was hoping for Dude I would reconsider WC for the cubic dollars you will save! I can assure you it will out last that AC and get better millage. |
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| Author: | hpfreak [ Wed Oct 02, 2013 7:13 pm ] |
| Post subject: | Re: 74mm crank? |
Red Barron wrote: hpfreak wrote: Thanks Wayne I appreciate all your help. It seems custom fitting push rods is something I better learn if I'm gonna stick with this sport. What's the worst that could happen my geometry could be off (I'm sure it already is). I believe I'm gonna go ahead and build a 2054 I just hope Santa is generous this year. I guess there goes the wheels I was hoping for Dude I would reconsider WC for the cubic dollars you will save! I can assure you it will out last that AC and get better millage. In case you haven't noticed I am weighing all my options. The initial cost of going wc and thought of blowing trannys is frightening but I am still weighing that as an option. Posted using the WoodsBuggy Mobile App |
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| Author: | gasman [ Wed Oct 02, 2013 8:21 pm ] |
| Post subject: | Re: 74mm crank? |
No way you could buy a wc motor,adapter,and all the other stuff to put it in your buggy cheaper than you can buy a crank and some push rods,and new bearings and rings and shims. You could even have your block clearanced and go to a 82 crank and still be cheaper it's not like your starting from scratch.jmo. Chad 
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| Author: | hpfreak [ Wed Oct 02, 2013 8:34 pm ] |
| Post subject: | Re: 74mm crank? |
I agree chad but how many times am I going to have to do this. Posted using the WoodsBuggy Mobile App |
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| Author: | hpfreak [ Wed Oct 02, 2013 8:39 pm ] |
| Post subject: | Re: 74mm crank? |
On the bright side I know now who might buy all my AC stuff now:grin::grin::grin: Posted using the WoodsBuggy Mobile App |
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