Title: 69 vs 74 Post by: louisb on September 15, 2010, 23:55:42 pm So I have all the stuff ready for the 1835 for the Manx buggy and now I am wondering if it might be worth it to swap out the 69mm CW crank for a 74mm CW crank. I figure I could do that without too much trouble at this point, just not sure it would be worth it.
The rest of the engine: Stock rebuilt rods 92 thickwall AA P&Cs Webcam 163 (between a 110 & 120) 40 idfs w/ 32 vents 010 dizzy 1.5 trimill bobtail exhaust (non-merged) stock rockers 8.5 comp w/ .060 deck Jeff Denham 40x35 heads, oval port nonwelded The only reason I was thinking of adding it was for more bottom end and to take advantage of my UD heads. I don't care about power over 6,000, I also don't want to change any other components or do extra machine work. The 74 w/ stock rods should only require minor clearance work and should go together pretty easy. I don't think I would have to run overly thick barrel spacers but width isn't an issue anyway. What do you guys think? Worth the extra $300? Thanks, --louis Title: Re: 69 vs 74 Post by: RFbuilt on September 16, 2010, 00:18:45 am 92x74 sounds very "porschey" with that alone.. il say go for it!
i think the extra 300$ expense, could be lesser, once all is said and done you can sell ur 69cw crank too to recover sum $ simple math 100 mm (from crank centerline to deck/base of case hole) 112.5 mm barrel length ------------------------------ 212.5 mm - 137 mm (rod length) - 37 mm (stroke/2) - 39.6 mm (piston pin height/compression height for A pistons) = 1.1mm out of the barrel or 0.043" out of the hole, would need just a 0.090" barrel spacer to put u in a groovy 0.046" deck/quench ? ur right, it wont be much of a issue the small width addition sounds good? ofcourse this is a very very rough estimate, 212.5 isnt always accurate, sum end up at 212.2mm etc but its a good way of having an idea short of actually mocking it up ok ....i ....must .... shut up :D Title: Re: 69 vs 74 Post by: kingsburgphil on September 16, 2010, 01:34:54 am Sounds pretty old school ;) Have you considered a 78x92b VW rod configuration? Cheap and easy to
build ;D Title: Re: 69 vs 74 Post by: louisb on September 16, 2010, 02:19:39 am I thought about the 78 but I don't want to have to change the pistons and it would mean the case would have to be sent off for machining which I want to avoid.
--louis Title: Re: 69 vs 74 Post by: kingsburgphil on September 16, 2010, 03:55:28 am Fair enough, I think anything better than a 40hp will still put a smile on your face. BTW thanks for letting the rest
of us share in your project ;) Title: Re: 69 vs 74 Post by: dyno don on September 16, 2010, 08:12:06 am save yourself some money and call DPR in santa ana,ca 714-979-9441 and ask for Jose and tell him you want the "dyno don" special non c/w 74 crank...or have someone closer to you perform the service...you DONT NEED counterweights with your engine design and I would also change down your exhaust to 1 1/2 for better bottom end and driving experience with those heads. I would also recommend 8 dowel to the crank. I JUST did a recent engine with simular parts and it was a blast to drive. enjoy...
Title: Re: 69 vs 74 Post by: louisb on September 16, 2010, 15:18:48 pm Thanks for the input Dyno, I will look into it.
--louis Title: Re: 69 vs 74 Post by: Zach Gomulka on September 16, 2010, 17:29:53 pm A Porsche journal 74 with shorter 136mm Porsche rods would work great, require little clearancing, and minimal shimming. Be very old school, too! Jose @ DPR also does a 73mm crank with chevy rod journals. With short 5.325's it would probably go together like a stocker.
I say keep it simple and stay with what you've got. Your buggy will be a blast with an 1835 ;) Title: Re: 69 vs 74 Post by: Diederick/DVK on September 16, 2010, 17:40:50 pm I say keep it simple and stay with what you've got. Your buggy will be a blast with an 1835 ;) true, i thought monkiboy's manx back then with a single DCN 1641 was a blast. can you imagine a manx with an 1835 or 1968cc. ;D good luck though! Title: Re: 69 vs 74 Post by: louisb on September 16, 2010, 17:46:43 pm KISS
That is probably the answer I needed to hear. --louis Title: Re: 69 vs 74 Post by: Kafur1 on September 18, 2010, 23:38:12 pm I used a 74 scat crank and scat rods and did not hav to any grinding on the case
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