1Pc Rear Main Seal Block or 2PC + 1 last rod question

Old 07-11-2009, 03:50 PM
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Join Date: Jul 2007
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Default 1Pc Rear Main Seal Block or 2PC + 1 last rod question

First, thanks to the group for great answers to my previous questions about a 383 stroker SBC. FYI, the engine will be in a 1980 Vette, backed by a Richmond 6 speed. 100% street duty. Will be built with a stout bottom end in case I decide I need a turbo or some other ’power adder’ down the road, but will normally aspirated, no nitrous at first. Low RPM, torque engine with max RPM maybe 6K. I want it to pull the 3:07 rear gear, .67 to 1 6th gear in the car down the freeway to get some mileage, so I’m hoping to find a cam/head combo that’ll fit the bill.
I have acquired a 1970 High Nickel 4 bolt 350 block, STD bore, for my 383. A friend suggests not using that and going with a newer style block with 1 pc rear main seal. He cites 2 main reasons:
1. No leaks. There’s a manual trans going behind my 383 so this is a valid concern.
2. Ease of installing a roller cam. Also a valid argument, as I want a roller.
His comments bring into play a third concern: Cost. I bought my 1970 block for $100. I notice the new style 1 pc r. main blocks on eBay in the neighborhood of $500-600.
Regarding rod length in my previous post, a new, unused 5.7 rotating assembly kit can be had from a friend for under a grand. If I choose a 6” rod rotating assembly package, the price doubles. I have no problem spending the cash, but it has to be a decent return for the $ spent.
So, the questions:
1. 1PC rear main seal block instead of the 2 Pc due to Roller cam cost?
A quick look at Comp Cams site looks like a retro roller kit for my 1970 block is a couple hundred more than a kit for a new style 1pc main seal block. I also recall a roller for my 1970 block would require a special cam gear. Are my estimates correct? Any other costs that I haven’t though of that would make the new style block get the nod? However, there seems to be lot better selection of used or ‘new, never used but I decided on a different cam’ type deals out there for GEN I blocks. I know 2 pc seals dribble. Any way to minimize/eliminate the dribble?
2. 5.7” or 6” rod?
Great answers to my other post, and those answers seem to favor a longer rod. Is there an RPM range where the longer rod is better, or is it better across the board? Will the long rod advantages make a noticeable difference on my relatively low RPM engine? If I spend the extra cash will I get a decent bang for the buck?

Sorry for the long post, but I need to make a quick and accurate decision on the rotating assembly my friend has ASAP. Thanks!
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