"Ramblin Rover - The Vivisector of Solihull" (RamblinRover) 07/11/2014 at 21:48 • Filed to: None

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Apparently, my loony Rover build plan will need only !!!error: Indecipherable SUB-paragraph formatting!!! . Way beyond what I need in strength, and way easier than it has any right to be.

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(The trick is matching small journal early Rover crank with unusual throw to big pin later Rover pistons. This does that.)

Grindintosecond > Ramblin Rover - The Vivisector of Solihull 07/11/2014 at 21:57

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That's not too unusual if you think about what hot-rodders have always had to do in the past. There's a guy not far from my area that built up a big power Volvo redblock using mitsubishi con rods and ford 3.8 inch pistons attached to the stock crank but ground down in journal size to match the big end of the rods...wihch were quite a bit smaller. What he did was grind that 8mm off the journal....but offset, so he increased the stroke and the total engine was now about 2.65 liters, up from the normal 2.3.

He topped it with a 16valve head from what you would think is a 740 turbo but was actually from the aq171 penta boat motor for the extra 1mm lift....and a nice turbo.

500hp for a $1500 short block investment in parts and machining.

Ramblin Rover - The Vivisector of Solihull > Grindintosecond 07/11/2014 at 22:27

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It's true that it's not unusual - I had just not realized before this point that my particular combo of weird needs was just about the easiest to do. Doing a late-style engine with altered length, matching the crank journal would have been a pain, and using early pistons, the wrist pin. Doing what I'm doing - odd stroke length with small journal crank and big journal Rover piston - just *happens* to call for an off-the-shelf part for a Chevy -an option that wouldn't have worked in any other combo, pretty much. I'm almost shocked.

Like... it should not have been that easy. We're talking about an engine where special rod/piston combinations frequently mean specialty pistons out of the UK or Ford pistons and unobtainium vintage Buick stuff or worse. This? This is cake.

I'm familiar with offset grinds, funny bushing-making, and mixing up odd manufacturers... in theory. I'd even contemplated matching bore spacing to see if any better heads were out there. However, at each step, it's turning out to not need anything crazy at all - and yet *nobody* builds a 4.2 for performance, unless you count TVR at the factory. Normally, if you do something wacky you don't find all the doors already open - and not even opened *by* anybody.

AMGtech - now with more recalls! > Ramblin Rover - The Vivisector of Solihull 07/12/2014 at 02:10

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I've done this. But I don't trust the factory liners. So at one point I had (with the help of my machinist) designed a new thicker top hat liner and had Darton make me a few sets. I did a couple with offset grinds, Chevy pistons (Keith Black from a 305 I think), and rods similar to what you found but they were Scat brand. Ported the heads, bigger valves, fat cam, shorty headers, freed up exhaust. etc. Etc. Etc.

But that was years ago and I don't have any specifics. I only remember >300whp, 5.0 litres. Doubled whp, so not terrible I guess. The only thing I remember is using www.thewedgeshop.com for some performance parts, mostly cams/valvetrain. Oh and Cometic head gaskets with ARP studs.

Ramblin Rover - The Vivisector of Solihull > AMGtech - now with more recalls! 07/12/2014 at 09:05

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There are numerous suppliers of top hat liners off the shelf now for the RV8, there didn't used to be. I'm going to evaluate the liners I have, since I'm not sure I want to ream and top hat if I don't have to - but it's an easier choice now than it was. I'll probably be ordering a stud kit from The Wedge Shop, but I may end up getting my cam through Dan LeGrou at D&D Fabrications. That depends on selection available.

I'm definitely porting, but I have the late style head that doesn't really take much bigger a valve than it already has. I have access to a book expressly on performance builds for the RV8, so I have some backup.

The easiest way to build one for straight power is to go the stroker route with either a Buick 300 crank, a Rover 4.6 crank, or one of several other options including custom grinds from a Ford blank (Wildcat Engineering does this). I'm sticking with the 4.2 crank, though, because I'm building for revs more than displacement. That also helps me not have to do a head swap for X rpm.

AMGtech - now with more recalls! > Ramblin Rover - The Vivisector of Solihull 07/12/2014 at 13:44

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I've bought from Dan at d&d also, but found woody at the wedge shop had a better range of performance cams and could do custom grinds as well. I never had any problem with them either, except one theysent me the wrong grind by mistake, but I caught that when I was degreeing it. When I was doing mine, no one sold off the shelf liners, just fitted blocks for a ton of money. I got out of that while game thoug. Too frustrating, too much work for very little reward. Too expensive.