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| Spring has sprung! Block ID questions https://slantsix.org/forum/viewtopic.php?t=48409 |
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| Author: | kipamore [ Thu Apr 05, 2012 9:45 am ] |
| Post subject: | Spring has sprung! Block ID questions |
Hi fellas. I've been out of the loop for a while since the Slantota truck crapped out it's rear end. Since the truck is on it's way to the scrap yard, it's time to refocus and get back to the turbo Valiant wagon. Hozannas! Several engines have gone in and out of the Valiant, but for hoarder reasons I hung on to the original engine. For no good reason, I was looking at it the other day. I don't know why I never noticed this before, but it's got modern alloy pistons in it. Looks like aluminum, that waffle pattern you see on modern alloy engines is present, and they are non-magnetic. This engine (and the whole car) came to me after sitting in a farmer's field for 9 years. So I have squat for history on it. Some interior and body work had been done to the car, so somebody loved her. Did they love her enough to do engine work? Dunno. Using the resources here, I measured a rod (in block) and I get almost exactly 7 inches, which indicates a 198ci slant. Maybe I'm high and it's really 6.7" which would be a 225, but I'm 90% I'm measuring it right. The pad by #1 reads J225 RT 67. Did I have an actual question? Oh yeah. I know a popular build involves a long rod and new pistons. What's the point of that again? Is there any reason to think that that combination would be bad for low pressure turbo use? Kip-on-truckin' |
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| Author: | SlantSixDan [ Thu Apr 05, 2012 10:02 am ] |
| Post subject: | |
Not sure I understand your piston comments; aluminum pistons have been standard equipment since before the slant-6 was first released. 198 and 225 use the same block (just different crank and rods) so it's possible you've got a 198 on your hands. If the engine's still assembled, check the stroke: 3.64" for a 198, 4.125" for a 225. The long-rod 225 conversion improves the "rod ratio" (ratio of rod length to crank stroke) which increases piston dwell time at TDC and BDC, which means more time at TDC for for combustion pressure to build up. It also reduces side loading of the piston against the cylinder wall. I can't think why any of this would be contraindicated for a turbo buildup, though you'd probably want to keep a careful eye (and calculator) on your compression ratio so you don't run into uncontrollable ping on street fuel. |
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| Author: | sandy in BC [ Thu Apr 05, 2012 11:05 am ] |
| Post subject: | |
If its the original motor and it says J225 RT67 on the block.......its a 225. |
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| Author: | SlantSixDan [ Thu Apr 05, 2012 11:08 am ] |
| Post subject: | |
'cept it's not the original engine. Valiant wagons ended before that format of engine ID stamping was adopted. |
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| Author: | Doc [ Thu Apr 05, 2012 11:11 am ] |
| Post subject: | |
The longer rod also allows use of a shorter / lighter piston, most of those pistons use thinner rings. Thinner rings means less friction & "drag". The main reason I like the long rod 225 is that you get increased static compression "right out of the box"... with-out doing a lot of head and block "decking". Thicker decks helps head gasket sealing. Long rod engines are not the best for Turbo applications, mostly because of the increased static compression ratios they produce and the fact that the lighter/ shorter piston, with a thinner ring package, does not hold-up as well under high boost. DD |
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| Author: | kipamore [ Thu Apr 05, 2012 3:11 pm ] |
| Post subject: | |
I took Dan's advice, flipped the engine over on the stand, and measured the stroke to the best of my ability. 4" and a bit, which tells me I do indeed have a 225. I did not know that about slant pistons. See, you learn something new everyday. I did a quick web search and found some pics of stock pistons, they do NOT look like what I've got. The car appears to be high mileage, though I don't know if it's 130k or 230k, but I'm sure it isn't 30k. The engine is red as opposed to blue, which means it's probably closer to the year of the car (65). Whatever. Maybe somebody rebuilt it in the modern age, maybe it's an old rebuild or swap. Who cares. I'm going to use it in the car, over my other choice which is a 73 and runs good but has an assload of blowby. I only ran this red engine once, driving back from where I bought it in Pennsylvania. The points crapped out, the brakes were nonexistent, the blower didn't work and it was -3degrees out - I had other things on my mind, but the engine seemed ok. Is there any way to do a compression test on a non-running engine? I pulled the plugs and can spin it by hand on the stand. My gauge shows 25lbs, but I can only spin it so fast. The oil pan is off, so I just squirted some motor oil into the bores. Something tells me that without pressurized oil and a starter motor, I'm not going to get an accurate reading. Fun stuff, can't wait to dig into it this spring. Turbo slant, 833OD, no hood, and I see no reason to put a muffler on it. |
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