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| Requesting input for LG motor "recipe" https://slantsix.org/forum/viewtopic.php?t=64194 |
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| Author: | justa170 [ Mon Nov 04, 2019 8:25 pm ] |
| Post subject: | Requesting input for LG motor "recipe" |
Help! I'm trying to come up with an LG (170ci block) build "recipe," but I keep going in circles. This is meant to go into a small, lightweight roadster for fair-weather use. I'm looking for 170hp+ and the ability to touch 7000RPM without blowing up. I don't know where to concentrate resources ($$$) and where to save a few bucks. I've looked at the build matrix thread, but I'm rather set on the LG block. Here's what I have in hand: 1961 LG block & matching head an extra head from a 1970 RG 170ci crank 198ci crank 170ci connecting rods 198ci connecting rods (I assume these won't fit.) "dumbbell" lifters 170ci pushrods stock exhaust manifold a set of oversized valves a couple of used stock cams Remy "mini" starter NOS water pump oil pump from a 1970 RG My thoughts so far: I plan to make the oiling system modifications described in Doug's book. Intake: No fuel injection, and no forced induction, for simplicity's sake. I'm thinking about a Super Six intake setup. I think an Aussiespeed manifold might provide more even fuel distribution, but they're pricey. The Offenhauser 5041 looks very cool, but the need for two perfectly-matched carbs makes it the costliest setup I've considered, and the increased complexity might be a concern. Are there other options better suited for this build? A four-barrel anything would be overkill, right? Heads: Given my modest power goals, would mild street porting/smoothing and stock valves be the way to go, or is it cost-effective to install oversized valves? Block: LG (170ci) with 0.0#0" overbore (0.040-0.080, depending on block condition and piston pricing). Do I stick with the stock 170ci crankshaft, or dive into a 198ci "stroker" build? I think clearancing/lightening/rebalancing the cranks would cost about the same, and grinding the block for crank clearance would be cheap, but I get COMPLETELY lost when I start thinking about potential rod and piston combinations for each crankshaft. Exhaust: I really like dual Dutra duals. I don't know if they will fit *on an LG block* with the Super Six, Aussiespeed, or Offy 5041 intake and the Remy "mini" starter. (The Aussiespeed rep I wrote to doesn't know; 170s are very rare in Australia.) Fuel pump, oil pump, water pump: I assume stock pieces will do the job. |
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| Author: | slantzilla [ Tue Nov 05, 2019 2:33 am ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Super Six, stock exhaust manifold and 7000 rpm aren't going to play well together, probably won't touch 170 horse either. |
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| Author: | Rick Covalt [ Tue Nov 05, 2019 3:25 am ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Go ahead and get a 4 barrel intake and carb. Then you have all the potential you need if you want it. You are only running on a 2 barrel anyway until you want that 170 HP!  A good set of headers and good flowing cylinder head and camshaft to go with it will be needed. Your goal of 170 HP will be easier with more cubic inches so going to the 198 crank would help. Good luck.
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| Author: | Doctor Dodge [ Wed Nov 06, 2019 3:39 pm ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Higher compression and proper cam selection will be the key to getting the power and high RPM. 170 engines will not take a lot of valve lift with-out piston notches so keep that in mind. DD |
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| Author: | GregCon [ Wed Nov 06, 2019 4:13 pm ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Why 7000RPM? 7000RPM reminds me of midnight....as in 'nothing good happens after midnight'. |
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| Author: | justa170 [ Wed Nov 06, 2019 9:33 pm ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Thanks for the input, everyone. I've got some more thinkin' to do. Quote: Why 7000RPM? 7000RPM reminds me of midnight....as in 'nothing good happens after midnight'. Heh. Yeah, I'm reconsidering that goal. 6000 would be plenty exciting (and less pricey).
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| Author: | GTS225 [ Thu Nov 07, 2019 4:27 am ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
I once saw a phrase stenciled across the leading edge of a hood at the dragstrip. "CAUTION; DRAMATIC ENGINE DISASSEMBLY IN PROGRESS" Just a bit of food for thought. Roger |
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| Author: | slantzilla [ Thu Nov 07, 2019 9:12 am ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Quote: Yeah, I'm reconsidering that goal. 6000 would be plenty exciting (and less pricey).
7000 isn't that hard to do. Good flowing head, big cam, good valvesprings, and lots of gear in the rear. Unfortunately, it doesn't really do anything because you spend very little time there. Biggest problem is, especially with a 170, you give up so much low end it takes that much longer to get to the powerband that you have a useless combination.On a little motor build for usable torque in the lower rpm range and just tell people you turn it 7000. You'll be a lot happier in the end. 
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| Author: | justa170 [ Thu Nov 07, 2019 10:31 am ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Quote: build for usable torque in the lower rpm range and just tell people you turn it 7000. You'll be a lot happier in the end. ^FACT.
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| Author: | MJF [ Thu Nov 07, 2019 10:42 am ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
My 170 will turn 6500 with mild cam, but I don't know what kind of power it makes at that rpm https://www.youtube.com/watch?v=2LzB9kJ-zyA |
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| Author: | drgonzo [ Thu Nov 07, 2019 1:18 pm ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Quote: My 170 will turn 6500 with mild cam, but I don't know what kind of power it makes at that rpm
I like it!
https://www.youtube.com/watch?v=2LzB9kJ-zyA |
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| Author: | Killer6 [ Thu Nov 07, 2019 4:13 pm ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Quote: Quote: build for usable torque in the lower rpm range and just tell people you turn it 7000. You'll be a lot happier in the end. ^FACT.If so, yes it's worth it to have them installed and the appropriate valve-job/bowl work done.......no matter what You plan on doing elsewhere. |
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| Author: | justa170 [ Thu Nov 07, 2019 5:50 pm ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
Quote: Oversize valves are the common 1.70"/1.41" combo?? If so, yes it's worth it to have them installed and the appropriate valve-job/bowl work done.......no matter what You plan on doing elsewhere. Good to know! Mine are the 1.72 / 1.50 valves available as Item #302060228934 on eBay:https://www.ebay.com/itm/1963-1986-Chev ... 2060228934 (The builder I'm working with is happy to let me source parts.) I'll make sure the block is bored out enough to avoid shrouding them. |
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| Author: | slantzilla [ Thu Nov 07, 2019 6:26 pm ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
I've turned my motors over 7000. All it does is makes noise. My Valiant goes a bunch faster when I shift at 6300. 
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| Author: | Joshie225 [ Thu Nov 07, 2019 7:02 pm ] |
| Post subject: | Re: Requesting input for LG motor "recipe" |
1.50" exhaust valves are overkill. The exhaust port works pretty well compared to the intake port and so the bigger intake is most of the benefit. I had quite good results with 1.78/1.45" Ford 300 valves. The exhaust had to be cut down to that size, but it all fit the +.030" cylinders. |
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