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Can i stroke my 290? |
Post Reply | Page 123 7> |
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Skwishy
AMC Apprentice Joined: Feb/01/2018 Location: Wisconsin Status: Offline Points: 208 |
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Posted: Apr/02/2020 at 9:59pm |
Hello everyone, long time lurker here.
I have been working on my 1968 amc ambassador. It has a 290 v8 woth 4bbl carb. Already have done some cool performance mods, mild cam, springs, bultear oil pump and timing cover, ported heads, and headers. Im trying to see what else i can do. From what i understand the eldebrock cylinder heads wont work and neither will 1970 and up heads might need modification. So now im left with the crankshaft and its components. So my thought is can i use the 360/401 connecting rods with my crankshaft? Or perhaps someone makes pistons with smaller dimensions. I have also read the Hot rod article on this and they didnt really cover the possibility of changing connecting rods. But i do understand that the crankshafts are different between 290-343 and 360-401. With that in minds has anyone here successfully used a larger crank in their engine and was there noticable power gains? And finally should i just ditch the 290 block and try and locate a 360/401 engine somewhere, though people around here really dont let go of their engines and usually the charge a fortune for one. My ultimate goal with this car is for it to be a cool hot rod that i can take out and have decent power on the street.
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Skwishy
AMC Apprentice Joined: Feb/01/2018 Location: Wisconsin Status: Offline Points: 208 |
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I shoukd also mention its bored .40 over
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PHAT69AMX
AMC Addicted Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5903 |
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Quick simple answer is yes, use a 304/360 3.44" Stroke Crank instead of the 3.28" Stroke 290 / 343 Crank
Edited by PHAT69AMX - Apr/02/2020 at 10:56pm |
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6t8amxetc
AMC Addicted Joined: Mar/11/2008 Location: Washington State Status: Offline Points: 630 |
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I really don't know much about this 290 but I do know they have it figured out!
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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If you use the 304/360 crank, you will get 304 cubes plus a couple more depending on overbore. 390 or 401 crank would work but you would need custom pistons at the very least and not gain a whole lot more displacement (somewhere around 320 cubes).
The easy answer is to use one of the larger engines, 343/390 and 360/401 up to 71 would be a direct bolt in. For later 360/401 you need to take into consideration the crank flange change for the torqueflite transmissions. I'd just enjoy the 290 for what it is rather than try to go crazy performance wise because as they say, you can't beat cubic inches and that means you really need to dump the 290 for something bigger. |
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I've finally given up drinking for good...........now I only drink for evil.
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PROSTOCKTOM
Supporter of TheAMCForum Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2424 |
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Obviously since you've already done some upgrades your not afraid to makes some more changes, so I'll offer this advice. First and foremost do you have a budget in mind? As you already know buying parts and having machine work adds up quickly. Second what are your honest performance goals? Sure you can play around and get that 290 to run better with 20-30 extra cubes, but at what cost and compromise compared to using larger engine. So I'll say this based on what information you have provided. You would be hands down better off buying a 360 engine and playing with it. Not to say a 390 or 401 would not be even better if you can find or afford one, but the absolute best bang for the buck is using a 360 for any AMC project. At the end of the day your the one that has to decide what you want and more importantly what your willing to pay for. Good luck with your journey, Tom
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Molnar Technologies Full Service Dealer - Crankshafts & Connecting Rods
1969 AMC Rambler Rouge Race Car 1974 AMC Hornet Hatchback, Wally Booth Outlaw Nostalgic Pro Stock Race Car Project |
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6746 |
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Ok, addicted to the number thing and have not built this so double check the math!
K455X125 pistons 4.125", CH 1.055, 22 CC dish 3.44 stroke, 6.385 rods, 0.042" gasket, 52 cc head, piston will be 0.015" below the deck, quench at 0.057 SCR 9.67:1 368 CI Taking Smokey's rule of throwing in the longest rod that can fit. As stated, never done it and don't know if it would fit - do the math!
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Heavy 488
AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3529 |
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In the privacy of your own home behind closed doors, stroke away.
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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A 401 crank with custom rods and some relief work at the bottom of the cylinders should work.
But why? |
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Gremlin Dreams
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6746 |
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Forged pistons and rods in a 290 to 360 will cost approximately the same.
A 390 or 401 is going to cost significantly more to build.
For street use, why not? And as far as stroking, I'll use the big or little head as per perspective:) |
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