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290 dead. 401 is...altered? |
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mixed up 
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Joined: Jun/16/2015 Location: Monroe mich Status: Offline Points: 2177 |
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 Posted: Jan/25/2016 at 2:14am |
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why do every body dog the little 290 my 290 in a 65 220 will run 12.30 all day long and stay together pulling 6000 rpm at top end no trouble here just rebore it 150$ new pistons cast 350$ your good to go your going to spend 200 just in gaskets on he 401 piston balance lets do it right yes you will have a ton more money in the 401 save it for a later date
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Lucas660
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Joined: Apr/16/2012 Location: Vic, Australia Status: Offline Points: 1344 |
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Posted: Jan/25/2016 at 3:09am |
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I often wonder the same. A 290 would be a nice cruiser. Especially in a small body. Won't drink as much either.
Edited by Lucas660 - Jan/25/2016 at 10:12am |
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uncljohn
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Joined: Jan/03/2013 Location: Peoria AZ Status: Offline Points: 5394 |
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Posted: Jan/26/2016 at 12:19am |
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Assuming efficiency and size are related is only one factor. Proper tuning certainly is an issue, gearing is another and misc. other factors enter in.
My 390 is capable of 23mpg at legal highway speeds but that is only one factor. In town it rarely gets better than 10mpg. And size does not explain those numbers. I built a leaning tower of power back in the days when 13:1 compression was workable due to 101 octane gasoline availability. That engine when done was a 22mpg commuter motor in the exact same car and gearing that it came from with a 1bbl carburetor and other OEM components but it was only good for about 13mpg. (Un-modified) A small 1bbl carburetor does not explain that difference either. An engine wants to develop it's HP efficiently and when it does, it will perform efficiently. The Formula for an efficient carburetor application is (Cubic Inch displacement X RPM)/3456. Calculating that for a 360 cu in engine at 6000 rpm comes up with 625 CFM. And every time I have used that formula to choose a carburetor size, the thing has pretty much worked out of the box. One can argue other sizes work and they have been used. For example using the same formula for a 258 I-6 comes up with 450 CFM. I have used 400 or 425 Carter AFB's with good success, but GM used a 750 CFM quadrajet on their 250 Cu in overhead cam sprint engine in the Pontiac. Which raises the question of how efficiency was calculated. And achieved. So the question of what makes a nice cruiser continues on fraught with personal opinions and I have mine! |
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70 390 5spd Donohue
74 Hornet In restoration 76 Hornet, 5.7L Mercury Marine Power 80 Fuel Injected I6 Spirit 74 232 I-6, 4bbl, 270HL Isky Cam |
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Eugor
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Joined: Nov/26/2013 Location: Vancouver, B.C. Status: Offline Points: 116 |
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Posted: Jan/26/2016 at 12:47am |
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More fun. Less happiness. Rethinking project entirely. Come on along for the ride. I hope nobody paid to have this thing put together! Turning to the LH cylinder head.
 I'd noticed the odd head bolts earlier. It hadn't occurred to me (should have) that the heads are too big to get a socket over. Luckily, they weren't too tight to be removed with an open end wrench...the rest of the bolts were at about 80 ft/lbs. Give or take about 15. I guess they didn't have a torque wrench or a spec sheet. Where do you get an open end torque wrench anyway?
 Just use what you have lying around I guess. The rear short bolt came out kind of tight. It was binding on the inside of the piece of pipe that had been substituted for the original thin wall dowel. Threads are a bit pooched.
 At least there is a reasonable (if not good) excuse for this.
 Pistons are all .030 over, and at least these all match. If you look closely, though all the notches are at the rear of the pistons - except #3. Interstingly, the notch on that piston is on the opposite side from the other 7...?!. So even thought it would appear to be in correctly, if the rest are wrong, so is that one.
 Relatively minor at this point, but I probably wouldn't have put that #5 intake valve in like that.
 Not sure about the two tone effect, but at least it would be cheap to fix.
We'll be back with act II. Really, it gets better. Like a Shakespeare tragedy.
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Eugor
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Joined: Nov/26/2013 Location: Vancouver, B.C. Status: Offline Points: 116 |
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Posted: Jan/26/2016 at 2:13am |
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Our curtain (oil pan) opens:
 No spacer, but I may have lost track. Do we not use those little plastic doohickies anymore?
 Pipe wrench?? Really guys, could you not think of an easier way to turn this thing???
 At least we stamped the crank. Rod bearings are .010. Haven't had the courage to take the main caps off yet.
 There has been a lot of grinding going on down here. The big end of #7 rod has had about 3/16" taken off it. In the background you can see the rod & cap #s have been ground off of every rod. Lord knows if they're still matched pairs. On a couple of them you can make out enough of a number to narrow it down to a 1or a 7 or a 3 or an 8. None of those are in a corresponding hole.
Plastigage on a couple random journals comes up about between .001 and .0015.. It's old stuff though and kind of brittle. Maybe not so accurate anymore.
 Side view of #7. In the previous picture you can see how tall that section is on the other rods. Some of the others have been ground some, but not even close to this extent.
 Not sure if this indicating something, a slip with the grinder, or marking territory like a stray cat. Anybody know? There are a few other random punch marks on things (#1 rod had 3 pin punch marks for instance - there are 4 punch marks in the main web beside #4 main - what, are you going to lose count?)
 Numbers in yellow are rod side clearances (in thousandths of course)
 Yes, that is 18 and....27 . Not what my manuals say they should be.
 I would have hoped for a nicer looking bearing, but probably shouldn't have expected it. 7 of the rod bearings did not have the squirt hole provision. 1 did.
 Almost looks like the journal wasn't polished to the edges?
 This is #4, the odd piston. Along with the deformation of the crown, this was done to both sides.
 I can't imagine how this was done accidentally, or why it would be done on purpose. It looks like someone has taken a punch and worked their way around the rod bolt on the mating surface. Maybe an attempt to "knurl" the surface to open up the clearance a bit?
 Maybe a hair tight.
 The misfit piston. Googling this provided surprisingly little information. I called a friend at a machine shop today and gave him the number. He immediately said it sounded like an Ohio part #, and, as he keeps old catalogs, he looked it up and sure enough it comes up as 68-70 390.
 As do the 1018Ps that the other 7 are marked. Would that even work? Wouldn't the taller compression height of the 390 piston put it into the head? Am I missing something? Probably. Too tired to think about it now.
It's too bad scrap cast is down under $100 a ton in this area.
It does look like a new distributor drive gear, so I guess it wasn't a complete waste.
 A costly project for a future time.
Thanks for listening to my tale of self inflicted woe. You've been a great audience.
Dave
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amxron
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Joined: Nov/18/2011 Status: Offline Points: 295 |
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Posted: Jan/26/2016 at 2:32am |
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Installing pistons reversed was an old speed trick, couple hp and some more noise.
7/8s more anyway..... Ron.
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AMXron
Fleet/Jeep Mgr. Orbit AMC/Jeep 50-1787 |
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uncljohn
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Joined: Jan/03/2013 Location: Peoria AZ Status: Offline Points: 5394 |
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Posted: Jan/26/2016 at 2:45am |
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It looks like it pays to run an inspection on a purchased assembled engine. Now I guess the objective becomes what are you going to do with it. Good luck!
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70 390 5spd Donohue
74 Hornet In restoration 76 Hornet, 5.7L Mercury Marine Power 80 Fuel Injected I6 Spirit 74 232 I-6, 4bbl, 270HL Isky Cam |
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farna
Supporter of TheAMCForum 
Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
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Posted: Jan/26/2016 at 7:03am |
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The pistons and rods out of order isn't a big deal. The rod caps not matched to the correct rods sure is though! The tight rod bearings is likely due to mismatched caps and rods. All those need to go for re-sizing and marking. They need to be checked for weight too since there has been some grinding on the big ends.
I don't see how a 304 is that much "better" than a 290. The 304 has the better exhaust ports (dogleg), but I don't think the small engine really needs the little bit extra flow. 14 inches isn't enough to sorry over to me. Would be for racing, but not for a street car. IIRC the 290 and 304 use the same pistons as the six cylinder engines. I know they are the same bore, but pin height and top of piston (chamber) may be different. You should be able to use a six piston. The 199 is a flat top and would raise compression though. Lots of choices for 258 pistons (199/232/258 are all 3.75" bore, same as the 290/304). |
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Frank Swygert
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Boris Badanov
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Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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Posted: Jan/26/2016 at 11:19am |
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I have owned several 304s and 290s.
The 304 has more nadds from top to bottom. Better heads and longer stroke make it much more potent in stock trim. Yes, you can feel it. But if I were to do a swap, the 401 or a 360 would be my first choices. |
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Gremlin Dreams
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wantajav
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Joined: Sep/04/2009 Location: PA Status: Offline Points: 1150 |
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Posted: Jan/27/2016 at 7:28am |
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Question
Can you use 304 pistons in a 290? Rock auto has stock 030 or 060 over pistons for $24. USD Like using a 360 piston in a 343, you'd get a slight boost in CR? Mike
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