Alright, I'm trying to do a budget rebuild of my Duster's slant 6 and I'm trying to do it for a reasonable amount of money. I want it bored .060 over, what else needs to be done in terms of machining? I assume balancing the crank, as the pistons obviously weigh differently, and new camshaft bearing are probably in order, but other people have given me long lists of different things that need to be done that end up at $1200 at the very least. I need to know what has to be done at a bare minimum to make it run for, say, 20,000-30,000 miles. The engine was running fine before I took it apart (minus some rodknock) and a lot of the machining stuff seems unnecessary.

And after that, it needs new headers. I've already got a 2bbl intake, but the hyper-pak headers are impossible to find and every online store charges $500 or more. I can't re-use the original because I snapped the bolts in it (I'm so smart) and there's 43 years of rust holding them in. If I can't find a proper semi-performance replacement I may just have someone cut a hole in a new stock manifold and weld a second pipe to it.

Feel free to call me an idiot or whatever. I can confirm that it is, in fact, a terrible idea to attempt to restore a car while in college.

Bare minimum for 20-30,000 miles: Cut cyl ridge, and hone cyls, with a "ball" hone, and new plain cast rings. With rod knock, check crank, and grind, if required. At the least check the rod on the cyl that had the bad bearing. Recondition if required. Use new bearings. Reuse cam and lifters keeping the lifters matched to the cam lobes they came off. New timing chain, and spockets. Hand lap valves. All new gaskets and valve guide seals.

If you really want/need to install new pistons, then have the block bored/honed by the machine shop, and use premium rings. Forget about balancing the crank, it is not necessary, even with oversize stock replacement pistons.

Anything else, you will need to balance cost vs benefit of increased longevity.

PS: A inline six cyl engine does not get the crank balanced with the piston/rod assy. The crank gets balanced alone, and doesn't care about the other weights. The rods get matched big end to big end, and total weight. The pistons/rings get matched to each other.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Please clarify. Are you referring to a stock manifold, genuine Hyperpak exhaust manifolds, or after market headers. What bolts did you snap?

Where are you located?

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Just curious, why do you want to bore 0.060" over? Often you can get the cylinder squared up (no taper) and have a fresh surface for the rings and pistons to ride in at 0.030" or 0.040" and have plenty of room for future rebuilds.

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If it was easy, everybody would be doing it.

Ditto on all the above. If you need more details on any of this stuff, ask away. I've done a couple ring and bearing jobs in my garage; it's not too hard if you take your time and acquire the right tools. What kind of space do you have available?

If you want a better than stock exhaust, there are a few options. Dutra duals are more expensive than they used to be. I think Doug's original run of these has now dried up, and the new ones are being made by AussieSpeed for a significantly higher price (plus shipping). If you know someone who can weld cast iron, you can fabricate your own. Headers can sometimes be found used for not too much money, but you lose the heat riser box of the stock manifold which can impact street driveability. We'd also need to know the year of the car. Earlier (pre-67) A-bodies are tighter in the engine bay, and it's harder to find headers that fit.

For a near-stock engine with a 2-barrel, you'd probably be fine with another stock manifold and a larger (2.25") single pipe out the back. Best to get the exhaust manifold milled flat where it meets the head; they tend to warp over time and become very difficult to seal.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

Thanks for the replies, everyone. Forgot to mention it's a '75 Duster - the whole left side of the engine bay is basically unused. I've already got the gasket set and new pistons - the old ones were pretty well worn out. Pressed the wrist pins out of the rods today but didn't bother measuring the roundness of the rods as I ran out of time. The engine is already completely disassembled, and I'm getting the /6 whiplash cam from Hughes as a replacement camshaft. The block needs to be bored out anyway, as the lip in the cylinders is way too wide, and I already had .060 oversize pistons from when I was originally planning to bore it out (this car/engine has gone through a few plans in the last five months). Any headers would be fine, i just don't know if the exhaust log is really that great for flow - I assumed it wasn't but I'm probably wrong.

This is the new cam; http://www.hughesengines.com/Index/prod ... d=31102#RP

0.060" over will be fine. You can usually go to 0.100" or more over on a 225, so you could rebuild it again.

Lou

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Home of Slant6-powered fun machines since 1988

Yeah, but .060 is the largest I can get on RockAuto. Although I saw how beefy the cylinder walls were and was getting confused when some people told me it would "wear the engine out faster."

0.060" over will have no effect on engine wear, assuming the machining is done properly. A well built and maintained 225 should last at least 100k miles. They key is to get good machine work done by a reputable shop (do not skimp on the costs there) and to carefully assemble everything and make sure lubrication and such is in order. Cutting corners may result in an engine that eats itself in 5-10k miles or even less.

Lou

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Home of Slant6-powered fun machines since 1988

Make sure you check the clearances on your oil pump. If I recall correctly, the tip to tip rotor clearance should be something like 0.005" max. (Also remove the relief valve assembly and make sure everything in there is clean.) If you have to replace the pump, you should know that historically there have been issues with Slant 6 oil pump gears and camshaft gears from certain manufacturers not necessarily getting along (and destroying engines when one of them fails). The best bet is usually to reuse your stock oil pump gear and get your stock camshaft reground because if the engine has survived this long, those gears are well matched. That being said, I've had good success with an aftermarket Melling oil pump on an Isky camshaft. If you want to be very careful no matter which route you choose, you should install the pump and camshaft in the engine and check the gear mesh using lapping compound. Doctor Dodge (Doug Dutra) has many posts on this forum with this and other good tips for engine assembly.

I don't know anything about Hughes cams. You may want to get some feedback from folks on here about their reputation for oil pump gears and to see what kind of static compression ratio (SCR) would be good for that specific cam. I don't suppose you checked the piston to deck clearance at TDC before you tore the engine down? If not, you can always just have the block deck cleaned up the minimum amount, check the deck height with your new pistons installed, and then get your head milled to reach the desired SCR. You'll also need to measure the volume of the combustion chambers on your head.

If you don't already have an FSM, it's a good investment. That'll give you all the clearances, torque specs, and everything else to make sure your reassembly goes right.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

That's the old oil pump. That's not painted black - that's 43 years of oil. It's so wrecked on the inside that I can barely turn it; it's no wonder the engine had rodknock, I'm surprised there wasn't already a hole in the side of it. The rest of the engine looked pretty similar to that, inside and out. I've got the new pump already, and I'll see if I can take the gear off of it.

I've heard good things about Hughes from a few people before, mainly that their cams don't require extra machining before going into an engine, but we'll see when it gets here. That cam is supposed to run with 8.5 compression or lower, which I should be getting after the rebuild - I was getting 120lbs maximum before. I'm having the head decked a little bit just to see what I can get out of it - which was another question. How much can I safely deck the head? Piston-to-deck clearance was minimal, probably only a couple thousandths before I tore it apart.

Also, I have no idea what an FSM is. I have access to Alldata and Prodemand and they've been useful so far.

You need to double check the deck clearance? Top of piston to top of the block should be in the .140-.200 range unless someone cut a bunch off the block. If it is really a couple thousands that will make a huge difference in what you can take off the head.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

An FSM = Factory Service Manual.

Alldata I know doesn't go quite far back enough, but most of the information in there related to slants should be more than relevant. I have not used Prodemand.

Other than having Mr. Dutra there himself, the FSM is the next best item to have on hand.

~THOR~

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1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing

Oh, all right. I can get one of those for about $40.

Gotcha. If the oiling in the engine was that bad, then I wouldn't give another thought to the old pump or the gear on it. I've put something like 60,000 miles on a Melling M66C driven by an aftermarket camshaft (from a good manufacturer), including hundreds of hours of hard laps on a road course. If Hughes knows how to properly cut the oil pump drive gear on the camshaft, you'll be fine.
What he said. If the engine was stock before, you should have a lot more space than that.

You can usually take up to 0.100" off a stock, uncut head, and more than that off the block, but you really need to know what you're starting out with on both sides. Otherwise your final SCR will be a total shot in the dark. Since the short block is already disassembled and you're not looking for a huge increase in SCR, I'd recommend waiting until you get the block back from the machine shop and checking the final deck height with one of your new pistons installed. (If you needed to increase your SCR so much that it required cutting a significant amount off the block AND head, then I'd reassemble one old piston/rod assembly into the block with your crank, and start with that measurement.)

Meanwhile, clean up all the combustion chambers in the head really well (I like Scotchbrite for this kind of thing) and measure their volumes with a combustion chamber measuring kit. The valves will need to be installed for this. A simple kit like this is all you need, so if you have a scrap of lexan and a 60 cc syringe you can save yourself $25. An uncut Slant 6 cylinder head will probably be somewhere in the 55-60 cc range for each cylinder. Use the average of all six for the following calculations; hopefully there's no more than a couple cc variation between cylinders.

Enter the above info, along with your final bore (3.460"), your stroke (4.125" for a 225), and typical numbers for a standard head gasket (3.5" bore diameter and ~0.040" compressed thickness) and plug them into a compression ratio calculator like this one. Piston dome volume is zero for flat pistons. This will give you your SCR before cutting the head. Play with the combustion chamber volume until you get the SCR you want (8.5 or whatever someone like Lou/Dart270 tells you to shoot for after looking at your camshaft specs). Take that difference in ccs and multiply it by 0.0067". That's how much you need to mill your head.



If all that is too much work and you're certain that both the block and head are uncut (you can check the block to see if the stamped numbers on the pad behind the alternator bracket are still there), then cut 0.060" off the head and be done with it. That'll probably get you into the 8.5-9 range, depending on manufacturing tolerances at Chrysler the week that engine came off the line.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing