Rebuild

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chongo25

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I starting to look into rebuilding the old slant 6 just because there is no telling how many actual miles are on it and fix all the leaks with oil ect. My question is how should I do it. My goal is to slap a 4 barrel on and get a cam, headers and all the stuff that goes with it. Should I get it bored for this? Im really new to this engine stuff so I have no idea. Just trying to understand and do it way that is smart and not wasting my money on stuff I dont need.

Also what should a rebuild cost? I was quoted 3k with: Balancing, valve job, Magna Flux and some other stuff. It was over the phone so i don't have a list in front of me that would include all the stuff being done. I was told 1500 would be on a high side from others before calling this place, but 3k caught me by surprised.
 
I suggest you get ahold of some local fabo members for recommendations for machine shop. get a mopar performance engine building book, read it and become knowledgable about the basics of blueprinting your engine and what a shop can do. don't let them think "the sky is the limit" or you might have a stupidly high build cost. read on here and slantsix.org about the rebuild subject.
and be realistic about what the engine will do, ie, mileage, drag race, run good, longi=evity???? etc.
to know what you engine needs , you or the shop has to determine the wear in the cylinders. maybe a hone will be adequate? find out their costs for each part of a rebuild, don't just throw them the engine and say do it!?
maybe your engine has been rebuilt some years back and just needs new gasket? some basic tests can tell you something about the condition, ie compression, leakdown, vacuum, etc.....
 
It's hard to say when it comes to a total rebuild. If it needs bored then you have a cost for pistons . They can range from as little as $20 to Well over $100 each depending on what you want. Then you have decking, hone, head milling, cam bearings, boil the block and the head (cleaning the inside passages) Crank work, recondition the rods, line bore the mains, new oil pump and so-on. All this cost Money. Do you need it? won't know until it is opened up. Look to spend around $1200+ for a 4 barrel carb, intake, header, cam/lifters if you plan on buying new parts just for those items. It gets pricey those dang gum little sixes. Just a thought....Oh I didn't even get into head work........
 
What are you useing this car for? Just fun on the street? Commuting daily? All out drag racing? You need to clue us in on that before any good reccommendations can be made.
 
You can take your time and look for bargains on stuff. I have gotten some killer deals lately, after a bit of a dry spell.
 
Thanks for all the replies and suggestions. Im really looking into get some more fun out of it on the street. Not looking for something extreme but want my money to be put to good useand not on stuff I don't need.

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Try turning it over by hand, using the fan belt. If you have to fight each piston and you hear them hiss down, it doesn't need a rebuild and that would be a waste of money. You can fix all oil leaks w/ the engine in car, ditto for a cam swap. A common leak is the spark plug tubes and new seals are cheap. That is if a 1975? and earlier engine (always tell us).
 
To answer a coupla questions: Boring won't add a lot to the performance; so it should be done just to striaghten up the cylinders that may be worn beyond usable limits. Usable limits means that the psitosn are too loose and they slap around and the rigns flutter going up and down rather than staying flat as they should. You only know this by:
- a poor compression test result that improves when you add oil into the cylinder and retest
- engine is disassembled and the bores measured and a judgement made

As for magnafluxing....you do it for use if you rare realy going to rev the engine a lot. If not, then it is less necessary. It is done just to detect small cracks in the surface that could become big cracks when revvd high. So, if you are keeping the revs down and not racing this engine all the time, then you get away with not doing it. I have done a lot of high revving race einges and never had things magnafluxed and got a way with it; that was on engines that had forged cranks as stock, and the /6 does have a forged crank prior to '77. (And maganfluxing does not guarantee against failed engine parts!)

Some basic balancing of the piston/rod assemblies should be done if you change pistons as part of a re-bore, IMO> But again, if this is not a high rev engine, then it may not be as needed. I personally would spend $$ on this before magnafluxing.

Speaking of revs.....I have not modifed or raced the /6 but all indications are that it si not a godd breathing engine. But, if you focus on mods that keep the engine revs low for the desired pieces, then any serious porting (expensive) can be dispnsed with and just some simpel port mathcing and port clean up done. (But you will probalby be OK even without that low level of work). This would point me in the direction of focusing on a low RPM, torque cam selection. If you are after just some fun on the street, then that probably works. And you get better gas mileage too.

Be aware of the fact that early /6 engine were solid lifter and later were hydraulic lifter, and that changing involves changing the rocker shaft.

For what you seem to be saying you want, then a simple cam, carb and exhaust upgrade will get the smiles that you are seeking. Keep the revs low and the torque high, and forget about the ultimate high end HP numbers.

I really would follow the recommendations of looking at slantsix.org ....

As for cost and who to use, it can be all over the map. Just be a wise shopper as for anything and go slow since you are new to this, and get a reasonable level of details on what is to be done and the approx cost for each item. I would stay local, at a place that you can easily drive to. Visits in-person rather than over the phone are invaluable.
 
Milling the head and bringing up the compression is the first and best thing you can do once you have established that the engine is in good shape. Without this, a cam means little and a 4bbl means even less. You can mill the head .060-.100 or deck the block, or a combination of the two, depending on your compression height and block requirements. You could probably safely shave .075 or so without having to cc the chambers or worrying about anything. Then a cam and 4bbl will give you that shot you are looking for.
My two sheckels!
 
I had one rebuilt for $1600 from a guy who does work out of his home garage. We just had to install it and put on the accessories (carb, alt, etc.) I also supplied a few parts, so it probably went around 2 k. He did all the block and head machine work and replaced the pistons. I had a custom cam ground by Dave Crower and it ran great.
 
Thank you for all the suggestions. I was told that I could just work on the head and and swap all the parts out needed. The engine runs great from what I could tell, but i thought maybe It needed to rebuilt but I will use all the suggestions given first before throwing money at this.

How can I tell what year my Slant 6 is? usually on these they have the vin number stamped on the pad near the passengers side but the pad is blank. Someone told me that back in the day when the car was still under warranty and engine went down, that the dealership would swap out the engine for another without the stamping. It does have a casting number if that would help at all.
 
chongo25 said:
Thank you for all the suggestions. I was told that I could just work on the head and and swap all the parts out needed. The engine runs great from what I could tell, but i thought maybe It needed to rebuilt but I will use all the suggestions given first before throwing money at this.

How can I tell what year my Slant 6 is? usually on these they have the vin number stamped on the pad near the passengers side but the pad is blank. Someone told me that back in the day when the car was still under warranty and engine went down, that the dealership would swap out the engine for another without the stamping. It does have a casting number if that would help at all.
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The VIN question is asked all the time about the /6 and there is no stamp on it from what I understand.
 
Have a comperssion test run or do it yourself; if you can change spark plugs, you can do this. If that comes up OK with no low cylinder readings without putting any oil in the cylinders, then it is likey OK to go ahead and not touch the bottom end. And besides, if the bottom end does go, then pull your reworked head and then do the bottom end; it's been done that way many a time. I WOULD be pulling the pan and replacing the oil pump, and would replace the timing chain when replacing the cam.

As for year, do you know if you have hydraulic (later) or solid (earlier) lifters? If solid, the rockers get adjusted.....What car is this in?
 
I don't know if it is s solid or hydraulic. As for the car it is in a 72 challenger.

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You could always efi the slant and add a turbo, just a thought.
 
A lot of people will recommend a turbo or efi, but seeing how you are new to motors and whatnot, I'd avoid it like the plague. A mild build will even require a lot of studying to get everything matched right. Don't just go slapping a lot of different parts together, everything needs to be matched. It's like a puzzle. And personally, for a mild street motor I wouldn't be too worried about balancing even. Just my 2 cents.
 
Brandon Weaver said:
A lot of people will recommend a turbo or efi, but seeing how you are new to motors and whatnot, I'd avoid it like the plague. A mild build will even require a lot of studying to get everything matched right. Don't just go slapping a lot of different parts together, everything needs to be matched. It's like a puzzle. And personally, for a mild street motor I wouldn't be too worried about balancing even. Just my 2 cents.
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X 2

Look at what you have tools, time, and skills to complete. It's sort of like carpentry where you measure twice and cut once. Good planning on the front end will save time and money as the build progresses.

For me, I plan to have the engine out of the car only once. I also look at what I can do in-house and what I will need to out-source. I usually have a machine shop "hot tank" the block and head. If I have any reason to believe the block or head is cracked, this is when I have it checked out. Also check to see if bores are worn out of spec.
 
I think my 64 slant needs rebuild. It runs great except for a definite knock in the bottom end. I am pretty sure it's either a rod bearing or wrist pin. Unfortunately I do not have the means to pull the motor. Is it possible to do this with it in the car? 64 dart gt. I don't have much income at the moment and can only do so much at a time. I do not want to ruin the engine however. Advice?
 
weaverjsnw said:
I think my 64 slant needs rebuild. It runs great except for a definite knock in the bottom end. I am pretty sure it's either a rod bearing or wrist pin. Unfortunately I do not have the means to pull the motor. Is it possible to do this with it in the car? 64 dart gt. I don't have much income at the moment and can only do so much at a time. I do not want to ruin the engine however. Advice?
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Rent/borrow an engine hoist and pull the motor. This will give you a much much better ideas of what is wrong can what needs to done to fix it.
 
yeah I will go that route. should probably recruit someone with some experience to at least get me started. I'll start looking for local fabo members and a cherry picker...
 
I pulled my first motor (351C) with a tripod of wood poles secured together at the top so there are many ways to skin that cat. With your rebuild involving the bottom end, it makes all the sense in the world to pull it so you can clean/measure/machine what is needed.
 
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