How much does it cost to rebuild a Slant 6

[LeaningTower]

Hey guys I am new to forums and was wondering how much it would cost to rebuild my 225ci slant 6. I have owned the car for a little over 9 months now and would like to rebuild it but am not to sure how I should go about the process. I would like to rebuild the motor to stop the leaks and gain some more power because a lot of horses have left the stable. I would like to do a lot of it myself but have limited tools. I am located in Atlanta Georgia. Any help or advice would be appreciated.
Here is a link to my youtube channel if you want to see more:https://www.youtube.com/channel/UCcot0IlDbOByOmUuHQsmS0g

 

[nm9stheham]

The cost will be all over the map; that is all dependent on how much you do yourself.

We just pulled and rebuilt one to stock specs; spent about $1,100 for this basic engine rebuild and that is about as cheap as you will get IMO for any significant work and good new parts all over. We pulled and disassembled ourselves and did the engine assembly and installation ourselves so saved a ton on labor.

Machine shop work was $440 total at a good shop but such work is pretty cheap here in the mountains; included block hot tank and rust tank, block bore and hone, all 12 new valve guides installed and fitted, above-average quality valve job, press off/on pins and pistons, install new cam bearings, shave head .030".

Parts were around $550 including these new parts: Stock cast pistons and moly top rings, main and rod bearings, cam bearings, timing chain, about half of the valves were replaced with new ones, all gaskets, blueprinted oil pump.

Add in some miscellaneous lubes and paint and other stuff and you end up at around $1100. All the non-machining labor we did here. We did not have any significantly damaged parts to replace, but we did replace the oil pump with a blueprinted one just to make the oiling system as soild as it can be.

If your engine is basically running good but is tired, then what we did for machine work tasks is representative of what you commonly run into as a minimum. Our crankshaft only needed a polish which we did here. If you are not familar with engines, then taking the crank and cam and lifters to the machine shop for inspection of individual parts is a good idea, but of course is added $$.

In addition to this, I decided to put in a mild upgraded cam, and all new valve springs (For $2 each, why not?!?) That all ran about another $300 shipped.

Your tools and skills is a separate discussion. Maybe you can tell us the type of repair and maintenance work you have done as a starting point. I like your car!

 

[racerhog]

What he said...

 

[Darter6]

What he said x-2. Last guy I talked to said his stock rebuild cost him $1000.
Nice car,I like the 67-72 Valiants.

 

[RustyRatRod]

Where are you in Georgia? I am in Jones County, just north east of Macon. I will be glad to build it reasonably for you. I use Reeves RPM Performance for machine work. They are very good.

http://www.reevesrpmperformance.com/

The slant six is never going to be a hot rod engine without some kind of power adder such as a blower, turbo or nitrous. You will be doing good to get 200 HP out of one. However, that will be more snappy even in a 4 door a body than you might imagine. It would be fin to drive and still get reasonable mileage.

 

[BillGrissom]

Why do you suspect it needs a rebuild? All oil leaks can be fixed easily and cheaply w/ engine in the car. Always do a compression check first. Before buying a gage ($15 @ HF), turn the engine over by hand by tugging on the fan belt. If you feel each cylinder (2 revs) and hear each one hiss down, the engine is perfect so don't make problems for yourself. Another poor-boy test is to remove the oil fill and PCV valve and see how much blow-by gas comes out the valve cover at idle. If it isn't puffing, the engine is probably fine.

You wouldn't gain much power or mileage simply from a rebuild, unless the engine was totally shot. Optimizing fuel and spark will usually give much more bang. Somebody smart has been under the hood since it has a modern Sanden AC compressor.

 

[LeaningTower]

The cost will be all over the map; that is all dependent on how much you do yourself.

We just pulled and rebuilt one to stock specs; spent about $1,100 for this basic engine rebuild and that is about as cheap as you will get IMO for any significant work and good new parts all over. We pulled and disassembled ourselves and did the engine assembly and installation ourselves so saved a ton on labor.

Machine shop work was $440 total at a good shop but such work is pretty cheap here in the mountains; included block hot tank and rust tank, block bore and hone, all 12 new valve guides installed and fitted, above-average quality valve job, press off/on pins and pistons, install new cam bearings, shave head .030".

Parts were around $550 including these new parts: Stock cast pistons and moly top rings, main and rod bearings, cam bearings, timing chain, about half of the valves were replaced with new ones, all gaskets, blueprinted oil pump.

Add in some miscellaneous lubes and paint and other stuff and you end up at around $1100. All the non-machining labor we did here. We did not have any significantly damaged parts to replace, but we did replace the oil pump with a blueprinted one just to make the oiling system as soild as it can be.

If your engine is basically running good but is tired, then what we did for machine work tasks is representative of what you commonly run into as a minimum. Our crankshaft only needed a polish which we did here. If you are not familar with engines, then taking the crank and cam and lifters to the machine shop for inspection of individual parts is a good idea, but of course is added $$.

In addition to this, I decided to put in a mild upgraded cam, and all new valve springs (For $2 each, why not?!?) That all ran about another $300 shipped.

Your tools and skills is a separate discussion. Maybe you can tell us the type of repair and maintenance work you have done as a starting point. I like your car!

I do not have a lot of experience with working on engines but I do know the ins and outs of one. The work that I have done is Valve cover gasket replacement, trans pan gasket (didn't go that great) and changing the oil.

 

[LeaningTower]

Why do you suspect it needs a rebuild? All oil leaks can be fixed easily and cheaply w/ engine in the car. Always do a compression check first. Before buying a gage ($15 @ HF), turn the engine over by hand by tugging on the fan belt. If you feel each cylinder (2 revs) and hear each one hiss down, the engine is perfect so don't make problems for yourself. Another poor-boy test is to remove the oil fill and PCV valve and see how much blow-by gas comes out the valve cover at idle. If it isn't puffing, the engine is probably fine.

You wouldn't gain much power or mileage simply from a rebuild, unless the engine was totally shot. Optimizing fuel and spark will usually give much more bang. Somebody smart has been under the hood since it has a modern Sanden AC compressor.

First off I am not exactly sure where to find the oil fill and PCV valve. How is it that I can fix all of the leaks by leaving the engine in the car. Currently I am leaking oil from various spots, tranny fluid, and coolant. I'll try and post some pictures of all of the leaks.

 

[nm9stheham]

Post pix and we can see what to do.

 

[sargentrs]

When I got my Dart , she ran like crap and was dumping a quart of oil, a quart of tranny fluid, 1/2 quart of p/s fluid and 1/2 gallon of coolant every week and had a nagging overheating issue and random electrical problems. I pulled the engine and transmission, replaced the seals and gaskets and while I had it out, replaced the water pump, thermostat and motor mount and tranny mount rubber bushings. Also replaced the PCV valve and breather cap filter. Had to replace the p/s pump and pressure line to stop those leaks. Overheating turned out to be the radiator so I replaced it too. Also did the ammeter and alternator bypass and installed a GM HEI ignition module which bypassed a lot of my electrical problems. Now she runs great and doesn't leak anymore. I'm far from an expert mechanic but a decent parts replacer and can follow other, smarter, people's directions. The people here are very patient and helpful if you'll listen. Before going to the expense and effort of rebuilding the engine, get what you have in the best condition possible, then evaluate the situation.

 

[VDART]

drive to Rustyrat rods place pay him for some mechanic'n & your problems will be answered, Lawrence

 

[red67gts]

wish I knew you needed one as about a year ago I sold a great running 225/904 with new alternator, distributor, all new ignition, radiator,starter ,new hoses, and other parts ready to set in and run for $200

 

[sireland67]

If you are close you may want to seriously consider Rusty Rat Rod's invitation to help.
He can rebuild the entire car for you, or just fix the leaky gaskets and get what you have running like a swiss watch.

 

[KosmicKuda]

Machine shop work was $440 total at a good shop but such work is pretty cheap here in the mountains; included block hot tank and rust tank, block bore and hone, all 12 new valve guides installed and fitted, above-average quality valve job, press off/on pins and pistons, install new cam bearings, shave head .030".

Parts were around $550 including these new parts: Stock cast pistons and moly top rings, main and rod bearings, cam bearings, timing chain, about half of the valves were replaced with new ones, all gaskets, blueprinted oil pump.

Add in some miscellaneous lubes and paint and other stuff and you end up at around $1100. All the non-machining labor we did here. We did not have any significantly damaged parts to replace, but we did replace the oil pump with a blueprinted one just to make the oiling system as soild as it can be.

In addition to this, I decided to put in a mild upgraded cam, and all new valve springs (For $2 each, why not?!?) That all ran about another $300 shipped.

Hey nm9stheham, just out of curiosity, what cam did you use and where did you get it?

I just picked up my unassembled 1964 225 short block over the weekend. He charged me $132 to bore and hone the 6 holes .040 over. He also thoroughly cleaned the block by tanking it and then shot blasting in a cabinet w/ a rotisserie. ($90?) I had miked the crank and was pretty sure it was good. He checked and said yeah it just needed polishing so standard main and rod bearings. I had him do the polishing for $36 since he has a lot more experience than me and I had him polish the rope seal serrations off the rear main seal area so I can use a "modern" rubber seal. Used an Enginetech premium ring (moly) kit that was less than $300. The pistons included are Silv-o-lite, rings are Hastings, and the bearings are King. So far I have just over $600 in the block work, parts and gaskets. I will do the assembly and painting. This engine had not been run since at least 1982 and I could not turn it over with a breaker bar. It turned out that 5 of the 6 connecting rod pins were frozen in the pistons. There was a lot of internal sludge and cooling system corrosion so i didn't want to skimp on the cleaning. The entire bottom of the engine was heavily oil-covered as was the manual 3 speed tranny. Every square inch of the tranny was caked with gunk. I just do not want to have any overheating issues in the future and want a solid engine I can drive anywhere.
I stiil have to get a head to him but Dutra says not to put any money in old heads but look for a 68 or newer which I have not found yet.

If I can find a better cam cheap I'll probably do that. Otherwise I'll just put this thing together as is so I can drive it by summer. The brakes need a lot of work for instance.

This guy is in his 70's and still works 7 days/week. Been machining engines since 1961. All his equipment is Sunnen and I really like his work. I was looking around his shop and saw that he has honing plates for SB and BB Chryslers. He is currently doing 2 340's for someone.

 

[nm9stheham]

IMO, for a stock rebuild I would not get hung up the older vs. newer head from all I can read. Port flow is not much different, it is just that the later head has more possibilities for improvement due to some chamber details. The older heads are not more prone to crack or warp or have valve seat issues that I know of.

Read the cylinder head article by Doug for on www.slantsix.org; he 'feels' it has the possibility of better fuel economy for the later head but there is no hard data discussed. You can get a sure (and more) combustion efficiency increase by just a simple compression increase of 1/2 point by a simple head shave operation.

But, if you are going to port it a lot and up the HP, then I would indeed go with the newer head.... just my view. It is more important for stock use to get the guides and valves worked over properly and get a good valve job; our local machinist put in a nice steep angle valve pocket grind (like a pocket reaming) to clean out some of the pocket irregulaties.

My cam came from Doug Dutra; he has some special grinds on file with a cam grinder. He also has lifter regrind machinery so can provide a fresh set of re-ground lifters for a good price. Ask him for his torque cam: .435" lift and 264 duration, with either 110 or 112 lobe sepration angles. Per Doug, the 110 is better for the 2 BBL and the 112 for the 1 BBL. I'll PM you the price I paid; I don't want to openly say it as he has the right to price as he sees fit.

This cam will use stock springs A-OK or the inexpensive replacement ones. I like the softer stock sping pressure levels; keeps the pressure off of the cam lobes and lifters, and you just don't need the higher spring force at the low-medium RPM's of a stock engine. They are more prone to valve sticking in a dirty/gummed/varnished engine as the spring force is low, but that is not an issue for a new rebuild.

Sounds like you have the right guy for this work; our local guy is similar. I have to take a pix of the shop front someday; it is a classic! But the place is PACKED with machines, parts etc. It will be a sad day when all the older machine shop guys retire.

BTW, I assume you got new cam bearings installed? DON'T skimp on this!

 

[LeaningTower]

Here are the pics of the leaks

 

[LeaningTower]

When I got my Dart , she ran like crap and was dumping a quart of oil, a quart of tranny fluid, 1/2 quart of p/s fluid and 1/2 gallon of coolant every week and had a nagging overheating issue and random electrical problems. I pulled the engine and transmission, replaced the seals and gaskets and while I had it out, replaced the water pump, thermostat and motor mount and tranny mount rubber bushings. Also replaced the PCV valve and breather cap filter. Had to replace the p/s pump and pressure line to stop those leaks. Overheating turned out to be the radiator so I replaced it too. Also did the ammeter and alternator bypass and installed a GM HEI ignition module which bypassed a lot of my electrical problems. Now she runs great and doesn't leak anymore. I'm far from an expert mechanic but a decent parts replacer and can follow other, smarter, people's directions. The people here are very patient and helpful if you'll listen. Before going to the expense and effort of rebuilding the engine, get what you have in the best condition possible, then evaluate the situation.

I also have some electrical problems like sometimes the car just won't crank at all. All I hear is the alternator click. Do you have any ideas?

 

[451Cuda]

Find a later model head if possible, will already have hardened seats installed. I think it started in '73?

 

[KosmicKuda]

IMO, for a stock rebuild I would not get hung up the older vs. newer head from all I can read. Port flow is not much different, it is just that the later head has more possibilities for improvement due to some chamber details. The older heads are not more prone to crack or warp or have valve seat issues that I know of.

Sounds like you have the right guy for this work; our local guy is similar. I have to take a pix of the shop front someday; it is a classic! But the place is PACKED with machines, parts etc. It will be a sad day when all the older machine shop guys retire.

BTW, I assume you got new cam bearings installed? DON'T skimp on this!

Thanks for all that info. I have read that article by Dutra on heads which is how I got side-tracked in the first place. IIRC he said there was a dead area in the early chambers. I'm just trying to take advantage wherever I can.

Yeah, new cam bearings installed. he also put the freeze plugs in. Just like your guy, he has a little bit of everything. When I was there on Sunday (yep he was there) I saw a complete 239 C.I. Ford flat head engine but it was scattered everywhere, a 400 Pontiac, small aluminum 4 valve Honda heads, John Deere tractor block, snowmobile heads, Harley heads, 5.9 Cummins rods and parts for a guy installing it into a Chevy PU, just too much to take all in. He doesn't grind cranks but he gave me the name of a guy up the road who does most of them in this area.

 

[goldfish65]

I can't give any tech advice but my $.02 take things one at a time and figure out what's really going on, you may very well not need a rebuild. Keep your Valiant no matter what, if not you will regret it, it is sweet and you won't find a better car out there.

 

[RustyRatRod]

Looks like normal leaks that happen over time. These are not made like new engines. They are GOING to leak at some point.

 

[CichliDart]

Here are the pics of the leaks

All that room under the hood for a turbo ;)

 

[nm9stheham]

The leaks on the oil filter side look to be a combination of the valve cover gasket and the spark plug tube gaskets. When you pull the spark plugs on the older head, there are aluminum tubes that go into the head and surround the plugs; these tubes just pul out and there are small gaskets around each one; easy to buy and replace. Same for the valve coer gasket.

There looks to be some sealer around the timing cover to pan gasket area. Not uncommon for leaks there. You pretty much need to jack or pull the engine up a few inches to work on the pan gasket. Timing cover gasket can be done in the car. I'd replace the timing chain if I did the timing cover gasket; will help performance very noticeably.

Looks like coolant on the k-member edge.

 

[WoodenNickle]

Rob,

if you're doing rebuilds, how much you want to build mine? I decided I'm gonna keep the slant.

 

[LeaningTower]

The leaks on the oil filter side look to be a combination of the valve cover gasket and the spark plug tube gaskets. When you pull the spark plugs on the older head, there are aluminum tubes that go into the head and surround the plugs; these tubes just pul out and there are small gaskets around each one; easy to buy and replace. Same for the valve coer gasket.

There looks to be some sealer around the timing cover to pan gasket area. Not uncommon for leaks there. You pretty much need to jack or pull the engine up a few inches to work on the pan gasket. Timing cover gasket can be done in the car. I'd replace the timing chain if I did the timing cover gasket; will help performance very noticeably.

Looks like coolant on the k-member edge.

Alright planning on doing the spark plugs this weekend. I'll let you know how it goes. Thanks for the tip.