rebuilding a 273 180 HP engine

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M

MAubrecht

66 Cuda
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does anyone have experience rebuilding this engine? Is there a kit that is available. I've never rebuilt anything before but would like to take on the project. I'm pretty tool handy but have never worked on cars just motorcycles. The engine is starting to blow blue smoke on start up and the first few minutes. I have a small oil leak but very minor. Everything else on the car is in excellent shape for a '66. Thanks, Mike
 
If it just blows a little smoke on start-up, you probably just need a new set of valve seals. As far as rebuilding one, except for pistons, it's virtuallty the same as all the other small block rebuilds. Any listing for a 318 or 340 will use the same bearings, cam, lifters, and most gaskets and seals. Some 360 parts are the same too but not all. Check with Summit, PAW, Jegs, Mancini, Mopar Performance, etc. for prices and availability.
 
pistons are the only oddity, everything else is a 318 (except the solid lifters, intake and intake bolt angles if it is prior to about 65 1/2, 66 should be OK 67 318 changed auto trans pilot hole in the crank for a larger convertor snout, youll need a bushing if you get a post 67 motor) Seals can be done "on the car" you just need a air compressor and a spark plug chuck. The air pressure keeps the valve closed while you take the spring and retainer off to get at the now desintigrated valve seals. If no compressor, you can stuff poly rope into the almost TDC piston spark plug hole and then gently rotate the crank so the rope is compressed under the valves, then you can use your rocker arm shaft as a fulcrum for a lever action spring compressor. The retainers come off with a little tap and the keepers can be retrived with a magnet (careful you dont drop them into the engine)
The new valve seals may come with a very small condom looking thing. That slips over the grooves of the valve so the seal slides over the grooves, not into them. While the spring is out, jiggle the valve. If there is more than just a hint of lateral movement, check the endplay wiht a mic and see if the heads need to be freshened up with new guides. A complete valve job runs about 150 if you bring the bare heads in, guides (check and see if they knurl them or bronze line them, knurling is not what you want) seats ground and valves faced. Tell them its a mechanical valvetrain and they might face the tops of the valves too, or elect not to becasue you already have adjustability on the rockers. They can reface the rockers too if the tips are galled. IF you are not interested in the nostalgic, but more of the driveability, a 318 is identical and can be had for next to nothing as a running motor and offers more torque.
 
If you pull those heads you might find the valves recessed into the heads and their edges razor sharp. Unleaded fuel has not been kind to these engines. Good luck
 
Pick up a copy of:
How To Rebuild Your Small-Block Mopar
By: Don Taylor & Larry Hofer
Copyright: 1982, Fisher Publishing
Soft Back
ISBN: 0-89586-128-3

That will give you the total overview. You should have no problems. The pistons for the 180HP engine are fairly easily located. As mentioned, everything else is just small block Mopar stuff.
 
The higher compression will require higher octane fuel too. Premium grade pump gas with no ethanol aint cheap.
 
Lets also include guys that a piston upgrade is going to cost him at least $600. Nothing wrong with what he has. The advertised CR was 8.8 to 1. That was with the steel shim gasket. Of course over the years heads are pulled and other gaskets are used. Overall it would not take much to bump a stock flat top motor over 9 to 1 which is more than adequate for a street motor.
 
dart4forte said:
Lets also include guys that a piston upgrade is going to cost him at least $600. Nothing wrong with what he has. The advertised CR was 8.8 to 1. That was with the steel shim gasket. Of course over the years heads are pulled and other gaskets are used. Overall it would not take much to bump a stock flat top motor over 9 to 1 which is more than adequate for a street motor.
Click to expand...

Thank you. Turning the flat top pistons 180 degrees bumps the stroke a hair also.
 
But if he has to buy pistons because of a re-bore why not get the ones that will help out performance a bit.
 
My 67 I put Egge 10.5's and an Isky cam. Granted I'm at 5280' in Denver but I had no problem with Reg. gas.
 
I had mine, formula s hipo version rebuilt and the egge pistons (10.5:1) after I waited for a few months for egge to cast up the new pistons, the turned out to be about 9:1. The machine shop checked and rechecked it, and even played with different gaskets. SO if you buy the low compression egge pistons, it will be extremely low. On the cam, good luck, the solid lifter ones (stock) are no longer available but Schneider cams, http://schneidercams.com/solidliftercamshafts-10.aspx makes one with a little more lope to it. A couple of more things that are different, front timing cover is a little different, I would take it off and check the passages for corrosion, my old one was welded up and smoothed out then sealed from the inside, there is also a separate timing tab, different water pump as well. And last but not least the harmonic damper is specific for some models.
 
cudamark said:
If it just blows a little smoke on start-up, you probably just need a new set of valve seals. As far as rebuilding one, except for pistons, it's virtually the same as all the other small block rebuilds. Any listing for a 318 or 340 will use the same bearings, cam, lifters, and most gaskets and seals. Some 360 parts are the same too but not all. Check with Summit, PAW, Jegs, Mancini, Mopar Performance, etc. for prices and availability.
Click to expand...

Right on Cudamark. That's a great place to start. There is a very good chance that the seals are originals if there's any seals left. A compression test will help you figure out whether you need a overhaul. A leakdown test works great too.
I rebuilt my HP 273 last winter and used the Egge HP pistons. They aren't 10.5/1 right out of the box. I shaved the heads and used a thinner Mopar Performance head gasket and ended up with a bit over 9.5/1 compression. I used a Isky E-4 cam which I found to be as close to stock HP specs as I could find. The whole project cost around $3000 and was a lot of fun to do.
Here's a link to my build. http://www.forabodiesonly.com/mopar/showthread.php?t=94343
toolman
 
probly the best bang for the buck in this situation is to pull the engine and do this...

fix whatever is leaking with a total gasket set (felpro-$70)
new oil pump and timing chain ($50-for stock replacements)
stock off the shelf 340 cam and hyd. lifters (seen them as cheap as $80 new)
junkyard late-model #302 heads, rocker assemblies, and pushrods (no more than $100)
performer intake with a small 4-barrel (swapmeets and craigslist...anywhere from $50-$250 for the pair)
general electronic ignition goodies (once again stock stuff...$100)

it fixes the leaks, the smokes, the miss that is most likely there, retains a 'regular' gas compression ratio, increases drivability, decreases maintainence, and will add somewhere in the area of 35-40 horsepower
 
dukes69 said:
..... On the cam, good luck, the solid lifter ones (stock) are no longer available but Schneider cams, http://schneidercams.com/solidliftercamshafts-10.aspx makes one with a little more lope to it....
Click to expand...

Racer Brown, Isky and Hughes all have a cam thats close to the stock High Performance cam profile. I know melling made a stock replacement at one time, could also check with them.

I have one of the melling stock replacements (used)(Part Number SPD14) and matched solid lifters that was in a 273 I parted out.
 
Here's mine with 10/1 egges and isky cam (I forgot which one but I could research it for you).

http://www.youtube.com/user/JimsMopars#p/a/u/1/NKlIiP43cVo

I wanted to keep a stock look so it had stock exhaust manifolds and stock 2V intake. I installed dual 2-1/2" pipes out the back thru turbo mufflers.

Very nice sound on the video, check it out.
Jim
 
There has been a bunch of great suggestions! I'll get to work on it and let you know how it goes. The next thing I'll need some suggestions are on the suspension. It runs good and drives just fine up to about 60 mph then it rides like a Harley Hard tail.
 
I agree with checking the engine first. If it is a good "air pump", no need for a rebuild. One test is compression. Should be >100 psi in all cylinders. Hard to say more since depends a lot on the cam, but all cylinders should be +/-10 psi. Another test is to turn the engine over by hand from the crank bolt. If you feel each cylinder strongly resist you like a spring, and each holds pressure >10 sec, the "air pump" is fine.

If a good air pump, but low compression, might have a wild cam with a lot of overlap (bad idle, but tuners love the thumpy sound).

If a leaky air pump, apply air pressure to each spark plug hole with the valves closed (piston at bottom) and try to see if it is hissing past the rings (hear in crank-case), intake (hear in carb inlet), or exhaust (hear in tail-pipe).

Re some fixes. I have tried the "hold valves up w/ air pressure" trick and don't like it. You must jam the engine in position or it may spin on you (has on me). I just bring the piston to TDC (use a wire in spark plug hole to verify), then the valves can't drop into the cylinder. You can pull the valve up w/ a magnet to hold while removing the keepers. Others suggest stuffing rope in the cylinder, but extra work. If you replace valve springs, double-check the closed length. I could just barely get some keepers in, especially on valves I shimmed tight to make spec length.

I switched to a hydraulic cam (common .422/.440 "RV/Torque"). The shorter pushrods needed were only ~$35 at Summit. I used Roades "leak-down" lifters as an attempt for better idle and mileage. Haven't driven yet. Keep your adjustable rockers, they are best and work fine w/ hydraulic lifters.
 
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