Slant Six Hp drop

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TheGrimSpeed

TheGrimSpeed

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hey there fellows new to this form. first time mopar owner 67 dodge dart original 4 speed!. well anyways my question is the motor is a 225 but its been smoking also comp is very low im talking about 1.90 2.85 3.80 4.75 5.83 6.110 pretty bad any ways my buddys mother has a 1980s dodge van with 27xxx miles on that slant six an is willing to give me the motor for free, but i saw online the rating for the 225 after 1971 dropped really low from 145 to 95 hp is this motor going to be slower then what i already have because if so i rather pass on the motor. All advice is welcome good or bad personal experience if any with the later 1976 plus motors thank you -Felix
 
-There power numbers are generated by different methods, so they are actually not that far apart when compared using the same methods.
- I have no idea what your compression numbers mean, unless they are in bar, in which case yes, they are sad.
-at this point I would recommend a leakdown test to see where the pressure is going. Numbers that low and that far apart usually point to bad valves. If that were proven, perhaps a valve-job would get you a few more years on the old girl.Perhaps the LD test wiil also show the rings to be done. But perhaps not.

- If that engine is original, it may not survive long after a fresh head goes on; and the reason is more likely related to your right foot than old age, heehee

- the leakdown test will govern the next step
 
You might want to do a valve adjustment first then redo the compression test both dry and wet.

That 80's slant from your buddy's Van is most likely a hydraulic motor which will eliminate the periodic valve adjustment you will have to do with your current motor.
 
yes i will get to checking that once i leave base.so the later slant six has the same horsepower as an early six i just didnt want to down grade in horsepower after doing all that work.
 
AJ/FormS said:
-at this point I would recommend a leakdown test to see where the pressure is going. Numbers that low and that far apart usually point to bad valves. If that were proven, perhaps a valve-job would get you a few more years on the old girl.

- the leakdown test will govern the next step
Click to expand...

What for?
It has low compression and smokes.
"Jerk that smoke wagon" in favor of the free van motor. :D
 
TheGrimSpeed said:
yes i will get to checking that once i leave base.so the later slant six has the same horsepower as an early six i just didnt want to down grade in horsepower after doing all that work.
Click to expand...

You have TWO things against you "in figures" with the late engine........a different HP rating (the newer "net" HP) and emissions requirements, IE leaned out fuel system, and a really poor distributor advance curve. I would toss that late engine in there in a second. you will want to diddle the distributor curve for a better advance curve, and either play with the newer carb, or use the carb off the 67
 
TrailBeast said:
What for?
It has low compression and smokes.
"Jerk that smoke wagon" in favor of the free van motor. :D
Click to expand...

Agreed,the rings are probably toast,screw it and take it out.By all means if
you want to rebuild the OE mill and put it back w/ a few improvements,that would be the
perfect opportunity,w/o leaving your ride disabled. Don't sweat spark curves,just drop the
OE intake/exh. system and distributor from your ride onto the new unit and go,you'll be fine.
:coffee2: P.S. you may have to plug exh tube hole in head,no biggie.
 
concur with suggestion to install newer engine. Newer engine should have hardened valve seats and no "drool" tubes. 1981 and later should also have hydraulic lifters.
 
By the way if the transmission out of the van "comes with" I'd use it too!!! Don't know about the six's but the V8s had a change in the converter snout register in the rear of the crank. If you put the new engine up against your old transmission (torqueflite?) you'll need an adapter ring to space it.
 
67Dart273 said:
By the way if the transmission out of the van "comes with" I'd use it too!!! Don't know about the six's but the V8s had a change in the converter snout register in the rear of the crank. If you put the new engine up against your old transmission (torqueflite?) you'll need an adapter ring to space it.
Click to expand...

This is correct.
Since this is a 4 speed vehicle, a late flywheel will be required. The flywheel from the 67 engine will not fit the new engine.
 
Charrlie_S said:
This is correct.
Since this is a 4 speed vehicle, a late flywheel will be required. The flywheel from the 67 engine will not fit the new engine.
Click to expand...

Yup did not catch that. "Might" be able to turn the flywheel center hole?
 
Certainly the flywheel can be trimmed up to the larger bore,but
if the OP decides to redo the OE mill,he'll be making a hub ring to go back.I'd find a '68
and up 'wheel and bolt it up,not made of unobtainium quite yet, and I'm sure folks like
TylerW who got tired of their 3-on-the-tree cars have them laying around cheap.DO IT!
 
To clarify, before 1972 the HP ratings were on a dyno w/ no parasitic loads from the water pump, alternator, etc. After 1972, they tested the engines with all accessories as actually used.

I don't understand why he shouldn't adjust the valves and re-measure. Valve adjustment on these solid lifter motors is a regular tune-up task, every 2 years or so. If the valves aren't fully closing, that would greatly decrease compression. It is also tricky to measure compression correctly. I wouldn't trust the "hold tight in hole" type gages and always use a screw-in type. The Schrader valve at the end must be the correct type (white w/ very weak spring) not one for a car or bicycle tire. You must prop the throttle and choke plates open and spin the engine at normal cranking speed.

Oil burning can come from things besides worn rings. Steady blue smoke, worse at high throttle is usually due to bad rings. Smoke when accelerating after sitting a long time at idle, that goes away when driving, is usually due to leakage past the valve stems. It is often fixed simply by installing new rubber "umbrella" stem seals. You can blow air thru the cylinder to find where it is leaking. The Harbor Freight compression kit makes air connection simple.
 
BillGrissom said:
To clarify, before 1972 the HP ratings were on a dyno w/ no parasitic loads from the water pump, alternator, etc. After 1972, they tested the engines with all accessories as actually used.
Click to expand...

Bill is 100% correct on this. My 1972 318 was factory rated at 230 HP in 1971, but the rating dropped to 150 HP in 1972, with NO mechanical changes, whatever.

My advice; get the new motor...:glasses7:
 
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