Finally, got my 5.9 Dart to the track. It went well, then it went to hell.

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LXguy

LXguy

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Hey All:

Track opened so I got the car together the best I could and took it out to Terre Haute on Saturday.

Combo is a 5.9 magnum shortblock pulled from the junkyard. Supposedly a low mile deal. 1.9 Iron Ram heads from Hughes. Custom Comp camshaft (224/230 hydraulic roller), air gap intake, stock 670 street avenger, 4.11 gear, MT 255 drag radial, Cal-tracks, built 904 with brake.

I only had 25* total timing in the car, 20 psi in the tires and shifted at 5500 RPM on the first pass, footbraking.

Car went a 1.81 60' time, 7.88 @ 88.92 mph. I was really pleased by this.

Used the brake the next time, set the two step at 2000, bumped shift point to 5700 RPM.

Car was still pulling hard at the shift light, and went a 1.71 60' time, 7.73 @ 88.79 mph.

I was told that I was doing a one-wheel peel on this pass, so the diffy is going out.

Next pass I must have overrevved it in the burnout box or something. On launch it busted up a pushrod and I still haven't torn it apart to find out what else might be the matter. Other than the hughes springs that came on the heads, the valvetrain is a all stock Magnum junk.

IMG_1193.jpg


Assuming I don't have a bunch of bent valves (or worse) I think this car has a lot of potential. Get the timing up, change the jetting (or get a racier carb), put some good shocks in the front, turn the two-step up, yada yada.

Broken Dart:

dartatthetrack.jpg
 
hey sorry to hear....but the dart looks terrific! I LOVE 70 darts!!! hope you have it up and running in no time! just get another junkyard 5.9 and ull be good to go!
 
Hey man, before that pushrod gave up the ghost that thing was a low 12 second car, like 12.1! Nice job.
 
Sorry to hear about your carnage .Hang in there and get that sucker back on the track after you upgrade the valve train.Its a great looking Dart BTW ...
 
Those hydraulic rollers are heavy. I wonder if the Hughes springs are enough... Whta lobes were spec'd on the cam?
 
I'll bet it was just the stock pushrod couldn't handle the extra load & RPMs, time to get a good set, i will say your car looks great & runs fantastic for a no thrills 360 magnum, this gives me hope of surely seeing very low 13s in mine, if not 12.9s which thats my goal.

What converter & carb are you useing??
 
mopardude318 said:
hey sorry to hear....but the dart looks terrific! I LOVE 70 darts!!! hope you have it up and running in no time! just get another junkyard 5.9 and ull be good to go!
Click to expand...
It's actually a '71. If you look closely you'll see the "DART Swinger" emblem on the fender.
 
Thanks guys:

The car is a 71. 33K original miles.

I'm running an out of the box Holley 670 Street Avenger. Never even had the bowls off of it (yet). I really think the car could use a bigger carburetor, but this'll have to do for a while. Assuming things go well I plan on jetting it up when I get it back together.

It's a 9" converter from Ultimate Converter Concepts. Lenny over there really knows his stuff.

The valve springs meet the specs that Comp recommended. I think I'll upgrade when I put it back together though.

Steve
 
I remember reading somwhere that stock magnum pushrods leave something to be desired in the strength department, supposedly only .080 wall or something like that, with flexing tendencies. I hope you luck out and only need a good set of pushrods. looks like a sweet ride, hope things turn out to be minor.
Alan
 
Nice dart and that is fast for a junk yard motor. Good luck with finding the problem. I am running the MP replacment magnum pushrods. Are they the same as stock?
 
Hope this is just a minor setback for you.Season is gonna start here at my local track next weekend(Easter).Sweet looking ride!
 
My 360 Magnum package I'm putting together is very close to yours with a 3.91 and a holley 750 vac sec with a Proform carb body, manual valve body, 3500 loose converter, and the knock-off China "air Gap" from Professional Products,a Mutha Thumpr from Comp Cams,and a 150 horse nitrous shot. I will be disappointed if I can't tune it the to run in low 12's in street trim thru the mufflers . Keep us posted on your progess.
I will be following closely as I plan on spinning mine to at least 6000.
Love that Dart!!
 
Badart said:
Nice dart and that is fast for a junk yard motor. Good luck with finding the problem. I am running the MP replacment magnum pushrods. Are they the same as stock?
Click to expand...

Yes, the same as stock. That is what I was actually running in the car. Turns out my backup set is the stockers.

I'm thinking getting some good ones is step 1. LOL

Steve
 
dustoff440 said:
My 360 Magnum package I'm putting together is very close to yours with a 3.91 and a holley 750 vac sec with a Proform carb body, manual valve body, 3500 loose converter, and the knock-off China "air Gap" from Professional Products,a Mutha Thumpr from Comp Cams,and a 150 horse nitrous shot. I will be disappointed if I can't tune it the to run in low 12's in street trim thru the mufflers . Keep us posted on your progess.
I will be following closely as I plan on spinning mine to at least 6000.
Love that Dart!!
Click to expand...

Cool.

Is the Thumpr cam hydraulic roller?

Steve
 
Got it apart last night.

Here's what not to do. Don't have a problem like this, then put in an Autozone pushrod to see if you can get it on the trailer without pushing.

IT busted the ball off the end of the pushrod and jammed the lifter in the bore at full lift. Then the pushrod hammered on the lifter a bit, taking a bite out of it.

Fortunately, I quickly turned the thing off when it started making the nasty metal on metal noises, because it looks like it would have just gotten worse. Even MORE fortunately, I had a bunch of friends to push the car up on the trailer, and some other ones to help push it in the garage at my house.

IMG_1196.jpg


The lifter came out easy enough. Removed all the hold-down stuff and tapped it lightly with a hammer and it popped down. Lifter bore looks good. Cam looks good also.

My block has a battle scar from the pushrod ball...

IMG_1200.jpg


All of the other pushrods/lifters seem to be fine (going in the trash anyway).

Doing a leakdown tonight. Kind of dreading it, but really hope I'll find that the valves are not bent. Its hard to tell, but it looks like the valve stem tops are a little dis-similar height-wise. That's probably not good.
 
An air line with a blow gun into the spark plug hole will tell you if the seat is leaking air (meaning valve is bent). I really like the Smith Bros pushrods. The hyd roller ones are pretty short and it's a steep angle on them. I guess if Comp said the springs were ok they probably should be.. Can you remove one or two and test them?
 
I can pull a couple off and check them.

I think I'm going to upgrade regardless though, assuming the heads don't have to come off to have the spring seats machined or something. Hopefully the stock EQ/Iron RAM head is more upgradeable valve spring wise than the stock Magnum.

Steve
 
I dont believe they are. But you may find room to shim or that they are ok anyway.
 
Called Hughes today. They Iron Rams are not upgradeable without machining the seats. Hmm. Should have had that done when I initially bought them. Talked to Tim over there again today. He says that the springs I have should be fine for this cam, which matches what Comp says.

If the heads have to come off, I'll have them machined. If not, maybe I'll have to stick with what I've got, but I'll buy a new set if it rolls that way.

Either way I'm going to measure everything when I've got a couple of springs off. Maybe I'll get lucky and a shelf Comp beehive or something will fit.

Steve
 
Steve, as good as your car is running, if its just a pushrod issue, i'd replace them & leave it the way it is, i'm sure it'll hit 11.99, that is Damn good for such a mild combo.
 
Were the springs checked for bind and retainer to seal/valve guide clearance with the higher lift from the magnum rockers? When I see bent pushrods, that's just the first thing that comes to mind.

Hopefully there's no bent valves.

BTW, that motors running pretty darn good with that small a carb. Pat yourself on the back. :)
 
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