Magnum Valiant- 91 octane
Dyno shop tested 318
- Thread starter Stroked408
- Start date
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@Stroked408 how do you like those mufflers?
cudajames- a loud car is cool for about the few minutes it's idling and acceleration, but after driving it 20-30 minutes on the freeway, not so much. Black Widow mufflers advertising says it increases horsepower with less drone. Let me tell you that there is definitely some drone. Not to mention that I have no padding or sound deadener under the carpet. The 3.0" exhaust turned down before the axle just brings that smell back into the car. In my neighborhood, I don't want to advertise every time I leave the house and come home. I don't mind a good rumbling exhaust but what I have now is a bit too much for around town. At the track it would be fine and wouldn't seem nearly as loud.
Well I got about one month's worth of fun driving, but after bringing it home from the dyno, it felt a little "off", ran just bit rough. After replacing cap & rotor, plugs, wires, header gaskets, intake gasket (oil leak), it started puffing smoke out the breather and exhaust. It wasn't the PCV system. Did a compression test and it showed me what I didn't want to see or believe. It got progressively worse each time I started it, to the point that it started to backfire bad. Didn't even drive it but a mile in February and March. Pulled the motor a couple of weeks ago and took it in to the machine shop. Blown head gasket, pushrod found it's way into the head and a spring retainer in the intake. My guess is that the person who put it together slapped in a new cam and lifters to an already worn engine without doing anything else. It wasn't so much an IF, as it was WHEN this was going to fail, the dyno pulls just sped up the process. There are already enough threads that ask "what should I do, build up a 318 stroker, 340 or 360/408". Knowing what it would cost to rebuild this 318 with a stroker kit or build the 1971 340 I had sitting around, I think I know which route I'm going with. I'll hold onto the block for now but will probably sell of the any of the good parts like the 273/318 heads.
gzig5
Well-Known Member
Sorry to see that. It sounded good when it was on the dyno. I'd keep that cam around for the 340.
For the exhaust, you might try adding a couple of 12" resonators before the mufflers, or after if you run it to the back. I have had good luck with Vibrant SS ones. They have a bottle style like I used or the ultra quiet version. Should knock down the amplitude and help with any drone.
Amazon.com : Vibrant Performance
For the exhaust, you might try adding a couple of 12" resonators before the mufflers, or after if you run it to the back. I have had good luck with Vibrant SS ones. They have a bottle style like I used or the ultra quiet version. Should knock down the amplitude and help with any drone.
Amazon.com : Vibrant Performance
Divenut
Well-Known Member
That seems like a solid build. Very nice numbers.
I would say run 2.5 pipe and some tailpipes.
LowDeck451
Well-Known Member
Nice Dart, that’s too bad. Maybe I missed something but you said a pushrod found its way into the head and a spring retainer in the intake. Is that a pushrod in the intake port? How?
I'm also completely baffled by this....how did you get a pushrod in the intake runner of the head?!?!? I've seen some weird stuff, but this is next level weird....
PRH
Well-Known Member
Pushrod in the intake port?? WTF??
I’ll be curious to hear what the answers to that are as well.
The head gasket failure is typical for when that happens with a SBM.
I’ll be curious to hear what the answers to that are as well.
The head gasket failure is typical for when that happens with a SBM.
TT5.9mag
Two atmospheres are better than one
How in the hell does a pushrod end up in an intake port? The only thing I can think of is someone dropped it down there during assembly. And replaced it when they couldn’t find it. Baffling
I had to ask the shop again, so clarifying a mistake, I thought it was a pushrod, just by seeing the top of it. It's a throttle return spring that fell inside the head, after taking the intake manifold off.
TT5.9mag
Two atmospheres are better than one
Ok that makes so much more sense. Funny it looks just like a cupped pushrod but once I zoom in it does in fact look like a spring. So at this point you have a blown head gasket.
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