71 Duster 360 turbo build

-
subcom said:
What are the symptoms of valve float? Does it happen under any amount of boost or only when you get up into the higher PSIs? Is this with the exhaust wide open? I noticed in my back pressure tests that my RPM was hitting a 5800-5900 ceiling when running through the muffler.
Click to expand...

Under boost on a pull it will rev to 6000, but not beyond no matter the boost level. It does make a breaking up noise, but not popping. AFR appears about normal and timing looks good. I closed the plug gap from 30 to 22 with no change.



Driving the car slowly increasing rpm(no boost) causes it to break up at 5800. It almost sounds like the valves are hitting the pistons for that fraction of a second, but I’ve noticed no repercussions; compression check still good.

Spring pressures before install were 130 on the seat and around 330 open(.600). Advertised as 145 and 360 open(no height given).


White is rpm. 6k flatline
IMG_2291.jpeg
 
Last edited:
Oregon camshaft did not have a valve spring recommendation for me. He just said he wouldn’t run more than I already have. Another shop I spoke with stated they typically run 170-420 with magnum lifters. I’m running Elgin HL-2269s lifters where are supposed to be a slow leak down type. I have 2.5 turns of preload on them which I’ve seen recommended for factory lifters. It was suggested that I try 1/4 turn preload since they’re slow leak down. Maybe I’m experience pump up?
 
Last edited:
Something does not seem right there. My iron headed 318 Magnum (stock cracked heads) with a Comp 20-746-9 HR cam (.506" lift), Magnum Swap valve springs, HD MP lifters and stock rockers will pull well past 7K under 20 psi of boost on E85 (and 18°of timing). I have an MSD Programmable box and a HVIC coil going thru an MP distributor, 8MM wires to NGK -7 plugs gapped at .045". I finally experienced blowing out the spark at 26 psi. My engine NA will not rev over 6K. I think it may be lifter pump up.
 
Is this Megasquirt? It’s not the rev limiter or AFR safety system kicking in at 6k?
 
Microsquirt. Rev limiter set at 6500rpm, and I do not believe I even have any AFR safety’s available.
 
Landy Duster said:
Something does not seem right there. My iron headed 318 Magnum (stock cracked heads) with a Comp 20-746-9 HR cam (.506" lift), Magnum Swap valve springs, HD MP lifters and stock rockers will pull well past 7K under 20 psi of boost on E85 (and 18°of timing). I have an MSD Programmable box and a HVIC coil going thru an MP distributor, 8MM wires to NGK -7 plugs gapped at .045". I finally experienced blowing out the spark at 26 psi. My engine NA will not rev over 6K. I think it may be lifter pump up.
Click to expand...
Mopar HD hydraulic roller lifters? How much preload?

The lifters I’m running are the stiffest I’ve ever dealt with. Before I adjust the rockers I have to slowly turn the engine over and let it sit at high lift spots so that the lifter will bleed down over a couple minutes.
 
Yes sir, Mopar Magnum HD roller lifters, I bought the last set in the US, slightly bigger shaft harder roller. Whatever preload the have with the thinner Cometic head gaskets and stock pushrods & rockers. Probably around .100". They creak when they bleed down and it takes a few minutes before they stop making noise. I would refurb a set of stock lifters (disassemble, inspect, clean, and reassemble) and use them.
 
What are your valve spring pressures? What’s the cam look like? I have confidence in my lifters. At least more in them than my valve springs at the moment. I’ve never had a small block that could turn more than 6k rpm so there is a significant possibility I’m doing something very wrong.
 
I have no clue what the spring pressures are, but I do plan on putting new springs and retainers on. These springs have about 100 passes on them and have been over 7k about 10 times, but usually gets shifted at 6600-6700. The cam looks fine. NA I don't think this cam would turn much over 6k.
 
Half way through valve spring replacement, and I have to say I’m glad I’m going through the valvetrain. The Speedmaster valve locks are in rough condition. Possibly because I was floating valves, but the majority I’ve removed are chewed up. The intake springs were all shimmed with 4 x .020 shims; 2 x .020 shims on the exhaust. Retainers and valves look fine. I’ll be sending the heads out for new valves this summer, and hope everything holds together for a couple races before then.

I’m also hoping to replace the lifter retainer wire clips with internal snap rings while I have it apart. If I can find them in time.
 
Engine is all back together and sitting for the summer until the heat dies off a bit. After months of debating I decided to order or build a Dana 60. The 8 3/4 might have handled the power just fine, but it’s the last “weak” link in my drivetrain so it’s going up for sale. I’m also looking to buy some ID1000 injectors to ensure my pistons stay the same shape. The uncapped ford injectors are definitely flowing well (scaled at 960), but guessing they all flow the same is a poor decision. This thing will make it to the drag strip…eventually.
 
Last edited:
turbovan said:
Microsquirt. Rev limiter set at 6500rpm, and I do not believe I even have any AFR safety’s available.
Click to expand...
are you sure your tach or what ever you are using it to read rpm is not off 500 rpm. I mean you could be hitting your 6500 rev limiter but its showing you are only revving it to 6000. have you tried setting the revlimter to 7000 and see what it revs to? I could be way off base here. but its just a thought.
 
turbovan said:
Engine is all back together and sitting for the summer until the heat dies off a bit. After months of debating I decided to order or build a Dana 60. The 8 3/4 might have handled the power just fine, but it’s the last “weak” link in my drivetrain so it’s going up for sale. I’m also looking to buy some ID1000 injectors to ensure my pistons stay the same shape. The uncapped ford injectors are definitely flowing well (scaled at 960), but guessing they all flow the same is a poor decision. This thing will make it to the drag strip…eventually.
Click to expand...
Have you considered a Ford 9”? That would be my choice if I was to replace my setup.
 
subcom said:
Have you considered a Ford 9”? That would be my choice if I was to replace my setup.
Click to expand...
I did in fact end up ordering a 9” from speedway. Parts started arriving today! I also came upon your thread regarding axle centerline to yoke difference for the 8 3/4 and ford 9”. I’ll throw an update in there for future users once I measure them side by side. I see 1” longer yokes available for the 9” so I’m hopeful that will be just enough to retain my Strange driveshaft.
 
turbovan said:
I did in fact end up ordering a 9” from speedway. Parts started arriving today! I also came upon your thread regarding axle centerline to yoke difference for the 8 3/4 and ford 9”. I’ll throw an update in there for future users once I measure them side by side. I see 1” longer yokes available for the 9” so I’m hopeful that will be just enough to retain my Strange driveshaft.
Click to expand...
Nice! I remember considering the Speedway 9” also. They had a good selection and price. Good call!
 
Finished the 9” rear end install with disc brakes. The 1” longer yoke did allow me to use the same driveshaft from my 8 3/4 so I was glad that worked out! Also installed sway bars front and rear.

Pulled the front end off so that I could make a little change. Finally “cooling” off here in Phoenix so I hope to be back on the road soon.

IMG_3340.jpeg


IMG_3344.jpeg
 
Last edited:
Picked up two dodge darts from Oregon over the summer. The black one is just a roller pieced together from ‘70-‘74 cars. The grey is a 318 swinger that runs and moves, but needs plenty of work. The black front end is going on my duster. With an extra 6+ inches in front of the radiator I’ll likely be installing an air/water heat exchanger…eventually.

Not sure what’s happening with the grey car yet. My 14yo son has to decide if he wants that, or the orange /6 ‘71 duster I bought for $100 in 2003. I’d love to turbo that slant, but the decision is his!

IMG_3082.jpeg


IMG_1033.jpeg
 
I had to modify the exhaust crossover so the front sway bar would fit. Once that was done I fired the motor for the first time since installing the new valve springs. I let it warm up and gave it a couple free revs. It hit the 6500 limiter so I’m hopeful that my rev issue is solved, but time will tell. I also removed the external oiling to my heads as it was planned before I knew pushrod oiling would be an option. It appears that was my low pressure issue. With oil temp at 190 I still had 30psi at idle.

IMG_3415.jpeg
 
It seems dart fenders are slightly tighter than the duster’s. Wheel fitment is incredibly flush. I’ve found zero rub even on the bump stops, but I’ll probably roll the fenders for good measure. The car should be back on the road next week.

IMG_3411.jpeg


IMG_3418.jpeg


IMG_3420.jpeg
 
looks like it’s time to wire up my second fuel pump. I’m using a knockoff aem 400

IMG_3845.jpeg


IMG_0597.jpeg
 
turbovan said:
looks like it’s time to wire up my second fuel pump. I’m using a knockoff aem 400

View attachment 1716314804

View attachment 1716314817
Click to expand...
Ok wow, 17psi of boost?! That must be boiling the tires. What injectors are these, still the uncapped Fords?
How’s fuel pressure look? How are you getting E50, mixing your own? I run basically the same pump setup. You should have plenty of headroom with both wired up. I kick my 2nd one on at >70% TPS.
 
subcom said:
Ok wow, 17psi of boost?! That must be boiling the tires. What injectors are these, still the uncapped Fords?
How’s fuel pressure look? How are you getting E50, mixing your own? I run basically the same pump setup. You should have plenty of headroom with both wired up. I kick my 2nd one on at >70% TPS.
Click to expand...
Still the uncapped fords. Not sure what fuel pressure was. I have a gauge, but it’s not been very reliable. I may have one more input available to log pressure. Looking into that now. I didn’t realize you were turning on a second pump, or that I would need one.
I have found the flex fuel function to be great with the microsquirt. I’ve run anywhere from straight 91oct to e85, and AFR stays right where it should. I do aim to mix right around 50% so fuel demand stays a little lower.
 
Last edited:
I have some re-tuning to do, but the second fuel pump did the trick. I don’t think AFR reads below 9.8, and it was definitely drowning in fuel this run.

Traction has been great(above 70)! Lol
Some decent feathering on the tires which have maybe 200 miles on them. Knowing little about tires…is this okay? Lowered tire pressure from 22 to 18psi after this picture. I have a MT ET street R setup sitting in my summit basket. Just waiting on the right beer to press the button. I still think I should prioritize a nice set of injectors…

IMG_3849.jpeg


IMG_3847.jpeg
 
Last edited:
You must log in or register to reply here.
-

Back
Top