Low idle rpm Perkins 6.354na ?

[Pack Mule]

What are y’all setting your low idle RPM at for Perkins 6.354na?

 

[High Wire]

The manual I have says 625 rpm* with a note saying it varies with application. I think I'm set at 700 cold which drops to mid 600's when warm. Anything less than 1000 allowed for shifting by the Borg Warner manual.

 

[Ski in NC]

I set them around 600, but be cautious: If prop is big and heavy, engine can stall on a shift, especially going from fwd through neut and quickly into rev. If that happens (try it) set rpm a bit higher.

 

[Pack Mule]

Mine is running at 1000 with Borg Warner velvet drive. I just replaced injection pump. It’s always been running about 900 to 1000 even before the rebuilt injection pump. I’m going to check my linkage adjustment and make sure it’s traveling far enough.

My tach could be off also. The tach does jump around some. I have to give it a couple a taps and it settles in. It shifts fine but it also has an aqua drive coupling.

 

[Barking Sands]

Mine is around 650 measure with laser tach. No issues with idle or going in or out of gear. Although it resonates at the lowest rpm. I usually bump it up to around 800 to smooth it a bit.

 

[Pack Mule]

Thanks everyone. I’m going to check it out this weekend.

 

[High Wire]

900-1000 would be shifting pretty harsh but the engine would be super smooth. At 650 the Velvet Drive shifts like velvet, no kidding, and the engine is a little rough. I bump the speed up to about 800 while sitting in neutral at bridges and locks.
Very important to verify RPMs with a photo tach because alternator driven tachs used on the Perkins (or any other engine) can be way off.

 

[Pack Mule]

My tach must be off because the shift is super smooth and always has been. I just replaced the injection pump and I would think they preset the idle speed setting right for that pump. I’ll check it out this weekend.

 

[Ski in NC]

Can you borrow/buy/steal a phototach? Very helpful setting rpm.

If motor is on soft mounts, 600 can be smooth. If on stiff mounts, 650 might be better.

 

[Pack Mule]

Can you borrow/buy/steal a phototach? Very helpful setting rpm.

If motor is on soft mounts, 600 can be smooth. If on stiff mounts, 650 might be better.

Yes I’m gonna try to locate one this weekend. Boats moves at about 6.5 knots at my currently tach reading of 1800 rpm. I have a video of idle speed if someone wants to hear it. I can’t load it here because it’s not a you tube video.

 

[Pack Mule]

I think we have one of these at work . I know it’s old school , but should it do the same thing ?

 

[Ski in NC]

Should work ok.

 

[Pack Mule]

I couldn’t find a phototach anywhere in town . I slowed Rpm down to 700 based off my tach reading. It seems to be doing fine (not stalling out). Thanks for all the help.

 

[kapnd]

900-1000 would be shifting pretty harsh but the engine would be super smooth. At 650 the Velvet Drive shifts like velvet, no kidding, and the engine is a little rough. I bump the speed up to about 800 while sitting in neutral at bridges and locks.
Very important to verify RPMs with a photo tach because alternator driven tachs used on the Perkins (or any other engine) can be way off.[/QUOTE


A small prop will offer less resistance when gear is engaged, making it seem to engage more smoothly, while a large propeller engaged at the same idle speed will jolt.
Motor mounts transmit the “feel” of the shift to the seat of the pants, so choice and condition of them is a factor too.
Dittos on the idle setting, I like to be able to get down in the 600 range, but will bump up to 800 or so for smooth idle while waiting.

 

[FlyWright]

Here's what I bought for under $20 to calibrate my tachs.

https://www.amazon.com/AGPtek®-Prof...igital+laser+tachometer&qid=1599332165&sr=8-4

 

[Barking Sands]

Here's what I bought for under $20 to calibrate my tachs.

https://www.amazon.com/AGPtek®-Prof...igital+laser+tachometer&qid=1599332165&sr=8-4

I have the same one. Works great. I have my tachs now reading pretty close to accurate. They were probably 200-300 rpm off.