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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
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 Posted: Thu Feb 28, 2019 11:43 am Post subject: Re: Robbie is building another engine… |
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| cdennisg wrote: |
| Have not heard that theory before, but it does make some sense. Interesting. |
Colin mentioned it to me years ago as well, but I have never read it on here. Then again, me and my 28hp don't spend much time in the performance forum. 
Robbie
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telford dorr
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Joined: March 11, 2009
Posts: 3555
Location: San Diego (Encinitas)
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| Posted: Fri Mar 01, 2019 12:21 am Post subject: Re: Robbie is building another engine… |
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I've heard / seen it before. Old Chevy 283 with worn cylinders had a noticeable ridge at the cylinder tops. It got spun up pretty good one day and broke the top rings as they hit the ridge. Nothing is rigid; everything flexes - a little. Especially engines.
You better be getting more than 28 hp... (even at the wheels).
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'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
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| Posted: Fri Mar 01, 2019 12:29 am Post subject: Re: Robbie is building another engine… |
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| telford dorr wrote: |
| You better be getting more than 28 hp... (even at the wheels). |
When I did a 0-60 pull on the old engine, around 60k, I weighed my chassis and did some math. 28hp at the wheels in 2017. Now I can’t stop passing people and accelerating like your bus... it just zings up past 4k with little effort.
Idle is honestly where I feel most difference from the CW crank. If my radio is on, I can’t feel weather or not the engine is on.
DPR balances fans, so I’ll be heading there next month to get rid of the last little bit of vibration....
Robbie
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Abscate
Samba Member
Joined: October 05, 2014
Posts: 22670
Location: NYC/Upstate/ROW
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| Posted: Fri Mar 01, 2019 3:48 am Post subject: Re: Robbie is building another engine… |
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DPR Balance’s Fan’s and DPRK Un Balances them?
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telford dorr
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Joined: March 11, 2009
Posts: 3555
Location: San Diego (Encinitas)
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| Posted: Fri Mar 01, 2019 9:50 am Post subject: Re: Robbie is building another engine… |
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| asiab3 wrote: |
| DPR balances fans, so I’ll be heading there next month to get rid of the last little bit of vibration.... |
And that's VERY important, because the fan is now the main weak point! Spinning to 5K and beyond will eventually cause a non-welded and/or unbalanced fan to EXPLODE! What a mess that makes. Completely destroys the fan housing and flaps. (Ask me how I know...)
The second weak point is valve springs. The stock springs can't keep the lifters in constant contact with the cam at 5K (valve float), so they start slamming instead of smoothly setting the valves back on their seats. You know what happens to unhappy valves and lifters...
It's a slippery slope down the rabbit hole. You build an engine with a nice crank that really wants to spin. And it sound sooo nice doing it that it's hard to resist. But that brings up weaknesses. So you improve the fan. Then you add heavy duty valve springs so the valves don't float, but those need steel push rods that don't flex. But then you need solid spacers on the rocker shafts to keep the rockers centered up nicely from the load of the heavy duty springs, etc., etc... And down the rabbit hole you go. Each step is so easy, and so hard to resist... 
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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cdennisg
Samba Member
Joined: November 02, 2004
Posts: 20279
Location: Sandpoint, ID
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| Posted: Fri Mar 01, 2019 10:24 am Post subject: Re: Robbie is building another engine… |
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| telford dorr wrote: |
| And down the rabbit hole you go. Each step is so easy, and so hard to resist... |
An old friend taught me about that. We called it the "might as well" theory. If you are going to do this, you might as well do this... It is indeed a rabbit hole.
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notchboy
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Joined: April 27, 2002
Posts: 22463
Location: Escondido CA
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| Posted: Fri Mar 01, 2019 11:01 am Post subject: Re: Robbie is building another engine… |
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| TomWesty wrote: |
| I lost a perfectly good night of sleep watching you assemble that beast, I hope it runs a long time. |
Ha. I think I was up drinking that night. 
Ditto hope it keeps you pluggin along.
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| t3kg wrote: |
OK, this thread is over. You win. |
Jason "notchboy" Weigel
1964 1500 S
1964 T34 S Convertible
1977 Westfalia Camper pop-top |
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SGKent 
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Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Fri Mar 01, 2019 8:21 pm Post subject: Re: Robbie is building another engine… |
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Seems like the common rev limiter was about 5200 RPM. New stock springs will easily go there but not much more. MY 71 DP had hd single springs and original springs at various times in its life. It could turn 6,000 RPM for hours on end. That is why it would only last 40,000 miles between something starting to fail like studs pulling. Stock crank that had been balanced professionally. almost 500,000 miles on two cranks. First one the shims cut to the dowels one night running in deep water. I was always more worried about the mass of the lifters, pushrods and rocker arms causing issues. They are actually pretty rugged engines.
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
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| Posted: Tue Mar 26, 2019 12:09 pm Post subject: Re: Robbie is building another engine… |
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| telford dorr wrote: |
| It's a slippery slope down the rabbit hole. You build an engine with a nice crank that really wants to spin. And it sound sooo nice doing it that it's hard to resist. But that brings up weaknesses. So you improve the fan. Then you add heavy duty valve springs so the valves don't float, but those need steel push rods that don't flex. But then you need solid spacers on the rocker shafts to keep the rockers centered up nicely from the load of the heavy duty springs, etc., etc... And down the rabbit hole you go. Each step is so easy, and so hard to resist... |
It's ok, I get to ride in Brian's bug for my fix there. (Not kidding, I had to break-out my handheld tach when he did a 6,000 RPM pull on Coast Highway. I did not believe it.)
--
New engine went from ~350 miles to ~1400 miles this weekend on a trip to Phoenix. Consumed about 1/2 quart of oil in the last 800 miles since I topped off. Pretty good, especially considering its age and the Colorado Build's penchant for eating oil.
It likes an honest-to-goodness 65mph "Maximum/Cruising Speed" at 18mpg, and will get me 20-21mpg at 60mph with no drop in head temps(?) Retarding the timing 3° for kicks did nothing besides make the engine smoother at high RPM, so I left it there.
I borrowed a middle seat and we crammed seven sweaty dudes in for a weekend of baseball games all over Phoenix. We passed some cars but mostly hung out in the right lane.
I'm calling it broken in for now.
Robbie
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telford dorr
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Joined: March 11, 2009
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Location: San Diego (Encinitas)
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| Posted: Tue Mar 26, 2019 12:32 pm Post subject: Re: Robbie is building another engine… |
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| asiab3 wrote: |
| It likes an honest-to-goodness 65mph "Maximum/Cruising Speed" at 18mpg, and will get me 20-21mpg at 60mph with no drop in head temps(?) Retarding the timing 3° for kicks did nothing besides make the engine smoother at high RPM, so I left it there. |
What's that in RPM? (My speedo is very optimistic, but I have never fixed it because of the novelty of being able to cruse down the freeway at an "indicated" 80+...)
| Quote: |
New engine went from ~350 miles to ~1400 miles this weekend on a trip to Phoenix.
I'm calling it broken in for now. |
Concur.
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
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| Posted: Tue Mar 26, 2019 2:18 pm Post subject: Re: Robbie is building another engine… |
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Re: RPM
forgot to attach this:
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Clatter
Samba Member
Joined: September 24, 2003
Posts: 7551
Location: Santa Cruz
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| Posted: Tue Mar 26, 2019 8:29 pm Post subject: Re: Robbie is building another engine… |
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Well Awlright!!
I end up in the same boat;
A motor that has plenty of reasons to be pulled out and apart,
But none of them pressing,
And another here all built up ready to go save for an excuse to do so..!
Just like a counterweighted crank,
A dynamic balance job is a plus for any motor.
Kind of like Hoover oiling mods,
Or single springs,
Or solid shafts,
Or swivel feet,
Or a deep sump,
Or full-flow,
Or.. Or..
Down the rabbit hole we go...
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