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Should run better than this....
https://slantsix.org/forum/viewtopic.php?t=53109		 Page 4 of 4
Author:  DCFAB.US [ Fri Aug 23, 2013 8:18 pm ]
Post subject:  recurve link
I read a link that described plotting the timing in 200 rpm increments from low to around 3k... here? Anyone feel like they know what im talking about?
Author:  wjajr [ Sat Aug 24, 2013 4:42 am ]
Post subject: 
I do.

Here at top of Engine page listed under ‘Sticky’are several discussions on recurving, and step by step process undertaken to dial in a curve.
Author:  Aggressive Ted [ Sat Aug 24, 2013 10:00 am ]
Post subject: 
If you don't want to plot at 200 rpm it will speed things up by plotting at 500 rpm to start with. You will find a few places where smaller increments will be nice to know....
I plot up to 3,500 rpm to check for spring stretch and see if they are holding.

If you get the recurve right, you can spin both tires off the line/or stop light and have a very spunky truck.
Author:  ceej [ Sat Aug 24, 2013 3:32 pm ]
Post subject: 
It will be interesting to see at what RPM mechanical advance stops coming in.
On the Hooptie, the stock dizzy went to better than 3500 before all the mechanical was done. Be very careful about holding the engine at that high an RPM with no load for a prolonged period of time. The harmonic balancer is only marginally capable of deadening harmonics along the crank. Without a load, there can be unwanted consequences.

To truly deaden harmonics, the balancer would have to weigh a hundred pounds, and be mounted in the middle of the crankshaft! :lol: I'm exaggerating, but you get my drift. Don't hold it above 2500 for very long. The engine will build heat doing this sort of testing also.

That's my 2¢. I'm sure there will be people that disagree, but I don't toss rods, or tear up main bearings either.

CJ
Author:  DCFAB.US [ Sun Aug 25, 2013 6:49 pm ]
Post subject:  Found GOLD today at local Pull A Part (nashville)
Super Six distributor #3874876 with 9R and a brand new cap/rotor w/brass inserts! Putting it in tomorrow!
Author:  Sam Powell [ Mon Aug 26, 2013 5:18 am ]
Post subject: 
Quote:
It will be interesting to see at what RPM mechanical advance stops coming in.
On the Hooptie, the stock dizzy went to better than 3500 before all the mechanical was done. Be very careful about holding the engine at that high an RPM with no load for a prolonged period of time. The harmonic balancer is only marginally capable of deadening harmonics along the crank. Without a load, there can be unwanted consequences.

To truly deaden harmonics, the balancer would have to weigh a hundred pounds, and be mounted in the middle of the crankshaft! :lol: I'm exaggerating, but you get my drift. Don't hold it above 2500 for very long. The engine will build heat doing this sort of testing also.

That's my 2¢. I'm sure there will be people that disagree, but I don't toss rods, or tear up main bearings either.

CJ
Interesting. I think I agree with that. My engine shakes a bit when not under load, but is quite smooth when pulling down the road. I wonder why the load smooths things out?

Sam
Author:  DCFAB.US [ Mon Aug 26, 2013 7:40 pm ]
Post subject:  Wow!!
Super 6 dist. made a huge differnce in acceleration and smoothed everything out... Little sluggish right at first then whammo and again better at upper gear and mid RPM (65-70mph in 3rd gear) but still a little flat... should I go even lighter on initial spring and maybe even second spring? or play with can, its adjustable?
Author:  Aggressive Ted [ Tue Aug 27, 2013 10:37 am ]
Post subject: 
You can try a lighter primary spring an rotate the spring post outward to keep it snug.
Author:  DCFAB.US [ Sun Sep 29, 2013 11:15 am ]
Post subject:  Update...
...I put ZFR5N's in this AM, WOW what a difference in idle quality and smoothness throughout the RPM range! I had the standard over the counter NGK V Power UR4"s which are shorter by an HALF INCH (1/2")! Im settled in with two medium springs, 9R governor, 12 initial deg, WEBER DGES 38/38 145 Idles, 160 Mains, 165 Air Correctors.... VERDICT= Runs better than ever!
Thanks ALL who helped! Now to fix the oil leak...rear of oil pan or rear main...Ohhh boy!
Author:  DusterIdiot [ Sun Sep 29, 2013 1:20 pm ]
Post subject:  Fyi...
Quote:
...I put ZFR5N's in this AM, WOW what a difference in idle quality and smoothness throughout the RPM range! I had the standard over the counter NGK V Power UR4"s which are shorter by an HALF INCH (1/2")!
Here's where fun goes to nightmare in 2 seconds....

The ZFRN plug is meant for the pre-1975 Head where the sealing of the plug is at the shoulder (and in other engine heads uses the crush washer), the 1975-1987 heads use the tapered seat to seal the plug and combustion chamber...so if you put a set of ZFRN's in a late head this is what may need to happen:

1) Have a machinist spot face the head where the plugs seat so you know the shoulder will seal against a flat surface (the BL plug heads vary here since they don't seal at this point). I've mocked this up and the "pocket"
where the plugs go in need some massaging to fully clear the wider shoulder on the ZFRN.
2) The BL heads have less thread depth than the drool heads, so the ZRFN plug will protrude into the chamber a bit (if the engine is high compression the piston may tank the electrode due to a lot less deck height). If the mix goes lean it might burn the threads making the plugs hard to remove, also if they get carboned up a bit they may also not want to come out.

FYI.

-D.Idiot

P.S. There are no commercially available extended electrode tapered seat spark plugs for the 1975-1987 heads.

Cheers.
Author:  DCFAB.US [ Mon Sep 30, 2013 9:09 am ]
Post subject:  Ouch!
Well thanks for letting me down easy! There's always a catch... suppose ill try the same heat range in the tapered seat. :roll:

PS But thanks for the heads up!
Author:  DusterIdiot [ Mon Sep 30, 2013 10:54 am ]
Post subject:  Yep...
Sorry for the bad news.

I went through this previously when Dan had made the statement about non extended electrode plugs for the BL heads.

I found that there was a plug that fit the bill but is used in another style of engine not suitable for our use and that the cost per plug was not in our budget range. I had also bought other plugs that were tapered seat to see if they might fit the bill (i.e. the modern corvette engine uses a similar setup but the threaded section is about 1"-1 1/4" long and protruded too far into the chamber....)

I had started a work around for this application by modifying a couple of plug anti-fouling bushings from Dormann to act as a spacer with the tapered seat that can be threaded onto the ZFRN plug and make it act as a UR plug with the proper thread spacing and tapered seat. I mocked up the project but didn't complete it. Possibly this would be an easy low $$ item that CNC dude or a hobbiest can pick up as it would allow the use of the ZFRN plug in the BL head making it available to a large number of late head users.

-D.Idiot
Author:  DCFAB.US [ Mon Sep 30, 2013 2:53 pm ]
Post subject: 
Oddly enough the base diameter of the zfrn's is larger than the ur's and it actually seealed in some way. Upon removal i expected the crush washer to be destroyed but it was not. The urs are nickle also and had the same/similar heat range so ill report back when i get them installed. I have a set of ZFR5N's fer sale!
Author:  DusterIdiot [ Mon Sep 30, 2013 5:54 pm ]
Post subject:  Fyi...
Quote:
The urs are nickle also and had the same/similar heat range so ill report back when i get them installed.
Just remember when you change something (i.e. electrode length) that heat range may be close but is not a complete match.

Oddly on a tightly tuned hi-po slant I found that AC Delco R-45TS was in between NGK UR-4 and 5 in heat range...

-D.Idiot
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