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Looking at Taller Gear Options
https://slantsix.org/forum/viewtopic.php?t=33286		 Page 2 of 2
Author:  wjajr [ Sat Jan 17, 2009 9:28 am ]
Post subject: 
Rock,

It is new vacuum gage, carb was rebuilt a few weeks ago, I taped vacuum at the center nipple, bottom of carburetor, labeled; "manifold vacuum".

At constant speed on flat ground she pulls 15 to 17 Hg of vacuum. I have sprayed a can of carb cleaner up & down, in and out, all over, looking for leaks, none to be found, unless the PCV valve is incorrect, I don't know what could be causing low readings other than an aggressive cam. Vacuum gage needle fluctuates aggressively below 650 rpm.

Valve lash has been adjusted within the last 200 miles +.002 over per Doc, which smoothed idle out, and compression is well with in spec. 125-140 psi with no adjacent cylinder more than 10 psi difference.

Timing steady at +12 with vacuum advance disconnected, and same at 1000 rpm connected. It works, no leaks.
Author:  Aggressive Ted [ Sat Jan 17, 2009 10:31 am ]
Post subject: 
Wjajr,

I am still running the stock converter, 18" vacuum out of gear, 16" in gear at 650 rpm with a slight lope. My timing is at 16 degrees initial and the valves are set loose, .012 and .022. hot. The feeler gauge slides easily. So I am erroring on the loose side for more seat time which smooths out the idle allot with the compression ratio that high. It also keeps it from pinging. My converter is very, very old and loose. It and the tranny are going to hit 400,000 miles in 4,000 miles, no leaks! The tranny shops that have driven my car say its locking at about 2000 rpm. So I drive it fast as I can to keep it locked since my cruise is at 2500 rpm, 60 mph. Back roads are 35 to 40 mph which is marginal and stop and go on the freeway is killer on mileage, but I make up for it when I can. At cruise (60 mph) it's in the "pocket" so to speak vacuum stays around 15 to 18". In that "pocket or sweet spot" I have allot of pedal freedom (wiggle room) and the vacuum doesn't change much.
Quote:
My questions are; what stall speed is your converter, and using SWAG** analyses what would be a good choice for my car?
The stall on mine is around 2000 so the tranny shop experts say from their driving tests, and I am guessing if you loosen up your valve train a little more, a 2500 rpm converter would be my pick. My buddy raced with a 2500 stall last year with a .528 lift cam and it was just right on the launches. He had pretty consistent 14 sec runs.
Author:  SV162 [ Sat Jan 17, 2009 8:39 pm ]
Post subject: 
wjajr
I wouldn't be worried about your vac readings, they are quite acceptable if you have a "hot" cam. My vac readings are 14" in N and 9" in gear because of my cam. Revs at idle are 950rpm in N and 750rpm in gear. It can idle lower but the engine trys to jump out of the engine bay :)
When my engine was first built I was using the standard converter and it was terrible. If it idled in gear I needed to press very hard on the brake otherwise the car would lurch forward with the rise and fall of the revs. No matter what I set the idle at it wouldn't idle higher than 650rpm in gear. I could set the idle in N to about 1500rpm then put it in gear and it would drop straight back to 650rpm. So the higher stall converter went in and problem solved. I went for a 2500rpm converter which works very well, sure a 3000rpm one would be quicker off the line but 2500 is very streetable. Especially with a 2.92 rear end.
See the link in my sig for my cam specs.
Author:  wjajr [ Sun Jan 18, 2009 5:40 am ]
Post subject: 
SV162
Quote:
When my engine was first built I was using the standard converter and it was terrible. If it idled in gear I needed to press very hard on the brake otherwise the car would lurch forward with the rise and fall of the revs.


Thanks SV162, that is what is going on with my set up. She is a beast, chomping at the bit, when on high idle, or any rpm over 1200 or so when stopped in traffic, or an intersection.

Perhaps I have a cam more on the hot side of cam land, and all this frigging around to get a higher vacuum readings has been a tail chase. Since rebuilding the carburetor, and replacing a badly ripped secondary diaphragm the vacuum readings have improved, and idle has smoothed out a bit.

This car has been a magical mystery tour since the first night's DOA at my house. I think the owner of 14 years that did the big rebuild, and all the hot roding must have had a nicely tuned set up. However, the 4 short time (flip) owners previous to my taking ownership did a bit of fiddling around that has need to be unraveled. With your example I think I'm getting close to a smooth & strong running car once a proper rated torque converter is installed.

Do you have duel exhaust, and any idea what kind of horse power & torque output you have with that very nice car of yours?
Author:  rock [ Sun Jan 18, 2009 3:37 pm ]
Post subject:  Hi wj, re cam and idle again
Hi Wj,

I responded as I did about vacuum when seeing your "This car likes to idle in "N" with steady vacuum of 13 Hg. at about 1000 rpm, in "First" with 8 Hg. at about 800+ rpm".....but indeed if you are running 15 -17 on road, that is a different matter. I use a 270 cam and solid lifters and my vac is between 16 and 18 when cruising. WOT drops to 10 down to 5. I run the 8007 also and it took a lot of time rejetting and recurving the dizzy to get the vacuum where it is now, most likely because of the cam.

As Ted does I run 16 degrees initial advance. It may well be you have done what you can re. vacuum until you do more recurving...and my lockup 2500 converter is a great match for what I run. To me it was easier to change jets and timing than the convertor...but if you change it I bet you will begin to get the performance you want, assuming you have a lockup tranny of course. Once it is in then you can recurve and rejet easily, of course.

rock
'64d100
Author:  Rug_Trucker [ Sun Jan 18, 2009 4:36 pm ]
Post subject:  Re: Hi wj, re cam and idle again
Quote:
I use a 270 cam and solid lifters and my vac is between 16 and 18 when cruising. WOT drops to 10 down to 5.
'64d100

I would think your vacuum needs to drop between 1-0" at WOT.
Author:  SV162 [ Sun Jan 18, 2009 6:13 pm ]
Post subject:  Re: Hi wj, re cam and idle again
Quote:
I would think your vacuum needs to drop between 1-0" at WOT.
That's what I was thinking.
Quote:
Do you have duel exhaust, and any idea what kind of horse power & torque output you have with that very nice car of yours?
No I don't have dual exhaust, just a single 2 1/4" running off the back of a set of mandrel bent headers.
I've never had the car on a dyno so I don't know the exact HP output. Putting my 1/4 mile times and speeds etc. into those online HP calculators it gives me somewhere between 160 and 175 HP at the wheels, depending on which calculator I use. I don't put much faith in some of those calculators. :?
Author:  wjajr [ Mon Jan 19, 2009 5:46 am ]
Post subject: 
SV162:
Quote:
Quote:
Rug_Trucker wrote:
I would think your vacuum needs to drop between 1-0" at WOT.
That's what I was thinking.
That is the what I also get; 1-0" @ WOT. At cruse she dips very easily to 7 - 8 Hg with a part throttle acceleration.

I installed a 3.5 power valve, and have, well, I can't find the jetting size, crap!... I don't want to take that thing apart a third time, Jezzzemrice. I kept the jets that were in the carb for what that bit of info is worth. Also have lightest vacuum secondary diaphragm spring installed, yup, I up graded to the quick spring change cover. Additionally vacuum advance is 7R, Governor 11R with Short red, and long black spring so I'm not getting a ton of advance. No pinging ever.

Only driven the car a mile since the second power valve install. Test drives are on hold around here for a few months until the roads become devoid of salt, sand, and melt water. In last 24 hours we got 18 inches dumped on us, and more to come today.
Author:  Rug_Trucker [ Mon Jan 19, 2009 8:52 am ]
Post subject: 
If you aren't getting 1-0 at WOT then the secondaries aren't opening all the way.
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