Timing Question |
Post Reply |
Author | ||
GranTorinoSport
Admin Group Admin of "The Org" Joined: 20-May-2003 Location: Seattle Status: Offline Points: 2287 |
Post Options
Thanks(0)
Posted: 03-June-2015 at 3:26AM |
|
75 Sport, 521 engine, 600 cfm edelbrock carb, c-6, 2.75 rear
So I have been driving my Sport this week (it now has no interior, quite loud and annoying). As I had experienced in the past, I get a touch of knocking going up a hill on the way home from work. To be a little more specific, this is a BIG hill. It is very steep and straight (I do not have a grade for you, sorry), but let's say the 99 VW Bug has to be in 2nd gear (5-spd manual) and still struggles with it. Of course the Torino does not struggle with it, but it is working to get the 4700 lb carcass up the hill. So, the engine is not running fast (say 2500 RPM? My tach is non working with the new ignition system), but vacuum should be high because it is under sustained load. I am not going very fast (25 MPH max) either. Anyway, I have noticed some knocking when going up the hill. I wanted to get some timing recommendations, as I think I probably have an issue with vacuum or mechanical advance. Some facts: 1. Mallory Unilite Distributor, factory advance settings. 2. Edelbrock 600 cfm carb (yes, I know it is too small, it was sitting around at the time I needed a carb). It is pretty close to factory rod/jet combo, a little rich I think but AF ratio is pretty good although I have not checked in a while. 3. Here are the engine specs: |
||
Scott Eklund
Webmaster |
||
Nuggets
Senior Member Joined: 07-November-2014 Location: UK Status: Offline Points: 869 |
Post Options
Thanks(0)
|
|
521cu ?
And you're trying to feed it with 600? Waaaay too small Edited by Nuggets - 03-June-2015 at 4:01AM |
||
Barnaby
429 powered 73 Stripper.....no comfort, just noise! |
||
Nuggets
Senior Member Joined: 07-November-2014 Location: UK Status: Offline Points: 869 |
Post Options
Thanks(0)
|
|
I don't reckon its timing, I reckon its running too lean at rpm when under high load......
See if you can borrow an 800cfm carb as a minimum, I'm going to be using a 750cfm carb on my 440 and thats too small really.....ideally I need an 800 |
||
Barnaby
429 powered 73 Stripper.....no comfort, just noise! |
||
GranTorinoSport
Admin Group Admin of "The Org" Joined: 20-May-2003 Location: Seattle Status: Offline Points: 2287 |
Post Options
Thanks(0)
|
|
So I searched Mallory's website and found the distributor has 24 deg of mechanical advance at 3000-3200 RPM.
I had heard somewhere that heavier cars need their distributors recurved for advance? |
||
Scott Eklund
Webmaster |
||
mcford
Senior Member Joined: 31-May-2003 Location: Utica, Michigan Status: Offline Points: 2160 |
Post Options
Thanks(0)
|
|
WHATS YOUR TOTAL TIMING?
|
||
Mike
|
||
GranTorinoSport
Admin Group Admin of "The Org" Joined: 20-May-2003 Location: Seattle Status: Offline Points: 2287 |
Post Options
Thanks(0)
|
|
What can I say, I had it sitting around so I used it? Due to roof and other problems with the poor car (nothing related to powertrain, the thing runs great) I just never went back and did anything about it. I was thinking fuel injection, but at $2000+ I think I need to get the body fixed first to make it driveable... Then focus on such things. However, a larger carb is within a reasonable price range. I was thinking the Edelbrock AVS 800. I wanted to stay E-brock of course (I have all the tune rods and jets, and other stuff), and that is the biggest they have, plus it has adjustable secondaries. I just want to make sure I am not affecting low end driveability, but here is the estimated performance of the engine from the builder (CarsByCarl): The theoretical cfm at 4000 rpm actually exceeds the capability of the carb... |
||
Scott Eklund
Webmaster |
||
GranTorinoSport
Admin Group Admin of "The Org" Joined: 20-May-2003 Location: Seattle Status: Offline Points: 2287 |
Post Options
Thanks(0)
|
|
Unknown at this time. I believe I initially timed it at 10 BTDC last year. I guess that would make a total of 34 at or around 3000 rpm. Although I am a little fuzzy on the contribution of vacuum advance and when/how it is a factor. In the specific knocking instance I refer to, the engine is not running that fast, maybe 2500-3000 rpm. If my tach worked, I could give you a better number, but I will have to send it in for modification... |
||
Scott Eklund
Webmaster |
||
aquartlow
Senior Member Joined: 19-December-2011 Location: Summerfield, Fl Status: Offline Points: 2271 |
Post Options
Thanks(0)
|
|
My "small" 472 w/ Dove heads and 9.33 to 1 CR running a Comp Cam's 280 Magnum(not the best choice, but is was chosen MANY years ago-engine built in '92) installed 1.5 degrees advanced, it likes 18 degrees initial with 35 degrees total all in by 2800rpm. I know I had a recent issue with a Crane HI-6 and it would pop and sputter at around 3K rpm(this was happening while trying to tune a Holley 870 Avenger, which sucked as I was blaming the carb for my ignition issues). At 3K my wideband gave an AFR of 14.0 but since I was experiencing the pop/sputter, I went up on main jets, down on air bleeds and ended up really tuning my carb out of the "ballpark". After changing ignitions I was able to correctly tune the carb. Definitely go bigger on the carb size, 850 at least and try to stay with vacuum secondary(Holley 870, Holley 80531 or possibly Quick Fuel 880 VS). I believe you will find that raising initial timing at least to 16 BTDC while keeping the total between 32-36 will REALLY wake up that beast, I would think with only 10 degrees initial you would be seeing glowing header tubes with prolonged engine running above idle(1200-1500 rpm). Good luck. Todd
|
||
www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires. No matter how good she looks, somebody, somewhere, is tired of her sh*t. Beauty is skin deep, ugliness goes clear to the bone. |
||
Big Bird
Senior Member Joined: 25-August-2013 Location: New York Status: Offline Points: 4194 |
Post Options
Thanks(0)
|
|
Basically, you are "Lugging" the engine, lowish RPM, Heavy car, uphill... Your vacuum advance is going to be maxed out, even though the mechanical advance isn't going up much. You either need a smaller amount of vacuum advance, less initial timing, or more octane. Your carb shouldn't be leaned out at that RPM, (Ford used much smaller 2-bbl carbs on 390s, 400s, and 429s, all flow about 400 CFM max or less)
Oh, more gears in the rear (3.25 or 3.50) will help this as well.
|
||
"What we do in full frontal view, is more honest than your cleaned-up mind."
Randy 1979 T-Bird 2005 F-150 STX RCSB 4.6, 3.55 LSD How the Heck does a REGULAR CAB SHORTBED weigh over 5200 pounds? |
||
GranTorinoSport
Admin Group Admin of "The Org" Joined: 20-May-2003 Location: Seattle Status: Offline Points: 2287 |
Post Options
Thanks(0)
|
|
Won't the additional advance just make the knocking under heavy load worse?
|
||
Scott Eklund
Webmaster |
||
Big Bird
Senior Member Joined: 25-August-2013 Location: New York Status: Offline Points: 4194 |
Post Options
Thanks(0)
|
|
Don't ADD advance, reduce it. Are you hooked up to ported or manifold vacuum?
|
||
"What we do in full frontal view, is more honest than your cleaned-up mind."
Randy 1979 T-Bird 2005 F-150 STX RCSB 4.6, 3.55 LSD How the Heck does a REGULAR CAB SHORTBED weigh over 5200 pounds? |
||
GranTorinoSport
Admin Group Admin of "The Org" Joined: 20-May-2003 Location: Seattle Status: Offline Points: 2287 |
Post Options
Thanks(0)
|
|
ported advance on the carb
|
||
Scott Eklund
Webmaster |
||
aquartlow
Senior Member Joined: 19-December-2011 Location: Summerfield, Fl Status: Offline Points: 2271 |
Post Options
Thanks(0)
|
|
Have you run a timing light on your engine to find when the mechanical advance starts and how aggressive it is and/or at what rpm it gets to total amount of mechanical advance? 10 degrees of additional advance from the vacuum advance canister is "usually" a good place to start(but every vehicle is different), is the Mallory unit adjustable?
|
||
www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires. No matter how good she looks, somebody, somewhere, is tired of her sh*t. Beauty is skin deep, ugliness goes clear to the bone. |
||
Big Bird
Senior Member Joined: 25-August-2013 Location: New York Status: Offline Points: 4194 |
Post Options
Thanks(0)
|
|
I would start with less vacuum advance. This might even let you run a little more initial timing, which your engine should like.
To see how much advance you need to lose, retard the timing until you can get up your hill without problems, subtract your new initial from the original, and that's how much less vacuum advance you need. You can use a vacuum pump to see how much advance you currently have, and get one with less, or get an adjustable one and set it using a timing light and vacuum pump. This is the cheapest mechanical route, swapping the rear gears would be the expensive route, (but the most fun). 104+ or any other octane booster is a quick-fix. - BTW, the gas in your tank isn't months and months old, is it? Stale gas will give you a lower octane and ping under load.
|
||
"What we do in full frontal view, is more honest than your cleaned-up mind."
Randy 1979 T-Bird 2005 F-150 STX RCSB 4.6, 3.55 LSD How the Heck does a REGULAR CAB SHORTBED weigh over 5200 pounds? |
||
VorbottenO
Senior Member Joined: 22-March-2008 Location: Atlanta Status: Offline Points: 375 |
Post Options
Thanks(0)
|
|
The big blocks do like higher initial and sounds like you could benefit from dizzy recurve.
I am running a Unilite as well, bought the curve spring kit and set it up for a two step mechanical advance so that i had a faster initial climb. Felt like I added 50hp. The kit also includes keys to ser the total advance limit so you can use a higher initial timing. I.e initial set at 14 degrees + 22 more mech (vs factory 24)= 36 total. |
||
Eric
72GTS-Ncode (429-477ci) |
||
GranTorinoSport
Admin Group Admin of "The Org" Joined: 20-May-2003 Location: Seattle Status: Offline Points: 2287 |
Post Options
Thanks(0)
|
|
Eric, I think I have the kit around somewhere, I purchased it when I got the Mopar Performance electronic distributor kit for my Chrysler (the distro is also made by Mallory and uses some same parts). Specifically what springs and in what locations did you use? I think that would be a good first step for me, along with dialing down the vacuum advance. Hopefully this weekend I can bust out the timing light and do a little research. |
||
Scott Eklund
Webmaster |
||
GranTorinoSport
Admin Group Admin of "The Org" Joined: 20-May-2003 Location: Seattle Status: Offline Points: 2287 |
Post Options
Thanks(0)
|
|
So to answer a previous question, I do not actually know if the vacuum advance on a Mallory Unilite series 47 is adjustable or not? There is nothing I can find anywhere about it?
|
||
Scott Eklund
Webmaster |
||
Nuggets
Senior Member Joined: 07-November-2014 Location: UK Status: Offline Points: 869 |
Post Options
Thanks(0)
|
|
The AVS series of carbs is pretty good, I've used the 650 on my old 351c. VS wont make a difference to low end as the engine will still only draw through what it needs its how I could run a 500cfm edelbrock on my puny 215 rover v8 |
||
Barnaby
429 powered 73 Stripper.....no comfort, just noise! |
||
Big Bird
Senior Member Joined: 25-August-2013 Location: New York Status: Offline Points: 4194 |
Post Options
Thanks(0)
|
|
http://www.summitracing.com/parts/maa-29332Adjustable advance for Mallory 47 series. Your existing is probably adjustable as well. usually the adjustment is done with a small allen wrench that you put in to the vacuum port on the advance canister.
|
||
"What we do in full frontal view, is more honest than your cleaned-up mind."
Randy 1979 T-Bird 2005 F-150 STX RCSB 4.6, 3.55 LSD How the Heck does a REGULAR CAB SHORTBED weigh over 5200 pounds? |
||
Billy C
Senior Member Joined: 10-February-2010 Location: Pittsburgh, PA Status: Offline Points: 948 |
Post Options
Thanks(0)
|
|
Did we solve this problem yet? I know I'm late (really) to the party. Just going through and checking out what I've missed the past months.
|
||
-Billy Conturo
|
||
Joel H
Brand New Member Joined: 23-January-2018 Location: Seguin tx Status: Offline Points: 1 |
Post Options
Thanks(0)
|
|
I have a 429 that I need to time Can anyone tell me what the timing needs to be. It starts and runs. But it’s off and u can tell. It hesitates when u try to rev it up and the faster u go it is sluggish
|
||
aquartlow
Senior Member Joined: 19-December-2011 Location: Summerfield, Fl Status: Offline Points: 2271 |
Post Options
Thanks(0)
|
|
Welcome to the forum! What are some of the engine's specs? (like compression ratio, cam, induction and ignition). If stock, 10-12 degree BTDC is a good place to start with total advance around 34-36(some like more-lower compression ratio and some like less-efficient combustion chamber/higher compression ratio) while using 93 pump gas. If engine work has been done, did they degree-in the camshaft or at least use an early timing set('68-'71)? The '72-'87 429-460 timing sets retard the cam timing 8 degrees and no amount of ignition advance will "fix" this, but engine should still run decent. Could also be a carb issue but no sense in wasting your time tuning the carb and/or ignition if the engine's cam timing isn't what it should be. Try the basics first: like a compression test, plug and wire condition, good running carb and good distributor, confirm no intake or exhaust leaks, vacuum reading at idle and etc. Has it always hesitated/run "sluggish" or just started doing this?
|
||
www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires. No matter how good she looks, somebody, somewhere, is tired of her sh*t. Beauty is skin deep, ugliness goes clear to the bone. |
||
Post Reply | |
Tweet |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |