Vintage Mustang Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
2,176 Posts
Discussion Starter #1
I decided to install heavier springs in my Duraspark distributor to slow down the advance, To make
a long story short the problem got alot worse. The car really pings..I thought I had the lightest springs
in the crane advace kit, turns out I was just one step lighter the stock. (all advance in by 3800).
I have read about other setups, they always say to get all the advance in early before it pings. This
kinda goes against what my thinking is. Any thoughts.

1966 Mustang Coupe, 302 custom roller cam, holley 650dp,http://www.289mustang.com
http://www.289mustang.com/images/vmfcar.jpg
 

·
Registered
Joined
·
1,669 Posts
I've been chasing the same problem in the Hi-Po for longer than I care to admit. Its been rebuilt to factory specs, not withstanding a 0.030 overbore, 0.010 true cut on the block and 0.014 off the heads to get rid of some pitting. Heavier distributor springs, retarded the static timing 2 degrees (anything more and it begins to get unhappy), 93 octane fuel, octane boost additive, etc., etc. Next on my list is a power valve that open at 10.5 inches of vacumm. No clue what the rating was of the valve that was in the generic rebuild kit. Ford manual speakes to color coded power valves but makes no mention of what that translates to in terms of opening vacumm rating. So far, everything has made some difference, but the total answer still alludes me. Maybe some 104 octane will do the trick.

If you find a cure for yours, pass it on please. I'm still searching

65 Hi-Po F/B (7 yr resto)
67 GTA F/B (small block) Mustang Owners Club of Austin (MOCA), TX
MCA 27479
http://albums.photopoint.com/j/View?u=1575609&a=11978710&p=43914197.jpg
 

·
Registered
Joined
·
2,176 Posts
Discussion Starter #3
To be honest I don't know the opening value on my power valves. I have a custom carb (so I wouldn't have these problems) My idle vaccum is about 8-9 inches. I'm gonna try the lighter springs just to make sure. I'm also going to call the guy who did my cam specs. He has alot of knowlege about these engine.

1966 Mustang Coupe, 302 custom roller cam, holley 650dp,http://www.289mustang.com
http://www.289mustang.com/images/vmfcar.jpg
 

·
Gone but never forgetten
Joined
·
25,239 Posts
There's 2 pieces to the puzzle on the mechanical advance: TOTAL advance, and HOW SOON you reach it. Performance tuners will say to try to get total advance by 2500-3000 RPMs, so if you don't have total advance until 3800, I would say that's not your problem. The question is what is your total advance?

Check out FordMuslce.com's article on it ... it's a great article:
http://www.fordmuscle.com/archives/2000/03/timing/index.shtml

If you always do what you've always done,
You'll always get what you've always got

http://www.classic-mustang.net/johnpro
 

·
Registered
Joined
·
10,587 Posts
Isn't tuning fun?

Too bad you don't have some pyrometer ports in the header tubes...it would be interesting to see what the changes are doing to your exhaust temps...

I'm with you on the advance....the earlier the plug fires, the more opportunity for a rogue flame front to develop if there are hot spots in the combustion chamber...I've never heard of an engine pinging because it didn't have enough advance...
Could be the fast ramp rates on the roller cam have something to do with it....higher cylinder pressures at a lower rpm, where, under load, detonation is easier to initiate...

Last 302 in the race car had 15 degrees of advance to start and 34 degrees running...I had two pickups on the crank trigger and could switch between them....no advance curve at all....once the engine was running, it had 34 degrees no matter what the rpm...
That was the stock headed 11.20 engine....running on race gas..

Another experiment to try is to get 5 gallons of 112 octane racing fuel and try a 10% mix... 1 gallon race gas to 10 gallons 92 octane...just to see what happens and compare performance...

IIRC, this isn't your daily driver, yes?

Keep us posted and don't give up yet!! *G*

Pat
http://albums.photopoint.com/j/View?u=1570936&a=11937754&p=42910787.jpg
 

·
Registered
Joined
·
2,176 Posts
Discussion Starter #6
I''ve changed the timing a few times, right now I'm at 15 initial with 35 total. I have to change the distributor curve back tonight. I may try some octane booster or race gas!

1966 Mustang Coupe, 302 custom roller cam, holley 650dp,http://www.289mustang.com
http://www.289mustang.com/images/vmfcar.jpg
 

·
Registered
Joined
·
1,667 Posts
I posted my response in the old post before I saw this so I guess I will just briefly repeat it here. I had the same problem with my 429 car which came with 10.5:1 compression from the factory. After I bored it .030 over it would clatter like what you are describing when I romped it. I tried all sorts of combinations of timing and advance springs but it didn't help. I had to run lead additive or octane booster in it.

I think you just have too much compression for pump 93 octane at this point even with the help of the aluminum heads. Retarding your timing will help but then your motor will be way down on power. My big block didn't slow down so much because it was a torque monster to start with but a small block with a big cam likes lots of timing to run good.

My 289 runs best at 18 and 38 degrees timing. All my timing is in by 2500. A small block that wraps up fast needs to advance quicker. If I run my initial much lower than that it will catch my carb on fire from the spit back.



You can see my 65 fastback at: http://hottarod.stangnet.com/
http://members.aol.com/macstang/Gifs/macstang3.jpg
 

·
Registered
Joined
·
2,176 Posts
Discussion Starter #8
I spoke with Ed Curtis at FTI (he did my cam). He suggested a faster power valve, I'm not really sure what a faster power valve is. I'm guessing that is squirts gas sooner, closer to your normal running vacuum?
He said to make my timing curve more gradual, I have a 10L and a 15L (using the 10L) weight in my distributor, sounds like a need a 12L, can you get these? I'm getting more confused as I go. I would take the car to a shop except most of the shops in my area are not up to the task of tuning a HP engine.

1966 Mustang Coupe, 302 custom roller cam, holley 650dp,http://www.289mustang.com
http://www.289mustang.com/images/vmfcar.jpg
 

·
Registered
Joined
·
3,848 Posts
I haven't worked on Holleys for awhile, but there should be a number on the power valve somewhere. The valve is activated by vacuum. If you have a #8 power valve it will be activated when engine vacuum reaches 8 in Hg.

65 FB "J" 302 lots of mods. 94 GT K&N only.
http://albums.photopoint.com/j/view?u=1590489&a=12113030&p=43871256.jpg
 
G

·
Guest
Joined
·
0 Posts
Your compression ratio must be sky high! Yikes! I'm not surprized that it wants to ping. Every time you rebuild you
are adding compression! Not to mention you shaved the
head and block and low cc head.....

Adam


'73 Stang 351W Lightning specs
'72 Stang
'65 Ford F-1
'91 Civic SI
 

·
Registered
Joined
·
2,176 Posts
Discussion Starter #11
The engine is a new Ford Motorsports shortblock, with 54cc heads. The compression should be a little les then 10-1. My
previous engine was a 289 with well over 10-1, it never pinged. I don't think compression is a big issue.

1966 Mustang Coupe, 302 custom roller cam, holley 650dp,http://www.289mustang.com
http://www.289mustang.com/images/vmfcar.jpg
 
1 - 11 of 11 Posts
Top