[73LeMans]

So I fired up the motor the other day for the first time, and I tried to time it, but the line on the balancer is bouncing all over the place. I'm not sure why. Any ideas? Let me tell you what I believe to be true, and then you can tell me what I'm overlooking?

• The balancer is a Fluiddamper. It slips on tight, and the key ways are not loose.

• The HEI distributor has been recurved by Larry Rowe and has new bronze distributor gear. The coil is about 3 years old. The cap is about the same. MSD does all of the real work in the dist and there is no module.

• Plug wires are 8mm Taylors in great condition. 3 years old. (less than 500 miles)

• The timing chain is old in age, (6 years) but can’t have but 500 miles on it. It’s a Comp Cam double roller. Been on and off the motor 5 times or so. Installed can straight up.

•The cam is a brand new Comp Cam solid roller. The engine fired right up when we initially started it so I don't think it’s the cam due to lobe/gear/wear, but I never checked the end play on the cam and I also don't have anything spacing out the cam where the fuel pump eccentric used to be. You think this could be it? I never ran the fuel pump eccentric with the old hydraulic Comp cam and never had this problem.

Someone I had spoken to claims the flexplate might be out of round and causing crank vibrations up to the cam… I don't buy it, but I haven’t seen everything…possible? The flexplate is a stock Pontiac one with the 3 holes for the converter slightly enlarged to 7/16ths. (up maybe a 16th from the original hole) Drilled it myself. Could be out of round, but wouldn’t that cause an erratic idle more than it would cause spark timing to be flaky?

I think I covered everything it could be…any thoughts?

Oh yeah…the timing gun is a relatively new Sears dial back gun. Works fine on others cars.

If you think of something, let me know. I’ll be checking back when I get the chance.


Thanks in advance.

Who needs nice and pretty, when you can have mean and nasty? 73 LeMans: 12.5 in the 1/4 on its way to 10.90's!

[Ken MacNicol]

Why does a dial type timing light not work with MSD? Mine seams to work just fine.

[Lerry: The Body Ventura..]

Too much slop in the gear end play will make it jump. It should be shimmed in the neighborhood of .010 to .020...

[Sun Tuned]

Head#96,
Not really any damaging effects from the dist advancing too soon. I mean that the motor won't be condemned by it and scatter pieces all over the neighbors yard. Performance, will be hampered. How much? Depends on how bad off it is. The main thing that you'll have a problem with is trying to set the mixture and idle speed on the thing, if the advance starts too early. No consistency in the mixture screws, idle speed, or both. The rest of the tuning parameters are affected by this.

Most guys that set up their distributors and even some of the so called "pros" will get so worked up over trying to get the thing "in by" a specific number rpm. That's a novel idea and really what your trying to do, but alot of people pro/nonpro severely blow it when it comes to the question I always like to ask...."Yes, but where does it start??" See, the springs that are commercially available are just as much to blame for this as anything. Most suck. You get into a situation where you jack with the thing long enough to get the curve in by say 3800, but the thing starts at 1200. Then you change up a spring or two and now the thing comes in by 3000, but now the blasted thing starts way down low like say 450. Scrap all that and try the 2 lightest springs most of these kits come with and now it starts at 450 and now it's in by 2000. ??????? You end up wanting to take a hammer and beat the whole damn car into some very small pieces, or you have to settle for what you get. Well, that is the exact reason I spent alot of time 5 mins across town worrying the blue hell out of the man what runs a spring company here. I have him make mine. Matched to the job I'm doing with them, not thrown in a box like 99% of these aftermarket kits as an afterthought. Sure they cost like hell cause I'm not buying them 4 million at a time and my last name isn't Hrudka, but they work for me. You can tweak some of these aftermarket springs. Bend on em, stretch em, etc. The main thing is to watch where the curve starts... just as important as where it ends in my opinion.

I think the spring, in my opinion, needs to be as stiff as possible. WHAT! Thats right, stiff. See the way I see it the stiffer the better, as long as the spring allows you to reach the selected range your trying to run your curve in. You will have less timing problems due to spring fatigue that way. These light hair thin jobs look cool but they woefully suck after a few good heat cycles, changing the curve specs from what they were originally set up for. People distributor springs around here get just as much attention as a set of valvesprings. Why not they are just as important. You want a spring that positively holds the weights on that advance cam lobe at idle in one spot and only in that spot till they are supposed to move from that spot. Then they need to allow the weights to follow the curvature of that cam lobe just as closely as you want the lifters in the valvetrain to follow the camshaft lobe itself. And just as sure as a set of cheap lightweight valvesprings will allow valvetrain problems, will a set of hair thin distributor springs cause an ignition problem. Without enough tension the weights will not return accurately to the at rest spot when needed either.

You really wanted the short version now...didn't you.

[FirebirdDave]

OK we pulled down the fron of the engine last night. The original thrust plate did hav a 30 thousanths to 40 thousanths space between it and the block. I replace the plate. I'll have to check to see which hole the excentric was in.I hope that I have found the smoking gun. As I said before the chain and gears are new and sure enough thye are fine. I have both type timing lights and have the same problem with both. I wish I could have the car back together this week so I could post my results from the repair, but Im several weeks away from driving the car.

69Firebird roundport/roller455
70Catalina 455
72Skylark Buick 455
89 Iroc 305 stock 192RWHP/263RWTQ
I cant leave anything alone.

[Larry Navarro]

If the balancer is degreed, use a regular timing light.

1973 SD455 T/A
1979 S.E. T/A
http://community.webshots.com/album/16587603rOyvmFCiHs

[head #96]

Suntuned, Thank you very much for your detailed response. I think I'm understanding this better now.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> You end up wanting to take a hammer and beat the whole damn car into some very small pieces <HR></BLOCKQUOTE>

yea your not kidding!

So is there a way I could purchase an assortment of your Holy Grail advance springs for some $$$? Thanks

Building a fast stock appearing street car.
homepage http://home.mchsi.com/~vroman6

[tikiklubracing]

A dialback timing light and multiple discharge spark systems won't work together.

BIGGERISBETTER-78 Catalina, 3650#, 13.750, 400 .060, 6x8, 4150-4779 Holley. 15 yrs in NHRA tech ret.

[62tempest]

CHECK YOUR BRONZE GEAR WEAR, MINE BOUNCED ALL OVER WHEN THE GEAR GOT WORN.

[Ray Cox]

MSD systems tend to screw up most timing lights you need to try the cheap ones, it seams silly but the cheep ones work better. the best ones are battery operated it helps reduce the interferance most of the real fast cars use the one from flaming river there about 45.00 no cords to connect either just hook it to a plug wire. the light itself runs on d batteries which is nice if your battery is in the trunk. also has a 2nd button on it to operate like a flash light which is handy to point it at the ballancer and find your timing marks before you start the car. well worth the investment!

T-Shirts For Sale "Dude Free In 2003"
8.90 @157 mph 3424 LBS. 77 Trans Am All Steel, on 10" tires

[FirebirdDave]

I am all over this problem. We built a 455 with a xR288 comp cam and it wont time. I have tried 3 different distributors, all HEI, 2 stock modules, 1 MSD module,2 coils, 2 distributor caps, 2 rotor buttons,3 different pick up coils, 2 different distributor gears, the engine had a brand new balancer, timming chain and gear set, I use an electric pump but I DID install the fuel pump excentric. I tried hot wiring the distributor to the battery directly. Nothing worked. The only thing that I think it can be is a bad thrust plate. I bought a grade 8 plate from Spotts and plan to install it tonight. I also had increadibly fast wear on my first bronze hear, 2800 miles. When the new one goes in another 1500 miles I plan to install the carbon fiber unit from BOP. This has been a nightmare. The wierd thing is I have a friend with almost exactly the same set up and his advances perfectly and times perfectly. This is very strange. I am also going to put my newest distributor on a Sun machine this week also.

69Firebird roundport/roller455
70Catalina 455
72Skylark Buick 455
89 Iroc 305 stock 192RWHP/263RWTQ
I cant leave anything alone.

[basketcase70gto]

Do you run a vaccum advance? if not the pick up locking plate may not be in the right position. Have you checked the rotor phase? Does it smooth out in the upper rpms and just bounce around at idle? Just a couple of ideas, I know how frustrating it can be.

[White Warrior]

Try setting your dialback timing lite to 0 and see if the timing mark is steady. I can't use the dial back feature on my car but at 0 it is fine. I have a MSD 6al and the multiple discharge is probably the culprit.

[Sun Tuned]

73 Lemans,
Where actually does the timing begin to advance?(may be hard to tell) You do not want such light springs on there that the timing mark is jumping all over due to the advance starting right off idle.

What I'm saying is, is that if the advance starts at say 800 and the idle is set at 900, then the weights are partially swung out from at rest position. Could be from being idled too high, fatigued springs, etc. Just something to check.

[73LeMans]

I think you hit the nail on the head Sun Tuned. The idle is a little high, and the springs in the dist offer almost no resitance. The dist. guy told me this was the case...advance is early and I wont get accurate timing light until all the advance is in (3000rpm). It does smooth out up in that range. (no that the exhaust is back on it, i could test!) Guess I have to decide on guessing where the timing will be, or locking out the dist. so I only have spark advance. (or taking out the springs, setting timing and putting them back in?) Hmmmmmm..........

not the blanacer though Goatee! I beat you too it. Keyways are tight, bolt is virutally welded on and all looks good.

~Mark

Who needs nice and pretty, when you can have mean and nasty? 73 LeMans: 12.5 in the 1/4 on its way to 10.90's!

[FirebirdDave]

We had some trouble with a cheap curve kit not returning like it was supposed to, but that wasnt the problem in my situatuation, this time.

69Firebird roundport/roller455
70Catalina 455
72Skylark Buick 455
89 Iroc 305 stock 192RWHP/263RWTQ
I cant leave anything alone.

[superdutydave]

Don`t kil yourself-go to basics-you said tim light was RECENTLY checked on another car-so -check chain by removing dist. cap and moving crank fore and aft to see if there is any play/stretch in chain. Check timing on another wire-don`t hav 2 b right, just regular. I run gear drives so if I see problem-it`s OVER! Check basics B4 you condem guy that "curved distibutor'.Also my Snapper 3-400$ timing light blew out 3-4 times, my 69.99 light is dead, and I have been using my 9.99 Sears light for. 6 months.

[73LeMans]

Great stuff guys. I appreciate the help.

I gave this some thought after I posted last night and I called the guy that did the distributor. (I hope no one condemns him...Larry Rowe rocks! ) He said with the lightweight springs and the radical cam (.660 lift, 270+ duration) I won't get steady timing until at least 3000 rpm. So it sounds like I need to reconnect the exhaust, and give this a shot when I go home. (trying this at 9 o clock at night with open headers tends to make neighbors upset)

If this doesnt work, I'm going to check all the other things you guys mentioned (regular light, rotor phase, timing chain stretch, bronze gear etc) and see if I can find a problem there. (no vacuum advance..its locked out. I'll check that plate as well).

If this does work, Im still going to scratch my head wondering how to set timing below 3000 when it should all be in well before then. Feel? Throttle response? Probably. Guess I'll just have to go to the track and start playing. How do you guys do it? I know there are plenty of sub 11 second cars on this page, some with cams far bigger than mine...do you guys have this problem? I wouldnt think so. I would think timing is something you can easily set in an 8 second car like you could a 14 second car. Am I wrong?

Who needs nice and pretty, when you can have mean and nasty? 73 LeMans: 12.5 in the 1/4 on its way to 10.90's!

[GTO]

If your fuel pump excentric tab is in the wrong hole in the cam your cam will walk and change your timing. Bin there done that. ... Eric.

[head #96]

Suntuned, what ill affects would there be by advancing to soon. On my engine my mark may occasionally bounce with the lope of the cam but goes right back steady.

I tried putting one heavier spring in, but than total doesn't come in till after 3000rpm. It's either one extreme or the other, seems very hard to find a happy medium. For me anyways?

Building a fast stock appearing street car.
homepage http://home.mchsi.com/~vroman6