[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!

[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!

[62tempest]

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

[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.

[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.

[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.

[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

[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.

[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.

[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.

[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!

[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.

[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.

[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.

[Gooatee]

Another thing to check is the balancer! I had this problem with a 12 second car and it was the stock balancer comming apart and I couldn't see it till it was too late! Make sure the bolt is tight and there is no wobble in the balancer. I thought it was the chain od the distributor till it let loose in the burnout box in the final round of eliminations and it cost me the win!!!!

[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!

[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

[Larry Navarro]

Hmmm....
73Lemans...if Rowe did the work, didn't he know what your setup was?
Seems he would have taken in to account that the springs were to light for the cam and idle qualities and used heavier springs for delayed advance.
Not trying to bash the guy, just an observation.

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

[Sun Tuned]

All I got to say about this is this...If you want to see if the advance is coming in too early, get a timing light, 2 stock (stiff) springs, and a screwdriver. Check the timing at idle...just look at it to see where it is, make note of it. Remove the presently installed dist springs and replace with the stiff ones, make this THE ONLY CHANGE. Reinstall rotor and cap, and light it back off, recheck the initial timing and if it changed... guess what? Your dist ain't right, or you got it idled too high for the way it was set up. Either way what ever total you THOUGHT you had is now the same number of degrees LESS what the timing just changed if any.

Initial is not supposed to change when set up properly with just the addition of stiffer springs. At least if everything is still o.k., it's not. Lots of variables here, so don't cast any stones unnecessarily. Timing should be steady period. Test Don't Guess.

Loose timing chain, loose clearances in the oil pump, defective pickup coil(HEI), worn dist gear, excessive endplay(I mean alot), worn advance mechanism, worn reluctor to shaft clearance, etc...all contribute to the timing mark appearing to jump all over.

Larry Rowe.... I understand the man works a good distributor. Have never met him and only spoken with him on 1 occasion...nice guy, real gentleman on the phone for the period I conversed with him. Give the dist guy benifit of the doubt...it may be a simple problem not related to the dist completely.

Anything else and I'd have to look at it myself, which I will be glad to do if you want a second opinion.

[Ken MacNicol]

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