jotto

Does anyone know if there is any difference in the springs in the 928g and 929g kits?
I have a HEI distributor and thought I had the 929 kit but it turns out I have the 928 kit which is supposedly for points style distributors.
I did a Google search and some threads I found said they used the springs from the 928 kit and weights from the 929!
I only need to tune with springs.
TIA

7t9l82

If you have a dial back timing light it would be easy enough to check them. I would be reluctant to just pull some springs out of a package and say it is good.

AkitaCJ75

Agreed. Stick em and check the timing with adj light. I'd probably do that even with springs I thought were right just to make sure.

jotto

Thanks, it was more the size I was worried about, wasnt sure if they were the same physical size.
Will try installing tomorrow and see what effect it has.

bluedawg

How's the vette running Paul?

jotto

Hey Blue, how are you and the family doing? Seems like a lifetime ago we were there cruising with you!
Just fitted my sidepipes, replaced the harmonic balancer and she is running like crap! Just chasing out where to go and what to do.
Going to verify TDC.
Going to recurve distributor as only seem to be getting 12 degrees mechanical and limit vacuum which is pulling 24 degrees.
Then on to the Qjet, Think I have a problem with the secondaries not opening but will start looking only after I have sorted timing.

CA-Legal-Vette

Evening Paul

Might be worth sending Lars an email on this one. I imagine he'd know but I don't think he comes around here any more.

bluedawg

All is well with the family, ive worked a ton this year, but in the times of 41$ a barrel for oil, im happy just to be working. Let's see, what did you change before it wasn't running good, in other words was it running good before you changed the damper and side pipes? When you say it's running like crap what's it doing? What prompted you to change the balancer? If you need springs or parts let me know, I can ship them as a gift so maybe you can save taxes.

I talked to josh a little via email a little while back.

leadfoot4

If you're referring to the "header-type" sidepipes, any chance you broke a spark plug, or damaged a plug wire, at that time?

jotto

Hey Mike, Such a shame Lars seems to have gone. I just hope he is well and that he has his health. Regards to B and the kids!

Hey Blue, changed the damper because I knew the outer ring had slipped. Turns out it had by about 90 degrees!

https://www.corvetteforum.com/forums...placement.html

To be honest car runs fine at low to mid RPM's as she has always done but now I have romped on her a few times and she is falling flat at WOT.

https://www.corvetteforum.com/forums...ning-lean.html

Appreciate the offer of parts, will let you know if I need anything. Josh is really enjoying his year in Australia.

Spark plugs were replaced after fitting side pipes and wires were removed for install. Wires probably have less than 500 miles on them.

So anyways, had a bit of a tinker today and now Im leaning towards a loose timing chain as well as other issues!!!

Replaced the springs in the distributor with one gold and one silver from the 928 kit.
Initial was 12 dgrees @ 720 rpm with vac plugged. Car idled nice and smooth.
All in was 34 degrees@ 3250 rpm and car had an off idle stumble ( just revving engine in garage )
When I hooked up vacuum, idle rose noticeably to around 900 and timing was @ 36 degrees.

According to my math, 34 all in - initial 12 = 22 mechanical advance.
36 vacuum - 12 initial = 24 vacuum
Making a grand total of 12+22+24 = 58 degrees = not good!

Now, when I removed the vacuum cap from port to re attach vacuum advance, idle dropped to 690rpm but engine didnt stuble and seemed fine revving it

I know I have to limit vacuum advance but I then decided to try different springs in the distributor to see if that made a difference.

Replaced springs with 2 silver ones and re checked. Distributor was not moved at all during these changes.

Initial was 11 degrees @ 625 rpm. Idled smooth.
All in was 35 degrees @ 2700 rpm, off idle hesitation gone.
Hooked up vacuum and rpms rose to 880 and timing was @ 39 degrees.

Again, according to my math, 35 all in - 12 initial = 24 mechanical advance.
39 vacuum - 11 initial = 28 vacuum
Making a total of 11+24+28 = 63 degrees!!!! WTF!

I also noticed that at idle, my timing mark was moving around. It stayed steady for a short while then would jump. Im not sure if it was regular so as to show a mis fire but its got me wondering if the timing chain is at fault. Under load ( reving the engine ) the mark on the balancer stays constant. At idle, it jumps around.

I guess I need to check with another timing light to see if I have the same issues. I just dont see how the timing readings for the vacuum can change like that at idle.

My other major concern is that when the vacuum can is connected up, the idle rises and I cannot get it lower. The idle speed screw is wound back and not touching the tang on the throttle shaft!

Will see if I can try another distributor as well to rule that out but at the moment Im thinking of changing the timing chain, carb and distributor!!!!

bluedawg

I found with the L48 and springs, my best luck was with the copper springs or the lightest weight ones. To set the total mechanical advance, i pull both springs off and run the car at idle and set to the total that I want and reinstall the springs. For figuring out the total vacuum, use the heaviest weight springs so that there is no mechanical advance and hook up the vacuum to see what the change is. As to the wot it sounds like you secondaries are opening to soon, there is an adjustment for that but I don't remember exactly how. Make one change at a time.

jotto

Will go back and try that. I just couldn't understand how the initial was less when I swapped to the lighter springs.
Interesting about you thinking the secondaries are opening too early, my initial thought was they were not opening. Would the engine not pick up after an initial bog if opening too early? Will see if I can get a video of whats happening.

bluedawg

Yea it should recover when the secondaries open to early and you should also be able part throttle until you rpm got high enough that full throttle shouldnt fall on its face, if they weren't opening I would think that it just quit pulling or not pull as hard.

jotto

Thats what it seems to do, just stop pulling.
Need to get the timing and the carb dialled in to see whats going on

bluedawg

It's the middle of the day over there paul, have you not worked on your vett? I believe if memory serves me correctly, Dr. Lars Grimsrud's email is fastv8cars@msn.com, you should shoot him a kite, he loves to share his writings and would send you his papers for free. Good dude that Norwegian mad man.

jotto

Sent you a PM Blue!