Two issues with the 75
Thread Starter
Racer
Joined: Mar 2012
Posts: 396
Likes: 13
From: New Bern NC
Two issues with the 75
I am having two issues:
1) I pulled the vac advance and plugged it to set the base timing...I can not get it to settle down. It bounces between 6 and 10* (I am trying to set it to 10*). Does this mean the springs for mechanical advance are bad?
2) Car is running rich...I can eat a 1/4 of gas driving 30 miles driving like I am driving Ms Daisy... and she will flood on start up if I pump the gas.
1) I pulled the vac advance and plugged it to set the base timing...I can not get it to settle down. It bounces between 6 and 10* (I am trying to set it to 10*). Does this mean the springs for mechanical advance are bad?
2) Car is running rich...I can eat a 1/4 of gas driving 30 miles driving like I am driving Ms Daisy... and she will flood on start up if I pump the gas.
Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
1) Could be a number of issue's.My problem was dizzy was worn out.Shaft had to much play.Check if weights are sticking.
2) Possible float adjustment,or carb needs a rebuild.If this is a Qjet contact Lar's for a rebuild his email V8FastCars@msn.com
Good Luck....
2) Possible float adjustment,or carb needs a rebuild.If this is a Qjet contact Lar's for a rebuild his email V8FastCars@msn.com
Good Luck....
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
it could mean that the distributor shaft is riding up and down from excessive end play....to fix this you pull the distributor and shim the bottom so the amount of up and down movement is limiited ...this end play when translated through the beveled gears means bouncing timing
Melting Slicks
Joined: Apr 2001
Posts: 3,399
Likes: 278
From: Olmsted Falls, Ohio
Are you saying you have 6200 miles on a NEW or REBUILT engine, or on the speedometer?
A worn distributor shaft or weights posts holes elongated will cause timing scatter and other problems.
Your problem is common to worn distributors in need of a rebuild or replacement.
Hence my confusion as to the 6200 miles.
A worn distributor shaft or weights posts holes elongated will cause timing scatter and other problems.
Your problem is common to worn distributors in need of a rebuild or replacement.
Hence my confusion as to the 6200 miles.
Thread Starter
Racer
Joined: Mar 2012
Posts: 396
Likes: 13
From: New Bern NC
6200 original miles on the original motor....I know the two previous owners, she was a garage queen and hasnt been registered since 1996 till I just registered her 2 weeks ago. The car is facotry installed original from tip to tail (minus bumper covers, tires, and brake calipers)
Thread Starter
Racer
Joined: Mar 2012
Posts: 396
Likes: 13
From: New Bern NC
I switched out my springs to the black ones in the 929 kit (couldnt find the 928G kit) as they were the "lighests" springs and nearly indentical to what was already in my dizzy. I was able to get base timing (no vac adv) set to 16* and my idle RPM down to 800rpms.
I have a nice easy hot start... cranked for about 1 1/2 seconds and fired up. I still have a little bit of a rough idle. I am assumming I need to tweak the carb now (air mixture screws) as they are sitting at 3 1/2 turns each which is where they were when I got the car. Does that sound about right or am I chasing the wrong dog?
I ran out of time to verify total timimg, but I set the idle speed after reconnecting the vac line. I have been using Lars paper.
I have a nice easy hot start... cranked for about 1 1/2 seconds and fired up. I still have a little bit of a rough idle. I am assumming I need to tweak the carb now (air mixture screws) as they are sitting at 3 1/2 turns each which is where they were when I got the car. Does that sound about right or am I chasing the wrong dog?
I ran out of time to verify total timimg, but I set the idle speed after reconnecting the vac line. I have been using Lars paper.
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Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
If you rev it up a little bit, does the timing settle down and stop bouncing around? You may have installed springs that are too light. The 929 kit should have some instructions that will recommend certain color springs for the desired curve. If your kit didn't come with them, here is a copy to go by:
http://static.summitracing.com/globa...9g%282%291.pdf
Good luck,
Keep the shiny side up!
Scott
http://static.summitracing.com/globa...9g%282%291.pdf
Good luck,
Keep the shiny side up!
Scott
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
I switched out my springs to the black ones in the 929 kit (couldnt find the 928G kit) as they were the "lighests" springs and nearly indentical to what was already in my dizzy. I was able to get base timing (no vac adv) set to 16* and my idle RPM down to 800rpms.
I have a nice easy hot start... cranked for about 1 1/2 seconds and fired up. I still have a little bit of a rough idle. I am assumming I need to tweak the carb now (air mixture screws) as they are sitting at 3 1/2 turns each which is where they were when I got the car. Does that sound about right or am I chasing the wrong dog?
I ran out of time to verify total timimg, but I set the idle speed after reconnecting the vac line. I have been using Lars paper.
I have a nice easy hot start... cranked for about 1 1/2 seconds and fired up. I still have a little bit of a rough idle. I am assumming I need to tweak the carb now (air mixture screws) as they are sitting at 3 1/2 turns each which is where they were when I got the car. Does that sound about right or am I chasing the wrong dog?
I ran out of time to verify total timimg, but I set the idle speed after reconnecting the vac line. I have been using Lars paper.
Keep the shiny side up!
Scott
Thread Starter
Racer
Joined: Mar 2012
Posts: 396
Likes: 13
From: New Bern NC
Scott,
I am trying to get 36* at 3000rpms (while 2700-3000rpm). I revved her a few times and she revved just fine. No odd noises, no popping, no bogging down.
I will adjust the idle air mixture screws this morning. I really want to smooth out the idle.
I am trying to get 36* at 3000rpms (while 2700-3000rpm). I revved her a few times and she revved just fine. No odd noises, no popping, no bogging down.
I will adjust the idle air mixture screws this morning. I really want to smooth out the idle.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
if i'm not mistaken (which I very well could be and if so I'm sure someone will correct me) your stock '75 distributor is only going to give you 20º mechanical advance so for a total timing of 36º your setting of initial timing at 16º sounds correct.
I think your idle rpm of 800 is too high and depending on the springs installed, especially if they are the light springs, you might just be at the point that at 800rpm the springs may just be allowing some mechanical advance to start and if it's right at the line could explain why the idle is bouncing up and down - as the advance kicks in and out.
i'd first make sure your idle fuel mixture is correct - set it with a vacuum gauge hooked to full manifold vacuum and adjust for the highest STEADY vacuum reading and make sure both idle screws (if your carb has two adjustment screws) are adjusted evenly.
Than go back and bring the idle speed down to a nice steady idle around 600rpm or so.
I think your idle rpm of 800 is too high and depending on the springs installed, especially if they are the light springs, you might just be at the point that at 800rpm the springs may just be allowing some mechanical advance to start and if it's right at the line could explain why the idle is bouncing up and down - as the advance kicks in and out.
i'd first make sure your idle fuel mixture is correct - set it with a vacuum gauge hooked to full manifold vacuum and adjust for the highest STEADY vacuum reading and make sure both idle screws (if your carb has two adjustment screws) are adjusted evenly.
Than go back and bring the idle speed down to a nice steady idle around 600rpm or so.
Thread Starter
Racer
Joined: Mar 2012
Posts: 396
Likes: 13
From: New Bern NC
Barry,
Which vac line can I pull without creating a "leak"? According the the manual the idle RPM for a 4sp manual is 800rpms, 600rpms for an automatic.
I had a cold start issue this morning. So I took the airfilter assy off and I noticed my butter fly was open 1/2 inches. I tweaked the coil spring housing to get it closer to 1/4 inch.
Which vac line can I pull without creating a "leak"? According the the manual the idle RPM for a 4sp manual is 800rpms, 600rpms for an automatic.
I had a cold start issue this morning. So I took the airfilter assy off and I noticed my butter fly was open 1/2 inches. I tweaked the coil spring housing to get it closer to 1/4 inch.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Barry,
Which vac line can I pull without creating a "leak"? According the the manual the idle RPM for a 4sp manual is 800rpms, 600rpms for an automatic.
I had a cold start issue this morning. So I took the airfilter assy off and I noticed my butter fly was open 1/2 inches. I tweaked the coil spring housing to get it closer to 1/4 inch.
Which vac line can I pull without creating a "leak"? According the the manual the idle RPM for a 4sp manual is 800rpms, 600rpms for an automatic.
I had a cold start issue this morning. So I took the airfilter assy off and I noticed my butter fly was open 1/2 inches. I tweaked the coil spring housing to get it closer to 1/4 inch.
ok, if your man calls for 800rpms than so be it. I'm surprised to see such a high RPM for a '75 though.
My '65 is set at 800-850 rpm but I have the 30-30 cam which was a VERY radical factory cam and it needs a higher rpm speed to idle at all so I'd expect that your '75 which has a much milder cam to have a slower idle speed
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Barry,
Which vac line can I pull without creating a "leak"? According the the manual the idle RPM for a 4sp manual is 800rpms, 600rpms for an automatic.
I had a cold start issue this morning. So I took the airfilter assy off and I noticed my butter fly was open 1/2 inches. I tweaked the coil spring housing to get it closer to 1/4 inch.
Which vac line can I pull without creating a "leak"? According the the manual the idle RPM for a 4sp manual is 800rpms, 600rpms for an automatic.
I had a cold start issue this morning. So I took the airfilter assy off and I noticed my butter fly was open 1/2 inches. I tweaked the coil spring housing to get it closer to 1/4 inch.
Keep the shiny side up!
Scott
Thread Starter
Racer
Joined: Mar 2012
Posts: 396
Likes: 13
From: New Bern NC
scott, I understand...I will aim from 700rpms... I need to figure out the idle air screws on the carb and the choke. I had a cold start issue and once fixed I developed a warm start issue.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Keep the shiny side up!
Scott