Need some tri-power help.
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,687
Likes: 199
From: Loveland, CO
Need some tri-power help.
I've been tuning my'69 L-71 after installing Brodix RR heads and a mild Chris Straub hydralic roller cam (221/235 @ .050, .571/.529" lift, 108 LSA). I get about 11" of vacuum at idle and 15" at cruise. I think I have the jets, PV, etc. adjusted with an LM-1 afr gauge. Not sure if these vacuum readings have anything to do with secondary operation.
The problem I am having is with the secondaries opening. I changed the rubber diaphrams and am down to the longer yellow spring. I have tried the paper clip on the secondary linkage and don't think they have opened. The engine runs strong and I have no complaints, but the secondaries have me confused.
The throttle cable side linkage return spring was rubbing on the back of the bolt that holds on the two rods to the secondaries. This was when I had the spring attached to the "V" shaped bracket that holds the throttle cable itself. I moved the spring over to the little bracket that attaches to the rear carb mounting bolt. This position provides clearance to everything, but the spring feels way too strong in this position.
I'll attach a few pictures and see if anyone has any suggestions.
Thanks, Ralph.
The problem I am having is with the secondaries opening. I changed the rubber diaphrams and am down to the longer yellow spring. I have tried the paper clip on the secondary linkage and don't think they have opened. The engine runs strong and I have no complaints, but the secondaries have me confused.
The throttle cable side linkage return spring was rubbing on the back of the bolt that holds on the two rods to the secondaries. This was when I had the spring attached to the "V" shaped bracket that holds the throttle cable itself. I moved the spring over to the little bracket that attaches to the rear carb mounting bolt. This position provides clearance to everything, but the spring feels way too strong in this position.
I'll attach a few pictures and see if anyone has any suggestions.
Thanks, Ralph.
Melting Slicks
Joined: Apr 2001
Posts: 2,030
Likes: 363
From: Lubbock Texas
I don't have any experience or knowledge about Tri-Power cars and that may be part of the problem. The knowledge base for those cars is a lot smaller.
I would contact Lars. And since you live in the same town, you might even be able to talk him into taking a look.
DC
Intermediate
Joined: Jul 2013
Posts: 42
Likes: 0
From: Mooresville North Carolina
How about a picture of the vacuum chambers and the hose routing. Should be a vacuum signal off the main (center) carb. Hook a vacuum gauge to it and see if your getting a vacuum to the pod at all while accelerating/driving. If you have a vacuum pump you can check it with the engine off. Attach a vacuum hose to the pod it open the center or disconnect the linkage to get around the close off.
Last edited by rli7275; Aug 16, 2013 at 09:13 PM.
Burning Brakes
Joined: Feb 2012
Posts: 925
Likes: 7
I've been tuning my'69 L-71 after installing Brodix RR heads and a mild Chris Straub hydralic roller cam (221/235 @ .050, .571/.529" lift, 108 LSA). I get about 11" of vacuum at idle and 15" at cruise. I think I have the jets, PV, etc. adjusted with an LM-1 afr gauge. Not sure if these vacuum readings have anything to do with secondary operation.
The problem I am having is with the secondaries opening. I changed the rubber diaphrams and am down to the longer yellow spring. I have tried the paper clip on the secondary linkage and don't think they have opened. The engine runs strong and I have no complaints, but the secondaries have me confused.
The throttle cable side linkage return spring was rubbing on the back of the bolt that holds on the two rods to the secondaries. This was when I had the spring attached to the "V" shaped bracket that holds the throttle cable itself. I moved the spring over to the little bracket that attaches to the rear carb mounting bolt. This position provides clearance to everything, but the spring feels way too strong in this position.
I'll attach a few pictures and see if anyone has any suggestions.
Thanks, Ralph.
The problem I am having is with the secondaries opening. I changed the rubber diaphrams and am down to the longer yellow spring. I have tried the paper clip on the secondary linkage and don't think they have opened. The engine runs strong and I have no complaints, but the secondaries have me confused.
The throttle cable side linkage return spring was rubbing on the back of the bolt that holds on the two rods to the secondaries. This was when I had the spring attached to the "V" shaped bracket that holds the throttle cable itself. I moved the spring over to the little bracket that attaches to the rear carb mounting bolt. This position provides clearance to everything, but the spring feels way too strong in this position.
I'll attach a few pictures and see if anyone has any suggestions.
Thanks, Ralph.
My 435 would run pretty well on the center carb up to around 3500-4000, then you could hear the intake roar of the tripower as the 2 secondary carbs opened. Are you not hearing the distinctive tripower intake noise?
As was suggested, post a few pics of the vacuum diaphragm side of the intake, with the air cleaner off. Again, it's been awhile, are the top half of the vacuum actuators on correctly, with the vacuum passage aligned with the vacuum hole on the bottom half? I don't remember if those can only go on one way.
Last edited by Super6; Aug 17, 2013 at 09:52 AM. Reason: Additional questions added.
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,687
Likes: 199
From: Loveland, CO
Good suggestion on hooking vacuum guage up to port that feeds secondaries. I have sucked on the two hoses that go to the diaphrams and they operate fairly easily. Have to hold the linkage fully open to center carb to allow for this. That way I can tell if I am getting vacuum out of the center carb at secondary speeds.
I visit with Lars often, but haven't run this problem by him yet.
There are two yellow springs, one long and one a bit shorter. They are pretty close in vacuum opening readings with the short one being the lightest, but I don't have two of the short yellows (so I am currently using the longer yellows). There is a white spring that is even lighter opening, but the chart I've see doesn't even have opening rates of it.
I'm going to be out of town for a week, so I can't do any more testing right now. Will update in a bit.
Thanks. Ralph.
I visit with Lars often, but haven't run this problem by him yet.
There are two yellow springs, one long and one a bit shorter. They are pretty close in vacuum opening readings with the short one being the lightest, but I don't have two of the short yellows (so I am currently using the longer yellows). There is a white spring that is even lighter opening, but the chart I've see doesn't even have opening rates of it.
I'm going to be out of town for a week, so I can't do any more testing right now. Will update in a bit.
Thanks. Ralph.
Race Director
Joined: Feb 1999
Posts: 16,978
Likes: 7
From: In Dreams There Is Truth Ohio
try the white spring, I think that's the one with least resistance and opens the secondaries the quickest. Make sure the rubber diaphragm is not blocking the vacuum passage...that is easy to do.
Also...the teflon tape...won't help seal the lines, worthless...
Also...the teflon tape...won't help seal the lines, worthless...
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,687
Likes: 199
From: Loveland, CO
Agree that teflon tape will not seal compression fittings. Only used as friction modifier to reduce thread friction and get all force on flared fitting. Could also us anti-seize, but chose teflon.
Ralph
Ralph
Last edited by rponfick; Aug 17, 2013 at 10:09 PM.
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Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,687
Likes: 199
From: Loveland, CO
Finally got back to playing with the car. Found my problem. The vacuum hose from the carb to the two secondaries had a split in it where it connects to the carb, and that was not visible on glancing inspection. Cut of end of hose and re-attached. Secondaries now open on paper clip verification.
Thanks for your patience. Ralph
Thanks for your patience. Ralph