Tri power tuning questions
Thread Starter
Drifting
Joined: Nov 2016
Posts: 1,964
Likes: 579
From: Pittsburgh PA
Tri power tuning questions
So I just installed a 427/435 tri power setup onto my c10 with a 496. These are brand new carbs
Haven't got to test drive it yet due to rain but having issues at idle already.
Here are my issues
1- pump gas to set choke everything is functioning correctly but truck does not fast idle. Just chugs
2- very rough idle. Truck shakes a smokes out tail pipes.
3- seems like fuel is dribbling out of center carb.
Here is what I know is good:
1- all 3 floats set correctly- remove plug fuel is at bottom.
2-outboard carbs are closed and not effecting idle. Can put my hand over them.
I THINK my main issue is fuel pressure. Truck was running fine with a 4 barrel but I noticed as soon as I started the truck I had 9 psi. My Holley pump is supposed to not need a regulator however I am doing to start first by installing one. What is a good psi to set it at for the tri power?
Haven't got to test drive it yet due to rain but having issues at idle already.
Here are my issues
1- pump gas to set choke everything is functioning correctly but truck does not fast idle. Just chugs
2- very rough idle. Truck shakes a smokes out tail pipes.
3- seems like fuel is dribbling out of center carb.
Here is what I know is good:
1- all 3 floats set correctly- remove plug fuel is at bottom.
2-outboard carbs are closed and not effecting idle. Can put my hand over them.
I THINK my main issue is fuel pressure. Truck was running fine with a 4 barrel but I noticed as soon as I started the truck I had 9 psi. My Holley pump is supposed to not need a regulator however I am doing to start first by installing one. What is a good psi to set it at for the tri power?
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
they are the 2300 type Holley ? if so are you aware the outboard carbs do have a fixed idle fuel feed. have you done a check for VACUUM leaks ?
Last edited by bazza77; May 8, 2017 at 09:36 AM. Reason: carb i.d
Thread Starter
Drifting
Joined: Nov 2016
Posts: 1,964
Likes: 579
From: Pittsburgh PA
truthfully no I haven't check for vacuum leaks yet- other than the obvious looking for a disconnected hose.
I know the outer carbs have the idle, but being my engine is much larger(496) and the original 427, if anything I figured I would have issues with not enough fuel, not too much.
what is a good fuel psi to set my regulator at? I know they say 6-6.5 but I have read some things that some carbs like it really low, like 5 or less
I know the outer carbs have the idle, but being my engine is much larger(496) and the original 427, if anything I figured I would have issues with not enough fuel, not too much.
what is a good fuel psi to set my regulator at? I know they say 6-6.5 but I have read some things that some carbs like it really low, like 5 or less
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
truthfully no I haven't check for vacuum leaks yet- other than the obvious looking for a disconnected hose.
I know the outer carbs have the idle, but being my engine is much larger(496) and the original 427, if anything I figured I would have issues with not enough fuel, not too much.
what is a good fuel psi to set my regulator at? I know they say 6-6.5 but I have read some things that some carbs like it really low, like 5 or less
I know the outer carbs have the idle, but being my engine is much larger(496) and the original 427, if anything I figured I would have issues with not enough fuel, not too much.
what is a good fuel psi to set my regulator at? I know they say 6-6.5 but I have read some things that some carbs like it really low, like 5 or less
Last edited by bazza77; May 8, 2017 at 10:46 AM.
Thread Starter
Drifting
Joined: Nov 2016
Posts: 1,964
Likes: 579
From: Pittsburgh PA
ya the K&N element that fits the tri power is on my to buy list.
I'm thinking the excess fuel pressure is my main issue right now. when truck was running and chugging last night, I looked down and could see fuel dripping out the boosters on the center carb. I'm thinkin 9 psi is just pushing past the needle valve. Plus i wasn't super happy with my fuel filter/gauge setup, so adding a regulator with a gauge lets me change that.
I just looked at my pic and i know its hard to tell but my fuel pressure gauge is at like 8.5 in the pic. that was right after I shut the truck off. So i definitely need to dial back the fuel pressure before i go any further
I'm thinking the excess fuel pressure is my main issue right now. when truck was running and chugging last night, I looked down and could see fuel dripping out the boosters on the center carb. I'm thinkin 9 psi is just pushing past the needle valve. Plus i wasn't super happy with my fuel filter/gauge setup, so adding a regulator with a gauge lets me change that.
I just looked at my pic and i know its hard to tell but my fuel pressure gauge is at like 8.5 in the pic. that was right after I shut the truck off. So i definitely need to dial back the fuel pressure before i go any further
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Race Director
Joined: Jun 2000
Posts: 10,046
Likes: 675
From: FL
The outboard carbs do provide some idle air/fuel so if you can block them with no effect, you have an issue.
I also did a 496 with the Tripower. You will want to tune it on the center carb first and then tune the end carbs for WOT. The fixed plates on the end carbs are an issue. My mechanic ended up using a wideband O2 to help with tuning.
After a year, I swapped to the Mopar Six Pack mechanical secondary carbs. Accelerator pumps and jets on all 3 carbs. A real kick in the pants when the secondaries came in.
My biggest issue was the fact that the engine wanted to die on hard braking since the fuel would slosh forward in the bowls. The idle was also a little rich for my wife. My solution was a custom 3x2 EFI using FAST XFI 2.0.
I also did a 496 with the Tripower. You will want to tune it on the center carb first and then tune the end carbs for WOT. The fixed plates on the end carbs are an issue. My mechanic ended up using a wideband O2 to help with tuning.
After a year, I swapped to the Mopar Six Pack mechanical secondary carbs. Accelerator pumps and jets on all 3 carbs. A real kick in the pants when the secondaries came in.
My biggest issue was the fact that the engine wanted to die on hard braking since the fuel would slosh forward in the bowls. The idle was also a little rich for my wife. My solution was a custom 3x2 EFI using FAST XFI 2.0.
Race Director
Joined: Jun 2000
Posts: 10,046
Likes: 675
From: FL
ya the K&N element that fits the tri power is on my to buy list.
I'm thinking the excess fuel pressure is my main issue right now. when truck was running and chugging last night, I looked down and could see fuel dripping out the boosters on the center carb. I'm thinkin 9 psi is just pushing past the needle valve. Plus i wasn't super happy with my fuel filter/gauge setup, so adding a regulator with a gauge lets me change that.
I just looked at my pic and i know its hard to tell but my fuel pressure gauge is at like 8.5 in the pic. that was right after I shut the truck off. So i definitely need to dial back the fuel pressure before i go any further
I'm thinking the excess fuel pressure is my main issue right now. when truck was running and chugging last night, I looked down and could see fuel dripping out the boosters on the center carb. I'm thinkin 9 psi is just pushing past the needle valve. Plus i wasn't super happy with my fuel filter/gauge setup, so adding a regulator with a gauge lets me change that.
I just looked at my pic and i know its hard to tell but my fuel pressure gauge is at like 8.5 in the pic. that was right after I shut the truck off. So i definitely need to dial back the fuel pressure before i go any further
FYI, K&N makes a stock height TriPower filter but they will also make you a custom height one as well. I had them make me one that is 3/4" taller than stock for my EFI setup.
Last edited by SteveG75; May 8, 2017 at 02:38 PM.
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
The outboard carbs do provide some idle air/fuel so if you can block them with no effect, you have an issue.
I also did a 496 with the Tripower. You will want to tune it on the center carb first and then tune the end carbs for WOT. The fixed plates on the end carbs are an issue. My mechanic ended up using a wideband O2 to help with tuning.
After a year, I swapped to the Mopar Six Pack mechanical secondary carbs. Accelerator pumps and jets on all 3 carbs. A real kick in the pants when the secondaries came in.
My biggest issue was the fact that the engine wanted to die on hard braking since the fuel would slosh forward in the bowls. The idle was also a little rich for my wife. My solution was a custom 3x2 EFI using FAST XFI 2.0.
I also did a 496 with the Tripower. You will want to tune it on the center carb first and then tune the end carbs for WOT. The fixed plates on the end carbs are an issue. My mechanic ended up using a wideband O2 to help with tuning.
After a year, I swapped to the Mopar Six Pack mechanical secondary carbs. Accelerator pumps and jets on all 3 carbs. A real kick in the pants when the secondaries came in.
My biggest issue was the fact that the engine wanted to die on hard braking since the fuel would slosh forward in the bowls. The idle was also a little rich for my wife. My solution was a custom 3x2 EFI using FAST XFI 2.0.
My solution was the Holley EFI , its still a work in progress though
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
ya the K&N element that fits the tri power is on my to buy list.
I'm thinking the excess fuel pressure is my main issue right now. when truck was running and chugging last night, I looked down and could see fuel dripping out the boosters on the center carb. I'm thinkin 9 psi is just pushing past the needle valve. Plus i wasn't super happy with my fuel filter/gauge setup, so adding a regulator with a gauge lets me change that.
I just looked at my pic and i know its hard to tell but my fuel pressure gauge is at like 8.5 in the pic. that was right after I shut the truck off. So i definitely need to dial back the fuel pressure before i go any further
I'm thinking the excess fuel pressure is my main issue right now. when truck was running and chugging last night, I looked down and could see fuel dripping out the boosters on the center carb. I'm thinkin 9 psi is just pushing past the needle valve. Plus i wasn't super happy with my fuel filter/gauge setup, so adding a regulator with a gauge lets me change that.
I just looked at my pic and i know its hard to tell but my fuel pressure gauge is at like 8.5 in the pic. that was right after I shut the truck off. So i definitely need to dial back the fuel pressure before i go any further
yours being all new you should be right with the carbs , just curious now , what manifold are you using (year?) btw if you can get more than a 3 inch high filter element on those carbs you should seriously think about doing it . GO TALL
I emailed K and N and requested they make a 3 inch for me , they were great to deal with .
Last edited by bazza77; May 8, 2017 at 06:06 PM.
Thread Starter
Drifting
Joined: Nov 2016
Posts: 1,964
Likes: 579
From: Pittsburgh PA
Intake is a 68. 3919852 I think
I had the intake and matching carbs but obviously they needed rebuilt from sitting. Since this isn't a vette and I'm not concerned with numbers I figured I'd be ahead to just buy the new carbs and toss the dated ones on the shelf
Oh ya and I've got tons of room for a taller air cleaner since this is in a pickup. Hell I could prolly run a 10" tall air cleaner
I had the intake and matching carbs but obviously they needed rebuilt from sitting. Since this isn't a vette and I'm not concerned with numbers I figured I'd be ahead to just buy the new carbs and toss the dated ones on the shelf
Oh ya and I've got tons of room for a taller air cleaner since this is in a pickup. Hell I could prolly run a 10" tall air cleaner
Last edited by Tiger Joe; May 8, 2017 at 08:29 PM.
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
10 inch tall cleaner , yeah that's what they need
Last edited by bazza77; May 8, 2017 at 07:57 PM.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
I've always found ~5.5 to 6.0 psi to be the sweet spot for trips. Cliff notes for Tri-power tuning...
Get ignition system 100% up to snuff before making carb adjustments.
Disconnect linkage from end carbs and verify they're fully closed.
Tune center carb as you would any Holley primary circuit (there are plenty of how to resources online for this part).
Reconnect linkage* to end carbs, adjusting so that it just does fully close the secondaries without effecting the primary throttle position.
Operate under load (sitting in the driveway doesn't count) at WOT from relatively low RPMs.
If it doesn't bog, install the next weakest set of secondary vacuum springs in the end pots. (Holley secondary vacuum spring kit #20-13, 2 sets required.)
Repeat previous step until it bogs, then reinstall the last weakest set that didn't.
Happy motoring!
* Unless you convert over to a Mopar type full mechanical secondary setup (or happen to be a glutton for self-punishment), do NOT attempt to reinvent the linkage to the end carbs.
Get ignition system 100% up to snuff before making carb adjustments.
Disconnect linkage from end carbs and verify they're fully closed.
Tune center carb as you would any Holley primary circuit (there are plenty of how to resources online for this part).
Reconnect linkage* to end carbs, adjusting so that it just does fully close the secondaries without effecting the primary throttle position.
Operate under load (sitting in the driveway doesn't count) at WOT from relatively low RPMs.
If it doesn't bog, install the next weakest set of secondary vacuum springs in the end pots. (Holley secondary vacuum spring kit #20-13, 2 sets required.)
Repeat previous step until it bogs, then reinstall the last weakest set that didn't.
Happy motoring!
* Unless you convert over to a Mopar type full mechanical secondary setup (or happen to be a glutton for self-punishment), do NOT attempt to reinvent the linkage to the end carbs.
Last edited by TheSkunkWorks; May 8, 2017 at 08:33 PM.
Thread Starter
Drifting
Joined: Nov 2016
Posts: 1,964
Likes: 579
From: Pittsburgh PA
Update.
Got regulator plumbed tonight. Set it at 5.5 to start. Good news is no more dripping out of the boosters.
Got truck started and it was still running rough. Started dialing back mixture screws. Started at 1 turn out each and think I have them out only 1/4 turn each. Good news smoke cleared up out tailpipes and I was able to take it around the block. It's a short block but I made it home at least!
Thinking being only 1/4 out means I need to get to jetting these carbs. Also makes me think I should maybe consider a wideband for tuning.
Got regulator plumbed tonight. Set it at 5.5 to start. Good news is no more dripping out of the boosters.
Got truck started and it was still running rough. Started dialing back mixture screws. Started at 1 turn out each and think I have them out only 1/4 turn each. Good news smoke cleared up out tailpipes and I was able to take it around the block. It's a short block but I made it home at least!
Thinking being only 1/4 out means I need to get to jetting these carbs. Also makes me think I should maybe consider a wideband for tuning.
Thread Starter
Drifting
Joined: Nov 2016
Posts: 1,964
Likes: 579
From: Pittsburgh PA
Forgot to add.
Ignition system is all good. Running all MSD- 6AL pro billet distributor.
Also when I was messing around it almost seemed like I could have closed the idle mixture screws completely and it would have kept running. Does this mean I've still got too much fuel at idle? But it seemed to run good around the block.
Ignition system is all good. Running all MSD- 6AL pro billet distributor.
Also when I was messing around it almost seemed like I could have closed the idle mixture screws completely and it would have kept running. Does this mean I've still got too much fuel at idle? But it seemed to run good around the block.
Thread Starter
Drifting
Joined: Nov 2016
Posts: 1,964
Likes: 579
From: Pittsburgh PA
Ok update.
Truck sat untouched for 24 hours. Pump gas hit the key it fires off instantly. Choke is working correctly but truck does not high idle. Just sorta chugs around 800 rpms. Hit the gas to take it off "high idle" and it drops down to 500 and sits there.
So I'm thinking I'm too rich at idle. Question how do I correct this? I think I need to pull apart my center carb and change idle restrictors? Are the Holley 2 barrel IFRs the same as any other Holley?
Truck sat untouched for 24 hours. Pump gas hit the key it fires off instantly. Choke is working correctly but truck does not high idle. Just sorta chugs around 800 rpms. Hit the gas to take it off "high idle" and it drops down to 500 and sits there.
So I'm thinking I'm too rich at idle. Question how do I correct this? I think I need to pull apart my center carb and change idle restrictors? Are the Holley 2 barrel IFRs the same as any other Holley?