454 wont idle below 1500 RPMs
04-11-2021 | 06:49 AM
#133
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From: Holland MI
Is this a 330hp454 or 365hp 454 ?
What part # Eddy intake ? Got a pic of it on the boat ? What I’m getting to on intake questions, if a spread bore intake, it needs a thin adapter/sealing plate between squarebore carb and spreadbore intake for carb baseplate gasket to seal.
Edelbrock 2732
What part # Eddy intake ? Got a pic of it on the boat ? What I’m getting to on intake questions, if a spread bore intake, it needs a thin adapter/sealing plate between squarebore carb and spreadbore intake for carb baseplate gasket to seal.
Edelbrock 2732
Shoot I get rid of the 1" adapter that's on it right now and just use the sealing plate and gasket you showed here? Or use both the sealing plate and the 1" thick adapter?
04-11-2021 | 01:52 PM
#134
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Joined: Sep 2001
Posts: 5,769
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From: tn
You have tried 4000 things.
Do this.
1) Get a piston stop, adjust your timing mark so that your TDC mark is correct on your balancer. Disconnect your throttle cable so you can do everything by hand back at the carb. Hook up a starter switch so you can restart the motor from back there. Put an alligator clip on the end of your + coil wire so you can kill power to the coil to kill the engine from back there. Dump your fuel filter canister, refill it with fresh gas and reinstall it. You say you already regulated your fuel pressure to under 7psi, Good.
2) Set your initial timing at 12 BTDC as best you can with it running as slow as you can make it. Shut motor off before it gets too hot. Pull all the plugs and do warm compression test and write down results. Make sure they are all within 10 psi of each other. If you have access to a leak down tester, go ahead and check it as well (you do have to put each piston at compression stroke TDC to check each cyl).
3) run the motor up and down thru 3000 rpm to watch the timing advance and come back. If it does so smoothly, then let's move on. If it is erratic or nonlinear, then there is an ignition issue that needs chased down.
4) Hook a decent vacuum gauge to the motor. Tape it where you can watch it. Run the motor around 2000, then start slowing it down. Watch only for any erratic movement of the needle. It should stay steady. Slow it down as slow as it will keep running. Again, make sure the needle is steady. Erratic needle points to an issue with a particular cylinder/valvespring/valve/pushrod/cam lobe, etc.
NOW you have fresh fuel in the can, proper fuel pressure, timing is set close enough, advance mechanism is working. Engine condition is good enough to proceed. You've sprayed/checked for vac leaks and there are none.
A) set idle screws 2 turns out.
B) run motor til above 150 degrees water temp.
C) slow motor until it wants to try to stall - adjust throttle stop screw to keep it just above that.
D) watch the vacuum hauge and adjust idle mix screws for max vacuum - if motor speeds up, let it.
E) back off the throttle stop screw and let motor slow down until it wants to stall again, go back up a touch. Watch vacuum gage and repeat adjusting idle mix screws (adjust them the same, you don't want one a different number of turns). Again, go for max vacuum.
F) repeat until you can't get it to idle any slower. Always watch vacuum gadgets for erratic needle. If you get erratic needle you have internal motor issues, not carb issues.
This method should get you to a slow, stable idle. Motor may run like crap everywhere else, but it should idle.
Am very interested what your idle vacuum and rpm ends up thus way. You should see 18 or more w stock cam.
And as others have suggested, you really ought to toss a known- good running carb on it just for kicks. Your 850 Hollet may have been previously installed on a motor that required drilling out the air bleeds and fuel restrictions that otherwise would NOT be needed on your motor. A lot of times, idle restrictions have to be modified to get a carb to work on a motor w a big cam. If you get a set of pin gages, you can measure your bleeds and restrictions and know the full story, but for now let's just see if the motor us healthy enough to idle AND if you can get it to idle.
Can go from there once we have a full picture.
but you got to stop running in circles.
Do this.
1) Get a piston stop, adjust your timing mark so that your TDC mark is correct on your balancer. Disconnect your throttle cable so you can do everything by hand back at the carb. Hook up a starter switch so you can restart the motor from back there. Put an alligator clip on the end of your + coil wire so you can kill power to the coil to kill the engine from back there. Dump your fuel filter canister, refill it with fresh gas and reinstall it. You say you already regulated your fuel pressure to under 7psi, Good.
2) Set your initial timing at 12 BTDC as best you can with it running as slow as you can make it. Shut motor off before it gets too hot. Pull all the plugs and do warm compression test and write down results. Make sure they are all within 10 psi of each other. If you have access to a leak down tester, go ahead and check it as well (you do have to put each piston at compression stroke TDC to check each cyl).
3) run the motor up and down thru 3000 rpm to watch the timing advance and come back. If it does so smoothly, then let's move on. If it is erratic or nonlinear, then there is an ignition issue that needs chased down.
4) Hook a decent vacuum gauge to the motor. Tape it where you can watch it. Run the motor around 2000, then start slowing it down. Watch only for any erratic movement of the needle. It should stay steady. Slow it down as slow as it will keep running. Again, make sure the needle is steady. Erratic needle points to an issue with a particular cylinder/valvespring/valve/pushrod/cam lobe, etc.
NOW you have fresh fuel in the can, proper fuel pressure, timing is set close enough, advance mechanism is working. Engine condition is good enough to proceed. You've sprayed/checked for vac leaks and there are none.
A) set idle screws 2 turns out.
B) run motor til above 150 degrees water temp.
C) slow motor until it wants to try to stall - adjust throttle stop screw to keep it just above that.
D) watch the vacuum hauge and adjust idle mix screws for max vacuum - if motor speeds up, let it.
E) back off the throttle stop screw and let motor slow down until it wants to stall again, go back up a touch. Watch vacuum gage and repeat adjusting idle mix screws (adjust them the same, you don't want one a different number of turns). Again, go for max vacuum.
F) repeat until you can't get it to idle any slower. Always watch vacuum gadgets for erratic needle. If you get erratic needle you have internal motor issues, not carb issues.
This method should get you to a slow, stable idle. Motor may run like crap everywhere else, but it should idle.
Am very interested what your idle vacuum and rpm ends up thus way. You should see 18 or more w stock cam.
And as others have suggested, you really ought to toss a known- good running carb on it just for kicks. Your 850 Hollet may have been previously installed on a motor that required drilling out the air bleeds and fuel restrictions that otherwise would NOT be needed on your motor. A lot of times, idle restrictions have to be modified to get a carb to work on a motor w a big cam. If you get a set of pin gages, you can measure your bleeds and restrictions and know the full story, but for now let's just see if the motor us healthy enough to idle AND if you can get it to idle.
Can go from there once we have a full picture.
but you got to stop running in circles.
04-11-2021 | 02:12 PM
#135
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Joined: Jun 2020
Posts: 523
Likes: 187
From: Holland MI
You have tried 4000 things.
Do this.
1) Get a piston stop, adjust your timing mark so that your TDC mark is correct on your balancer. Disconnect your throttle cable so you can do everything by hand back at the carb. Hook up a starter switch so you can restart the motor from back there. Put an alligator clip on the end of your + coil wire so you can kill power to the coil to kill the engine from back there. Dump your fuel filter canister, refill it with fresh gas and reinstall it. You say you already regulated your fuel pressure to under 7psi, Good.
2) Set your initial timing at 12 BTDC as best you can with it running as slow as you can make it. Shut motor off before it gets too hot. Pull all the plugs and do warm compression test and write down results. Make sure they are all within 10 psi of each other. If you have access to a leak down tester, go ahead and check it as well (you do have to put each piston at compression stroke TDC to check each cyl).
3) run the motor up and down thru 3000 rpm to watch the timing advance and come back. If it does so smoothly, then let's move on. If it is erratic or nonlinear, then there is an ignition issue that needs chased down.
4) Hook a decent vacuum gauge to the motor. Tape it where you can watch it. Run the motor around 2000, then start slowing it down. Watch only for any erratic movement of the needle. It should stay steady. Slow it down as slow as it will keep running. Again, make sure the needle is steady. Erratic needle points to an issue with a particular cylinder/valvespring/valve/pushrod/cam lobe, etc.
NOW you have fresh fuel in the can, proper fuel pressure, timing is set close enough, advance mechanism is working. Engine condition is good enough to proceed. You've sprayed/checked for vac leaks and there are none.
A) set idle screws 2 turns out.
B) run motor til above 150 degrees water temp.
C) slow motor until it wants to try to stall - adjust throttle stop screw to keep it just above that.
D) watch the vacuum hauge and adjust idle mix screws for max vacuum - if motor speeds up, let it.
E) back off the throttle stop screw and let motor slow down until it wants to stall again, go back up a touch. Watch vacuum gage and repeat adjusting idle mix screws (adjust them the same, you don't want one a different number of turns). Again, go for max vacuum.
F) repeat until you can't get it to idle any slower. Always watch vacuum gadgets for erratic needle. If you get erratic needle you have internal motor issues, not carb issues.
This method should get you to a slow, stable idle. Motor may run like crap everywhere else, but it should idle.
Am very interested what your idle vacuum and rpm ends up thus way. You should see 18 or more w stock cam.
And as others have suggested, you really ought to toss a known- good running carb on it just for kicks. Your 850 Hollet may have been previously installed on a motor that required drilling out the air bleeds and fuel restrictions that otherwise would NOT be needed on your motor. A lot of times, idle restrictions have to be modified to get a carb to work on a motor w a big cam. If you get a set of pin gages, you can measure your bleeds and restrictions and know the full story, but for now let's just see if the motor us healthy enough to idle AND if you can get it to idle.
Can go from there once we have a full picture.
but you got to stop running in circles.
Do this.
1) Get a piston stop, adjust your timing mark so that your TDC mark is correct on your balancer. Disconnect your throttle cable so you can do everything by hand back at the carb. Hook up a starter switch so you can restart the motor from back there. Put an alligator clip on the end of your + coil wire so you can kill power to the coil to kill the engine from back there. Dump your fuel filter canister, refill it with fresh gas and reinstall it. You say you already regulated your fuel pressure to under 7psi, Good.
2) Set your initial timing at 12 BTDC as best you can with it running as slow as you can make it. Shut motor off before it gets too hot. Pull all the plugs and do warm compression test and write down results. Make sure they are all within 10 psi of each other. If you have access to a leak down tester, go ahead and check it as well (you do have to put each piston at compression stroke TDC to check each cyl).
3) run the motor up and down thru 3000 rpm to watch the timing advance and come back. If it does so smoothly, then let's move on. If it is erratic or nonlinear, then there is an ignition issue that needs chased down.
4) Hook a decent vacuum gauge to the motor. Tape it where you can watch it. Run the motor around 2000, then start slowing it down. Watch only for any erratic movement of the needle. It should stay steady. Slow it down as slow as it will keep running. Again, make sure the needle is steady. Erratic needle points to an issue with a particular cylinder/valvespring/valve/pushrod/cam lobe, etc.
NOW you have fresh fuel in the can, proper fuel pressure, timing is set close enough, advance mechanism is working. Engine condition is good enough to proceed. You've sprayed/checked for vac leaks and there are none.
A) set idle screws 2 turns out.
B) run motor til above 150 degrees water temp.
C) slow motor until it wants to try to stall - adjust throttle stop screw to keep it just above that.
D) watch the vacuum hauge and adjust idle mix screws for max vacuum - if motor speeds up, let it.
E) back off the throttle stop screw and let motor slow down until it wants to stall again, go back up a touch. Watch vacuum gage and repeat adjusting idle mix screws (adjust them the same, you don't want one a different number of turns). Again, go for max vacuum.
F) repeat until you can't get it to idle any slower. Always watch vacuum gadgets for erratic needle. If you get erratic needle you have internal motor issues, not carb issues.
This method should get you to a slow, stable idle. Motor may run like crap everywhere else, but it should idle.
Am very interested what your idle vacuum and rpm ends up thus way. You should see 18 or more w stock cam.
And as others have suggested, you really ought to toss a known- good running carb on it just for kicks. Your 850 Hollet may have been previously installed on a motor that required drilling out the air bleeds and fuel restrictions that otherwise would NOT be needed on your motor. A lot of times, idle restrictions have to be modified to get a carb to work on a motor w a big cam. If you get a set of pin gages, you can measure your bleeds and restrictions and know the full story, but for now let's just see if the motor us healthy enough to idle AND if you can get it to idle.
Can go from there once we have a full picture.
but you got to stop running in circles.
-I have seen 10 degrees of timing at 1000 rpms, the motor stalled out shortly after that. I have only been working on this myself and have not had a chance to watch timing advance with more throttle. I did not use a piston stop and degree wheel but I used a piece of welding wire to verify the balancer mark at TDC. I saw 15 in hg of vaccum at about 2000 rpms last week when i fired it up again. Motor stalled after that and was not able to move up and down in the rpms.
This motor is a PITA to keep running and check this stuff. It only starts decent when cold and I can rarely get it to stay running below 2000 rpms or more after warm. It takes a bunch of throttle to get it started after warm and as soon as you start backing off the throttle it stumbles and quits and there is no saving it.
On steps A-E:
I have tried all this. My next step is to put another carb on it which I have ready to go on from another boat, I just need to know what combination of gaskets/adapters/sealing plate is the correct way to do it.
04-11-2021 | 03:43 PM
#136
Registered
Joined: Nov 2004
Posts: 14,141
Likes: 3,708
From: On A Dirt Floor
Plate:
open spreadbore gasket on intake
then plate
then open squatebore gasket
then swuarebore carb
1” adapter - which is it ? Various styles ?
If completely open (no 4 throttle bore holes)
-open spreadbore gasket to intake
-soreadbore side of adapter to spreadbore gasket
-open squarebore gasket on top of adapter
- squarebore carb
open spreadbore gasket on intake
then plate
then open squatebore gasket
then swuarebore carb
1” adapter - which is it ? Various styles ?
If completely open (no 4 throttle bore holes)
-open spreadbore gasket to intake
-soreadbore side of adapter to spreadbore gasket
-open squarebore gasket on top of adapter
- squarebore carb
04-11-2021 | 07:23 PM
#137
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Registered
Joined: Jun 2020
Posts: 523
Likes: 187
From: Holland MI
Plate:
open spreadbore gasket on intake
then plate
then open squatebore gasket
then swuarebore carb
1” adapter - which is it ? Various styles ?
If completely open (no 4 throttle bore holes)
-open spreadbore gasket to intake
-soreadbore side of adapter to spreadbore gasket
-open squarebore gasket on top of adapter
- squarebore carb
open spreadbore gasket on intake
then plate
then open squatebore gasket
then swuarebore carb
1” adapter - which is it ? Various styles ?
If completely open (no 4 throttle bore holes)
-open spreadbore gasket to intake
-soreadbore side of adapter to spreadbore gasket
-open squarebore gasket on top of adapter
- squarebore carb
04-13-2021 | 01:22 PM
#139
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Registered
Joined: Jun 2020
Posts: 523
Likes: 187
From: Holland MI
Can anybody give me a part number for a spread bore base gasket with the 5 1/8" width hole pattern? The square bore gasket I got has both sets of holes but the spread bore gasket I got only has the holes 4 1/4" apart.
