Go Back   The Ford Barn > General Discussion > Late V8 (1954+)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 02-10-2019, 05:16 PM   #1
quinn-grant
Junior Member
 
Join Date: Jun 2018
Location: CO Springs, CO
Posts: 7
Default More fun with Holley 4000 Teapot!

I'm hoping someone can give me some suggestions with my latest Teapot issue.

Rebuilt the carb using a Mike's Carbs kit, and everything seemed to go well (although whoever designed those secondary down-tubes was a sadist!). Car started right up, however I now have a massive flat-spot in acceleration.
Car will rev from 600RPM to about 1000 using 1/4 pedal. However from there, no increase in revs until I get to over 2/3 pedal, at which point the engine will rev all the way up as normal (same when manually manipulating the linkage).

Suspecting the accelerator pump, I watched near the main booster venturis as I moved the linkage. I'm seeing strong fuel squirt for about 1/3 - 1/2 pump travel, and then nothing for the rest of the way down.

I can only guess that the accelerator pump plunger is pulling up fuel half way, and then air the rest of the way. Although, if I'm at 1/2 throttle, shouldn't the engine rev up eventually to an appropriate RPM, pump-squirt or not? Thanks in advance for any suggestions!
-Matt
quinn-grant is offline   Reply With Quote
Old 02-10-2019, 06:34 PM   #2
scicala
Senior Member
 
scicala's Avatar
 
Join Date: Jun 2010
Location: Detroit suburb, MI
Posts: 2,253
Default Re: More fun with Holley 4000 Teapot!

If your car didn't have that condition before you rebuilt the carb, I agree it should be a carb issue. The 4000 teapot Holley carbs are difficult to work on and especially get right.
If you mean both accel pump nozzles give a steady stream for 1/3 to 1/2 of the throttle lever travel, that would be a good shot since the pump only goes down that far, then bottoms out in the pump bore. Carbs normally backfire if the accel pump isn't up to snuff, which makes it a little tough to understand. If the pump squirt is just weak, maybe there is an issue with the pump check ball in the bottom of the pump bore not being in there if the round wire clip wasn't installed when put back together. If so, most of the fuel would go back to the bowl instead of out of the nozzles. Maybe a bad seat for the check ball too. Also possibly a pump piston problem. Tough to diagnose without being there.
This is all considering your ignition system is up to snuff too.


Sal
scicala is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 02-11-2019, 06:56 PM   #3
quinn-grant
Junior Member
 
Join Date: Jun 2018
Location: CO Springs, CO
Posts: 7
Default Re: More fun with Holley 4000 Teapot!

Sal, Thank you for the reply!
I did not have this condition before the rebuild, so It's likely I dorked something up. Both accel nozzles give a strong stream for about 1/3 linkage travel, right into the boost venturis. If you're saying that's normal, then I clearly need to look elsewhere. Makes sense, else why would the pump piston have a spring!
I think the main clue is that I get no increase in RPM at all between 1/3 and 2/3 linkage travel. Even without the accelerator pump, shouldn't the RPMs increase linearly with the butterfly valve, just not as immediately?
Thank you again for the advice!
-Matt
quinn-grant is offline   Reply With Quote
Old 02-11-2019, 10:19 PM   #4
scicala
Senior Member
 
scicala's Avatar
 
Join Date: Jun 2010
Location: Detroit suburb, MI
Posts: 2,253
Default Re: More fun with Holley 4000 Teapot!

Quinn, yes, it's very strange that the engine won't accelerate at all when between 1/3 and 2/3 throttle. Also kind of tells me it's not really a lean condition, or it seems like it would backfire out of the carb. Don't know what to tell you without being there, other than recheck your work and all of the channels in the carburetor.


Sal
scicala is offline   Reply With Quote
Old 02-12-2019, 04:27 AM   #5
fiddy6
Member
 
Join Date: Jul 2018
Posts: 33
Default Re: More fun with Holley 4000 Teapot!

What is the choke doing through all this?

I reassembled my teapot recently and had issues with the choke not opening properly.
fiddy6 is offline   Reply With Quote
Old 02-13-2019, 01:08 PM   #6
packrat5
Senior Member
 
Join Date: Mar 2015
Location: Wisconsin
Posts: 180
Default Re: More fun with Holley 4000 Teapot!

Do you have the pump arm in the recommended position?
packrat5 is offline   Reply With Quote
Old 02-13-2019, 07:38 PM   #7
quinn-grant
Junior Member
 
Join Date: Jun 2018
Location: CO Springs, CO
Posts: 7
Default Re: More fun with Holley 4000 Teapot!

Good news is I've pretty much fixed the problem. The detailed solution is very complicated, but the short answer is: I'm a knuckle-head.
Turns out the accel pump is just fine. I sat in the car watching the entire linkage as I pushed on the accelerator pedal just to see what was happening. Turns out the throttle rod never moved -- it was just sliding immediately up the kickdown slot without pulling on the carb linkage. Only when it topped out in the kickdown slot was it forcibly pulled back, explaining why no RPM increase until over 1/2 pedal travel.
Then I did something crazy -- I followed the instructions on how to set the throttle rod length/position! With a phillips screwdriver through the linkage guide holes, the throttle rod stuck out a good 1/2" past the hole in the carb linkage. Not sure how, but fixing that made all the difference. The kickdown spring now holds the throttle rod in the down position for as long as it is supposed to. Next job is to fix the choke as you suggest, fiddy6, as it is clearly way off!
Thank you all for your patience with this newb!
-Matt
quinn-grant is offline   Reply With Quote
Old 02-13-2019, 09:41 PM   #8
scicala
Senior Member
 
scicala's Avatar
 
Join Date: Jun 2010
Location: Detroit suburb, MI
Posts: 2,253
Default Re: More fun with Holley 4000 Teapot!

Thanks for posting what you found.


Sal
scicala is offline   Reply With Quote
Old 02-13-2019, 10:37 PM   #9
miker98038
Senior Member
 
miker98038's Avatar
 
Join Date: Mar 2013
Location: Kent, WA. Tucson, AZ
Posts: 603
Default Re: More fun with Holley 4000 Teapot!

Well, if you just joined the knuckle head club, especially on the kick down linkage, you’re 52 years behind me. And I’m still re upping my membership on a regular basis. Thanks for following thru on the solution.
miker98038 is offline   Reply With Quote
Old Yesterday, 01:52 AM   #10
fiddy6
Member
 
Join Date: Jul 2018
Posts: 33
Default Re: More fun with Holley 4000 Teapot!

The choke issue I had was when I reassembled it. When cold it stayed completely closed until full throttle. Letting off the throttle would slam it shut. I'd have to pull the air cleaner off and pull the choke cam forward to open it a little... it would start then and operate normally as it warmed up.
fiddy6 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 11:34 AM.