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Reccomendations on 4bbl carb

bluesbish

Full Member
Joined
Jan 30, 2011
Messages
278
Loc.
Upstate New York
I am currently running a factory ford holley off of a mid 80's windsor HO on my 351. I modified it slightly for off road use with a crossover vent tube. It is functioning well on the street at this point other than a long delay before the secondarys open, and on cold start I have to feather the throttle for about 20 seconds before it will stay running on high idle. I have high idle set at about 1400 rpms, it used to stay running at about 1800 on start up but I did not like it so high so I turned it down some, I have adjusted the choke t-stat to where I think it should be and that seems to be opening at a normal rate of time. Should I keep tinkering with this thing or purchase a q-jet or holley TA? Please spare me the lectures on how I should convert to Fuel injection, I am well aware of the benefits and have considered it long and hard while I was building this bronco and decided to stay carbed. If I convert to Q-jet, should I just grab a non feedback type from a chevy 350 and bolt it on with necessary adapter? Or are there modifacations I should make on the q-jet? I am looking for jump in the truck, pump accelerator pedal once, turn key and drive!! and of couse maintain good manners offroad. not doing extreme rock crawling or anything but some nice trail riding with obstacles. I used to have a 460 in a f350 with factory holley that never stumbled ever no matter what, that is what I was trying to reproduce with the carb I am running now. Thanks for any ideas guys.
 

TN1776

Bronco Guru
Joined
Oct 24, 2006
Messages
2,632
I'm not too familiar with Holley carbs so I'll share a little of what I know about the qjet swap...

I run a 1978 Camaro quadrajet that I rebuilt with a $20 kit from the local parts store. Its bolted to the adapter plate sold by BCB and I've done nothing else to it. It runs pretty well off road and while rock crawling. It starts to misbehave a little when I get really high up in elevation (8000+ feet) but I can keep it going. My Bronco came with the factory dash throttle control and I've found that when its getting unhappy in high elevations that setting the idle up to about 1000 rpms will keep it lit for the most part.

I am sure that I could adjust the mixture at high elevations and get past some of this. It acts like its vapor locking but I've cured most of that by running insulated base gaskets above and below the adapter plate, and insulating my fuel supply line from the pump all the way to the carb. Its not perfect but it will work for me until one day I upgrade to EFI.

I hope this helps.
 
OP
OP
bluesbish

bluesbish

Full Member
Joined
Jan 30, 2011
Messages
278
Loc.
Upstate New York
Great info, thanks. I am nowhere near 8000 feet so that does not concern me. So you just rebuilt a q-jet from a 78 camaro and bolted it on and you are good to go? do you get the pump it once, fire it up and drive off affect that I am looking for?
 

TN1776

Bronco Guru
Joined
Oct 24, 2006
Messages
2,632
Great info, thanks. I am nowhere near 8000 feet so that does not concern me. So you just rebuilt a q-jet from a 78 camaro and bolted it on and you are good to go? do you get the pump it once, fire it up and drive off affect that I am looking for?

That's pretty much it. I forgot to mention that I added an electric choke which works pretty well but adjusting it takes a little bit of trial and error. If I drive it once every few days its definitely the pump once, fire it up performance that you're looking for; if it sits for a week I have to crank it a while to get the fuel pumping back up to it, but I know that an electric fuel pump would solve that problem. I really like that it has small primaries and huge secondaries; stomping on the throttle wakes it up pretty well. I live near sea level and its pretty much dialed for home where 90% of my driving takes place.

I went this direction because the carb was given to me for free, but overall I have no complaints.
 

fungus

Bronco Guru
Joined
May 27, 2009
Messages
1,548
Loc.
Kaneohe Bay, Oahu
I'll say my experience w/ the Q-jet is slightly better than 1776's. I pulled one for $8 at the junkyard off a '79 Buick. It looked so clean I just sprayed the outside w/ carb cleaner and didn't even rebuild it! On it went w/ the adapter plate and BC throttle cable. I robbed an electric choke from a Rochester 2 barrel and converted it. Thing has run flawlessly from sea level to wheelin' at over 8000' in Big Bear, CA. Never stumbles, loads up or dies and fires right up no matter how long she sits. I've had it sit for almost 3 months and gone out, 1/4 throttle to set the choke & crank. She'll fire by the 3rd rev of the crank everytime and settle into a sweet 1100 RPM idle. Hit the throttle to disengage the choke and she drops right down to 650 and stays there all day every day. I decided to build an EFI 5.0 on my back porch that's about 3/4 the way back together. NOT because of carb issues but just because I had all the parts! Kindof scared to tell you the truth cuz I don't want to F up a perfectly great runnin' rig!
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
Keep tinkering with what you have when you get it right you'll be happy again. As for the secondaries they open when needed and you should never feel them kick in if you do they are actually opening to soon. I'm not real big on the holleys that were factory installed in the 80's as they are emissions carbs but still a the standard tuning process applies you can get a spring kit to tune the secondaries to open how you want. You cohke issue is just a adjustment issue get a manual on how to actually set the choke and follow it setting where you think it should be doesnt always mean its correct.
Even if you get a new carb you'll more than likely need to tune it as well.
 
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