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post #1 of (permalink) Old 09-21-2004, 10:14 PM
scottyhallman
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new carb and intake

Hey Guys,
Hoping the experienced guys out there can give me some help. I have a 79 bronco with a 351 Modified and t-18 transmission. I am getting ready to put an edelbrock dual plane manifold and an edelbrock 600 cfm 4barrel carb on it. I was wondering if anyone out there can tell me what jetting i need. i live in the colorado springs area and the elevation here is around 6500 feet. I also go up the mountains to about 8500 feet some times. I am wondering if this is a good setup for a 351M or is anyone else running a different carb and intake on one of these engines that has been a good performer. Thanks for any help you guys can give me.
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post #2 of (permalink) Old 09-22-2004, 02:44 AM
 
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Re: new carb and intake

The Edlebrock/Carter AFB is a good street carb and some use it with good results offroad. There are some mods you can make that I am unfamiliar with that make it less likely of puking out at steep angles. I ran one on my Bronco for awhile and it would cut out at really steep angles up or down. I then tried a Qjet and wasn't impressed with it either. I now am running an autolite 2150 and am hoping for better offroad manners. Both the 2100 and 2150s are known to be great offroad carbs. Yes you will suffer in the top end so it depends on what's important to you. Best offroad performance can be had running Fuel Injection. If you aren't going to wheel hard then the AFB will probably work great. I loved it on the street. [img]images/graemlins/smile.gif[/img]
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post #3 of (permalink) Old 09-22-2004, 03:26 AM
 
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Timming/Cam

I would highly recomend sticking an edelbrock performer cam or summit's equivilent grind and a double roller timming chain in. This will really wake up your 351m. If anything you need to change your timming gear/chain set out for a pre 73' 351 cleavland set. All the post 73 M motors have a factory timming retard (via timming gears) of somthing like 13 degree's. This is the big reason why these engines were so wimpy and gas hogs. Changing out the timming set alone is probably good for 20+ horsepower. I've changed several and it makes a BIG diffrence. Also I have a few friends running 351m's and 400m's with performer and performer RPM components and I tell you what if you change the intake,cam,lifters,timming chain and carb to matching edelbrock pieces it will feel like you have twise the power! And probably get much better mileage(if you stay out of the 4bbl) as for street and average every day offroading the edelbrock is an excelent choice. Once you set it up you dont have to mess with it. As for severe off camber situations I'd have to agree with norm. But I will say the worst carb i've ever ran on a 4x4 was a 4bbl holley. It was terrible on the street and off-road. Q-jets are awesome performers if you have a good one. Truck carbs are better the car q-jets are 850cfm truck is 895cfm. Also Pre-73 carbs are also better(non-emmision). There are alot of little tricks you can do to a q-jet to really make one perform. For downright throw you back in the seat performance a q-jet is the way to go. You can plug the vac on the actuator that holds the air dam over the secondaries shut and you will get ALOT more ummph when you kick it open. Also there is a small cam on the side that prevents the 4bbls from opening at all times remove it. You will have a 4bbl when you kick the gas pedal down. Without doing these things it will open only at higher RPMS where this way you can get it up to a higher RPM alot faster. Gas mileage wise the edelbrock is better than the Q-jet hands down. Smaller primaries=better economy.
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post #4 of (permalink) Old 09-22-2004, 08:55 PM
 
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Re: Timming/Cam

Damn Jake where were you when I had my Qjet on. I might have to pull another one on 1/2 price day and do some of your mods you mentioned. I'm going to try the autolite first but power has appeal. [img]images/graemlins/smile.gif[/img]
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post #5 of (permalink) Old 09-23-2004, 12:09 PM
 
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Re: Timming/Cam

I've bought non-emmision q-jets refurbished at Autozone for 100$ before and those are a great place to start with a little modification.
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post #6 of (permalink) Old 09-24-2004, 03:22 AM
 
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Re: Timming/Cam

I forgot to mention.... Where alot of people go wrong on Ford q-jet swaps is the intake adapter considering ford intakes are 99% of the time square bore and q-jet is spread bore. The only adapters that will work right are the 4-hole type NOT the open type those things are crap and will give you ALOT of problems. Edelbrock seems to make the best one out there. Also a Q-jet will like a bit more timming advance. And if you are running larger engine (351+) step up the accelerator pump just move the rod that runs up to the lever that pushes it down to the hole on the end if its to much back off a hole. The only reason I know about q-jets is my first 4x4 was a crap chevy. I will say i had mine in some wierd angles and never had any fuel starvation problems. A properly working q-jet will work just about any angle (except upside down) [img]images/graemlins/smile.gif[/img] And for bouncing around they aren't bad eaither. its just a matter of starting with a good one and setting it up right after that they are pretty darn trouble free. One day when I get another 460 I will most likely go the Q-jet route instead of Edelbrock considering that a 460 will really apreceate that 895 cfm!
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post #7 of (permalink) Old 09-24-2004, 08:12 PM
 
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Re: Timming/Cam

Thanx for your help Jacob. I have the open style adaptor. I wish I knew this before. You know alot about this so I'll send you another question. Off of which year chevy/model would be a good donor for the 351W? I love salvaging wrecking yards. There's something cool about bringing pieces back from the grave and put it into something you pieced together and watching it work.
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post #8 of (permalink) Old 09-25-2004, 04:35 AM
 
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Re: Timming/Cam

I would almost deffinately say that the open style adapter was your problem. The Q-jet's idle circuit will not work right with those. I've not even had very good luck with edelbrocks on those adapters always ended up with a dead spot. Anyway on what Q_jet to get....hmmmm deffinately want a truck q-jet. I would try to aim for pre-73 carb. Somthing pre EGR. The older the carb the less useless junk is on it. probably ideal years would be 68/72. The automatic choke setup is never all that great so your best bet is to convert to a hand choke. Take a look at some of the newer q-jets and then look at the older ones and you will notice the older the carb the less junk on it. I know you have an OBA setup so you might want to get one with an A/C idle kick up. Deffinately stear clear of the ones with the electronic plug on the front. If you rebuild it they can be interesting to put back together the way the metering rods and crap are setup. I can give a few tips on that. Also as I said before I'd imaging your 351w can stand for bit more advance with a Q-jet. This is somthing that you will just have to play with. I always try to run as much advance as possible without it pinging or being hard to start. Some of the older Q-jets even had a nice positive stop in the throttle before the secondaries opened!. Those are real nice but I have only seen a few. Felt like edelbrocks do that is a really nice feature. Your kickdown linkage might get interesting.. what tranny are you running? I don't remember.. I know the stupid linkage arm for the kickdown on c4's and c6's might take some fabbing to work with the Q-jet but would be worth it in the long run.
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post #9 of (permalink) Old 09-25-2004, 04:39 AM
 
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Re: Timming/Cam

ohhh one more thing I forgot to mention. You can go later years in 3/4,1 ton and heavier trucks. Alot of them had little or no emmision crap on them. Back in my young and stupid days I had a 79 1ton dually chevy 4x4 with 454/4spd(back before I knew better sigh...) anyway it came from the factory with dual exaust, no EGR, no smog pump, no cats. So the heavier trucks are a place to look. Nothing after 80 thats when they started that electronic spark advance and electronic idle mixture crap. crap is exactly what that system was too. you can't do a damn thing with it. One of chevys Gay idea's before they figured out fuel injection.
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post #10 of (permalink) Old 09-25-2004, 06:26 PM
 
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Re: Timming/Cam

Thanx man. [img]images/graemlins/grin.gif[/img] The secondaries never worked too good for me on the Qjet. Black smoke and stumbling if I got on it fast. It wasn't so bad if I engaged it slow... but what fun is that? I'll send you a pic of the Qjet I have in the garage. It's off of a pre 70s boat with a 305.
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