67 Bronco: 170 Engine – Carb & MSD Questions

Long-time lurker, first-time poster here. I’ve read a lot on this forum and the Falcon Six handbook but have a few questions I’d like to pose for feedback, please.

I have a 67 Bronco used for street-only, casual, local driving 2-3 times a week (no off-roading).

Goal: Better consistency with starting/idling/running, additional pep/power, hopefully a little higher top-end speed just for occasionally getting on highway, etc. Not necessarily concerned with gas mileage.

Current setup: 170 stock engine (54k miles), Autolite 1100 carb with Load-o-Matic distributor, Pertronics Ignition & Coil, 3 speed manual transmission

Parts I Have But Not Yet Installed: DSII (from ws111 here on the site), Pertronics 8.0 Spark Wires, Headers, 2” single exhaust system

Parts Planning to Buy Short-Term: MSD-6al and MSD cable adapter #8869, Better, bigger carb, 2 to 1 Carb Adapter

Longer Term Plan (probably a year from now): Get 77+ 200 head modified to accept direct bolt-on 2 barrel carb, better CAM, and other build recommendations from Falcon Six Handbook

Questions:

Given current engine is stock 170, would I be better off going with a larger 1 barrel carb rather than a 2 barrel with adapter? I was planning to get an Autolite 2100 (1.02 or 1.08) and a 2-to-1 carb adapter but I’m wondering if this will work ok or if I should get a single barrel instead since it is clearly noted that larger isn’t necessarily better. I’ve read a few posts where people have used the Autolite 2100 with an adapter and have been pleased with the results but those have been on 200 Engines so I wasn’t sure if expecting similar results on a 170 is realistic. I’ve also considered a Weber 32/36 but I’m a carb novice and would probably do better with something easier to tune/maintain.

MSD 6AL – Will adding this over the stock Ford or GM module make much difference? Does MSD part number 6200 vs 6420 vs 6421 vs 6425 matter?

DSII – Is there a particular distributor cap recommended?

Adding the Wsa111 curved DSII that you have will be by far be your biggest improvement towards your goal of the better starting, idling, and running. Even using it with a stock Motorcraft (or NAPA) control box and coil the difference is like night and day. For distributor caps and other Ignistion parts, I like to use Autolite or Motorcraft plugs along with high a quality cap, rotor (these will have brass contacts) and the better plug wire sets, NAPA has them as well as some others. The 170's are a good engine and the same mods as used on a 200 will work quite well. Good luck

2X what he said !

I'd get the DSII full system, but that's just me. That's the ford module - use the one w/the blue strain relief(at the place where the wires come out). It's available, reliable, more peppie, inexpensive, durable. No real gain w/the MSD for the expense. I'm not sure how the petronix/DSII work together. Esp. w/the LOM/SCV (assume U will ditch them).

You're never gunna get modern econobox (my DD is an 01 ford focus) pep from a motor designed as a lill tractor (my 170 is still in & I've been drivin it since 1983 - for 2 lane DD/wrk off rd/trailer haulin). However these and other suggestions will move U along the rd. better. Think abt a modern cam. Some change them w/o engine removal…

Thanks very much for the feedback.

Chad, yes, I'll be doing away with the Pertronics part of the equation as well as the LOM/SCV carb. Hadn't really thought about making CAM improvements on the 170 and had kinda just jumped ahead thinking about replacing with a 200 head. I'll definitely give that more consideration and appreciate you pointing out that option.

Bubba, I think you have the 200 head in the for sale section I've been keeping an eye on. I'm not familiar with exactly what the references I see occasionally for 'Fox Chasis'. I know it's a reference to Mustangs but that's the extent of what I know about it. Anything about the larger head you have from the fox chasis that would pertain to putting it in a Bronco/any reason for concern? I'm thinking probably not but thought I'd ask to be sure. As far as the smog parts, EGR, can those be capped off? I don't know that it would even be necessary, I just seem to remember someone on the Bronco forum saying something along these lines at some point.

Hi, my 66 Bronco is basically stock, original carb and ignition. The engine was rebuilt once in 1990. It starts every time (after some gas pedal pumping when cold, right away when being used) has decent pickup with 3.50 gears, does 60-65 MPH no problem and get @15 MPG. What do you expect from a Bronco? I have a very good tune up on it with the best quality parts. I would do a compression test before anything else. Have fun.

B RON CO":1bzz3glu said:

Hi, my 66 Bronco is basically stock, original carb and ignition. The engine was rebuilt once in 1990. It starts every time (after some gas pedal pumping when cold, right away when being used) has decent pickup with 3.50 gears, does 60-65 MPH no problem and get @15 MPG. What do you expect from a Bronco? I have a very good tune up on it with the best quality parts. I would do a compression test before anything else. Have fun.

Click to expand...

I haven't had the Bronco very long but I absolutely LOVE it. I've only driven it very close to home around my neighborhood due to an intermittent issue I have going on that I haven't figured out yet. Occasionally it will be running fine but then when I'm at a stop sign the next thing I know it won't accelerate. It will stay running and will continue idling but when I give it gas it doesn't accelerate/the engine doesn't rev and doesn't move forward. Most of the time after a few minutes it will pick back up and will accelerate and will move forward enough to get it back home. Then I'll park and get in it the next day to take it for a drive and it will act fine. Sometimes I can take a drive in it for 20 minutes or so 3 days in a row and I don't have any issues but it inevitably comes back at some point. I changed from points to a Pertronix ignition and coil a couple of months ago and then changed the accelerator pump last weekend but that didn't solve the problem.

I'm not much of a mechanic and just kind of learning as I go. I don't expect it to be a speed demon by any stretch and I haven't had it on the highway so I don't even know how fast it will go.

Thanks for the compression test suggestion. I thought about that last week and will definitely plan to do that.

"…not much of a mechanic…"
ur doin FINE swerve, if U put a prt in a carb ! (acc pump)

I'm wondering if U got a SCV to match ur LOM dizzy…
(remember the Classic Inlines tech pages referral. It will bring U up to speed on this system).

For those who want more mpg a fella w/that name did some wrk to increase mpg. Use the search above to find his thread. A 170/200 should get 20 mpg easy - in good tune.

The Fox chassis description pertains to quite a number of the late 1970's up Ford, Mercury, and even Lincoln's. Of corse in the case of the last few of the 200 engines built they were offered in the US market in the Ford Fairmonts & Mercury Zephyrs beginning in 1978 as well as the Mercury Capris & as you said the Mustangs in 1979 up to 1982. These late 200 heads (some 1980, all 1981 & 1982) have the largest logs and like the 1977 and up heads stock will also have the biggest intake valves and hardened valve seats. The I6 heads from at least 1974 and up have the hard seats, that was needed for them to survive when the Feds mandated unleaded fuels. The later heads are a little different externally from the earlier heads but are still completely interchangeable. The smog system parts are all external parts, so yes they could be left off and or capped off.

From your description it sounds like your carb sure needs a rebuild or at least a new needle and seat, plus and or the float needs to be repaired or replaced. Good luck

Oh good another Bronco!
What size tires do you have and do you know what gears? Probably 4:11 you should hit 65 on the highway unless huge tires if you want to listen to it that is. What headers do you have? As stated definitely get the DSII on it is a big improvement and you might be happy with a single barrel Autolite or Carter off a 200 I think that is the way I would go with a 170. These two mods will make a difference if your motor is sound the compression test will tell you what you have going on. Getting that late model head from bubba would be great addition to the DSII and carb.
You should already have a 2" exhaust system mine does.
There's nothing more fun than driving a Bronco.

bubba22349":260wluu8 said:

The Fox chassis description pertains to quite a number of the late 1970's up Ford, Mercury, and even Lincoln's. Of corse in the case of the last few of the 200 engines built they were offered in the US market in the Ford Fairmonts & Mercury Zephyrs beginning in 1978 as well as the Mercury Capris & as you said the Mustangs in 1979 up to 1982. These late 200 heads (1981 & 82) have the largest logs and like the 1975 and up heads have big valves and hardened valve seats that was needed to survive when the Feds mandated unleaded fuels. The heads are a little different externally from the early heads but are still completely interchangeable. The smog system parts are all external so yes they could be left off and or capped off.

From your description it sounds like your carb needs a rebuild or at least a new needle and seat, plus or the float needs to be repaired or replaced. Good luck

Click to expand...

Thanks for the info! You're probably right on the carb issues. I think it's carb related, too. Rather than getting the carb I have rebuilt (Autolite 1100 with the SCV) I've been planning to get a different one, plus I got the DSII so would rather replace the carb rather than messing with plugging the SCV on the one I have. I've been thinking I'd go with an Autolite 2100 and 2-to-1 adapter but the last few days have been leaning more towards going with a single barrel. Sounds like from Bmbm40s feedback that's probably the better route to take for now and I think I'll probably go with a different single barrel.

bmbm40":1mq7z6af said:

Oh good another Bronco!
What size tires do you have and do you know what gears? Probably 4:11 you should hit 65 on the highway unless huge tires if you want to listen to it that is. What headers do you have? As stated definitely get the DSII on it is a big improvement and you might be happy with a single barrel Autolite or Carter off a 200 I think that is the way I would go with a 170. These two mods will make a difference if your motor is sound the compression test will tell you what you have going on. Getting that late model head from bubba would be great addition to the DSII and carb.
You should already have a 2" exhaust system mine does.
There's nothing more fun than driving a Bronco.

Click to expand...

The tires I have on it right now are just small/stock tires that came on it when I bought it. I don't know the size but their pretty narrow. Bronco has uncut fenders which I'll be leaving as they are so it won't ever have very large tires on it. I have some new tires I bought but they aren't on it yet and they are 31 x 10.5. The headers I have (also not installed yet) are the 'speed daddy' headers mentioned in some of the other posts. Yes, the current exhaust is either 1.75 or 2" but it's in pretty rough shape and needs to be replaced so I've got a new 2" exhaust system stacked among the other parts that I've been accumulating over the last couple of months As far as the gears go I really don't know but would guess they are probably 4:11 if that's what most of the 3-speeds came with originally. Pretty much everything as far as I can tell is what came on the truck originally other than the fuel pump and then the radiator which I replaced recently.

Thanks for the feedback on the carb size. That's kinda what I've been thinking and likely what I'll go with (single barrel from a 200).

chad":n4mcoelb said:

"…not much of a mechanic…"
ur doin FINE swerve, if U put a prt in a carb ! (acc pump)

I'm wondering if U got a SCV to match ur LOM dizzy…
(remember the Classic Inlines tech pages referral. It will bring U up to speed on this system).

For those who want more mpg a fella w/that name did some wrk to increase mpg. Use the search above to find his thread. A 170/200 should get 20 mpg easy - in good tune.

Click to expand...

Yes, I've got the SCV on the carb. I know the classic inline tech pages well What a wealth of info! That's actually how I found this forum was from the CI site a few months ago.

"…Classic Inline tech pages well What a wealth of info!…"
Unfortunately the guy who developed that (not sure if it wuz single handed) just passed away.
He also developed the CI sales co. AND spun off this site as well. He developed an alu head, tested, raced, advised… Quite a guy!

One of our (ford6) 'members' has upgraded this site (pic function much better, other enhancements) and developed a test site because the owner did not plan on his succession so no "keys" to this or the CI site (can't correct the money acceptance/no parts left to sell problem over there). Another member is beginning a new ford6 or Falcon Motor parts sales company (a sorta replacement for CI). So stay tuned for the results of the mostly volunteer effort to carry on after this yr. (March to March) of changes…

OK uncut is good. Going from the stock size tire to the 31's you will notice a slightly lower rpm than before, not much but will decrease some engine noise on the highway. Will probably notice slightly decreased acceleration. You may want to mount one 31x10.5 and test fit rear of vehicle. Use your spare. See if you have clearance problems. The 31's look nice on the Bronco more so uncut with little or no lift in my opinion. If your Bronco appears to sit low in the back it is because the rear springs are old and sagging.
Just something to consider is finding a 200 and rebuild it while driving your 170 around. Swap the rebuilt in when done and no downtime. With a mild cam and bubbas late model head and all your other goodies and you should have plenty of power for what you use it for.
A good Bronco site is classicbroncos.com for general Bronco info but there is not much six cylinder stuff on there.

"…probably 4:11 if that's what most of the 3-speeds came with originally…"
I think it's "motors/rear gears" matchin. Yes, we better look at the whole drive train (tire sz, rear gear, transfer, displacement).
If you have no tag on ur rear end (decode it to get ring/pinon sz) & can't find castings to figure it - count tire rotations versus drive shaft & that will give U r/p gear w/o opening the third member 2 count teeth.

Speaking of tire…can U guys get nine fifty width tires? Back East it's getting harder to get that tire. Esp @ 33 inch tall.

Hi, remember to match the carb and distributor. If you have the original load o matic I would get a rebuild kit for it and some carb cleaner and clean it up. The carb kits, we used to call them Hy-Grade kits, are on e-bay for $20. They come with great instructions. A one barrel should take a couple of hours to do the whole job. I've cleaned up plenty of old carbs this way and it works great unless the throttle shaft is worn out. It is a good learning experience and you will get a lot of satisfaction out of actually fixing something. When you upgrade to a ds11 you can put the old carb and distributor on the shelf. By the way my Bronco has 31 x 10.5 tires with a 3" lift and stock sheet metal. Good luck.

"…a 3" lift and stock sheet metal…."
"LUEBer"
Lifted Uncut Early Bronco
8)