CarburetorsCarb discussion and questions. Upgrading a Third Gen carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
Welcome to ThirdGen.org!
Welcome to ThirdGen.org.
You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!
To the OP,
I currently drive a 5 speed/Cammed 350 car with a Holley 670 truck avenger(got it for a rebuilt q jet). As Far as drivability goes, if i cruise, it does great, but just as five7kid was trying to explain, if i go WOT and bang shift the wee out of it, there is a second where the secondaries are still open right after i change gears, most of the time this is not a problem, but i have had it cause me to bog a bit from time to time. As far as looking at used carbs, i personally will buy a new carb before i buy an old one a rebuild it. Youll save maybe half of what a new HP carb cost, but will have none of the benefits. Compare a new 670 street avenger, or a new 4165, then debate on all the unknowns of the ebay carb. Only reason ive brought this up is ive gone the cheap route, and its been a bitch and a half at times. Rebuilt a double pumper to later find out whoever cut off the choke tower got aluminum flakes inside the carb (dont ask me how) and ruined one of the metering blocks.
Just my opinion.
This ad is not displayed to registered members. Register your free account today and become a member on ThirdGen!
Sponsored Links
Registered users do not see this ad. Click here to register for free!
if i go WOT and bang shift the wee out of it, there is a second where the secondaries are still open right after i change gears
Couple of questions....
This is whats confusing me about it. With a vacuum secondary You get this flare(Secondaries stay open after you shift.) I could never tell on mine, but on yours you say you can tell if you speed shift(bang shift the wee out of it)
1. OK, if you speed shift a double pumper they stay open as well. So whats the difference ?
2. Maybe on mine, since I had much bigger heads, cam,ect. Them being opened didnt hurt it as much. Because it could actually use that extra air ?
3. Also why do the factory Holleys on the Fords not have this problem ? Being a Ford has nothing to do with it. 95% of the time people do use too big of a carb. Maybe this is only a problem if your carbs too big to begin with ?
This is whats confusing me about it. With a vacuum secondary You get this flare(Secondaries stay open after you shift.) I could never tell on mine, but on yours you say you can tell if you speed shift(bang shift the wee out of it)
1. OK, if you speed shift a double pumper they stay open as well. So whats the difference ?
2. Maybe on mine, since I had much bigger heads, cam,ect. Them being opened didnt hurt it as much. Because it could actually use that extra air ?
3. Also why do the factory Holleys on the Fords not have this problem ? Being a Ford has nothing to do with it. 95% of the time people do use too big of a carb. Maybe this is only a problem if your carbs too big to begin with ?
When you shift, theres a second when your foot isnt mashing the gas, a double pumper will close the secondaries as soon as you let off enough, a vacuum secondary will not, it takes a moment for them to close. My bog could be caused by a number of things working together, but i didnt have the bog when i did a a few test runs with my friends Holley HP with mechanical secondaries. Its only something i have noticed with my truck avenger, but like i said its nots everytime, typically happens when im at the track.
1. OK, if you speed shift a double pumper they stay open as well. So whats the difference ?
The point is you shouldn't speed shift a T5. I know the OP indicated he wasn't going to do that, but for everyone else reading this thread with its very generally-worded subject line, you 1) shouldn't speed shift a T5; and 2) if you have a T5, you should use a mechanical secondary carb just in case you get a hair someday and decide to do some spirited driving.
Ok, so its not necessarily the best choice for a manual trans. Just best if you have a Chevy T-5 ? Im not saying thats wrong. Im just trying to make sense of all this. Like most others probably are. lol I always let off the gas when shifting too. Even when racing. Maybe thats why I never noticed it.
five7kid, My intentions were not to confuse anyone, i run a tremec 3550. To the OP, its not because its a gm t5 that a mechanical secondary is the best, its because its a 5 speed in general. five7kid is saying use that "in case" you do some spirited driving as it will act much better then a vac secondary. Although i personally wouldnt beat on it with a t-5 since i grenaded one behind the H.O. 305 my car had origionally.
five7kid, My intentions were not to confuse anyone, i run a tremec 3550. To the OP, its not because its a gm t5 that a mechanical secondary is the best, its because its a 5 speed in general. five7kid is saying use that "in case" you do some spirited driving as it will act much better then a vac secondary. Although i personally wouldnt beat on it with a t-5 since i grenaded one behind the H.O. 305 my car had origionally.
Ok, thats what I thought. I still dont understand why its OK on a Mustang, and not on a Camaro. A engine is a engine, a carbs a carb, and vacuum is vacuum. No matter what brand the parts are. If it does it on one car, it should do it on all cars right ? I know if it was really a problem though Ford wouldnt have mass produced the combination. Especially as well as those cars ran. The '85 was one of the fastest 5.0 stangs. It had a factory 4180 Holley vaccuum secondary carb on it. That was my first "performance" car. Im NOT saying your wrong. I've read that several places. It just doesnt make sense why its OK for one and not the other. You understand what I mean ? Was there something different about those carbs ? If so, then get one from a junkyard and rebuild it. At 580 cfm's it would be about perfect for his 305.
If it does it on one car, it should do it on all cars right?
Not all cars are created equal. Ford may have been getting the T5 from another manufacturer than GM did. Ford may have had a different throttle setup than GM did. Ford may have had a special setup in the clutch that GM didn't. GM could have made an engine more powerful than the T5 was designed for. God could have blessed Ford with unnatural transmission life. God could have blessed GM with shear amounts of raw power. Maybe Jupiter was in the right spot on the right day when Ford put a VS carb together with the T5. Etc. Ect. Ect.
There are so many what ifs between a VS carb on a Ford and a VS carb on a GM that it would be illogical to assume that what works for one is going to work for the other.
1." Ford may have been getting the T5 from another manufacturer than GM did."
This wouldnt matter if this is the rule for ANY manual transmission"
2."Ford may have had a different throttle setup than GM did."
That would be in the carb. Which was built by Holley
3."Ford may have had a special setup in the clutch that GM didn't."
See answer for #1
4. "GM could have made an engine more powerful than the T5 was designed for."
They did. Thats why you could only get an auto 5.7L. What does that have to do with it ?
5. "God could have blessed Ford with unnatural transmission life.
God could have blessed GM with shear amounts of raw power. Maybe Jupiter was in the right spot on the right day when Ford put a VS carb together with the T5. Etc. Ect. Ect.
lmao. Nothing to do with anything I asked......Funny though.
6. "There are so many what ifs between a VS carb on a Ford and a VS carb on a GM that it would be illogical to assume that what works for one is going to work for the other."
A VS carb works the same on both engines. Vacuum is vacuum. No matter what the source is. It has nothing to do with the engine itself. Unless the vacuum stops instantly on a Ford. When you let off the throttle.
1." Ford may have been getting the T5 from another manufacturer than GM did."
This wouldnt matter if this is the rule for ANY manual transmission"
Borg Warner didn't build all of the T5's ever made. Borg Warner built and sold T5's until they sold their design to TREMEC. As far as I understand, you can't take a Ford T5 and mate it to a GM engine. And at that, I can just about guarantee that even while Borg Warner owned the design, they weren't manufacturing every transmission being supplied to OEM's. I'll bet they farmed alot of it out to suppliers for both GM and Ford.
Quote:
Originally Posted by Z2887
2."Ford may have had a different throttle setup than GM did."
That would be in the carb. Which was built by Holley
As far as I know, Rochester was the major OEM carb for the Thirdgen from 82-88 for GM. I've found nothing on Holley being a supplier of OEM carbs for either Ford or GM.
Quote:
Originally Posted by Z2887
3."Ford may have had a special setup in the clutch that GM didn't."
See answer for #1
As far as I know, you can't take a Ford clutch and use it in a GM drivetrain.
Quote:
Originally Posted by Z2887
4. "GM could have made an engine more powerful than the T5 was designed for."
They did. Thats why you could only get an auto 5.7L. What does that have to do with it ?
GM severely doubted that the T5 would hold up to a stock LO3, LG4, or LB9. And at that, they were doubtful that a 700R4 would hold up to either of those engines or the L98.
Quote:
Originally Posted by Z2887
5. "God could have blessed Ford with unnatural transmission life.
God could have blessed GM with shear amounts of raw power. Maybe Jupiter was in the right spot on the right day when Ford put a VS carb together with the T5. Etc. Ect. Ect.
lmao. Nothing to do with anything I asked......Funny though.
Anything can and will happen when human hands and heads are involved in making anything. And sometimes its just plain amazing what happens.
Quote:
Originally Posted by Z2887
6. "There are so many what ifs between a VS carb on a Ford and a VS carb on a GM that it would be illogical to assume that what works for one is going to work for the other."
A VS carb works the same on both engines. Vacuum is vacuum. No matter what the source is. It has nothing to do with the engine itself. Unless the vacuum stops instantly on a Ford. When you let off the throttle.
I know that vacuum works the same either way. What I'm getting at is that no one really knows all the ins and out of this type of setup on BOTH Fords and GMs. For all I know, Ford could have a valve that controls the amount of vacuum on the secondaires on the carb that is connected to the throttle cable and calibrated so that it opens the secondaries based on throttle position and not just pure vacuum. So if that vacuum suddenly decreases, the secondaries close in response to lower vacuum.
As far as I understand, you can't take a Ford T5 and mate it to a GM engine.
Really no kidding maybe has something to do with different bell housings
As far as I know, Rochester was the major OEM carb for the Thirdgen from 82-88 for GM. I've found nothing on Holley being a supplier of OEM carbs for either Ford or GM.
Holley/Autolite made carbs for Ford.
I know that vacuum works the same either way. What I'm getting at is that no one really knows all the ins and out of this type of setup on BOTH Fords and GMs. For all I know, Ford could have a valve that controls the amount of vacuum on the secondaires on the carb that is connected to the throttle cable and calibrated so that it opens the secondaries based on throttle position and not just pure vacuum. So if that vacuum suddenly decreases, the secondaries close in response to lower vacuum.
If you dont know the ins and outs of Ford carbs why open your mouth and talk about something you dont know about ? His question is valid and until you are able to answer it without all your BS, I would quit talking.
If you dont know the ins and outs of Ford carbs why open your mouth and talk about something you dont know about ? His question is valid and until you are able to answer it without all your BS, I would quit talking.
Wasn't saying I knew anything. In fact I know less than either you or him about carbs. But I do know enough to know that there are similarities between each manufacturer as well as differences. I was simply pointing out that just because they both look similar doesn't mean they are identical.
Guys, first of all read post 28 again please. That explains how the carb works. To be honest theres a million variables that can lead to one carb running great on one car and running differently on another. Despite the differences in both motors, im sure a mechanical carb would run better on the ford then the vacuum as long as it was behind a manual.
"Borg Warner didn't build all of the T5's ever made. Borg Warner built and sold T5's until they sold their design to TREMEC. As far as I understand, you can't take a Ford T5 and mate it to a GM engine. And at that, I can just about guarantee that even while Borg Warner owned the design, they weren't manufacturing every transmission being supplied to OEM's. I'll bet they farmed alot of it out to suppliers for both GM and Ford."
Right, but I still dont see who made the tranny has to do with anything we're discussing.....IF the rule applies to ANY manual transmission car.
"As far as I know, Rochester was the major OEM carb for the Thirdgen from 82-88 for GM. I've found nothing on Holley being a supplier of OEM carbs for either Ford or GM."
About everyone supplied Ford with carbs at one time or another. Carter, Holley, a few even came with quadrajets. Holley supplied the ones for the 79-85 Mustangs/Capri's though.
" For all I know, Ford could have a valve that controls the amount of vacuum on the secondaires on the carb that is connected to the throttle cable and calibrated so that it opens the secondaries based on throttle position and not just pure vacuum. So if that vacuum suddenly decreases, the secondaries close in response to lower vacuum."
Well if that is the case, then THAT would answer my question. Which is what Im looking for. Except it needs to say that without the "For all I know" in front of it. Its "For all I know" too. Which is why I asked the question. Because I dont know.
Guys, first of all read post 28 again please. That explains how the carb works. To be honest theres a million variables that can lead to one carb running great on one car and running differently on another. Despite the differences in both motors, im sure a mechanical carb would run better on the ford then the vacuum as long as it was behind a manual.
I tend to agree...Depending on what is meant by "better". I would guess Ford used a Vacuum secondary carb for "better" gas mileage, and emissions purposes. Which is the posters goal. I have read that "a mechanical secondary carb works better on stick cars". That statement has always been followed by "with steeper gears, and large cams" though.
Maybe,........but that is one of the reasons I started this thread, Ive learned more about carbs and what to look for when choosing one for a particular application, and what, if any, drawbacks there are when selecting a certain carb.And I can say it hasnt made the selection of said carb MILES easier (mostly due to cost), but now I am armed with the knowledge to make a better decision as to what would best suit my needs for my particular application.......1st thing is that ANY PROPERLY FUNCTIONING CARB wiil produce serious gains in not only MPG but performance as well, Its just weather I lean towards performance or MPG, VS -better MPG vs MS - Better performance.........but in my own mind I am getting a MS Holley - probobly a 4165 for two reasons; first I like it when Im smater than the car I drive, ie: it does what I tell it to do, so I am kinda diggin the fact that the secondaries open when I want them to....and if I keep my foot out of it I should get just as good MPG as a VS unit, second 4165s are a dime a dozen MANY a Q-Jet replaced with them waiting to be had as a used or rebuilt unit. A close third no more Bog when the secondaries open....or so Ive heard. But like Ive stated Im not looking for a $hit ton of performance from my 84 T/A YET......Id settle for not taking out a loan just to keep gas in the damn thing....the main reason the Q-Jet gotta go....and for Five7Kid, If I could afford to keep the Superior Performance of the CC Q-Jet I would but right now its not a finacially feasable option right now.....now when I get the 350 in spring..........
I never found a good answer to the 4165 electric choke question. I didn't take the time to hook up a cable, so I just suffered through the cold engine poor performance until the engine warmed up a little. It was summertime, so it wasn't as bad as it would have been if I had tried that during the winter.
My q-jet doesn't bog at all. I haven't done anything special on it, just set it to specs.
I never found a good answer to the 4165 electric choke question. I didn't take the time to hook up a cable, so I just suffered through the cold engine poor performance until the engine warmed up a little. It was summertime, so it wasn't as bad as it would have been if I had tried that during the winter.
My q-jet doesn't bog at all. I haven't done anything special on it, just set it to specs.
His q-jet should have had an electric choke on it from the factory, if the 4165 has one he can just hook up the existing wire, if it doesnt he can get the electric choke kit from summit for rather inexpensive.
There are no mysterious car Gods fellas, let's stop throwing our hands up in the air and blaming the machine spirit for the way things function and instead attempt to understand them.
1) Holley = Autolite, similar to carter = Edelbrock. Autolite/holley 550 and 600 CFM Vacuum Secondary carburetors came factory on 5 liter 5 speed mustangs for a good deal of the "Fox Body" mustang's production up until the implementation of EFI in that particular model of car. Ford did NOT have some sort of mystical vacuum valve that controlled the secondaries. They just slapped the carb on there and called it a day, and for all intents and purposes it worked.
According to this forum and many owner testimonies, GM T5's and Ford T5's are not the same transmission. Why this is escapes me, save perhaps investing in a cheaper variant to save money. World Class T5's can be purchased for our vehicles.
The VS bog theory 5-7 has presented makes some sense. I will be testing it with my own vehicle (having both a 600 cfm VS holley and a spread bore DP). I'll let you know what I think. Fear not, I doubt my impressive 143 HP dyno'd will grenade my transmission.
Did you know Mustands weigh almost 1000 lbs less than a firebird and put out 50 more HP and 50 more ft-lb factory? How suck is that . Oh well, my car is sexier.
According to this forum and many owner testimonies, GM T5's and Ford T5's are not the same transmission. Why this is escapes me, save perhaps investing in a cheaper variant to save money. World Class T5's can be purchased for our vehicles.
The VS bog theory 5-7 has presented makes some sense. I will be testing it with my own vehicle (having both a 600 cfm VS holley and a spread bore DP). I'll let you know what I think. Fear not, I doubt my impressive 143 HP dyno'd will grenade my transmission.
The T-5's are quite a bit different. You cant even swap bellhousings, and input shafts to make it work. You can get WC, T-5's for Chevy's, but your money would probably be better spent getting a TKO.
When you do the carb test, make sure you adjust the accelerator pump and put the correct shooter in the Holley. That, and the right spring in the secondaries. It will not bog or hesitate if both of those are set up correctly.
According to this forum and many owner testimonies, GM T5's and Ford T5's are not the same transmission. Why this is escapes me, save perhaps investing in a cheaper variant to save money. World Class T5's can be purchased for our vehicles.
GM T5's had a weaker, flimsier case presumably due to GM's costcutting.
Sorry, didn't have time to read the entire thread. Just a question, how could metal shavings from removing the choke tower destroy the metering block? Just take the carb apart, clean all the passages out, and rebuild it.
From what I have gathered (with respect to ALL manufacturers QC), I would do this anyway with any carb purchase, new or not.
The T-5's are quite a bit different. You cant even swap bellhousings, and input shafts to make it work. You can get WC, T-5's for Chevy's, but your money would probably be better spent getting a TKO.
When you do the carb test, make sure you adjust the accelerator pump and put the correct shooter in the Holley. That, and the right spring in the secondaries. It will not bog or hesitate if both of those are set up correctly.
We need to talk. What is a tko, and what are shooters/ the secondary "spring". Do you mean the throttle return spring? I'm very interested in what you're saying, please elaborate!
We need to talk. What is a tko, and what are shooters/ the secondary "spring". Do you mean the throttle return spring? I'm very interested in what you're saying, please elaborate!
TKO is a transmission made by Tremec. Couple of different versions rated up to 600lbs of torque.
No,its not the throttle return spring. There is a spring that controls the opening of the secondaries. Basically the stiffer the spring the more vaccuum it takes for the secondaries to open.
shooters are what actually squirts the gas in. Some people call them squirters.
I'll get some links for you.
Part 6: ADJUSTING THE OPENING POINT OF VACUUM SECONDARIES
There are a number of ways to tune the moment when the vacuum secondaries open on a Holley 4 barrel carb. The vacuum secondaries are controlled by a diaphragm and a color coded spring. Holley makes a number of different springs with different tension on these springs. You can change the springs and change the opening point. The color coded springs run from a light to heavy tension:
White - Lightest
Yellow (Short Spring)
Yellow
Purple
Plain (Steel gray)
Brown
Black - Heaviest
If there is a bog or hesitation when the secondaries open, the spring tension is too light, so go to the next heavier spring. Holley offers a kit (PN-20-13) which contains one each of the above color springs. When you change springs you'll note that the stock cover over the spring and diaphragm is not all that easy to get to. Holley makes a special open style cover (PN-20-59) that makes spring changes quick. Finally, Holley also makes a completely adjustable thumbscrew operated diaphragm cover (PN-20-99). This cover limits the travel of the diaphragm and therefore limits how far the secondary throttle plate can open. It makes secondary throttle opening adjustable. Very nice to have if you are a bracket racer and are using a carb with vacuum secondaries. You can adjust the throttle for changes in weather and track conditions or for changes in your "dial in".
Most of your questions can be found here. http://www.holley.com/TechService/FAQ.asp
These are the shooters/squirters/ discharge nozzles. look down through the top of the carb, and you can see them. They come in varios sizes, and brands to fit Holleys. http://www.summitracing.com/parts/HL...0/?image=large
You can find about all the info you want on the Holley site. If not, I have always had excellent customer service from them.
Sorry for hijacking your carb thread with tranny info. I guess it kind of is a tranny thread too though. Since supposedly a VC carb will break your T-5.
Quote:
Originally Posted by DJ_91RS
This link will fill you in on the Tremec TKO trans.... www.tremec.com/
Heres a Chevy TKO600. This is D&D's site. Thats who I usually like to deal with on transmissions. They know their stuff, and will answer any qustions you may have. http://www.ddperformance.com/shop/pr...47cPath=107_91
There are others too. Liberty, Astro, and G-Force all build T-5's with ratings over 500 lbs of torque. You can get various options to raise or lower the rating. Pro shifted or with syncro's, ect, ect.
Yep that will do it too. If you want to buy one thats the way to go. I showed him those because it looks like what he would be seeing on a out of the box carb.
The 4165 is only available with divorced choke. If you can find an electric choke conversion for divorced choke, problem solved. I never found one.
Ah, old school. Only Downside with the divorced choke is it relies on manifold temp and i have yet to see a good intake with the ability to hook one up. His best bet would be to take a dremel and knock out the choke butterfly and just live with te ill temperment it will have in cooler weather and on first startups.
An easier option would to be grab a mr gasket carb adapter, and rebuild a 650DP. Better carb in general, and they are literally everywhere.
Holleys avenger series use the quick change secondaries and speaking from experience they are a pain to get to a sweet spot with because you are limited to what spring they give you. QFT's uses a screw which can make 10x more adjustments then the spring kit. Another option is the Proform, albeit its the same thing at a slightly higher cost.
I never found a good answer to the 4165 electric choke question. I didn't take the time to hook up a cable, so I just suffered through the cold engine poor performance until the engine warmed up a little. It was summertime, so it wasn't as bad as it would have been if I had tried that during the winter.
My q-jet doesn't bog at all. I haven't done anything special on it, just set it to specs.
Q-jet? I must be behind the times of what you're running five7kid. I dont get on here much, admittedly, but, reading all your posts, you're the guy who's convinced me to run a DP with my 5 speed on my 86 SC/Berlinetta. I've had great luck with my 650 DP after some local help and some tips from here, and the Dave Emmanuel's Holley book's tips.
An easier option would to be grab a mr gasket carb adapter, and rebuild a 650DP. Better carb in general, and they are literally everywhere.
Are you speaking of the Holley 4150 instead of the 4165? I did wonder what that "divorced choke" meant looks like I may have some more research to do...
I actually have a spread bore holley 650 DP, it's just in piss poor condition at the moment. I decided to purchase a second holley for a pretty reasonable price instead of go through the hassle of finding somebody to rebuild it at the moment. All in good time.
I may be wrong, but it's my understanding that the spreadbore Holleys dont have much in common with the squarebore ones.
Quote:
Question: Is the Holley spreadbore better than my Rochester Quadrajet?
Answer: Not at all. The Holley spreadbore carb is a poor imitation of the Rochester Quadrajet. Here's why.
The Rochester Quadrajet is a modern design, and uses some very forward-thinking features such as a central float bowl with one float, vacuum-operated metering rods for power enrichment, an air-door controlled secondary, and no gaskets below fuel level. A couple of disadvantages are its sliding cup accelerator pump, and hard-to-find parts.
So, how does this relate to Holleys, since this is a Holley page? The design of the Holley spreadbore replacement leaves out many of the good features Holleys are famous for, and leaves off most of the good features of Rochester Quadrajets.
The Holley spreadbore lacks the following features, which are standard on its squarebores: Externally adjustable floats, standard accelerator pump nozzles, standard gaskets.
All Holleys lack the following features, standard on a Rochester Quadrajet: Metering rods for power enrichment, air-door controlled secondary.
Since the Holley is lacking in so many things that the Quadrajet excels at, I recommend to anyone who is thinking of putting a Holley spreadbore on any engine: Don't! If you have a spreadbore intake, use a Rochester Quadrajet. If you really want a Holley, change the intake manifold to use a squarebore Holley. Don't use adapters, either! They are proven power robbers.
I wouldn't call an air door a desirable feature. It's a crutch - which happens to work better than vacuum secondaries, in my biased opinion.
Perhaps the ideal carb would have an air door on the primaries as well so you wouldn't have to have an accelerator pump at all.
The issues I had with the 4165 (List 6210):
- Couldn't get the divorced choke to work.
- I was adding complexity by maintaining the CC ignition - I hooked up an external TPS to keep the computer happy (kept the TCC lock-up and knock sensor functional).
- I'd get a surface street cruise (40-45 mph, TCC locked) lean O2 error code - the car was running fine, but apparently the CC system actually runs richer than the Holley under those conditions.
- Even though I used a TV corrector bracket, the tranny didn't shift quite as ideally as it does with the q-jet, typically under slightly aggressive street driving conditions. Wasn't "bad", just not as "nice".
- At the track, the car wasn't any quicker than it was with the q-jet (but it wasn't any slower, either).
I'd still keep/fix a CC q-jet before putting on a 4165.
. Oh well, my car is sexier. 
