satellite66
Well-Known Member
Just wondering what is the process and what I need to know to convert my 318 from 2bbl to 4bbl. I have a factory 4bbl intake. Can I just bolt it in or are there other things to address first?
Converting from 2bbl to 4bbl
- Thread starter satellite66
- Start date
RustyRatRod
Well-Known Member
Yes, you certainly can. Chrysler did it straight from the factory in just about every 318 4 barrel application.......except for some of the police engines that had the larger port 360 heads. Chrysler never made a small port 4 barrel intake except for the 273, so they used what they had and slammed 4 barrel large port intakes right on top of small port heads. I bet I've torn down 100 or more 318s straight from the factory like that.......it worked good.
Now, all that said if "I" was gonna do that now, I would have the machine shop......or me if I thought I could open the 318 intake port entrances up to match the larger intake ports. That way, there would be less turbulance going into the intake port. But, you can do it as is. Chrysler sure did and it didn't seem to squelch performance that much. Oh and you will want to use the 340/360 large port intake gaskets too.
Now, all that said if "I" was gonna do that now, I would have the machine shop......or me if I thought I could open the 318 intake port entrances up to match the larger intake ports. That way, there would be less turbulance going into the intake port. But, you can do it as is. Chrysler sure did and it didn't seem to squelch performance that much. Oh and you will want to use the 340/360 large port intake gaskets too.
67 coronet
Well-Known Member
mostly just bolt on stuff.only things to watch are;
1)fuel hook up
2)throttle and shift linkage
3)choke hook up
4)check to make sure heat cross over is not pluged up in heads,common problem.
as long as you address those before bolting together,it should go very easy.
1)fuel hook up
2)throttle and shift linkage
3)choke hook up
4)check to make sure heat cross over is not pluged up in heads,common problem.
as long as you address those before bolting together,it should go very easy.
RustyRatRod
Well-Known Member
Not necessarily decreased fuel economy. If he uses a thermoquad in good tune, mileage can increase dramatically from a 2 barrel.......IF it's driven right. lol
WP29440SE
Well-Known Member
exactly. I get better mileage with my 1406 than I ever did with the BBD. until I put my foot in it
satellite66
Well-Known Member
Thanks for the input! I'll post some pics of what I've got tonight. I bought the intake a couple of years ago and it came with a carb that appears to be rebuilt, or clean at least. I don't know what kind it is though, of the top of my head.
Dako
Well-Known Member
You will possibly have to make some 'adjustments' to the kick-down linkage...i.e.:
1. Straighten it, because the 4bbl carb is significantly wider than the 2bbl
2. Possibly lengthen it.
Easy way to figure this out. With the intake bolted in place, bolt the carb on, then bolt the original kick-down linkage in place. You will notice 'holes' in both the rotating and stationary portion of the linkage. Align the holes and put an appropiate sized drill bit (1/8th, 3/16th?) through the holes. This 'pins' the linkage at its starting point. Next, attempt to slip the forward portion of the kick-down over the carbs' input. The shaft on the carb should be at the back of the slotted hole with the carb in the closed position.
You may find the hookup point is too far to the driver's side and/ or possibly too far forward. I could be wrong since you are using a different carb than I did. I used an Edelbrock carb on mine and had to 'remove the bends' in the rod, then had to add approximately 1 1/2 inches in the center to reach the attaching point on the carb.
I also had to fab an 'extention' to the throttle cable hold-down to get it closer to the carb. When you get to the point of installing this stuff, let me know and I will post photos. I didn't take many during the fab process, but you will be able to compare what yours looks like now to what mine looks like finnished.
Also know this: Due to the low hood, you can end up with clearance issues adding a carb spacer. Not saying don't do it. I have a 1" spacer and am pleased with the results, but the filter housing retaining nut is an inch into the insulation...and that's using a 1 1/2 inch dropped base filter housing. I also had to use a 1/2" base riser to get it up off the carb to clear the elctric choke!
Hotrodding is fun, but for every modification there are often two (or three!) opposite modifications required to make it all work!
1. Straighten it, because the 4bbl carb is significantly wider than the 2bbl
2. Possibly lengthen it.
Easy way to figure this out. With the intake bolted in place, bolt the carb on, then bolt the original kick-down linkage in place. You will notice 'holes' in both the rotating and stationary portion of the linkage. Align the holes and put an appropiate sized drill bit (1/8th, 3/16th?) through the holes. This 'pins' the linkage at its starting point. Next, attempt to slip the forward portion of the kick-down over the carbs' input. The shaft on the carb should be at the back of the slotted hole with the carb in the closed position.
You may find the hookup point is too far to the driver's side and/ or possibly too far forward. I could be wrong since you are using a different carb than I did. I used an Edelbrock carb on mine and had to 'remove the bends' in the rod, then had to add approximately 1 1/2 inches in the center to reach the attaching point on the carb.
I also had to fab an 'extention' to the throttle cable hold-down to get it closer to the carb. When you get to the point of installing this stuff, let me know and I will post photos. I didn't take many during the fab process, but you will be able to compare what yours looks like now to what mine looks like finnished.
Also know this: Due to the low hood, you can end up with clearance issues adding a carb spacer. Not saying don't do it. I have a 1" spacer and am pleased with the results, but the filter housing retaining nut is an inch into the insulation...and that's using a 1 1/2 inch dropped base filter housing. I also had to use a 1/2" base riser to get it up off the carb to clear the elctric choke!
Hotrodding is fun, but for every modification there are often two (or three!) opposite modifications required to make it all work!
satellite66
Well-Known Member
I have a couple of extra kickdown linkages. I think they're for a 360 so I've got some stuff to work with anyway. I would like to do the porting but I don't think I can do it this time around. I'm not pulling the engine and I don't think it can be ported while installed (?) In a year or two, I'm going to have the whole car redone and will have the engine pulled and rebuilt then. I just thought it might be fun to have the 4bbl on there for this season.
There are few different kickdown (the correct term is throttle pressure arm) linkage arms that bolt to the transmission shaft. It is critical that the geometry be correct to prevent transmission damage. Push the linkage all the way forward at the trans. The rear side of the slotted linkage at the carb should be just touching the carb stud. Floor the throttle, the trans arm should be pushed all the way back. If its not this way you have to either move the carb stud up or down towards the throttle shaft or change the length of the trans lever. There are 2 common lengths of trans levers. You can also cut and weld if necesary. I have plenty of spare armsif you need one. Get it right or you'll end up learning how to rebuild Torqueflites like I did over 30 years ago when my 1st mod was to switch my 360 2brl to a 4 brl.
Take your time, get it right, and move on to your next mods cause it only starts here.
Doug
Take your time, get it right, and move on to your next mods cause it only starts here.
Doug
WP29440SE
Well-Known Member
RustyRatRod
Well-Known Member
You need to learn to take pics boy. lol
satellite66
Well-Known Member
Here are some pics of what I have now and the 4bbl intake and carb.
satellite66
Well-Known Member
It's a Carter AFB. It has the following embossed on the base: E7 6212S. On the tag is 6212S(or 8) 1467 and 67. I'm going to try and find out what the CFM rate is for this one, if I can.
Dako
Well-Known Member
Not to critique color choice...it's your car, but you are aware the original motor color is Red, correct? For all I know you may have a color scheme already planned. If so, please ignore my **** rentive comment.
As for the linkage, looks like you will have to lengthen or swap the 'kickdown'/ throttle pressure arm. dvw mentioned he may have the correct one? Otherwise you can either cut your rod and splice (weld) in a piece of round stock, or do what super77se did and use one of those barrel nuts and a piece of threaded stock.
You may need to make adjustments to the return spring anchor bracket to get it further forward. If not, find one that sits further forward.
You also may need to fab up an 'extention' to the throttle cable mount to get it further forward (closer) to the carb. You 'can' simply clamp down on the black cable casing, but that's not what it was designed for.
I will dig up some photos of what I did to make mine work when I get a chance.
As for the linkage, looks like you will have to lengthen or swap the 'kickdown'/ throttle pressure arm. dvw mentioned he may have the correct one? Otherwise you can either cut your rod and splice (weld) in a piece of round stock, or do what super77se did and use one of those barrel nuts and a piece of threaded stock.
You may need to make adjustments to the return spring anchor bracket to get it further forward. If not, find one that sits further forward.
You also may need to fab up an 'extention' to the throttle cable mount to get it further forward (closer) to the carb. You 'can' simply clamp down on the black cable casing, but that's not what it was designed for.
I will dig up some photos of what I did to make mine work when I get a chance.
satellite66
Well-Known Member
Yeah, I like the orange better. I will probably change the color of the car too. Not too keen on the beige/yellow color. The carb is a marine application so I don't know if I'll use it or not, leaning towards not.
Dako
Well-Known Member
Here are a couple photos of what I was referring to earlier. The yellow circles show the holes you will insert a drill bit through to 'pin' the linkage. Don't forget the 3rd hole in the stationary bracket you must also go through or everything keeps moving! This gives you a reference point to ensure adustments are correct. Provided your car was opperating fine before, you shouldn't need to adjust the rod going down to the transmission.
The blue circle shows where the throttle cable was clamped in place. Using my sawz-all, drill, grinder and jewelers files, I made the bracket (2nd & 3rd photos) by cutting down and bending some scrap 1" angle iron I had. I put the 'step-up' in it by clamping it in the vise and 'working it' with a 2lb sledge. This got the proper angle to the input rod. You will also notice the cable is now mounted on the 'outside' of the original clamp bolt. This is done to get it inline with the (wider) 4bbl carb input.
I re-used the original throttle cable clamp, just reversed it (inside to out). To make it work in the fabbed adapter, I drilled a hole then welded in a bolt (welding not req'd), then marked where the alignment tab goes on the opposite side, drilled multiple holes in line, then filed the opening rectangular with jewelers files. Took an evening, but it looks like it could have come on the car. Hope this helps.
The blue circle shows where the throttle cable was clamped in place. Using my sawz-all, drill, grinder and jewelers files, I made the bracket (2nd & 3rd photos) by cutting down and bending some scrap 1" angle iron I had. I put the 'step-up' in it by clamping it in the vise and 'working it' with a 2lb sledge. This got the proper angle to the input rod. You will also notice the cable is now mounted on the 'outside' of the original clamp bolt. This is done to get it inline with the (wider) 4bbl carb input.
I re-used the original throttle cable clamp, just reversed it (inside to out). To make it work in the fabbed adapter, I drilled a hole then welded in a bolt (welding not req'd), then marked where the alignment tab goes on the opposite side, drilled multiple holes in line, then filed the opening rectangular with jewelers files. Took an evening, but it looks like it could have come on the car. Hope this helps.
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