1967 a108 installing a 273

Want to swap out the slant 6 for a 273 with twin 4 barrel carbs or can I do a six pak on the 273 and will I need to change the transmission

good 4 you - ther 3=2's make better sence as was a factory option also in 65 up 273 motors , Happy vannin = send some pics!!

You CAN do the 6 pack on a 273 however be prepared for some serious sticker shock. There was an original 6 pack small block manifold on craigslist that only included the manifold and linkages for $2K. It sold rather quickly. The carbs themselves are spendy as well, although Holley has recently started producing them again for people wanting to run the setup now.
You may find that twin 4 barrels on a 273 will probably be overkill unless you run really small carbs like 500 cfm jobbers.
I'm not trying to diss your ideas, either setup would be cool to run but may not be worth the additional investment on a 273. A nicely set up single 4 barrel would run very very well and the extra money saved could go towards a 4" stroker crank, a nice cam, headwork, etc..
As far as transmission, you cant run the 6 banger setup with a V8 without some changes, different bellhousings between the 2. If your transmission is an automatic look for a V8 904 or 727 out of an A-body. They should be short enough to work without extensive driveline mods. If you run a 3 speed manual then you should be able to just buy a V8 bellhousing and bolt it up.

if you have a /6 with a 3 speed you may have a 391 rear center section and may need to lower those gears as well for the 904 or the 727.

My '64 pickup came with 3.55's and the donor van I pulled the axles from also came with 3.55's. Both are /6 3 on the tree rigs. Those gears would be okayish for a V8 auto, anything numerically higher would lose top speed quite badly.

The biggest they put on a 273 is a single 4 bbl. That would be the max I'd put on one.
Due to the small bore, they really aren't a good start for a performance motor. If you bolt on a set of bigger valve heads, you have to notch the bore to clear. Obviously, they can't breathe as well.
Dead stone reliable in stock form, doing much to them tends to be more effort than swapping to a 318, 340, 360 or a stroker. The 340 is the only one that had the 6 barrel stock (AAR and TA E bodys).
The 64 and 65 273 engines also had a different intake manifold bolt pattern. If yours is one of those, the 6 barrel won't work anyway.
If your 67 has the special adapter for the /6 to V8 auto trans, you are set. If it's a typical /6 trans, you will need to swap trans (auto) or bellhousing (stick). The /6 starter sits much higher.
There are also the body brackets, insulators and mounts to consider, along with a V8 radiator.
Don't forget throttle linkage/cable, hoses, starter, exhaust, and kickdown (auto).
When wanting more speed, don't forget about increasing stopping ability too.

The 273 I'm looking at is a 1964 so the manifold would be a problem also waiting to see if I can get a 273 long block from dodge brothers a part manager thinks its available the van it's going in is a 3 speed standard so I'll need to change out the bell housing just put new 3 core hi effi radiator in should be good there should probably change the rear also not really going for speed just like the sound of a v8

You should really try for a 318 or 360 if possible.
The 318 is externally the same and has more torque.
The 360 will require a bit more effort, but they can usually be found cheap too.
http://longisland.craigslist.org/pts/2597558273.html
http://longisland.craigslist.org/pts/2665171164.html
http://longisland.craigslist.org/pts/2640416093.html

The 360 requires a different driver's side motor mount and is externally balanced, which means the balancer and the flywheel will be different.
The rear axle is going to be an 8.75 across the board, the only difference is the ratio. The original will be shown on the serial number tag in the door jamb, but who knows if it's been changed. Tire size can be changes to help with that too. A stock 13" wheel with a short tire will be like a deeper gear, a 15" wheel with a taller tire will be more like a taller gear. Changing wheels and tires is usually cheaper than a gear change.

My '65 has a 273 in it. It is not a bad motor, but what you can do it to make power is limited. I am swapping in a LD4B intake and 600cfm Holley this spring that I have. If you want to four barrel yours with out changing the head to the later ones that have the "normal" bolt pattern, look for a '64-65 factory cast iron manifold or an Edelbrock D4B.
Gear ratio will not matter to much as I have 3.91s in mine and it has never been a problem, but it has never saw much highway driving.

I bought the 318 off of Craigslist ad said motor was together got there it was completely pulled apart took it any way now I just need to rebuild it find the bell housing and manifold I just recored the radiator for the slant 6 might have to change that should I tunnel the doghouse to help keep it cool

The stock V8s didn't need the tunnel. They do get warm, but if all is right you shouldn't have to modify.

Thanks rod should I change out the radiator or will I be ok with what I have just spent 600 to get it recored it's 2 core hi efficiency and I just bought the six pak manifold now I need to find the carb set up any suggestions thanks again

I don't know on the radiator.
Still stuck on that 6 pack, aren't ya?
You should get fresh carbs so you have fewer issues.
Add in all the other parts and it gets pricy. Here's a good source, although once you have the part #s you can shop around. pssst, don't use Jim's!!!!

http://www.mopartsracing.com/parts/fuel.html

here is the center carb.http://holley.com/0-4792.asp here is the outboard carb.http://holley.com/0-4365-1.asp here is the holley site http://holley.com/types/O.E.%20Muscle%20Car%20Carbs.asp

some of the engines do run hotter than others I used a new alluminum rad then a hi volume 8 blabe mopar proformance water pump, a 160 stat A over flow bottle. A 15 lb cap, also a hi volume fan. and built a shroud. and still had to cut the belly pan and built a scoop to help get more air up there. I didn't want to cut the floor for a tunnel. the front ends are weak enough. And I didn't went to add to that. now the problem is getting the hot air out of the dog house. scottie from a-100 groups turned me on to a rear defroster fan. I will mount that near the top back corner of the dog house and dump the air thru the floor. I do not know why mine ran so hot but going down the hiway i would unlock the engine cover lid still being latched it will rise about 3/4 inch and my temp. would drop 20 degrease in a hurry. that tells me the hot air is not moving. This is every thing i added this summer after the converion. and are all good things to do regardless. If you do take the tunnel route i would make sure that you install supports in were you cut it. maybe Rod may have some input on this aswell..

My /6 jumps right up to 190, but stays there. Don't worry, a thermostat IS on the list!
The A-100 is a bare box right now, no experience with a hot V8 yet.
The basic idea is to get airflow through the radiator, around the engine and out. Obviously a box that is the same bottom height front to back isn't the best flow through design. Add a hot lump in the middle that blocks air flow and radiates heat isn't helping, but not many of us want to push our vans around. Most don't want stacks from the top back of the box up out through the roof (hot rises) either!
One of the guys on the Yahoo site did a periscope deal where he used tubing to reach up to the top back of the doghouse, and extended it down and under the floor all inside the box. He then had a fan at this outlet, pulling hot air out of the box. That should work great, but I haven't messed with this. You better make sure the carb isn't flooding too, feeding an electric motor a hot air/fuel mix is not good!

Im going to go along with Dix on the tunnel , if you can't get the air out of the DH fast enough the tunnel isnt going to help as much as you'd think it would. I noticed the problem more on Highway speeds. I was creating a hot air dam between the rad and the engine. My accidental cure was lowering the radiator a few inches and opening up the area at the top of the rad to the engine. It kinda goes against the logic of cramming more air to the rad but if it cant escape....JM2C

mount the rear deforster fan behind the drivers seat on the outside of the D.H. and run a 2in flex duct down thru the the floor . if you lay it out you can go inside the frame rail. my rad had a 25 degree temp drop from top to the bottom. But at the stat it was about 30 degrees higher than the rad. I also was thinking extending the dog house back. but most of my interior was in place . Digz mine was mostly from runningdown the hiway aswell. also I would install a real set of manual gauges...

I don't want to get off topic to far but thought Id chime in on the heat issue with my own comments. I hadn't thought about mounting an exhaust fan on the DH behind the drivers seat, that's a very good idea and should be easy enough to hide. What I had thought about doing to help vent the DH was to mount a marine (weatherproof) inline bilge blower fan on the frame rail towards the back of the van somewhere. You can then use 3" aluminum flex duct to pipe from the rear inside of the DH to the fan. Switch it on the dash and all the moving parts and ugliness is hidden under the van.

Here's a sample fan off amazon for $22:


My 273 used to get hot, really hot, hot enough to perc the carb off and leave me stranded with a fuel perc/flooding situation. It had a 190 tstat in it which was fine for northern AZ where it came from but was way too hot for GA where it is now. My carb will cook off at about 210-230 degrees ambient temp, the changes I made keep it between 170-200 in the summer as long I'm moving around fairly well.

What I did to help control the heat was this:
~removed the OEM oil bath air cleaner that smothered the carb and added a slimmer paper filter type so more air could move around the dog house.
~swapped the OEM 5 blade 16" steel fan for a Summit "high flow" 6 blade fan (this made a huge difference in the amount of air moving through the top of the DH at idle).
~used a 160 tstat instead of 190, I don't have any temp issues in the winter and it helps keep the heat down in the summer.
~I added a 16" electric "pusher" fan to the front of the radiator, I only use it if I'm stuck in traffic in the summertime.
~ I added a 1/2" "cabinet grade maple" wooden spacer to the bottom of the carb as heat insulation. The maple is fine grain and doesn't split easily, phenolic material is better but costs big $$ so fine grain wood works in its place. If I had a 4bbl instead of a BBD 2bbl I could have just bought an aftermarket spacer but they don't make them for a "small rochester pattern" 2bbl.
~I rerouted all the fuel lines away from the exhaust manifold and took them up the firewall by the distributor instead. Also added an electric fuel pump.
~I insulated all the fuel lines in the DH with heat sleeve.

What I intend to do to my future motor build in addition to the above is:
~add a high flow water pump
~4 core radiator
~use wrapped shorty headers to help keep exhaust heat of the DH.
~vent the DH with either the bilge fan or some other exhaust fan like is mentioned above.

gave up on the six pak for the 318 just way to costly just about ready to send the block out to be preped need to know if ill have a problem fitting the headers in the doghouse or do i have to modify it

Headers will fit no problem on the passenger's side. I tried a set of B-body 3 inch collector headers on my 273 and they fit fine on the passenger's side. The driver's was a different story. Due to the shift linkage for the 3-speed I was unable to get it in. I believe they would have fit if I had removed the linkage and starter, then re-installed the starter. The 3-speed linkage appeared to be totally in the way of the big B-body headers though. Luckily I was test fitting the headers before purchasing them. The same friend has a set of A-body headers in storage and I hope to test fit them sometime after he retrieves them. I have been told the A-body headers clear the 3-speed linkage, but have yet to see pictures.

Finally sent the block and heads out for the 318 going with forged pistons towing cam roller rockers with edelbrock 650 carb and dual plane manifold don't know what headers to use yet and going to change over to an automatic still need a dash shifter if anyone has one for sale will post some pics of the build soon