'64 Valiant 273 to 318 to 360

I have a '64 valiant that came factory with a 273.  Before I bought it someone dropped in a 318.  I plan to change it to a 360.  Looking thru Hot Rod's Chrysler 273-318-340&360 book, there is talk about how the 273 was created to fit in the '64 Darts and Valiants.  Apparently a notch was created in the left block and head to accomodate the steering box.  So getting worried my plans for a 360 will be smashed I looked under my hood.  The left head has a notch but the 318 (confirmed with engine stamp) has no notch.  Will the 273 heads fit on the 318?  The book also states the 273 valves are in line like the B engines.  Are the 318 head valves out on line?  Is that why they used 273 heads?  I have about 1/2" clearance from the steering box to the block and about the same from my dual pot master to the valve cover.  Too close?  I also have a 360 truck and the valve covers are the same size as the ones on my valaiant (273?).  So the big questions are: if I have 318 in the Valiant now, the 360 should fit too, correct (if 1/2" clearance is OK?)?  And since the valve covers are the same from my truck to the Valiant should the 360 heads fit and miss the master?  And finally the Valiant has the up turned left exhaust manifold, will that bolt to the 360?  


Thanks in advance for any help.  

Reading further into the Chrysler book, the Darts and Valiants getting the 273 would also get a new single plane intake manifold to clear the hood.  Does this single plane intake work on the 360 block?  If so, how is this going to affect my HP when I use it on the 360?  Are there any dual plane low profile intake set ups I can consider?  I am not hot on a hood scoop but if i have to to reach my Hi HP goal, I will.  Thanks again.  

The physical external dimensions are the same on 273LA-360LA engines, Really the biggest difference is the "360LA is an external balanced engine" {you need to use the harmonic damper & torque converter or flywheel from the 360LA for the proper balance unless you have the engine internally balanced}, the rest of the parts are pretty much interchangeable, the combustion chambers are larger on the 360 so they would drop the compression if used on a 273LA or 318LA {273LA, 318LA, 340LA engines are all internally balanced}... Intakes & manifolds are interchangeable some very minor differences in port sizes over the many years, all the engines mentioned have wedge inline valve heads, the early HIPO 273LA had adjustable rocker arms not used on production 318LA or 360LA engines.... Good luck with your project...  
"Fill Your Library Before You Fill Your Garage" Good Luck  "Budnicks"

Thanks Budnicks.  I plan to use all 360 components, block, heads, etc.  Do you have any input on the single plan intake?  Do these reduce output horse power?  I currently have a 2 BBL and will want a 4 BBL on the 360.  Do you know who makes and where to get a 4 BBL intake that is single plane?

Stephen  

A single-plane intake is not necessarily lower profile than a dual-plane. IMHO you really want a dual-plane manifold for street use. About all you can do is measure your hood clearance (a ball of Play-Dough works well for this). Then start comparing intakes. I think if you stick with an "street" type dual-plane intake you won't have hood clearance issues. There are low-profile air cleaners that can gain you an inch (or even more) of hood clearance too.  

340 Thanks.  I trust your opinion as it matches a lot of other info I have seen recently.  Presently I have a 318 block with what I think are 273 heads (they have the notch in the left one to clear the steering box).  I have seen many dual plane intakes for the 318 that say you must have 340 or 360 heads.  Do the 273 heads also work in place of the 340/360 heads?  I would like to get the DP intake now and use it on my 318 but hope it wil also work later on the 360.  Trying not to spend more $$$ than necessary.  If the 273 heads are like the 318 heads and won't work with these intakes I will hold off on getting the new intake until I get the 360.  

NO expert here, but 273s and early 318s do need a special intake manifold. And as far as I know, all the other 318s, 340s, and pre-Magnum 360s use the same intake.  

All mopar LA are the same except for 273 from 64-65. The big difference is the angle of the intake bolt to the heads. they have an other angle on these.

Otherwise there is no problem to put heads from an later 273 or 318 on a 360, but you will lose power

single plan intake is not an option if you want a clear register from 1500 to 6500 rpm. you wanna have a dual plan, open air alu intake, "there is very good ones on Ebay for a smal cost". why? you ask, because these keep your engines cool on hot summer days
Buy an edelbrock low air cleaner and you wont have any problem with the hood

the exhaust mainfold on your left side are special for early A-body and they will fit your 360 like a glove. But they dont bread very well so if you wanna have power, go for TTI headers.  

Valle thanks for the update.  I think what I have is a '74 318 block with the original '64 273 intake and heads on it.  I imagine they blew up the 273 block, replaced it with a 318 block and transfered all other 273 parts onto the 318 block.  I can't see any other reason why I would have 273 heads on a 318 block.  Is there any way to confirm I have '64 273 heads besides the bolt angle?  Are there any identifying marks on them?  I only want to get an intake now if it will work with the 318 block and 273 heads I have now and if it will also work with the future 360 block and 360 heads.  If it doesn't work now it may be sitting around for a while until the 360 arrives.

SS  

You could use an newer intake if you notch the holes so you can put it on the heads. I recomend that you use pinnbolts insted of the regular bolts. then its easer to tight it on the gaskets. I did use an newer intake on my 64 273, and it works just great. Right now I have ported 318 heads with 2.02/1.60 valves on the same motor, it works to, when I notched the cylinder for the valves  

with good rubber on your engine mounts 1/2" is ok. the 1964-66 318 was polysphere heads,valves not inline, 1967+ 318 and all 273,340,360 inline. the 273 and 1967+ 318 have smaller intake and smaller exhausts ports than a 340 or 360, so stuff bolts on but the port size mismatch drops power some. the stock low profile single plane intake was used up to 1972 on 318's and is fine for street, it has small volume runners-anyone who says a single plane is not for the street is thinking about a race Victor or Strip Dominator. cast crank 340's are externally balanced. to identify mopar heads look between the valve springs for a 7 digit casting number, such as 2531894 - 1968-70 340, 2465315 1964-65 273. so go with like a Performer dual plane intake(about an inch taller than stock) and grind the 12 bolt holes some to match the 273 angle, and it will later work on 340 or 360 with some good washers, a Performer RPM or air gap type is about another inch taller.  

Thanks Marco.  Lots of good info.  I will hold off on getting the intake.  Not interested in buggering it up to fit the current 318.  Just not necessary now.  I will hold off until I get the 360 set up.  I don't know anything about the current 318 except for the box of twisted push rods I found in the trunk.  So I don't want to start adding HP parts and blowing it up.  Its better as a daily driver until I can get the 360 in.