318/360 swap questions

duallyDave · Post by **duallyDave** » Wed Apr 21, 2004 10:39 pm

I have a '65 crewcab with stock 318 poly/2bbl/727 with camper. It runs ok on the flats but is certainly no speedster. When it sees a hill, it has no power and eventually tends to overheat.

I am considering swapping in a 360 w/ 4bbl. Do you think the increased performance is worth the cost? Or is there something I can do about the 318? I am relatively new to this and don't want the added hassles of putting in a big block.

If so, what version 360 would you suggest? Pre or post magnum or something else? I get a little confused with all the different head designs etc.
thanks,
Dave

farmhand66css · Post by **farmhand66css** » Thu Apr 22, 2004 5:02 am

Dave too funny, I just pulled my 360 out of the truck to put in a 318 poly. wanted an original engine for it. My 360 was from a 77. where are you located?

Matt

MountainMoparRobin · Post by **MountainMoparRobin** » Thu Apr 22, 2004 5:46 am

Both engines can be built! so make the decision on which way to go and then we can give ya ideas of a engine build up!

Post by **cowboy** » Thu Apr 22, 2004 7:43 am

Dave , on the 360 , in these older trucks you have to reset one of the steel mounts on your block ( pass side I think) or it wont set in right , the 360 block mounts holes are off a bit, diff from the 318 , now what gear is in your truck ? how's the cooling system ? she should not over heat just going up a hill , you can put a 4bbl on you 318 , headers or just duel exhaust (2in) clean out you cooling system , welcome to the site & feel free to ask questions , we'll all try to help you out , between all of us we have a brain :D
8)

Post by **oneowner71** » Thu Apr 22, 2004 11:34 am

As you will find out if you talk with Wideblock enough, you can make a poly perform almost as good as a stock big block (or better in some cases)... it just takes money, time, and the availability of parts. If you have a 360 sitting around, it may be cheaper to just switch them out, but that doesn't sound like the case. I agree with Dave that the truck really shouldn't overheat, unless that camper is REALLY heavy, so you may want to give the cooling system a quick once over. As the old adage says, there is no substitute for cubic inches... whether that tells you to put in the 360 or bore the poly (and you can bore quite a bit), you can get pretty good performance out of it.

Website · Post by **wideblock** » Thu Apr 22, 2004 5:20 pm

go with the poly. 360's are for the guys that dont know how to make horsepower without the extra cubes!!! i responded to your post on norms site, but there were a couple things i left out. the dual exhaust made such a difference in the way the truck ran i had to retune the thing when i got it home. it was running like crap with the old settings. also, get you an open element air cleaner, the better she can breath, the better she will run. as far as the over heating, do you have a seperate tranny cooler or are you relying on the one in the radiator? seperate cooler is the way to go, you would be surprised how much a tranny can heat up the water in the rad when you work it hard. when was the last time it had a tranny flush? dirty fluid will kill performance and cause over heating. my poly with 135k on it pulled a 3850 pound load of garbage to the dump in a trailer and never broke a sweat. and this was over the pass to get where i had to go, aprox. 2000foot in elevation difference from top to bottom and they wernt nice on the incline. if you like, i can tell you how to pull as much as 410hp out of a poly, or anywhere in between. i say why modify if what you got can do the same job for equal or less money. and the fact its a poly just makes it better. where are you located? theres a 360/727 combo in the paper here, says it runs good for $500 o.b.o. for the set, if your stuck on bigger cubes.

duallyDave · Post by **duallyDave** » Thu Apr 22, 2004 8:47 pm

More info:
Fan is stock 4 blade, hard mounted to the pulley. Have both the radiator cooler as well as an additional one for the tranny. There is a trany temp gauge in one of the hoses that barely ever gets warm. Water pump, thermostat, and hoses were replaced recently. Tranny was rebuilt a couple of years ago with a new, HD torque converter.

The door plate says a 4.1 rr? It is one of those dually conversions with the big, full floating rear axel. Don't know if the plate is accurrate or not.

The camper is one of those 11 footers from the mid-70's, so yes it is heavy. And the truck is a crewcab to boot. But it still shouldn't overheat, I would think.

I am worried that the block is clogged after 40 years but don't know how to check.

FYI, as far as I know, the truck/motor has around 100k original miles. Mostly used for RV purposes.

Also, I can say that the truck doesn't overheat without the camper. Though still not great torque.

Post by **cowboy** » Thu Apr 22, 2004 10:06 pm

Dave , as far as checking your water flow , let it warm up with the rad cap off & it should flow like a river , at your trucks running temp , if it only over heating with the camper on, you just might have a small clog in the system , check on some of the do it your self flush kits , or a good shop you trust to clean it out ,
8)

Website · Post by **wideblock** » Thu Apr 22, 2004 10:46 pm

hey dave, when was the last time the exhaust system was checked?? a clogged stock muffler can cause it to be sluggish and over heat under a load simply due to the lack of flow. you say it was mostly used for rv use, so im assuming its not drivin regularly, this will cause rust build up in the block as well as the condensation that builds up in the muffler causes it to rust up, little pieces flake off here and there and eventually clog it up. berrymans makes a good rad and block flush you might try circulating thru the system and see what comes out. do you still have the little piece of rubber that goes between the rad support and the top of the rad? this keeps air from flowing over the rad instead of thru it. you might also try a good tune up, if your timing aint right or the carbs running a bit off this could be a contributor to your problem. it may just be a small portion of everything that has been mentioned so far. its hard to tell not being there to see the truck in person. but i can vouch for the poly man, i work the crap out of mine, she never gets hot, even in taco bell drive thru at lunch :D all i did to the cooling system is a recored 3 row rad, a good block flush, and new hoses and t-stat(180).. that brings another thing to mind, does your lower rad hose have a spring in it? if it doesnt it may be collapsing under the extra strain of the trailer. this has happened to me before, the truck never ran hot empty, but as soon as a load got on it she always got hot. i blamed it at first on the fact it was a chevy, but then found the hose was collapsing at speed, still got plenty of flow to stay cool under noramll operation, but not under any strain. you shgould be able to tell with a simple squeeze. if it squeezes it aint got a spring and you need to change it, if it dont youll be able to feel the spring inside, and make sure it runs the whole length of the hose within a couple inches of each end. these rust out over time and are washed into the system, so if your hoses arent a recent change, you might be suffering from this over looked problem.

Post by **Hobcobble** » Fri Apr 23, 2004 7:26 am

You may also consider popping out some of the soft plugs and checking
for some build-up in the engine block passages. Before I dropped my Poly
into my truck, I replaced all the soft plugs and also scraped, chipped &
vacuumed out as much crap as I could.... and a lot came out of it. This,
along with a 3 row re-core, new hoses, t-stat, fan shroud & top tank
shroud [core support-to-rad clip-on piece] keeps me running nice and
cool.
John