Mild 318 engine build advice

[coryw]

As a background, I have a 48 plymouth that a 1965 273 was swapped into at some point in its life. This site has been a great source for info on these little motors and that is why I joined here. Recently I went on a trip with the car (Bonneville) that was roughly 2300 miles (1050 each way plus a week of driving while I was there) and the car went through 7 gallons of oil for the trip. We were adding between 1 and 1.5 quarts every 100-125 miles (had to stop more often for oil than for gas). The car doesn't really smoke and doesn't leave puddles (or at least not large ones) but the inside of the tailpipes are coated with soot.

With that in mind I am considering building a 318 to replace the little 273 and I know someone with a 1973 318 that I can purchase. Previously I found a D64 dual quad intake that fits the old 1964-5 heads so I've already purchased a second set of 1965 heads that I would like to use on the 318. These heads came stock with 1.78/1.5 valves. This car is mainly a cruiser, has 2.94 gears so racing is not in its future. Would you recommend having the heads re-worked for larger valves? What size?

Besides a camshaft (Hughes 318 Whiplash purchased from the classifieds here) I'm planning on keeping everything else pretty much stock. Any recommendations for valve springs? Any other advice? Thanks.

 

[70aarcuda]

http://www.hughesengines.com/Index/products.php?browse=search&search=1110&partid=10280

those are the one hughes recommends for that cam.....

 

[rumblefish360]

Use the recommended valve springs from the cam manufacturer, in this case, Hughes engines. As far as valve size goes, use the 360 valves. They are 1.88-1.60.

 

[C130 Chief]

Consider some KB167 pistons to boost compression. Should make for a nice street cruiser 318.

 

[273]

I'd be careful with KB and the closed chamber heads you might end up with too much CR your probably looking for 9:1-9.5:1 CR, stock valved 273/318 heads will flow enough for 300-325hp with 268+ cam, I wouldn't go bigger valves unless your gonna open the bowls up for the larger valves, but if your willing to do a performance 3 angle valve job and a little porting you'll hit 350hp.

 

[coryw]

Thanks everyone.

Based on what you've said 273, I'll probably leave the valves alone since the 273 2bbl pushed the car around just fine for what it is. If any of you have any other suggestions or things I should look out for I would appreciate your input. Thanks.

 

[coryw]

Have a few more questions. I might have a chance at a little bit newer and lower mileage 318. Guy seemed a little confused on what year it was but it sounded like it might be new enough to have roller lifters (pre magnum though). I already have a set of 1965 heads I want to run (have a matching intake) and a camshaft for hydraulic lifters which I'd like to use. What I'm having a hard time figuring out is what I'd need to change to run non-roller hydraulic lifters in a block that originally came with roller lifters. I'm guessing the rocker arms and pushrods will be different, is there anything else I need to watch out for before I buy the engine? Thanks.

 

[C130 Chief]

You would only have to install regular flat tappet hydraulic lifters and non-roller pushrods.

I would question putting 65 heads on a late LA engine. If your core engine is a late 80's pre-magnum 318 it already has the best production 318 heads (302 casting), the 65 heads are probably closer to the worst especially with their oddball bolt angles. I understand you have an intake already, but consider trading it for a similar unit with the common LA bolt pattern.

 

[273]

All non magnum 273/318 flow about the same the only thing that make 302 special is there closed chambers just like early 273 heads which the only thing wrong with them is the odd bolt angle and non harden valve seats which shouldn't be a problem in a summer toy. But if the 318 you bought has 302 heads you could get a machine shop to drill your intake to fit.