Critique this 318 engine combo....

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LXguy

LXguy

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Hey All:

I've got a lot of parts laying around for a 360 swap, but for some reason I keep thinking of using the stock 318, just to see what it would do.

Here's the combo:

stock untouched 318 1971 shortblock with 33,000 miles

Edelbrock Magnum aluminum heads
(assuming pistons are .080 in the hole, Compression Ratio would be 9.14:1)

Voodoo 268 hydraulic camshaft
http://www.voodoocams.com/Product.aspx?id=1545&gid=287

Edelbrock Magnum Air gap intake

TTI headers / exhaust

650 double pumper

Either a windage tray or a good oil pan

4.11 gear

Obviously, all this assumes that the engine will pass a leakdown and compression test. Runs pretty good though.

Anyone think this might run decent, or would it probably just come flying apart?

Any guesses on horsepower?

Any thoughts appreciated!

Steve
 
Skip the double pumper if it's an automatic. With such a good flowing top end, I'd even consider a 750 CFM carb, especially if you plan to put these parts on a 318 and run it for a season while you build a 360 short block.

The engine shouldn't come flying apart if you keep it under 6000 RPM, but bear in mind you have cast pistons and possibly the early rods (my 72 318 had the larger rods with bushed small ends, so you may get lucky).

Horsepower wise? 350?

Also, figure the bucks for a GOOD (efficient) converter.
 
Cam's too big unless you get in another half point (at least) of compression. What are you going to use it for? If it's for a street vehicle I'd go with a Voodoo 262 cam and some higher-comp. pistons (preferably some flat-tops to take advantage of that squish pad). You could run as high as 10.5:1 no problem with that combo. I think that would still give you higher overall horsepower (maybe 400) as well as a more livable torque curve. Besides, if you kept your originally planned cam and compression you'd need to rev it above 6000 RPM to make serious power, and from what C130 Chief suggests your stock bottom end might not handle that very well for long.
 
Consult Bobby from BJS racing here.

He is the 318 master engine builder and can give you all the info you need.

I will most likely be getting him to build a screamer 318 for my swinger.
 
Are you sure you will get that much compression with the pistons that far down (and does .080 include the gasket)? Also consider that the Eddy head will have a closed chamber that is designed to take advantage of a zero decked piston for quench and squish.
 
I'd go with the 360 block with some good pistons at zero deck. Then you'll be making some really good power.
 
You are not going to want to use an Airgap with that setup. To much. Unless you plan on changing the pistons as well. If you gonna spend the money on the heads, might as well do the pistons? No?
 
Put it together with the parts you have listed and have some fun. It will run just fine. Use as thin a head gasket as you can - mopar makes a .024 I believe. check the pushrods for clearance where they pass through the heads.
340 can tell you all about what happens if you don't have enough clearance.

LXguy said:
Hey All:

I've got a lot of parts laying around for a 360 swap, but for some reason I keep thinking of using the stock 318, just to see what it would do.

Here's the combo:

stock untouched 318 1971 shortblock with 33,000 miles

Edelbrock Magnum aluminum heads
(assuming pistons are .080 in the hole, Compression Ratio would be 9.14:1)

Voodoo 268 hydraulic camshaft
http://www.voodoocams.com/Product.aspx?id=1545&gid=287

Edelbrock Magnum Air gap intake

TTI headers / exhaust

650 double pumper

Either a windage tray or a good oil pan

4.11 gear

Obviously, all this assumes that the engine will pass a leakdown and compression test. Runs pretty good though.

Anyone think this might run decent, or would it probably just come flying apart?

Any guesses on horsepower?

Any thoughts appreciated!

Steve
Click to expand...
 
Thanks for the responses guys.

Mopar seems to have discontinued their skinny head gasket, but I found a Mr Gasket that's almost as good. It's .28 compressed.

The piston is only supposed to be .05 down in the hole on this engine, which would make the compression 9.79:1 with the aforementioned gasket, but I've been told that the tolerances varied a lot on these motors, so I was planning to be prepared for the worst.

I already have all the parts other than the camshaft and 318 oil pan, which is why I chose them for the build. If I spend any money on rotating assembly its going into the 5.9.

I planned on ordering a good converter for the 5.9, but it comes with one free restall so I'd just get it set up for the 318 and restall it for the 5.9 later.

It'd be pretty cool if I could make 350 horsepower (or maybe a little more). That would probably turn a pretty decent ET in this 3000 lb car if I could get it to hook.
 
388dart said:
check the pushrods for clearance where they pass through the heads. 340 can tell you all about what happens if you don't have enough clearance.
Click to expand...

I heard that. I am like the push rod clearance poster child.
 
I think it's too much head for what you're running for cam and gear. I know you have the heads... But, I'd go with 1.92 intake iron Magnum heads, mill them .020 and the intake surface .020, and the same other stuff. If you run the Magnum RPMs, you should notch the cylinder bores to just above the top ring wear mark, in the intake valve area. It should push the compression up to about 9.5:1 and have no valve shrouding issues. I ran a '74 318 short, with 2.02 X heads, and the older High Energy 268H Comp cam. It passed emissions, and was about .3 slower than the 340 short that broke. With more torque, it would be a riot.
 
I like everything that you 'HAVE' to work with.

I think the cam choice is fine installed 4* advanced.
So the port volume is a lil big, oh well.
Those beaker rods attached to little 318 slugs will hold up just fine to 6-6500rpm but thats really pushing it on stock bottom end, then again you say 33k is all the motor has so......

Run a dual plane FOR SURE, rpm/airgap sounds good to me.

Then push the initial timing as high as you can with it still being able to turn over then limit the total advance to what the engine wants or runs the best with, this will help with it's low speed responsiveness.

See the crucial thing that will make this work is that you have 4.10 gears.

And with all the above done a convertor with 2800 stall will ice this cake.
 
I saw an article of a 318 build a while back that got just short of 400 HP/379 lbs TQ with a little more aggressive cam (231/237 @.050 and .525 lift). They used different heads than you have, along with some KB flat-top pistons. They used an RPM air gap too. Little else was done to it (they later ported the heads and got 425/402). With the cam and heads you're using, you should go with a 700 or 750 carb. Use what you have, add some flat top pistons and Fel-Pro head gaskets and it should bring up compression to around 9.6:1-9.8:1 (just my own hip-pocket estimate with no calculation behind it). There are other pistons besides KB flat top pistons that will work if you're on a budget. Good Luck.
 
I also like the Fed-mougal coated slugs, you can get them with rings from Summit racing I think I seen it in. Not a bad deal at all.
 
LX, if you meant mine... the car was a '74 Cuda, 3.23, 4sp and as I recall with the 340 went 13.80s@98, with 175hp plate went 12.60s@107. With the 318 it went 14.0s. I detonated the ring lands off the 340... so I never ran the 318 with the plate, then I totaled the car 3 months later (not my fault...lol) That was in the late 80s.
 
moper said:
I think it's too much head for what you're running for cam and gear. I know you have the heads... But, I'd go with 1.92 intake iron Magnum heads, mill them .020 and the intake surface .020, and the same other stuff.
Click to expand...

Hey:

I don't think I could run that Lunati camshaft with the factory Magnums because of the added lift with the 1.6 rockers, and the stock Magnums limits on cam lift.

Steve
 
You are cery close to the limit using the Chevy valves in the EQ heads to get the addition lift... that clears to .550 from what I've heard.. but you could order a smaller camshaft too. (I know, complete rethink and more buying..lol) You can always try it and see what it does. I think it will feel soft with those heads until you're over 3500.
 
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