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Opinions wanted on a 318

RT6PK

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Opinions wanted

I have a ’67 Belvedere with a tired old 318 in it. I would like something with a little more oomph. I don’t need a rocket ship, just enough power to merge into freeway traffic without having to turn the a/c off. I have access to a ’74 318 with only 25,000 miles on it. Compression and oil pressure are good; and it doesn’t smoke. How well would the motor respond to a mild cam, headers, and an intake and 4 barrel, being that it still a low compression motor with restrictive heads? Would it be worth the money spent for the upgrades? If so, can anyone recommend a particular cam?

ALSO, I am probably going to install this motor regardless if I make the upgrades or not since my current motor smokes and holds only about 15 psi of oil pressure at hot idle. My next question is how should I prep the engine block to put a fresh coat of paint on it. I just don’t want the new ’67 red paint to start flaking off to reveal the blue ’74 paint underneath.

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Opinions wanted

I have a ’67 Belvedere with a tired old 318 in it. I would like something with a little more oomph. I don’t need a rocket ship, just enough power to merge into freeway traffic without having to turn the a/c off. I have access to a ’74 318 with only 25,000 miles on it. Compression and oil pressure are good; and it doesn’t smoke. How well would the motor respond to a mild cam, headers, and an intake and 4 barrel, being that it still a low compression motor with restrictive heads? Would it be worth the money spent for the upgrades? If so, can anyone recommend a particular cam?

ALSO, I am probably going to install this motor regardless if I make the upgrades or not since my current motor smokes and holds only about 15 psi of oil pressure at hot idle. My next question is how should I prep the engine block to put a fresh coat of paint on it. I just don’t want the new ’67 red paint to start flaking off to reveal the blue ’74 paint underneath.

View attachment 844847
A 318 is...well a 318, this engine is hamstrung by the stock heads. Cam, headers and an intake will be a disappointment since they all have to work with poor flowing heads. Find some 340 X heads or some aftermarket aluminums and wake that little guy up. If it were me I would pull the teen and drop in a 360, it will bolt right up to the trans you have and pretty much all the tin and externals will transfer over from the teen. My philosophy has always been "no replacement for displacement" when it comes to moving 3500 + lbs off its ***.. IMO
 
This is what I did;

LD4B
600 AFB
Typical headers
2-1/2 “H” piped exhaust
Recurve then distributor
MP chrome box, an MSD would do well here.

Crane cam: 272/284 - 216/228 - .454/.480 - 112
No extra stall on the converter needed.
3.21 gears and stock tires.

If you have less gear, a numerically lower ratio, step down in cam size. If you have the Hwy. ratio of a 2.76 or similar ratio sub 3.00, a cam of 210 @ .050 is as large as I would go.

This will help a lot. Mileage should not take a dive. Tune the carb well!
 
My 60,000 original mile 318 has no problem in my 3700 pound car merging or at highway speeds. This is with the factory 2 barrel and cam, with manifolds and 2.25 dual exhaust.

There are several "318 cam" threads but most do not really answer the question.

A simple swap meet $100 Edelbrock intake and another $100 Edelbrock 600 CFM AFB carb should yield a few HP over stock.

A "small" cam like comp 256, Lunati comparable or the Summit 6900/6901 should also help. (I'd stay under .450 lift or you might need head machining, and the stock lift is only .399/,400, so .450 is quite a jump)

First order IMO would be dual exhaust if you don't have them already.

Headers are another story entirely.
 
As 68Moparmaniac said your heads will be the problem. Replace them and you'll be much happier with the difference. Do it once and do it right.
 
...also there's a little more to a 360 swap, like the converter.

and another 12K aluminum head, solid roller cam, stroker build suggestion in a "little more power from a 318" thread in 5...4...3...2...
 
No one has answered the paint question...
 
Adhesion promoter?

I've been told by several sources that no prep was done from the factory.

When I painted mine 3 years ago, I just got off all the loose old paint with Gunk, then oven cleaner, pressure washed it real good, and painted it with Mopar 70's blue, no primer.

I did try to use several thin coats.

Still holding up.

Painting over paint puts you at the mercy of the prep done to the old paint, plus all the wear that's already happened to it.

Tip- replace the freeze plugs with deep brass ones, especially the ones that get covered by the trans.
 
If your interested I have a rebuilt 318 HP (360 heads and intake) I would sell. Over $3,000 invested, less than 1,000 miles on it. Complete carb to pan $1,500. Add a rebuilt 727 for $500 more and a rebuilt 8 3/4 with 3:23 sure grip for another $1,000.
 
Before I finally rebuilt my poly, since the motor ran so solid I kept putting it off for years, I added dual exhaust, 4BBL, and electronic ignition - mine being a '63 no stock elec ig yet (also added 3:23 sure grip). This woke it up nicely over what it had been; but the earlier motor had a bit higher compression ratio. As posted, 318 certainly has limitations; but some potential depending how far you want to go. Years back, while always being a durable motor, they were more for boat anchors as opposed to a motor to find giddy giddee-up. Sounds like you are pondering a bit on how much go-go you want. If looking for a street burner that's gonna involve some more heady machining and swapping such as posted. A nice condition motor you have a line on with a few mods might be all you want for relatively painless cash drop without looking to do burnouts. After dumping a ton in redoing my motor, it's not exactly what I was hoping for; but then I didn't take a few added steps either. My 1st inclination was a 360 crate over the 318 and for the money and time...I'd take my 1st choice over what I did.
 
I have a stock with RV cam, performer manifold and EFI. Also have one with Toth ported heads 9.5:1 Wiseco pistons, performer manifold, RV cam and an edelbrock. Problem is I have them in the wrong cars! First is in the Coronet second is in the Duster. Heads and compression make a huge difference.
 
I think the compression ratio in '74 was 8.6:1, but I still think the engine will be fine for what you need with a few mods. I had a 69 Barracuda with a 318, they were 9.2:1 back then, but with headers, 600 Holley, Edelbrock Performer cam and intake, electronic ignition etc that thing flew, certainly fast enough to join the freeway. I know it was a lighter A body but it went really well. Your perception of speed is important too. Ask guys with 440's and they'll think your car is slow, but compared to the tired engine you have now, it might seem pretty fast.
 
You can’t get factory pistons that get you more than 7.5:1 today. They are all the low compression emission deck height. That is why I had to go to Wiseco to get good compression. Yes my 68 was 9.2:1 factory with a deck height of about 0.025”. The sealed power pistons were more than 0.090 in the hole on my 68 rebuild.
 
Opinions wanted

I have a ’67 Belvedere with a tired old 318 in it. I would like something with a little more oomph. I don’t need a rocket ship, just enough power to merge into freeway traffic without having to turn the a/c off. I have access to a ’74 318 with only 25,000 miles on it. Compression and oil pressure are good; and it doesn’t smoke. How well would the motor respond to a mild cam, headers, and an intake and 4 barrel, being that it still a low compression motor with restrictive heads? Would it be worth the money spent for the upgrades? If so, can anyone recommend a particular cam?

ALSO, I am probably going to install this motor regardless if I make the upgrades or not since my current motor smokes and holds only about 15 psi of oil pressure at hot idle. My next question is how should I prep the engine block to put a fresh coat of paint on it. I just don’t want the new ’67 red paint to start flaking off to reveal the blue ’74 paint underneath.

View attachment 844847


If you have the original '67 318 engine, it should have the closed chamber heads like the 273 which may help compression.
Not sure if there is any different in flow, so use whichever head is in the best condition (Check the valve guides and valve seats for wear.)
You can gain quite a bit of power, compared to stock, with a small 600 cfm 4-bbl carb/intake and dual exhaust, and re-curving the ignition advance.
I would not change cams unless changing gearing and converter stall speed.
If you need to change the timing chain/gear set and want to change the cam, use a cam with 210 or less duration @ 0.050"
Something like the Hughes Engines SEH0610AL cam. That cam has way more lift than stock, while still being mild duration.
 
Any 4 barrel intake would be worth it over a 2 barrel even a cast iron one. Headers will help too and worth it if you get a decent set that doesn't have a exhaust leak. Cam you can't go very big...there are grinds designed to help build compression..if you want bottom end and a midrange power burst
..go with a comp xe or voodoo or a bullet .904 grind and stay towards the small end of their list with around a max of 220 at .050. The generic RV and rpm cams 204/214 and 214/224 I have run both in a stock small block w 4 barrel/headers and they are ok for the buck. I enjoyed shifting a little higher rpm, but from a standing start it was not much better then the stock cam. Imo the stock 318 valve springs are junk and need to go with any cam switch.
We just use a steam cleaner and just paint..but have to be careful not get water where you don't want it. Have also used a solvent gun off the air compressor and came back with cleaners...I think any paint shot with a gun verse aerosol is just better paint. The aerosols are convenient but don't last. It's hard to beat removing all the old paint with a wire wheel.
 
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On the painting. 1st thing is to degrease it, The wipe it down with a grease and wax remover or some thinner.
then scuff every inch with a red scotch bright pad, epoxy prime/seal then your color coat.
 
if you do end up installing 360 heads, make sure you grab the exhaust manifolds to go with it. i seem to recall the 318 manifolds leaving a bit of a gap on the exhaust ports when mounted to 360 heads. can anyone verify or correct me on this?
 
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