Need 318 help/advice

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Claude C

Claude C

Twin '66 Cudas
Joined
Oct 17, 2017
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Location
Upstate NY
Bought a 1970 318cid. Engine has 340X heads, new Holley Growler 600cfm, electronic ign., 3.23 sure grip. Had a cam that was too big for what I wanted (didn't want to idle, exh. smelled like unburnt fuel due to what I was told was the cam overlap?, and was doggy on take-off)and had 3,200 stall conv. Inquired here and was recommended Comp Cam #20-224-4 (.488 lift/274 duration). Had this cam installed and changed stall cov. to 1,800-2,200. Sounds nice and goes nice down the road, but still doggy with no initial take-off, will barely chirp the tires. Just wanted to make it (1966 Barracuda) a weekend driver to drive around with the kids.... and maybe squeal the tires at a light if needed! :) I haven't had the time to do any of the work so have had a couple local mechanics doing the work. I am just wondering if they are missing something? It seems like the engine has all it would need so I am seeking opinions here . Wondering if it could be fuel/ignition. I had to jump start it yesterday and alternator wasn't charging well. Full-fielded the alternator and jumps way up. Could possibly be poor ground at regulator?..and this issue would probably cause weaker spark/ignition? I am tempted to switch back to old distributer with points & condensor. Opinions welcomed. Thanks-Claude
 
340 X heads on a 318 with a cam that closes the intake valve 63 degrees ABDC spells 1 thing: LOW COMPRESSION. You need to build up your compression ratio.
 
A few thoughts and Im sure I may be wrong, but doggy takeoff Id check timing, unburnt fuel at idle, after timing is set carb needs to be set at lean best idle,not turn the screws untill it is at best idle speed etc. there is a way to set /check timing and carb with a vacuum guage. The previous mentioned low compression may be an issue, but id make sure timing and carb idle is set then go from there.
problem with local mechanics is you dont know how into detail they are going to go with their checks, yeah its easy to blame the cam...but did they check and ajust the carb? or just leave it at a bench diagnosis that the cam is too big?

Think of it this way even with low compression the thing should run at an acceptable performance level. "Low compression" is a 318 hallmark and they run just fine. Id hook up a vacuum guage and see what it reads just for starters. The X heads are what they are, maybe 72 ccs, but many have put 360 heads on a 318 and most say they run real well...they are about 65 ccs. So yes you may lose compression but the car should still run enough to get moving from a stop. it may not do a top fuel burrn out though:)
 
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Dartswinger70 said:
A few thoughts and Im sure I may be wrong, but doggy takeoff Id check timing, unburnt fuel at idle, after timing is set carb needs to be set at lean best idle,not turn the screws untill it is at best idle speed etc. there is a way to set /check timing and carb with a vacuum guage. The previous mentioned low compression may be an issue, but id make sure timing and carb idle is set then go from there.
problem with local mechanics is you dont know how into detail they are going to go with their checks, yeah its easy to blame the cam...but did they check and ajust the carb? or just leave it at a bench diagnosis that the cam is too big?

Think of it this way even with low compression the thing should run at an acceptable performance level. "Low compression" is a 318 hallmark and they run just fine. Id hook up a vacuum guage and see what it reads just for starters.
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Most local mechanics don't know **** about old cars.
I took my duster into a trusted shop we have used for years with our newer cars. They were supposed to check over everything, inspect the brakes etc. We picked it up three days later and the carb was still acting funny, and when I drove it to school, the front brake fell apart.
As it turns out, they only looked in the adjustment window on the back of the drums to see if it had drums still. they didn't even take the wheels off. And all of the lug nuts were loose.
I fixed the brakes myself, and they are never touching my car again. AND I'M 17!!! you'd think professional 20 year mechanics would do better than that.
 
Look for a good set of 302 heads.
.027 head gaskets.
Advance cam 2-4 degrees.
Advance timing until light pinging under load,then back off 2-3 degrees.
Adjust carburetor to leanest smooth idle with highest vacuum.
I do not know much about that particular carburetor, you will need to play with pump squirter.
Definitely get that regulator well grounded.
 
That above! That’s where ya start!
Good question by 318WR that the op needs to answer.
 
" Where is your initial and total timing set? "

Will check with mechanic tonight.
 
Claude C said:
" Where is your initial and total timing set? "

Will check with mechanic tonight.
Click to expand...
I sure hope your mechanic is familiar with old cars. Really (please takes this the right way), you need to learn this for yourself. Checking timing is so simple and crucial to these older cars.
 
" I sure hope your mechanic is familiar with old cars. Really (please takes this the right way), you need to learn this for yourself. Checking timing is so simple and crucial to these older cars. "

He actually is. He is a mechanic in our shop (Mack Truck shop)....He is 64 and had numerous Mopars growing up. I will check with him tonight on where he set the timing.
 
If the damper slipped you may have issues going by the marks...id also hook up a vacuum gauge see what its reading before adjusting anything...the timing and carb relationship sometimes requires check and double check...
 
Claude C said:
Bought a 1970 318cid. Engine has 340X heads, new Holley Growler 600cfm, electronic ign., 3.23 sure grip. Had a cam that was too big for what I wanted (didn't want to idle, exh. smelled like unburnt fuel due to what I was told was the cam overlap?, and was doggy on take-off)and had 3,200 stall conv. Inquired here and was recommended Comp Cam #20-224-4 (.488 lift/274 duration). Had this cam installed and changed stall cov. to 1,800-2,200. Sounds nice and goes nice down the road, but still doggy with no initial take-off, will barely chirp the tires. Just wanted to make it (1966 Barracuda) a weekend driver to drive around with the kids.... and maybe squeal the tires at a light if needed! :) I haven't had the time to do any of the work so have had a couple local mechanics doing the work. I am just wondering if they are missing something? It seems like the engine has all it would need so I am seeking opinions here . Wondering if it could be fuel/ignition. I had to jump start it yesterday and alternator wasn't charging well. Full-fielded the alternator and jumps way up. Could possibly be poor ground at regulator?..and this issue would probably cause weaker spark/ignition? I am tempted to switch back to old distributer with points & condensor. Opinions welcomed. Thanks-Claude
Click to expand...
You were steered wrong with the cam.
You are also being steered wrong into 302 heads. On behalf of the board, I apologize.
 
^^^ I agree. I am always in favor of diagnosis and checks before throwing parts at something. OP did say they installed a different cam though...the .488 lift cam.is that the one that steered him wrong? I have the SUMMIT .444 in my 340 and it runs pretty good. I did run the .444 in a 318 also with good results in a street engine, stock heads and springs, it pulled ok to a point then kinda leveled out...
 
Dartswinger70 said:
^^^ I agree. I am always in favor of diagnosis and checks before throwing parts at something. OP did say they installed a different cam though...the .488 lift cam.is that the one that steered him wrong? I have the SUMMIT .444 in my 340 and it runs pretty good. I did run the .444 in a 318 also with good results in a street engine, stock heads and springs, it pulled ok to a point then kinda leveled out...
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8.1 compression is a delicate animal when choosing a cam. Sometimes narrow lsa is good , idle is hype, and the sleeper is born...
If he advanced it 4 degrees and bumped the initial timing up to 18 or 22 degrees and limited the mechanical advance to 10-16 degrees for a total=32-34 degrees full advance by 2800rpm ..it would do burnouts, if that what he wants.
 
MOPAROFFICIAL said:
8.1 compression is a delicate animal when choosing a cam. Sometimes narrow lsa is good , idle is hype, and the sleeper is born...
If he advanced it 4 degrees and bumped the initial timing up to 18 or 22 degrees and limited the mechanical advance to 11-12 degrees for a total=32-34 degrees full advance by 2800rpm ..it would do burnouts, if that what he wants.
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I recall wanting to run 360 heads on my 318 with that Summit cam, but stock with stock heads because I didn't want to lower compression. It was an interim engine until I got my 340 buttoned up.
 
Dartswinger70 said:
I recall wanting to run 360 heads on my 318 with that Summit cam, but stock with stock heads because I didn't want to lower compression. It was an interim engine until I got my 340 buttoned up.
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Had a friend with a 70 340 4 speed Dart. It had a 77 360 with 474 cam ld340 intake and headers. It cranked 117-130 lbs 3.91 gears and it was dead till 3000 rpm and fell off at 6500. Lol
 
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MOPAROFFICIAL said:
Add a friend with a 70 340 4 speed Dart. It had a 77 360 with 474 cam ld340 intake and headers. It cranked 117-130 lbs 3.91 gears and it was dead till 3000 rpm and fell off at 6500. Lol
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Ouch! As Rich H’s shirt says…


“WRONG CAM”
 
The problem with the internet is you get all kinds of answers from well meaning people. You don't know which is the right answer for you. When picking a cam, try calling a cam manufacturer, tell them what you want, and as much as you can about your car. I would say you would want somewhere between 260 and 268 duration and less than .500 lift. I would also say that you should tune it as much as possible before you change anything, especially timing.
 
Dartswinger70 said:
A few thoughts and Im sure I may be wrong, but doggy takeoff Id check timing, unburnt fuel at idle, after timing is set carb needs to be set at lean best idle,not turn the screws untill it is at best idle speed etc. there is a way to set /check timing and carb with a vacuum guage. The previous mentioned low compression may be an issue, but id make sure timing and carb idle is set then go from there.
problem with local mechanics is you dont know how into detail they are going to go with their checks, yeah its easy to blame the cam...but did they check and ajust the carb? or just leave it at a bench diagnosis that the cam is too big?

Think of it this way even with low compression the thing should run at an acceptable performance level. "Low compression" is a 318 hallmark and they run just fine. Id hook up a vacuum guage and see what it reads just for starters. The X heads are what they are, maybe 72 ccs, but many have put 360 heads on a 318 and most say they run real well...they are about 65 ccs. So yes you may lose compression but the car should still run enough to get moving from a stop. it may not do a top fuel burrn out though:)
Click to expand...

Not sure where you are getting your head chamber volumes. For unmilled heads-Early 318 heads measure around 68 cc, 360 heads measure 73 cc, X heads (I hear, I have not measured mine yet) are a little less than 360 heads, 273 heads measure about 65 cc. Not sure what later heads measure, but these I know.
 
DO a compression test!
Lets see how bad it is.
Bottom end is mostly about having the pressure, and having it peak at the right crank-position. You can bandaid it with a hi-stall and gears, but without the pressure it will still be lazy.
And if your power band gets to be 3500 to 6000, in a streeter, IMO: that's crazy. With 3.91s in Second gear, that is from about 50 to 86 mph. IMO, for a streeter, you need the power at from 30 to 50/55 maybe as high as 60, but the last 4/5mph, with good heads, can be on the downside of the power curve. After that, it's nice to have tire-shredding from a dead-stop capability, but that's not mandatory.. But just chirping, I agree, sucks no matter what.


Claude C said:
Had a cam that was too big for what I wanted (didn't want to idle, exh. smelled like unburnt fuel due to what I was told was the cam overlap?
Click to expand...
If the cam was smaller than the 292/292/108 Mopar cam,both of those can easily be tuned out. I had that cam in my 360 and it putted around the parking lot at 550 rpm with 5* advance in 2.66 low gear with 3.55s in the back. It sounded great!

With your new 274 cam and lo-stall, yur still gonna need a bunch of cylinder pressure, and now, timing will be much more important.

DO a compression test!
Lets see how bad it is.
 
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