want more power from my 318...

-
kyle's 73 sport

kyle's 73 sport

Member
Joined
May 8, 2009
Messages
15
Reaction score
0
Location
Sebastopol, Ca.
it's in a '68 dart gt. I just bought it, and i'm new to mopars. It has a 318 w/ edelbrock performer plus intake, edelbrock 600 cfm vac. secondaries, accel ingition w/ pertronics, hooker headers, and I don't know what it has for internals but it sounds like it has a small cam but I think one of the exhaust lobes has gone flat on me, so I want to replace it with a bigger cam. I have a TCI performance streetfighter 727 tans., TCI 1100 RPM stall converter and an 8 3/4 rearend unknown gearing but it will spin the tires.

So, my questions are;
What cam should I get? I would like it to sound really healthy but still have good power down in the low end.
How do I tell what heads I have?
I would like to run low 14's/ high 13's in the 1/4 mi.
 
I really like the comp cam # 268 477/480 for the 318 i think thats a great cam i.m.o
 
They're most likely stock 318 open chamber heads; take off a valve cover and read the casting number on the head. If you don't intend to get better heads on there in the near future I'd recommend a cam no bigger than the Lunati Voodoo 262/268 or Comp XE262. 1968 318 heads while marginally better than ones from the late '70s-early '80s still don't flow very well at all and your engine would see an improvement with some mildly ported 302-casting heads or better yet some Magnum heads (stock if you can find them without cracks or the very cost-effective and updated EngineQuest replacements).

And by "Performer Plus" intake do you mean just Performer or Performer RPM?
 
MOPEkidD-3 said:
They're most likely stock 318 open chamber heads; take off a valve cover and read the casting number on the head. If you don't intend to get better heads on there in the near future I'd recommend a cam no bigger than the Lunati Voodoo 262/268 or Comp XE262. 1968 318 heads while marginally better than ones from the late '70s-early '80s still don't flow very well at all and your engine would see an improvement with some mildly ported 302-casting heads or better yet some Magnum heads (stock if you can find them without cracks or the very cost-effective and updated EngineQuest replacements).

And by "Performer Plus" intake do you mean just Performer or Performer RPM?
Click to expand...

Good info. The compression isn't high enough to support a bigger cam and still have good low end torque. Also you say you have an 1100 rpm stall??? That's lower that stock?? You need at least a 2000 rpm stall and preferably 2500 or higher stall for decent street perf. especially when putting a bigger cam in it.

BTW: There seems to be some myth that you can slap in a big nasty sounding cam and still have good low end torque with a 8.5 to 1, 318 cubic inch engine. It don't work plain and simple. You can put in the nasty sounding cam but you probably won't be able to spin the tires in the rain.
 
Ok, the intake is the performer. The heads have: 4027168 on the inside and on the other side of the pedistool it has 555 on it. My stall converter is actually a 2500 rpm stall I went and looked up the part # on the TCI website. When I took the valve cover off ov the passenger side head I noticed that one of the rocker arms looked different than all of the others. It was casted metal instead of stamped out like all of the others, and where the pushrod contacts the rocker arm there is an adjustable screw with a place for a wrench to go on it, so you can adjust it. I thought these valves were not adjustable? And it seems to be pretty loose, I can move it side to side approximately 1/4" and up and down approximately 1/16". Is this supposed to be like this?

015.jpg
 
Wow looks like someone just stuck an adjustable rocker on there and it doesn't line up. Looks like it is missing a couple of parts also. Kind of scary. Makes you wonder what else is going on with your engine.
 
Ah 2500 stall. That's better. That'll work fine. And no that rocker arm isn't supposed to be there. At least not in conjunction with a stamped rocker next to it. That's an old style 273 adjustable rocker arm. They even require different pushrods. You need to find a stamped rocker and correct pushrod and swap it out or if you go with a bigger cam it's a good idea to get a set of good adjustable rockers to go with them so you can set the pre-load right. BTW: The old 273 rockers are just fine when all the pieces are there. Yours is missing the spring/spacer so it's a wonder it hasn't ate up things from slopping around. Heck it's barely contacting the valve tip. WOW!!
 
Um, yah. I deffinately wasn't expecting to see that when I took the valve cover off. the reason it's not lined up with the valve is because I was showing how much it could wiggle back and forth because of how loose it is.
 
kyle's 73 sport said:
what is the rpm range of this cam?
Click to expand...
The comp cam # 268 477/ 480 has a rpm range 1600 to 5800 and acording to comp cams they say its the largest cam to run for a stock converter. You can check it out if you like go to www.compcams.com and under the word SEARCH, Type in 20-223-3, it will tell you all about it. I run this cam in my 318, i had my 318 heads worked on with better valves, the heads were also milled to raise the compression.
 
STOP! There are things wrong with it. Dont run it. You need to replace that rocker immediately... and any others that are messed up. There may be a member near you who can give you some. I'm on the wrong side of the continent. Also, the exh valves have rotators... I havent seen them before on a 318 but that might just be me... In any case, you cannot replace the cam until you replace those with std retainers and the valve springs. I think if you fixt the issues like this you might be surprised at how much better it runs... Then you can spend and get new stuff...
 
moper said:
STOP! There are things wrong with it. Dont run it. You need to replace that rocker immediately... and any others that are messed up. There may be a member near you who can give you some. I'm on the wrong side of the continent. Also, the exh valves have rotators... I havent seen them before on a 318 but that might just be me... In any case, you cannot replace the cam until you replace those with std retainers and the valve springs. I think if you fixt the issues like this you might be surprised at how much better it runs... Then you can spend and get new stuff...
Click to expand...


Could you explain this a little more to me i'm confused?
 
Wow,I cant find any info regarding those casting #s. Are you sure you have the #'s right? They are usually on the top of an intake runner.

For a cheap and quick compression bump,use 302 castings. Port them for more power. Magnums are another smart swap and have several advantages like 1.6 ratio rockers,small combustion chambers and excellent exhaust ports. They will make just as much power as 302 castings without the porting work,but there are extra parts needed for the swap.
 
Kyle, PM me your address and I'll send you out some rocker arms to replace that mechanical one for a Hyd unit like the rest. Also how many do you need?
 
The notch and oiling holes on the rocker shaft should be facing down as well. I'm not sure how severely this may have impacted the rockers.
 
doktor_x said:
The notch and oiling holes on the rocker shaft should be facing down as well. I'm not sure how severely this may have impacted the rockers.
Click to expand...

I was going to say that too. Not much oil getting to the bottom of those shafts!
That is scary, who knows what lurks inside that 318?
 
rumblefish360 said:
Kyle, PM me your address and I'll send you out some rocker arms to replace that mechanical one for a Hyd unit like the rest. Also how many do you need?
Click to expand...


I already went to the parts store and ordered the rocker arm and pushrod. Thanks though. So I should flip the rocker shaft so the oil hole his facing the head? I'm going to check the other side to see if it's like that too.
 
kyle's 73 sport said:
I already went to the parts store and ordered the rocker arm and pushrod. Thanks though. So I should flip the rocker shaft so the oil hole his facing the head? I'm going to check the other side to see if it's like that too.
Click to expand...
Yep. The notch should also be to the left side of each cylinder head (as you're looking down on it from the side of the car).
 
Which part was confusing?

On the rotators... If you look at the top of the valve springs... You'll see the intake valves have a plain flat steel spring retainer. The exh valves have a thicker assembly on top of the spring that is designed to rotate the exh valve during use. This maintains the valve seat integrity. Those get in the way when you try to add a perforamnc camshaft because they are a lot thicker... 360s had them. I dont recall ever seeing them on 318s, even later ones. But I havent had a bunch of them open either.
 
Kyle you asked what heads you have and I can't find that casting number you listed but I did find a 4027163 listed. Could that last number be a 3? If so those are standard 1977-1980 318 heads.
 
Yeah, you've got crappy run-of-the-mill 318 heads, NOT very good for performance. After seeing that rocker fudge-up I'd strongly recommend pulling the engine and looking at the inside, or at least pulling the intake and heads from the engine in the car and inspecting the inside. With those heads I also strongly recommend you go to some 302s or Magnums, even J heads will still work better overall (though you would need some taller pistons and might lose a little bottom end) before you pick a cam and intake.
 
You must log in or register to reply here.
-

Back
Top