another 318 hop up question

-
AHcuda

AHcuda

Well-Known Member
Joined
Sep 12, 2014
Messages
118
Reaction score
1
Location
Kentucky
I have a '68 318 engine. I plan to do a compression test, the engine runs good but I want to add some pop to it.

Im thinking a cam change, aluminum intake, 600 cfm carb. It's a bone stock 318 w/ about 74K on it.

I have headers, good dual exhaust system and 3.23 posi in it now.

I have considered this cam kit: http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=636&sb=2

I plan to use the stock torque converter thats in the car. IM just looking to add a bit of power and still have driveability for street & highway. Not interested in racing, just cruising.

any thoughts on this setup?
I have a option on a '71 340 stock engine & a E58 360 engine , both of which need a complete rebuild. That would have to happen later. Probably going to go with the 340 for a later build.
 
That's a little too much cam I'd go with the xe256H or xe262H, with your combo of parts should give you around 260 or 280 horsepower respectively.
 
hmm... 318's don't have a lot of compression but the 68's were decent. For the cam I'd go with an XE262H instead of the 275DEH. The RPM band is more suited for what you're going for and it's good for the gearing you've got too. Add a double roller timing chain while you're in there. Throw on some 901-16 springs too, they're cheap and will work well here. LD4B intake would be the best choice for the 'teener if you can find one. 600CFM is a good size for a 318, vacuum secondaries for an auto trans or mechanical if you've got the right amount of pedals (3). I love 318's :D

As for the 340 or 360... both are good choices. I'm building a 340 and feel like I made the right choice over a 360 but I'm sure plenty of people out there will disagree :p
 
If you want to rev the thing get a 340, get a 360 if you want to cruise the thing.
 
I used to put stock 340 cams in 318's and they ran nice with the mods you are talking about doing. They were about 268 duration. I think you could go that big, but have to agree with the others about your first cam.
 
Comp's cam pick is a 268AH , which appears to be same as a stock 340 cam. I want something sounding a bit better than a stk cam but still drivable.
 
1970Duster said:
If you want to rev the thing get a 340, get a 360 if you want to cruise the thing.
Click to expand...

I don't agree with that statement, what makes a 340 more of an rev engine is not the shorter stroke. Has more to do with cfm to Cid ratio. 273 is considered a rev engine which has about the same cfm to Cid ratio as a 340 and a 318 which is practically identical to the 273 (especially in the years they were both in production together) other than bore is not considered a rev engine cause its cfm to Cid ratio sucks. And it's not about Bobweight since 273/318/360 all have similar and 340 being Heavier.

340 has some advantages in the Rev department being slightly bigger bore, smaller mains and steel crank which will allow 340 rev a lot higher than a 360. But in street rpm range those difference don't matter much.

Best engine would be 360 crank in a 340.
That said I'd probably go 340.
 
AHcuda said:
Comp's cam pick is a 268AH , which appears to be same as a stock 340 cam. I want something sounding a bit better than a stk cam but still drivable.
Click to expand...

The factory 340 would be a good choice it's more mild than both comps xe256H and xe262H though.
 
X3 on too much cam.

IMO, the 275DEH is going to want more compression (10.0-10.5:1) and rear gear (3.55-3.73:1) than is available.

Carb size is right on. The LD4B is ok. Current products worth considering are the Edelbrock Performer 2176 or the Weiand Stealth 8022. Both are designed for the small port LA heads. A big port intake, like an Air Gap, will produce less throttle response.
 
AHcuda

I am about to be the only person here ready to agree with the cam choice provided the rest of the combo falls in line with the intended purpose of the build.

What I want to know is, what is the compression ratio of the engine?
It was listed @ *** from the books but the actual ratio is something different.
The next thing of concern is the true size to be used with the gear ratio.
IF you go to a taller tire, this effectively reduces the gear ratio. The stock tire size diameter should not be enlarged, only widened.

The lobe of these cams are not aggressive. So that 219 @ .050 intake duration isn't so steep or long as to cause issues. Even more so vs. the advertised duration. The last cam I havd in a 318 was a Crane cam with 214 @ .050. It worked very well. It's power band was slightly less than what is advertised by Comp for there cam and it makes sense due to the 5*'s less duration.

With that Comp Cam, I would not enlarge the tire Daimeter or use a higher/ numerically lower gear ratio. 3.23 / 3.21 is as low as I'd go.
I would like to see a nothing lower than an actual 8-1 comp ratio, not more than 9-1.

On the cheap, use ether 340 intake and the TQ if the carb is good. If one of the carbs has the small primary, use that one first.
Min exhaust size of 2-1/4.
 
Between the "71" 340 and the E58 360, I'd always pick the 340. The "71" 340 was about the pinnacle of small block power and durability. The E58 360 had all the best 360 parts shot peened crank, double roller timing set, 340 valve train, cam, premium valves and rings, windage tray. Both are great engines. Like 1970Duster said, 360's are have the torque but don't rev as high. Once a 340 hits 3K on the tach they really take off and will easily and quickly pull past 6K. I typically don't shift until 3k minimum.
 
66fs said:
Between the "71" 340 and the E58 360, I'd always pick the 340. The "71" 340 was about the pinnacle of small block power and durability. The E58 360 had all the best 360 parts shot peened crank, double roller timing set, 340 valve train, cam, premium valves and rings, windage tray. Both are great engines. Like 1970Duster said, 360's are have the torque but don't rev as high. Once a 340 hits 3K on the tach they really take off and will easily and quickly pull past 6K. I typically don't shift until 3k minimum.
Click to expand...

Then again, it's a 318 thread and both replies need not have been writen. It allways turns into a 340 vs. 360 thread when it started as a 318 thread.
As much as I'd love to argue....... A 318 thread it will stay. LMAO!
 
AHcuda said:
Comp's cam pick is a 268AH , which appears to be same as a stock 340 cam. I want something sounding a bit better than a stk cam but still drivable.
Click to expand...

I run the HE268H in my teen,

318, Comp HE268, Weiand 8007 Action Plus, Summit 600cfm Street/Strip,
1 5/8" Headers, 904/Transgo TF-2, 8 3/4 3.55 Suregrip

It runs really well for what it is, I was in a similar position with a relatively low mileage engine (84,000) and just wanted to add to the fun factor.
 
Getting back to the cam question, with the OP's idea of adding just a bit of power, without losing driveability, in mind...

I would think something along the aforementioned Voodoo 256/262 or the Comp XE262H would be a little more street friendly than the 275DEH. Is the 275DEH too much cam? Maybe. But IMHO, either of the other two grinds will fit the bill without going with more than you need.

Couple either one of those cams with a good manifold - I like the Weiand Stealth that 2 Darts mentioned - your choice of 600cfm carb, and a good exhaust and I think you would be cruising.

Just my 2 cents.
 
AHcuda said:
...I have a option on a '71 340 stock engine & a E58 360 engine , both of which need a complete rebuild. That would have to happen later. Probably going to go with the 340 for a later build.
Click to expand...

"Then again, it's a 318 thread and both replies need not have been writen. It allways turns into a 340 vs. 360 thread when it started as a 318 thread.
As much as I'd love to argue....... A 318 thread it will stay. LMAO! "

Rumblefish, believe me, I'm with you on that brother. My opinion is that you can make any Mopar engine fly, even a 170 cu in Monster. I was only giving thought to his other question...
 
I ran the Comp High Energy 268H in a 70s 318 with bolt ons. It works well, but can have a bit of romp to the idle. I think it would be a better choice for what you currently have.
 
thanks for all the replies. As far as tires, I have a 275/60/15 rear tire.
I am going for the 340 to build later or over time. But concentrating on the 318 right now and hopefully a cam that will be good in either engine.
 
AHcuda said:
thanks for all the replies. As far as tires, I have a 275/60/15 rear tire.
I am going for the 340 to build later or over time. But concentrating on the 318 right now and hopefully a cam that will be good in either engine.
Click to expand...

I Wouldn't try to find a cam for both engines, sell the 318 as a complete engine when the time comes.
 
AHcuda said:
thanks for all the replies. As far as tires, I have a 275/60/15 rear tire.
I am going for the 340 to build later or over time. But concentrating on the 318 right now and hopefully a cam that will be good in either engine.
Click to expand...

That's a big tire. Go for the next cam down.
 
moper said:
I ran the Comp High Energy 268H in a 70s 318 with bolt ons. It works well, but can have a bit of romp to the idle. I think it would be a better choice for what you currently have.
Click to expand...

by "romp" do you mean a choppy idle? I want something that will have a better sound and performance than a stock cam.
 
AHcuda said:
by "romp" do you mean a choppy idle? I want something that will have a better sound and performance than a stock cam.
Click to expand...

Here is the Comp HE268H in my teen.

[ame="https://www.youtube.com/watch?v=rlNLaJaZzGQ"]100 3366 - YouTube[/ame]
 
Your 318's favorite song is this:

[ame="https://www.youtube.com/watch?v=69fPof-ZTnU"]Billy Squier - The Stroke - YouTube[/ame]
 
You must log in or register to reply here.
-

Back
Top