318, max cam size for stock pistons

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604

604

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Any one happen to know ball park max lift a person can go with stock 318 non valve relief pistons? I remember in High school I ran 340 J heads, and a MP .484 lift cam on a stock 1973 318 bottom end and had plenty of clearance. And never had an issue. Just want to liven up this 318 while I get my long term big motor done. Thanks!
 
The lift is inconsequential. It's the duration you need to concern yourself with.
 
Another thing to take in consideration is your heads. You will have to make sure your valve springs can handle the "lift" and be able to flow with the duration, Also what kind of compression are you at?
 
valve guides will need cutting before you hit pistons.

what can u get ...about .530?

i say you couldnt 'run' a cam big enough to cause issue, not with those pistons.....you'd run out of cyl pressure 1st.lol
 
Thanks every one. That is about what I thought. Here is the specks on the engine.

1971 stock short block

1971 318 heads, with 360 valves, ported polished and gasket matched, Edelbrock Torquer-RPM valve spring kit. Heads shaved just enough to help compression a little, but not enough to cause alignment issues.

Thin .o25 head gaskets.

273 adjustable rockers

Holley street dominator intake.

Carterbrock 650 AVS


904 with full manual reverse valve body (TQ to be determined by cam)

8 3/4 with 3.55 gears

Stock manifolds (for now) gasket matched, heat riser removed

TTI 2.5in duel exhaust system, with cut outs, and flow master mufflers


These are the three cams I was looking at. I thought they would be in the ball park.


http://www.summitracing.com/parts/CCA-CL20-222-3/

http://www.summitracing.com/parts/CCA-CL20-223-3/

http://www.summitracing.com/parts/CCA-CL20-418-3/



Thanks every one!

Like I said this is just a budget build to get my buy until I get the biggy done.
 
Kevin sounds like you are building a combo pretty similar to one that I have done in the past. I have run a couple of the comp XE cams in the past and I was really happy with them. Like Wild and Crazy was saying if you go with too much duration you will loose cylinder pressure.

I don't know what your deck height is, but I installed the XE256 in a 318 with KB flat top pistons that sat .050" in the hole with a set of magnum heads and 1.6 roller rockers, so I did have a little more lift and duration. I did have the advantage of the closed chamber heads, but the thing ran like a scalded cat for a 318. Personally I would go with the 262 or even the 268.

Here is a video of my dart before I pulled the 318 a couple of years ago with the 256. Idle was actually pretty good. BTW your steering column and gear box should be there on Monday. John

[ame="http://www.youtube.com/watch?v=dCjc1rPRiCw"]Dart before teardown - YouTube[/ame]
 
Badart said:
Kevin sounds like you are building a combo pretty similar to one that I have done in the past. I have run a couple of the comp XE cams in the past and I was really happy with them. Like Wild and Crazy was saying if you go with too much duration you will loose cylinder pressure.

I don't know what your deck height is, but I installed the XE256 in a 318 with KB flat top pistons that sat .050" in the hole with a set of magnum heads and 1.6 roller rockers, so I did have a little more lift and duration. I did have the advantage of the closed chamber heads, but the thing ran like a scalded cat for a 318. Personally I would go with the 262 or even the 268.

Here is a video of my dart before I pulled the 318 a couple of years ago with the 256. Idle was actually pretty good. BTW your steering column and gear box should be there on Monday. John

Dart before teardown - YouTube
Click to expand...


Hay thanks! That is the way I was leaning. I would like it to have a little bit of a lope to it. I like to hear it a little.

Now I am trying to figure out the hole push rod thing. When I bought the 273 rockers and push rods I did not even think about 273's having solid lifters. Drat! Now I need to figure out what length of push rods I need.
 
604 said:
When I bought the 273 rockers and push rods I did not even think about 273's having solid lifters. Drat! Now I need to figure out what length of push rods I need.
Click to expand...


??So?? Buy a solid lifter cam.
 
How often would a solid cam typically need the lash set-checked? I have never had a solid cam.
 
Any one ever try the Comp Cams Thumpr cams? Looks to be the same theory as the Wiplash cams, but a lot smaller price. The clips I found on line really sound good to!
 
If you have quality valve train components,a solid MIGHT need adjusting once a year for a street car.

...and if your 273 stuff is in good shape, that counts as high quality stuff.
 
Not at all for the benefits it offers.
 
Well after talking to Comp Cams I decided on the 20-600-4 thumpr. Well got it in and checked valve clearance. Not going to work. Valves are way to close even with a thick head gasket. So for any one wanting to try one with factory pistons DON'T. Despite what they tell you it will not work. Now I have to figure out how much smaller a cam I have to go. I will just pull it out and grease it up extra good and save it for the next engine. Man I was really looking forward to the sound of that cam!
 
604 said:
How often would a solid cam typically need the lash set-checked? I have never had a solid cam.
Click to expand...

StrokerScamp said:
If you have quality valve train components,a solid MIGHT need adjusting once a year for a street car.

...and if your 273 stuff is in good shape, that counts as high quality stuff.
Click to expand...

Once a year if you drive the freaking snot out of it. LOL!!!!!


Also, the timing events of the Thumper are a bit whacked so they can get that sound. A more conventional cam/timing events should not have this problem at all.

A milder cam than the ol'284/.484 cam you ran back in the day would bet he 340 replacement cam. It will have a nice idle. (Some choppiness to it.) Also, IMO, it will work better.
 
rumblefish360 said:
Once a year if you drive the freaking snot out of it. LOL!!!!!


Also, the timing events of the Thumper are a bit whacked so they can get that sound. A more conventional cam/timing events should not have this problem at all.

A milder cam than the ol'284/.484 cam you ran back in the day would bet he 340 replacement cam. It will have a nice idle. (Some choppiness to it.) Also, IMO, it will work better.
Click to expand...

Thanks for all the great info rumblefish! Now I just need to decide on a smaller cam. I sure will not ask there tec support! LOL.

As this engine is only going to be in the car for a year or so as a stop gap till I get a biggy together, I am thinking about one of the cheep Summit sum-6901 cams. Just hope it is big enough to make a noticeable deference.


Any one need a Thumpr cam??? I would trade it for a smaller cam! LOL
 
Badart that sounds sweet!!!! I can't wait to get my 318 assembled. I bought that cam.
 
Talked to comp, and they agreed with me that it sounds like the cam is advanced for some reason. Going to get a degree kit and check it out. They were helpfully, and said to call them back once I check it out and that they would help me git it worked out. Will keep posted as to what shakes out. Thanks to all for the help!
 
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