Purple Shaft 280/280 cam

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to fishy68.
What i am saying is initial timing is not really a performance setting.

I assume you mean a WOT performance setting because it does affect part throttle performance.
YES it will give you all the things you said \\ better mpg \\cleaner plugs\\
smoother idlle.UNDER LIGHT THROTTLE ONLY.
But i am a little confused by your statment that your motor will have spark knock with at anymore then 35 degrees total timing???

Anymore than 35 degrees total timing it spark knocks at WOT. Not under light throttle, at WOT.
Yes i understand your motor suffers from spark knock at 35,but how is hooking up your vacume advance with 18 MORE DEGREES of timing going to take the spark knock away???

Ok let me rephrase that. My engine will only accept 35 degrees total timing at WOT. It will accept more at part throttle cruising because the load on the engine is lower. I didn't think I made it sound like the vacuum advance will make spark knock go away. That's not what I meant.
Your motor has too much cyilinder presure,thats why you can't go past 35 degrees total.

You said this happens when you run your motor with the distributer vacume advance system not hooked up.(less timing=more knock Please explain, you lost me there.)

What I said above. The only time it has more timing is under light throttle since the vacuum advance is hooked up to ported vacuum.
I was saying that a motor properly tuned will not need anymore then the total timing set to run really good as far as drag performance goes.
THE WAY YOU HAVE YOUR CAR SET UP WILL BEAT MINE IN THE ECONOMY DEPARTMENT FOR SURE.I am trying to make a faster car and not a gas saver.:) I say that with no disrespect

I mean no disrespect either.
The part i was saying about the vacume advance when not hooked up can affect your timing at high rpm's(over 5000 grand)is that it does move and is part of the distributers timing system and will affect your timing.
People that run high rpm motors will take the hole vacume canister right off the distributer and put a lock out rod in there.

I still can't understand how the vacuum advance causes erratic timing at high rpm's when it does not move. I think in most cases it's the control box that is causing the erratic timing, not the distributor. Most stock control boxes don't work well at high rpm so that's why you swap to a better system.
GO TO MANCINIS SITE AND YOU WILL FIND THIS LOCK OUT DEVICE, EVEN FOR MSD DISRIBUTERS THAT HAVE A VACUME CANISTER.

Yeah I know what your talking about. I've used them before.
Everyone knows when they time a stock distributer motor and rev it past 5000 you will see the timing marks start to shake and become not a single line anymore.This is because the stock distributers internal parts start to move and screw with your timing.

Again what I said above. I believe it's more to do with the control boxes. Now if the shaft bushings are worn out or something is loose it can cause erratic timing. That's why when you go through the distributor you make sure everything is tight.
When you use a stock distributer ,for a performance DRAG CAR\STREET CAR ,the list of performance improvments go's like this:


1)CHANGE THE ADVANCED WEIGHT SPRINGS \\ JUST LIKE THE MOPAR THE PERFORMANCE DISTRIBUTER.
2)TAKE OFF THE VACUME ADVANCE CANISTER AND LOCK IT OUT.

Sorry but I can't agree that you remove the vacuum advance on a street car. A street driven car will almost always benefit from a vacuum advance IMO.
3)LOCK OUT THE ADVANCE WEIGHTS

4)GET A MSD OR BETTER DISTRIBUTER CAUSE YOU DON'T NEED A FACTORY ONE ANYMORE.

I did not get my info from 30 years ago and i never even talked about what vacume port to hook a vacume advance up to for it to work correctly and yes the shop rags do talk to me and i have a name for each one.:-D

I realize you didn't say what port to hook the vacuum to but the only one that can provide vacuum signal at idle is a full time vacuum port. I did make an assumption but it was based on you saying "The vacume advance on a stock engine gives the engine more initial timing". That was a direct quote from your earlier post.
P.s.|||phisy68 waiting for your reply about how more timing helps you with your spark knock:-k

Read my statement above explaining it.
BUY THE WAY I LIKE YOUR CUDA \\IT'S COOL

Thank you
.

Everyone has there own way of doing stuff and thats what makes it fun.

Yes they do and after this last post of yours I see your explaining more like race car settings when I was referring to street/strip settings.
 
FISHY68 \\\\\\\\\\\\\\\\\:thumleft::thumleft::thumleft:
 
WHY are you going to a mechanical cam.
Don't you have stock heads????
 
Yes, stock heads just pocket ported.

If I choose a hydraulic cam, with up to .470" lift, the stock rocker arms would break. A friend of mine have a 280/474 cam and his rocker arms were breaking everytime, so he had to buy roller rockers. If I need to buy a set of roller rockers, I prefer to use a mechanical cam, it has more power and idles much better than the hydraulic one. The guy who will build my engine uses the 284/528 in one of his cars and recommends it a lot.
 
There is somthing on your freinds motor that has been changed from stock.
Thats not to big for any stock motor.
The only thing you need to watch out for is the rocker arm hitting the valve guide boss(top of valve guides)
what are you trying to do \\
Build it the same as a stock motor.
The only thing that it has, thats differant, will be the cam
Use a small hyd. cam with the right valve spring and your done.
 
I didn't get your point.
This 318 is brazillian, I don't know if it's exactly the same. The trouble with the rockers is a fact, many people here had the same problem.

The stock 318 here is: 7.5:1 compression, 300 cfm two barrell carb and shitty manifolds.

Mine will be 10:1 compression, 650 double pumper carb, performer rpm intake, headers, the 284 solid cam and roller rockers. Not exactly a stock motor, at least for me.
 
My point is you can use a stamped steel rocker with up to a .509 lift cam.
Most .509 lift cammed crate motors come with heavy duty stamped steel rockers.
BUT SINCE YOUR GOING TO A SOLID CAM ,YOU CAN'T USE A HYD. ROCKER ARM.
 
If I choose a hydraulic cam, with up to .470" lift, the stock rocker arms would break. A friend of mine have a 280/474 cam and his rocker arms were breaking everytime, so he had to buy roller rockers.


really? your friend had to be doing something wrong. i have run and djv is running that 280/474 mp cam with stock rockers. i also ran the 284/484 mp cam with stock rockers, and in my dart now i was running the 292/508 mp cam for years with sock rockers and never had a problem. maybe your buddies push rods were too long or something.
 
Nothing wrong. Like I said, the same problem happened with more cars here, at least 3 that I know. It's not the lift only, but those performance cams needs better valve springs, and the extra pressure plus the high lift comparing to stock, really break the rockers.

I've got a set of CAT roller rockers and comp pushrods now.
 
I've heard of a few guys having problems with stock rocker arms failing but not many. I'm running stock rockers with a Lunati 60404 and some pretty stiff valve springs. Got a little over 4k on it now with no problem. Ran the snot out of it too.
 
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