484 purple cam..JUNK

-
jameskernz

jameskernz

duster Man
Joined
Jun 29, 2011
Messages
186
Reaction score
10
Location
Inverness, Florida
I have a 340 with a 4 spd.,single plane intake, headman headers, stock heads, holley 650 DP., 3.73 gears. It has the 484 /108 cam in it and I have tuned it many times. Getting it to idle and perform, drivability is terrible. I have decided today after another tuning session to get a new cam! :protest:Does anyone have any suggestion? I would like good drivability, with a good sound..95% street driving
Thanks,
Jim
 
If you have adjustable rockers, the MP 528 would be a kick in the pants compared to the 484.
 
Did you degree it when installed? In a 340, they like to be installed at 102ish.

I'd crank as much initial timing into it as the starter will handle and see where you end up. It may want 28*. I have a tight lashed 284/528 mechanical in a stock compression 70 340, liked 24* initial and will idle real easy at 800 rpm.
 
jameskernz said:
I have a 340 with a 4 spd.,single plane intake, headman headers, stock heads, holley 650 DP., 3.73 gears. It has the 484 /108 cam in it and I have tuned it many times. Getting it to idle and perform, drivability is terrible. I have decided today after another tuning session to get a new cam! :protest:Does anyone have any suggestion? I would like good drivability, with a good sound..95% street driving.

Thanks,
Jim
Click to expand...


Don't give up on that cam yet!

Install a set of Rhoades lifters P/N 2018. I have the same cam in my 68 Barracuda 340 - S and it runs great with the Rhaodes lifters. They take out 15° duration and .025" lift at idle and slowly ramp up to full lift and duration of the cam by 3500 RPM. I have a stock 340 with the .484 - 284 MP cam, auto with stock converter, 3.91 and Holley 6711 650 DP with a stock thermoquad spread bore cast iron intake and it runs great with Rhoades liftes. Without them I could hardly idle at 1100 RPM, with them, I"m idling at 850 RPM. I can smoke the tires all the way to 6500 red line. It is installed straight up like stock cam, no degreeing. I'm running electronic distributor without vacuum advance hooked up, recurved, 17° idle and 36° total.


http://www.rhoadslifters.com/Pages/PartNumber.html


Read the test at the bottom of this page:

http://rhodeslifters.com/Pages/Articles.html


Order a set from Summit Racing and give them a try. They'll help.


If you give up on the cam and want to throw it in the trash, I'll take it off your hands.....
 
Try More timing first.

Remove carb and look at the transfer slots on primary side. If they are more than a square shape opening, try opening the secondaries a little via adjustment screw so you can close up primaries to maintain idle speed.

IMO, it should idle pretty easily in the 800-900 range and not burn your eyes out from a rich idle setting. Being a 4 speed it can idle a bit higher, but, shouldn't be necessary.
 
I did open the secondaries some. I have been doing this also, put the secondaries adjustment srew in from the top down for easy adjustment. Even brought the float levels up for crisp idle but that didn;t work well at stops. I will try some more tomorrow, after I get the floats correct. we put a snapon scope on it today to get it as good as it is, got it to idle at about 900, but driving it with the floats set high was a challenge, with idle all over the place. Thought about drilling the throttle plates but did not. It also sucks gas like crazy
Thanks
 
I agree with trying to tune what you have. That's not the original question you asked though, so I gave my recommendation.
 
jameskernz said:
I did open the secondaries some. I have been doing this also, put the secondaries adjustment srew in from the top down for easy adjustment. Even brought the float levels up for crisp idle but that didn;t work well at stops. I will try some more tomorrow, after I get the floats correct. we put a snapon scope on it today to get it as good as it is, got it to idle at about 900, but driving it with the floats set high was a challenge, with idle all over the place. Thought about drilling the throttle plates but did not. It also sucks gas like crazy
Thanks
Click to expand...

no offense do you know how to tune a carb? sent the floats to where the it barely dribbles out RUNNING out and leave it alone. start at 2.5 turns out on the idle mix screws. as they said make sure you have plenty of timing into it, at least 18* at idle, say 34 total @ 2500 rpm.

now you can start tuning it...
 
Set floats so it barely wets the threads of your sight plug hole at idle.

Higher float levels make the rich idle worse!
 
"484 purple cam is junk"

That cam has been around a long time and a good piece.

I have always installed them @ 108 on the 340.

Sounds like something else is being overlooked!

Like said before check your initial and total timing. If this is an early hi-po 340 that 650 DP should make it idle and perform pretty good right out of the box. I would be using a 750 DP though.

Some times you do to many things trying to get it right that your tune goes way to the bad and you need to go back to square 1.
 
I think the single plane intake is killing you.
I would start by going to a good dual plane intake. (Ede RPM or Air-Gap).
 
Man! I had a bud make 430 HP in that one with a lot left on the table.
 
Even in a low comp 340, that cam should be tunable with your combo, for reasonable street manners. Send it to me and i'll get it right......and have it back to you in a year or so :mrgreen::mrgreen::mrgreen:.
 
You must log in or register to reply here.
-

Back
Top