/6 to much cam

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themoparman73

themoparman73

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I might of over cam my slant 6. It won't run right. I've done a complete 3 angle valve job with comp cam springs. Up to 500 lift. Switched to hei. I'm running a 276/490 (PURPLE CAMSHAFT ) headers 500cfm. just don't know what else to do. Any info would help.

Thanks Fabo
 
Where did you install it?
 
themoparman73 said:
I did it here at home.
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lol. Not exactly what I meant. Did you degree it? Did you install it in the engine PER the camshaft card, OR per the compression ratio?

In other words, looking at the timing chain set from the front, WHERE in the 360* rotation of the camshaft gear did you install it? Did you just "line the dots up"?

If so, there's a WHOLE LOT MORE to it than that.
 
themoparman73 said:
I just lined up the dots. Nothing else. It runs but no power.
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Then it's not installed in the right place. It should be degreed at least based on the cam card........but IMO it should be degreed based on static compression ratio.
 
The thing is, my friend didn't have the cam card when I got it. I took the cam in to my buddy 's machine shop and did the math on the cam. I hope I didn't screw my engine up.
 
you didnt screw up anything but if you can tell us (heck, not me..) what the specs are of the cam, I bet triple-R could tell you a better degree to install it to (Centerline 106-104) and what compression it needs. Unfortunately you cant throw an MP .509 cam in even a low compression 2.76 reared 318/360 and have it turn into a beast. the cam is generally what you start with and then you build up around it. Could say the same for a HP target or even torque but its a complete system that has to have all of the parts thought out. Sixes are a little different. Low flowing heads and abysmal compression made them indestructible in Valiant all the way to dump trucks. Your going to have to do a little work but asking is the first step for sure. I bet your compression is pretty low, but a skim cut of the head could solve that.

"Where did you install it? .....Here, at home..." That's a great reply :rofl:
 
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I had another slant six with a smaller purple cam years back and it was a screamer. People thought it was a 318. But yes, I might have to ask about getting the right degree on the cam.
 
Couple of questions. What transmission? If auto, what converter? What rear end ratio? What compression ratio? What does the car weigh? That cam is getting up there a little, and really needs other then stock rear gearing and/or converter. Should have a compression ratio increase, and as stated previously, degreeing the cam is a must.
 
There could be a dozen reasons why it's not running right. So don't feel bad. Just start with the basics:
1. Do a simple compression test with the engine warm, all plugs out, and the throttle blocked wide open. Post the results.
2. Check the timing setup. either use a timing tape if your light does not have advancing functions, or use an advance light and with the vacuum advance hose unplugged and capped at the distributor tell us what you have for initial timing, total timing at 2300 rpm, and again at 4000 rpm.
3. Get a vacuum reading at idle, in neutral if it's a manual transmission or in drive if automatic.
 
themoparman73 said:
I might of over cam my slant 6. It won't run right. I've done a complete 3 angle valve job with comp cam springs. Up to 500 lift. Switched to hei. I'm running a 276/490 (PURPLE CAMSHAFT ) headers 500cfm. just don't know what else to do. Any info would help.

Thanks Fabo
Click to expand...
I ran that same cam w/3.55's & 4.10's, but the real problem was the stock torque converter, get the right one & the gears won't matter so much. BTW, I ran that car year-
round, w/no choke.........yes that included -5deg. starts in PA. Took a handful of start/stalls then pumping & babying, but only the addition of a shroud around the header
& a heated air hose to the air cleaner were needed to make it possible. It sucked, lol, but it worked for 8 years. I limited the mech. advance, ran no vac. adv., and had the
total set at 33deg.......think the initial was around 18deg. My engine ran 9.35:1 compression(static), always idled fine w/an aggressive lope, but never had a die-
out or stalling issue, so please......................more details sir........................

Oh crap, almost forgot the most obvious thing, the valve lash is WAAAAY wider on
the Purple Shafts, .028"/.032" Int./Exh. is the spec. only the smallest /6 cam was
set w/the .010"/.020" lash.
 
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Even if the cam is straight up, it should still run very acceptably. Maybe low on power, but run good.

Something else could be amiss. If you can answer the questions Charlie asked, that might give us an idea of where best to install the cam......but you should correct any other running problems or they will persist even after the cam is properly degreed.
 
themoparman73 said:
I might of over cam my slant 6. It won't run right. I've done a complete 3 angle valve job with comp cam springs. Up to 500 lift. Switched to hei. I'm running a 276/490 (PURPLE CAMSHAFT ) headers 500cfm. just don't know what else to do. Any info would help.

Thanks Fabo
Click to expand...
It won't run right.
That's a pretty broad statement.
And so is "it runs but no power".
Hang tuff, the guys will get you going in no time.
 
Killer6 said:
I ran that same cam w/3.55's & 4.10's, but the real problem was the stock torque converter, get the right one & the gears won't matter so much. BTW, I ran that car year-
round, w/no choke.........yes that included -5deg. starts in PA. Took a handful of start/stalls then pumping & babying, but only the addition of a shroud around the header
& a heated air hose to the air cleaner were needed to make it possible. It sucked, lol, but it worked for 8 years. I limited the mech. advance, ran no vac. adv., and had the
total set at 33deg.......think the initial was around 18deg. My engine ran 9.35:1 compression(static), always idled fine w/an aggressive lope, but never had a die-
out or stalling issue, so please......................more details sir........................

Oh crap, almost forgot the most obvious thing, the valve lash is WAAAAY wider on
the Purple Shafts, .028"/.032" Int./Exh. is the spec. only the smallest /6 cam was
set w/the .010"/.020" lash.
Click to expand...
This, right here. The Slant NEEDS a converter or better still, a clutch.
The problem is not what you did, but what the Slant is.
The bore/stroke ratio is much better suited to a lawn tractor than any sort of muscle car application... The rod ratio on the 225 is way too high for any bottom end grunt. Increasing the size of the can and intake only magnifies these shortcomings.
Get that thing up into the 3500 rpm range on launch, and it will become a whole different animal.
Oh, and also, that 500 CFM carb is not too big, but it is jetted way too fat to be happy on a Slant.
Block off the power valve and drop the primary jets down into the 60s.
Taking fuel away will really wake that thing up, with no other changes
 
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