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summit 8601

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matty 401 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote matty 401 Quote  Post ReplyReply Direct Link To This Post Topic: summit 8601
    Posted: May/26/2018 at 8:16pm
well i got my 401 running with the Summit 8601 cam  it has a very smooth idle i think my old cam was more lumpy   lol  anybody else running this cam  how does it sound ? 
72 matador 401 the beast
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 69 ambassador 390 Quote  Post ReplyReply Direct Link To This Post Posted: May/26/2018 at 10:34pm
The 8601 is a split pattern and actually idles like a smaller cam. It's a great all around cam and will run better than cams with a single pattern and lumpy idle. I use them all the time in 400 to 425 hp builds.
Steve Brown

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Post Options Post Options   Thanks (0) Thanks(0)   Quote matty 401 Quote  Post ReplyReply Direct Link To This Post Posted: May/26/2018 at 10:55pm
std bore 401 60119 eldo heads and a torker intake  just was expecting more lope out of it  with the 304 duration 

72 matador 401 the beast
79 concord 2 door
72 matador 304 grasshopper
68 Rogue 406
93 Cherokee 4.0 5 speed

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: May/27/2018 at 12:28am
Big advertised duration with moderate .050 numbers, and a wide centerline = plenty of gross overlap but not much overlap at .050" lift and beyond.

What Std pistons are you running?

I'm also putting together a Std 401 with Eddy heads,

but I went with a smaller, fast acting cam (278 gross, 228 @ .050")with a narrower centerline (108*) to try to boost dynamic compression ratio with the stock low compression pistons.

I'm thinking the 108 CL will probably give a healthy lope with the 228 net duration.

I'm leaning towards the R4B for an intake with Dougs 103 headers.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: May/27/2018 at 12:39am



Summit 8601
https://www.summitracing.com/parts/sum-k8601
.050" numbers:
224 intake
234 exhaust
114 lobe seperation

=1* net overlap (59* gross overlap w/282 & 292 gross) 
^it shows 300/304 gross numbers in the description and 282/292 in the specs


my smaller cam
.050" numbers
228 intake
228 exhaust
108 lobe seperation

= 12* net overlap (62* gross overlap w/278 & 278 gross)



Edited by jpnjim - May/27/2018 at 12:42am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: May/27/2018 at 1:44am
If I may ask, if I'm understanding correctly, it's Overlap at .050 Lift that gives a Cam Lope?
Is it the 1* Overlap at .050 that the Summit 8601 Cam has that gives it so little Lope?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote matty 401 Quote  Post ReplyReply Direct Link To This Post Posted: May/27/2018 at 6:17am
Originally posted by jpnjim jpnjim wrote:

Big advertised duration with moderate .050 numbers, and a wide centerline = plenty of gross overlap but not much overlap at .050" lift and beyond.

What Std pistons are you running?

I'm also putting together a Std 401 with Eddy heads,

but I went with a smaller, fast acting cam (278 gross, 228 @ .050")with a narrower centerline (108*) to try to boost dynamic compression ratio with the stock low compression pistons.

I'm thinking the 108 CL will probably give a healthy lope with the 228 net duration.

I'm leaning towards the R4B for an intake with Dougs 103 headers.

stock 8.25  pistons 
72 matador 401 the beast
79 concord 2 door
72 matador 304 grasshopper
68 Rogue 406
93 Cherokee 4.0 5 speed

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Post Options Post Options   Thanks (0) Thanks(0)   Quote matty 401 Quote  Post ReplyReply Direct Link To This Post Posted: May/27/2018 at 7:29am
car has 456 gears  stick a stock converter  lol  i know get that changed  hope to take it out for a test run later today 
72 matador 401 the beast
79 concord 2 door
72 matador 304 grasshopper
68 Rogue 406
93 Cherokee 4.0 5 speed

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: May/27/2018 at 8:16am
Originally posted by PHAT69AMX PHAT69AMX wrote:

If I may ask, if I'm understanding correctly, it's Overlap at .050 Lift that gives a Cam Lope?
Is it the 1* Overlap at .050 that the Summit 8601 Cam has that gives it so little Lope?

I'm not claiming to be a cam expert,
but I would say yes.

My non-expert thoughts:
There's a lot going on with overlap,
and it varies throughout the RPM range of the engine.

You have the exploding gasses escaping out the exhaust valve, as the piston is rising,
then towards the end of the exhaust cycle,
when air is speeding up past the closing exhaust valve,
the intake starts to open.

Hopefully, at certain RPM's (depending on the rest of the combo) the exiting exhaust actually pulls air into the chamber at this point.
That's the benefit of cylinder filling you hopefully get from overlap (some people have called it the 5th cycle).

At lower RPM's,
the escaping exhaust gasses use the opeing intake valve as another escape path.
That's when you get the lope from exhaust gasses entering the intake.

My thoughts are, 
even though the exhaust gasses are under pressure at this point,
how much is going to escape the intake valve at under .050" lift?

If you crack open your welding tank .050", a lot of gas comes out,
crack your window open .050" and you're just breaking the seal and not much transfers, 
so everything is relative.

If you think about it, 
the factory cams were rated at 266* advertised originally,
then later (emission) cams went to
263.5* intake
293.32* exhaust

and the 1971 401 cam's advertised duration was 296.32*/303.55*

^that was not a rip snorting cam by anyone's defintion so the advertised duration (under .050")
seem to have a much smaller effect than the fatter part of the curve,
past .050 and further.


I picked a cam that was as wide as possible at .200 lift,
but tried to keep the advertised number well under 280* (278*), and the .050" lift under 230* (228* in my case) to have the cam flow well, but still have some manners with the a lobe centerline thats slightly tight (108*).

I have the same low-ish CR as the original poster here, so I did the above because I wanted an intake valve that closed early to maintain Dynamic CR.

We'll see how it works out when it's finally together LOL






71 P-code 4spd Javelin/AMX
some Jeeps and some Fords
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: May/27/2018 at 8:26am
Originally posted by matty 401 matty 401 wrote:

car has 456 gears  stick a stock converter  lol  i know get that changed  hope to take it out for a test run later today 

You're doing a lot better than me,
 mine is an assembled short block on the stand and I'm moving at a snails pace.

Did you do anything to the heads?

What head gasket did you use, and what do you think you compression ratio is?

I'm leaning towards using the (not recommended) stamped steel gasket to get the slightly thinned compressed height,
but even with that I think compression ratio will be in the 8.9:1 range (I haven't done the formula yet, but think that's close).

I'm leaning towards the R4B because the divided runners help isolate that exhaust gas that enters the manifold at low RPM,
and should give a slightly better idle.
We'll see what it actually idles like when it's where your build is at now,
a Torker would be my next choice as well.

By the way,
I'm heading on the opposite direction as you gear wise,
I took out the 3.91's and went to 3.15's for this build LOL

But going from a 2.23 first T-10 to a 2.64 first with a shorter tire makes first gear a wash.

71 P-code 4spd Javelin/AMX
some Jeeps and some Fords
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