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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 Posted: May/27/2018 at 10:43am
want to sell the 391's ?  used eldo head gaskets harland sharp rockers S4003 and eldo push rods according to the web site is saying bumps the compression to 9.5  they have a smaller chamber inbetween the 291c's and the later heads 
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 11:03am
Originally posted by matty 401 matty 401 wrote:

want to sell the 391's ?  used eldo head gaskets harland sharp rockers S4003 and eldo push rods according to the web site is saying bumps the compression to 9.5  they have a smaller chamber inbetween the 291c's and the later heads 

I'm keeping the 3.91 rear since it's original to the car (I swapped in a whole 3.15 rear in),

Dennis addressed the 9.5:1 cr thing at one point,
the answer didn't entirely make sense but he wasn't the ad exec that came up with it, so I don't blame him at all.
I also appreciate him tracking down the answer (I'll try to find the post).

The answer went something like:
 stock 401 will have 9.5:1 compression with Eddy 54cc heads,
but not with the stock pistons. LOL
I believe he gave the piston dish volume needed, and it wasn't any stock piston I had heard of.

Someone did the formula (might even have been the same thread) and I believe it was in the upper 8's,
like 8.8 or 8.9 or so.

I'm using Crane Gold Rockers I got here from jtsllc1,
and I just made an adjustable pushrod last night to try to figure what length I need with them.
I'm kicking myself for not being able to find any used head gaskets here just to check for pushrod lenght and valve clearance
(don't want to torque down and then remove a new gasket to check piston to valve clearance)


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 11:13am
This isn't the thread I was looking for,
but "RB401" calculated compression with stock low compression pistons to about 8.8:1 here


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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 12:25pm
edelbrock claims the changed the design of the chamber  not sure if it is true or not  that is where they come up with the 9.5 with the stock piston 
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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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 Posted: May/27/2018 at 12:27pm
the rockers you have are they for 3/8 or 7/16 stud 
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 Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: May/27/2018 at 12:51pm
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.

I once had a 224 duration on 108 in a 401, and it had a nice lope, good mid range torque, and pulled to about 6,000 rpm with R4B and headers, 10.2 c.r. About 13 in. vacuum at 800 rpm idle, if I remember correctly.
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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 1:27pm

Originally posted by matty 401 matty 401 wrote:

edelbrock claims the changed the design of the chamber  not sure if it is true or not  that is where they come up with the 9.5 with the stock piston 

The chambers do look different/more modern/better to me,
but if they're 54 cc's they'd still drop compression ratio compared to the 51's.

I think I might scrape 9:1 with the thin stamped gaskets,
or if I spent the money for thin Copper Gaskets,
but with the Low CR stock pistons and Eddy gaskets I'm *thinking* it's in the 8.7-8.8 ballpark.

I looked for the post where I remember Dennis clarifying which pistons were used for 9.5:1 
but I got sidetracked before I could find it.
Maybe it was on the other board(?)




Originally posted by matty 401 matty 401 wrote:

the rockers you have are they for 3/8 or 7/16 stud 

They're 7/16",
Jim was nice enough to include the 7/16" studs. Clap

If I was going to keep the 3/8" studs I was thinking about just running stock rockers (assuming they'd work),
but it worked out with the 7/16" Cranes,
so far anyway Smile




Originally posted by Sonic Silver Sonic Silver wrote:

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.

I once had a 224 duration on 108 in a 401, and it had a nice lope, good mid range torque, and pulled to about 6,000 rpm with R4B and headers, 10.2 c.r. About 13 in. vacuum at 800 rpm idle, if I remember correctly.

That's pretty much what I'm hoping for,
I still have the stock rod bolts so I don't want to risk spinning it too high.
Self imposed 5800 RPM should be perfect for me.
& I'd be thrilled with 13" of vacuum, I put manual brakes in the car a long time ago anticipating a stupid big cam that I never ended up with.
If the vacuum is there I'll put the power booster back on.

I'm hoping this combo will have a nice fat torque curve right in the middle,
to pull the gears no problem,
but hopefully it won't challenge the low-ish torque rating of the 2.64 T-10.

I'll just have to play nice with 1st and 2nd gears I think.
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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 9:54pm
Originally posted by jpnjim jpnjim wrote:

I'm kicking myself for not being able to find any used head gaskets here just to check for pushrod lenght and valve clearance
(don't want to torque down and then remove a new gasket to check piston to valve clearance)



Well,
I checked the piston to valve clearance with a little hobby clay,
without any gasket (since I didn't have a used one here),

I was worried with the close lobe seperation and .564" lift the intake might get close to the piston LOL

yeah,
it doesn't.

Those stock cereal bowl pistons sure give you lots of valve clearance


 

valves don't get within a mile of them with this cam

Just thought I'd follow up on it here since I mentioned it earlier in this thread.


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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/29/2018 at 10:45am
IT IS ALIVE !!!!!!!!!!!!!!!!!!!!!!!!!!!!  runs really good  turns 5000 in a heart beat  now i need a rev limiter  hahahahahahahahahaha
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/29/2018 at 2:11pm
Originally posted by matty 401 matty 401 wrote:

IT IS ALIVE !!!!!!!!!!!!!!!!!!!!!!!!!!!!  runs really good  turns 5000 in a heart beat  now i need a rev limiter  hahahahahahahahahaha

YOU are the rev limiter LOL

Are you running the stock rod bolts like I am Matty?
I'm going to try to keep my RPM's under 5500 just because it would be a shame to put a window in a 401 block Ouch

my old 360 never complained about 6000-6500 with the stock bottom end but you can find 360's stacked like cord-wood for pennies a pound Big smile

Glad to hear it's moving around under it's own power,
I bet if you set the idle real low the cam will lope like you want Smile
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