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long rod 400, 915 heads #2746795
02/26/20 05:36 PM
02/26/20 05:36 PM
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Washington
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hemienvy Offline OP
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This is a motor I've been thinking about for some time, already have most of the pieces.

A flat top piston would put the compression pretty close to 10:1, depending of course...….

So, for a 10:1 iron head motor with good quench (915 heads), how much cam duration would I need to
be able to run 91 pump gas ? Assuming decent cooling, not too lean, smooth out the sharp edges, etc.

Re: long rod 400, 915 heads [Re: hemienvy] #2746806
02/26/20 06:03 PM
02/26/20 06:03 PM
Joined: Aug 2011
Posts: 1,867
KATY TEXAS
csk Offline
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Originally Posted by hemienvy
This is a motor I've been thinking about for some time, already have most of the pieces.

A flat top piston would put the compression pretty close to 10:1, depending of course...….

So, for a 10:1 iron head motor with good quench (915 heads), how much cam duration would I need to
be able to run 91 pump gas ? Assuming decent cooling, not too lean, smooth out the sharp edges, etc.


Wont work down here in Southeast Texas, not on pump gas


[img]https://live.staticflickr.com/65535/49699175113_7f39889fbc.jpg[/img]87379033_2843330729058951_8904448720599252992_o by Charlie Keel, on Flickr
1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 3.54gear A518 OD 4100lb,11.04@123 full street car trim
Re: long rod 400, 915 heads [Re: hemienvy] #2746861
02/26/20 08:33 PM
02/26/20 08:33 PM
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Missouri
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jwb123 Online content
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I don't live in Texas, but in Missouri, I would plug all the engine info into my engine program, and input the octane fuel, and it would tell me exactly what would live. From my experience some where with 110 centerline and 230 or so duration should work just fine, built several like that for street cars. Just finished a 406 small block chevy, it has right at 10 to 1 pistons, it has a 110 centerline, advanced 4 degrees, 220 duration, with .500 lift approximately, it has around 140 psi cold cranking compression, and runs fine on pump gas. Dyno said it makes 357 HP @ 5,500 rpm and 457 ft. lbs of torque @ 4,000 rpm. from my memory. Went into an older corvette. Built several stroker 360 mopars with basically the same combo they all worked great as well.

Re: long rod 400, 915 heads [Re: hemienvy] #2746901
02/26/20 10:09 PM
02/26/20 10:09 PM
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Scully Offline
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Originally Posted by hemienvy
This is a motor I've been thinking about for some time, already have most of the pieces.

A flat top piston would put the compression pretty close to 10:1, depending of course...….

So, for a 10:1 iron head motor with good quench (915 heads), how much cam duration would I need to
be able to run 91 pump gas ? Assuming decent cooling, not too lean, smooth out the sharp edges, etc.

If you mean a 440 rod in a 400, it wont fit, it's about .400" longer. I mentioned in another thread that a budget 400 can be built using a .040" over 72 style 440 piston making a .020" over 400 with the same deck height as a 68-9 383.

Re: long rod 400, 915 heads [Re: Scully] #2746907
02/26/20 10:25 PM
02/26/20 10:25 PM
Joined: May 2018
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Minnesota
TrackPack Offline
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Diamond makes a piston for this combo.

Re: long rod 400, 915 heads [Re: TrackPack] #2746908
02/26/20 10:31 PM
02/26/20 10:31 PM
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Posts: 4,017
Prospect, PA
BSB67 Offline
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Really? I must have missed it. What's the part number? What stroke?

A 1.48 CH 440 piston would do it. Would need some deck cutting to get quench, or just have the pin moved up 0.020" - 0.030"

Re: long rod 400, 915 heads [Re: BSB67] #2746915
02/26/20 11:18 PM
02/26/20 11:18 PM
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DFW
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mr_340 Offline
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440 rod and crank, mains cut down to 400 journals.

https://www.manciniracing.com/37strokcran4.html

383 crank but with 440 rods.

https://www.manciniracing.com/di94bo3st2.html


Floyd Lippencott IV
Re: long rod 400, 915 heads [Re: BSB67] #2746927
02/27/20 12:28 AM
02/27/20 12:28 AM
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Bend,OR USA
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Cab_Burge Online content
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The first 400 block stroker motor I put together was with a 440 stock stroke forge steel OEM crank with the mains cut down and stock OEM 440 rods with flat top Ross pistons with valve reliefs for pump gas with stock type blue printed 906 heads.
I tried to get the customer to allow me to have it offset stroked to 3.91 and use a set of BB Chevy type long H beam rods but he said no shruggy
My first pump gas stroker motor I made for myself had a 4.25 stroke crank with a set of 6.800 long BB Chevy type rods with another custom made set of Ross pistons with 22 CC dish for CA 91 octane pump swill, that motor ran fine, it flat exceeded my wildest dreams boogie grin


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: long rod 400, 915 heads [Re: jwb123] #2746979
02/27/20 09:21 AM
02/27/20 09:21 AM
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Posts: 259
Washington
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hemienvy Offline OP
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jwb123, Thanks much, very helpful.

The rest of the replies on this thread make it very difficult to remain polite.

Re: long rod 400, 915 heads [Re: hemienvy] #2747002
02/27/20 10:36 AM
02/27/20 10:36 AM
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Arlington, Texas
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bobby66 Offline
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Andy F posted a long rod 400 a while back that ran on pump gas and made good power. Maybe he'll chime in.


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Re: long rod 400, 915 heads [Re: hemienvy] #2747017
02/27/20 11:03 AM
02/27/20 11:03 AM
Joined: Aug 2011
Posts: 1,867
KATY TEXAS
csk Offline
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Originally Posted by hemienvy
jwb123, Thanks much, very helpful.

The rest of the replies on this thread make it very difficult to remain polite.


WOW !!! I still stand my ground, An IRON head 10-1 motor will be a PING monster in the heat down here, we are also at about sea level, I don't know what I posted that would be something to get upset about ?


[img]https://live.staticflickr.com/65535/49699175113_7f39889fbc.jpg[/img]87379033_2843330729058951_8904448720599252992_o by Charlie Keel, on Flickr
1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 3.54gear A518 OD 4100lb,11.04@123 full street car trim
Re: long rod 400, 915 heads [Re: bobby66] #2747031
02/27/20 12:02 PM
02/27/20 12:02 PM
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Oregon
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Originally Posted by bobby66
Andy F posted a long rod 400 a while back that ran on pump gas and made good power. Maybe he'll chime in.


We did build a long rod 400 street engine that worked pretty good but it was totally different than what the OP is talking about. We used ported Edelbrock heads for one thing and Hemi+0.100 rods with off the shelf stroker pistons. It pushed a street driver Duster to 10.90 times at the local track. Nice running combo but not really very economical to build. I don't see any point in building another one.

Re: long rod 400, 915 heads [Re: AndyF] #2747077
02/27/20 01:53 PM
02/27/20 01:53 PM
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junction city oregon
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viperblue72 Online content
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I’m not so sure a flat top 400 even with closed chambers is 10 to 1. More like 8.5 to 1

Last edited by viperblue72; 02/27/20 01:56 PM.
Re: long rod 400, 915 heads [Re: viperblue72] #2747085
02/27/20 02:06 PM
02/27/20 02:06 PM
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Scully Offline
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Originally Posted by viperblue72
I’m not so sure a flat top 400 even with closed chambers is 10 to 1. More like 8.5 to 1

It all depends on the deck height, gasket and chamber size. A .035" over 400 with zero deck height, a steel shim gasket and 75 cc heads would have a compression of 11.39.

Re: long rod 400, 915 heads [Re: Scully] #2747105
02/27/20 02:41 PM
02/27/20 02:41 PM
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Kalispell Mt.
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HotRodDave Offline
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I ran a 11.5 iron head magnum 410 stroker, it ran fine with pump premium .030 quench and a 230@.050 cam 110LSA in a heavy 99 dakota RT. I did take many precautions to prevent detonation like true cold air intake, air gap intake, smoothed all the sharp edges on everything, EFI, routed fuel lines re-routed as far as possible from any heat source, 180 T-stat, ceramic coated headers to keep heat out of engine compartment, I opened up all the webbing in the accessoriy drive bracket to let air flow across the intake, big fan to keep air moving through engine bay... I did everything I could to nip it in the bud right from the git go and it worked great. I would think if you did everything right you would be fine. The one thing I would say is maybe get your quench just a hair bigger like .035 or so with the bigger bore.


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: long rod 400, 915 heads [Re: Scully] #2747134
02/27/20 04:56 PM
02/27/20 04:56 PM
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junction city oregon
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viperblue72 Online content
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Originally Posted by Scully
Originally Posted by viperblue72
I’m not so sure a flat top 400 even with closed chambers is 10 to 1. More like 8.5 to 1

It all depends on the deck height, gasket and chamber size. A .035" over 400 with zero deck height, a steel shim gasket and 75 cc heads would have a compression of 11.39.


Except you can’t have .020 quench.

Re: long rod 400, 915 heads [Re: viperblue72] #2747161
02/27/20 06:25 PM
02/27/20 06:25 PM
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fredericksburg,va
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cudaman1969 Offline
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A shorter rod would get the piston out of the head quicker, maybe less chance to detonate.

Re: long rod 400, 915 heads [Re: cudaman1969] #2747171
02/27/20 06:47 PM
02/27/20 06:47 PM
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New York
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Re: long rod 400, 915 heads [Re: polyspheric] #2747202
02/27/20 09:12 PM
02/27/20 09:12 PM
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Washington
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hemienvy Offline OP
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Well, I will say thanks to everyone, I know folks are trying to be helpful.

I thought this would be a simple cam thread, then it shoots off into a piston and rod discussion.

Why do I want to build this ? The answer is not really relevant, but I will say that the combination
just intrigues me, it's just a big small block, big bore/short stroke/long rod deal. And I happen to have
most of the stuff already, including the 6.96 rods and the 1.320 Ross flattops (which they don't make anymore).
I want to make it run on pump gas, which OF COURSE will be possible, with the right cam. That is what I'm seeking.

To CSK, you seem to claim that NO CAM POSSIBLE will make this combo work in SE Texas. That rubbed me wrong.

I am grateful to read about 230-degree cams that the two guys had success with.

Thanks again.

Re: long rod 400, 915 heads [Re: hemienvy] #2747214
02/27/20 09:52 PM
02/27/20 09:52 PM
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Oregon
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I don't think your question makes any sense. The camshaft doesn't change the compression ratio. If you put a big cam in a high compression engine you can reduce cylinder filling at low speeds, but as soon as the engine comes up on the cam you have a high compression engine.

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