8.7 deck sbf, Whats the biggest stroke possible?

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Post Reply
fomocosteve
Member
Member
Posts: 127
Joined: Wed May 25, 2016 11:06 pm
Location:

8.7 deck sbf, Whats the biggest stroke possible?

Post by fomocosteve »

Just wondering how much stroke is the maximum possible in a 8.7 deck sbf. ? 3.850 with 5.625 rods and 1.15 compression height?
Whats been done? I cant find much of anything on the net. Cheers, Steve
dwilliams
Guru
Guru
Posts: 1132
Joined: Sun Oct 15, 2006 10:00 am
Location:

Post by dwilliams »

Your limits are:
a) pan width by starter
b) how bulky the big end of the rod is (pin diameter, capscrew vs. through bolt)
c) length of the bore (having the bottom of the wristpin drop much below the bore gets you into reliability problems)
d) how much room you have to grind for rod clearance before you hit water

I can tell you a 3.6" stroke in a 289 block is at the practical limit, but I have no idea how your 8.7" block compares to a stock Ford block.
User avatar
panic
Guru
Guru
Posts: 2295
Joined: Sat Dec 11, 2004 12:04 pm
Location: Ecbatana
Contact:

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by panic »

Not aware of a 8.7" deck, more information?
ProPower engines
Guru
Guru
Posts: 8686
Joined: Sun Jan 21, 2007 1:16 pm
Location: Victoria BC Canada

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by ProPower engines »

panic wrote:Not aware of a 8.7" deck, more information?

X 2

WTF block are you using??
No stock block has a 8.7 deck height
Is it an aftermarket block such as Dart or World products or a off shore block???
Real Race Cars Don't Have Doors
paulzig
Expert
Expert
Posts: 643
Joined: Sun Aug 03, 2008 6:29 am
Location: Australia

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by paulzig »

panic wrote:Not aware of a 8.7" deck, more information?
Dart make them.
cjperformance
Guru
Guru
Posts: 3661
Joined: Tue Aug 19, 2008 7:20 am
Location: South Australia

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by cjperformance »

SBF , will just reference 302 and 351 factory here for ease,, but these 2 blocks have the same pan rail widths, the same cam/crank c/line distance, now on the 351 block a 4.25" stroke fits with realistically very little trouble, a 4" stroke literally falls in there.
On the 302 block the bottom of the bores come a little closer to the crank centerline so counterweight and rod clearance here will be an issue.
So with your 8.7" block (i have not personally seen one) a 3.85" stroke may well be doable but realistically i would be going a little shorter in stroke and using the 8.7 deck bore length as a strength advantage for better piston support at BDC and just build to to rpm a little higher to regain any HP you may have lost by dropping stroke down from 3.85".
Craig.
fomocosteve
Member
Member
Posts: 127
Joined: Wed May 25, 2016 11:06 pm
Location:

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by fomocosteve »

Yeah, Dart, and SVO make a 8.7 deck block. Have seen a few diffent strokes that might work, 3.625 / 3.750 / 3.850 / 3.900 better RS ratio with 3.625 and 3.750, so maybe your right, spin it hard, though I was planning to do that anyway.
grant6395
Pro
Pro
Posts: 400
Joined: Mon Oct 18, 2010 4:51 pm
Location:

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by grant6395 »

We have used a 3.6 stroke in an 8.2 deck before. Honda Manley rod 1.88 . minimal grinding. A 3.75 stroke in an 8.7 has been done also. Again. A honda rod with an 8.16 pin. It amazes me that a few" well known " engine builders haven't heard of an 8.7 deck sbf. A lot of good Ford comp elim. Engines are based off this block. Best manifold runner alignment for sure.
fomocosteve
Member
Member
Posts: 127
Joined: Wed May 25, 2016 11:06 pm
Location:

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by fomocosteve »

Thanks for your replies, much appreciated :D
1972ho
Guru
Guru
Posts: 1299
Joined: Thu Nov 21, 2013 12:52 am
Location:

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by 1972ho »

WOW over 5 years ago so what did you come with for a max stroke and did you actually build this engine.
n2omike
Guru
Guru
Posts: 1067
Joined: Sat Sep 02, 2006 10:56 pm
Location: West Virginia

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by n2omike »

8.7" is generally used as an alternative to the 8.2" for building 363-385 engines and maintaining a decent rod length.
Guys wanting max cubes will go with a 9.5" deck.
User avatar
Caprimaniac
Guru
Guru
Posts: 1060
Joined: Fri Nov 18, 2011 1:17 pm
Location: NORWAY

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by Caprimaniac »

Didn’t even «Ford Racing» dept. offer an 8.7 back in the day?

8.2-8.7-9.2-9.5
How to turn GURU in an instant.....
Walter R. Malik
Guru
Guru
Posts: 6355
Joined: Tue Jul 24, 2012 11:15 am
Location: Roseville, Michigan (just north of Detroit)
Contact:

Re: 8.7 deck sbf, Whats the biggest stroke possible?

Post by Walter R. Malik »

Caprimaniac wrote: Thu Feb 02, 2023 11:38 am Didn’t even «Ford Racing» dept. offer an 8.7 back in the day?

8.2-8.7-9.2-9.5
YES, a bare block ... Intake manifolds, too.

For some reason, they didn't catch-on very well.
http://www.rmcompetition.com
Specialty engine building at its finest.
Post Reply