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FE bore & stroke
I am trying to choose what bore and stroke combination to go with for a new aluminum Shelby motor.
4.250 bore x 4.125 stroke = 468ci 4.250 bore x 4.250 stroke = 482ci 4.375 bore x 4.125 stroke = 496ci 4.375 bore x 4.250 stroke = 510ci 4.375 bore x 4.375 stroke = 526ci. I think I got those right. What are the advantages of one size vs. another? Should I stay away from the "big bore blocks"? Is it "let your wallet be your guide"? Thanks for your help! Mike |
I have 4.280 bore x 4.250 stroke = 489ci. Not a big bore, so plenty of meat left on the cylinder walls, but the bores were going to need to be cleaned up from casting anyway, so why not get the .03 during the clean up.
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I ended up with the 4.375 bore x 4.125 stroke = 496ci.
It's got the KC StageII heads with hyd. roller cam. This setup makes a ton of torque at low RPM's so I never need to turn it past 5500. I just edited this post: My bore is 4.315 x 4.250 stroke = 496ci. |
Thanks! I appreciate the input!
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I think this is a matter of how much power do you want and where do you want it to be. Also if you go bigger than 4.250 stroke on the crankshaft you will have to go billet which you may plan on doing anyway. I have built them in all the C.I. you listed and have not had anyone disappointed yet. The big bore blocks are 500.00 more and they do have special sleeved installed so the sleeves are not thin and we have seen no running hot problems which i think concerned some people. We have all the parts in stock to build any of the above com binations. Let me know if we can help. Thanks, Keith Craft
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Mike.....
I'd build the Shelby to at least a 4.270" bore, leaves enough wall to bore to 4.280, 4.290 4.300 and 4.310 in the future for eventual freshening. I'd likely not take it all the way to the max bore For a street Cobra.....new sleeves are going to be expensive and availability will always be an additional expense and risk in the future. Resale Value! The manifold you asked about will fit in CSX4815. This view shows the Barry Grant Carb in the right Blue. 2x4 With BG Look 2x4 With BF Look Superior Crankshaft 4.375 Stroke Superior 4.375 Stroke Oliver Max Rods 6.535 Oliver Max Rods Edelbrock Heads using 11/32" valves (Top Image CNC vs From Edelbrock on Bottom) CNC Heads CNC Heads CNC View CNC View George |
Thanks Keith and George for your replys!
George, When we talked you didn't think that the tunnel wedge intake would fit under the hood of the CSX cars...that I need to consider the Blue Thunder intake from Tony Banta. Is that a tunnel wedge in your photos? Do you think it might work after all? Also the 4.270 bore, is that from the standard bore block at 4.250 + 020 oversize? Thanks! Mike |
George / Keith,
What is the standard bore size of the Shelby big bore option, and then what is the maximum bore it can be taken out to? |
Mike,
Vince (Shelby LV) measured an HST 4000 with the Blue Thunder, we compared the intake heights (we have both on hand) and jointly verified it will fit in the 4000 HST Glass cars and the A/C Aluminum cars. The BG Blue Carbs will fit even better. These are some different views of each manifold. Tunnel Wedge View Tunnel Wedge View Tunnel Wedge View Tunnel Wedge View Tunnel Wedge View Tunnel Wedge View Tunnel Wedge View Blue Thunder Blue Thunder Blue Thunder Blue Thunder Blue Thunder Blue Thunder Blue Thunder Blue Thunder |
Thanks George! You always have cool pictures to see!
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Allan...that little baby motor.....in CSX7034.....this is it's Big Brother in Steve McDonald's SPF from Last week at the SPF
Branson Superformance Owners Ralley 4/25/05.. he has two intakes for the motor.....one Tunnel Wedge and then this one for the Road Trips....this trip was 2100 Miles per Steve.. http://www.gessford.com/work/images/PICT0144_2.JPG |
Thanks Mike.....we've been doing those combination since the early 90's and of course I run that Tunnel Wedge on my Cobra...so I like the look....
G My Old Motor |
Geez Georgie...!
Georgie (Mr Hastings),
I don't know what kinda motors you boys build out there in Nebraska, but us boys out here in Kalifornie build them so they don't need to be rebuilt later.:D Bore that ***** out to the max! How many miles they gonna put on a Cobra anyway? Most of these guys here will have their grandkids driving these cars before the engine needs work. Besides, if they DO need an overhaul, they can just buy another block or replace all the sleeves! These Cobra guys got lottsa money! Just look at Turk!:D Job security!:D --Mike |
Turk's moving to Florida.....they don't have SB100...hahahaha
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I was sweating bullets when I took my engine apart, afraid the bore would not clean up. Whew, sure glad I didn't have to deal with that over bore issue. After final hone I was .019 over bore for the custom pistons.
...by the way George, the motor is doing really well. I'm very happy with the results, thanks again for your expertise in helping me get it right! :D |
The big bore Shelby block comes 4.375. The over bore size is not limited to the block as much as a good head gasket that is available that will not hang into the bore. The Fel-Pro is listed as 4.420 I believe and the Cometic 4.400. I believe you could run one at 4.400 with out any problems. Thanks, Keith
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