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Discussion Starter #1
David, I'm building a 425 CI Windsor with the same internal rotating parts as yours, except rods are Scat Pro Comp light weights similar to what you used. Are you using a full size base circle cam and if so, did you experience any interference problems with the 4.17" stroke? My crank is an RPM Int. internal balance.
 

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David, I'm building a 425 CI Windsor with the same internal rotating parts as yours, except rods are Scat Pro Comp light weights similar to what you used. Are you using a full size base circle cam
Yes.
and if so, did you experience any interference problems with the 4.17" stroke?
No. Plenty of clearance, but always check as the cam timing has more to do with it than base circle. What rod length and piston CH are you using? I found clearancing required with the 4.17" crank at the cylinder skirts, oil pump boss, and OK but bare minimums at the piston pin bosses and piston skirts with the crank weights.

David
 

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A couple of the pics I took of the "cheap-street" 427W build. A bit fuzzy, but you can see the cylinder relief ground for the other rod on the same crank throw. The angle makes the piston/weight clearance look tighter than it is.

David



 

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Discussion Starter #4 (Edited)
Thanks David, that's a big relieve. The photo's really help, too. I'm using Probe SRS model 12360 pistons, 1.280 compression height. These were ordered with a custom 30 CC dish, which gives me a near perfect 9.78 compression ratio with .040 head gaskets and 0 piston deck height. Rods are 6.125". I figured I would need to clearance the areas you described as well as the main stud girdle I plan to use. Or I may order the Probe one that is already stroker clearanced.

One more question: what brand and style of hydraulic roller lifters are you using?
 

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Thanks David, that's a big relieve. The photo's really help, too. I'm using Probe SRS model 12360 pistons, 1.280 compression height. These were ordered with a custom 30 CC dish, which gives me a near perfect 9.78 compression ratio with .040 head gaskets and 0 piston deck height.
You should be able to run regular-grade 87 octane pump gas with that static compression depending on the cam choice. My cam builds a lot of low-rpm dynamic compression, and runs 91 octane with 205 cranking PSI at 10.6:1 static compression. Full ignition timing with no det at 175°F average running temp. A 180°F thermostat (~195° running temp) would probably put it into det on a long pull. I probably cut it a bit too close, as a cruiser I could get a tank of crappy fuel on the road and limit my performance.
Rods are 6.125". I figured I would need to clearance the areas you described as well as the main stud girdle I plan to use. Or I may order the Probe one that is already stroker clearanced.
If you are going to use a girdle, I have one clearanced for a 4.17" stroke but never run. PM if interested in a good deal.
One more question: what brand and style of hydraulic roller lifters are you using?
Not. To maximize cruise performance (mileage) along with higher rpm torque, I used a flat-tappet cam. I chose it as the valve acceleration is higher (valve opens quicker) than a roller cam up to about .300 lift, giving deeper breathing at lower rpm with the different intake flow characteristics of a long-stroker. A very aggressive but noisy profile. Since I'm thinking of pulling-back from the edge a tiny bit, I may go roller to soften the valve train loads, even though performance may take a small hit. Even though the lift isn't high, those parts are working hard, and a roller should extend the lifespan to match the rest of the engine. Morel 5517 rollers under whatever branding would be a good choice for this application, and are a great value at around $300/set if you shop. There are other options, but you need a lifter that will not just last a couple hundred 1/4-miles, but 100k street miles, plus 1/4-miles.
:tup:
David

[EDIT] Oops, you said hydraulic rollers - those are solids. I would strongly consider a solid for this use. Maintenance on solid rollers is next to nothing these days. And the noise... well, it's a performance engine. ;)
 

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Discussion Starter #6
Yeah, I errored on the side of caution with the CR this time. I run 10.2:1 in my 351w Mustang and, with only 91 octane available and 90 degree plus days in the summer, I am tired of readjusting my timing to get rid of the ping. I also want to keep the heat down in this car as well.

I'm going to stick with the hydraulic roller cam just to keep things a little forgiving in the valve train. I hear a lot of good about the Morels but the price is just too high. Cheapest I've seen them on e-Bay is $360. Since this is a street engine, I think I'll just pick a good set of OE style lifters.

I PM's you on the stud girdle.
 
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