Don't forget to use a crank scraper with the windage tray and you may get the extra 25HP. What year 351 block are you using................if it is a 70/74 I've got a set of 4blt center mains...........................everything helps when you are building a motor to stay together.................IMHO
Going through my computer trying to clean up files I found this article. Gromm is the one that did the refreshen on my motor and heads..........he certainly knows heads and has been featured in quite a few magazines. This article is from some years ago but may be worth reading as it pertains to your Roush 200 heads; http://www.fordmuscle.com/archives/2001/09/roush200/index2.php
Also found this which is old, but really comprehensive...........enjoy! http://www.carbdford.com/tech/flowdata.htm
I have a girdle which the tray bolts to,good 74 model blk,some articles say on this app. a girdle is better because installing the 3 4blts in the cntr weakens the blk.Plus I will Not have to have it alighnhoned.My girdle is notched between the caps and bolts and also on the sides to clear the throws of the crank.This makes the tray sit very close to the crank,it is made by WAPP.
Just from my own personal experience (and a Mechanical Engineer) the articles you read really don't know what they are talking about.................a mid to late 71 through mid to late 74 block (351w) weighs almost 10lbs more than a 75 and later block. The reason is that the main web area has more material. I put 4blt mains on my late 71 block and the material for a (straight up and down) 4blt main on the center three mains must have been planned by Ford...............because there are built in bosses there for them...........along with extra material. So, I know somebody may criticize what I am about to say but again this is just from own experience............not reading books or looking on the internet.......................a main bearing girdle does nothing more than tie all of the mains together...............and this would be great if the strongest force on the mains was front to rear...........but unfortunately it isn't.............it's in a 360 degree circle with forces exerted around the circumference of the bearing surface. So, although a girdle does help a little it could never stiffen the block as much as 4blt mains. When Bob Gromm was getting ready to line hone the block he put the mains in along with the girdle that had been in the motor since it was put together by CHP.................when he torque'd the mains with the girdle he got different readings every time............sometimes it was 0.00075 to 0.0001.......................he even let me do this procedure once or twice and I couldn't get an accurate reading either....................then he just laughed.......................Bob has been putting race motors together for over 30 years and told me in all that time he has never/and would never put a girdle on................for this same reason...................that's when he suggested going with the 4blt on the center three mains. After he line bored the new mains and we had the crank worked (and the crank was in place with the mains torqued) you could spin the crank with two fingers.......................the way it should be. So, when you put the girdle in and torque it down with the bearings (lubed or course)..................see if you can spin the crank with two fingers. Also, when I built my blown Ford V8 Flathead I built a main web setup to try and get some of the twisting out of the 65lb crank..............mainly because the Ford V8 Flathead only has 3 main bearings(the center main taking most of the force when the crank is trying to twist out of the block at 5200rpm)............and the motor was making over 350ftlbs of torque..................but I tied the main web into the blocks pan rail and the center main(I had some billet mains made for all three mains)...................the only way to distribute the 360 degree forces of the twisting crank.........again this is just from own personal experience...........................IMHO
way beyond me. Makes me VERY glad I went with a mild setup on my motor. Stock bottom end (new bearings and bolts and goodies), stock rods, and just aftermarket pistons that weren't too far off from stock weight, and a set of heads and cam. Should last a very long time!
