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Are AFR 205's bolt on for 392W?
So I'm thinking about upgrading my Motorsport 392 Windsor (year 2000, 430hp version) by upgrading the heads. I've been researching AFR 205's and have read that they're a straight bolt on, but have also read that I'd need to change my pistons to get needed valve clearance.
Has anyone made this swap? I think the new heads would flow enough that I could get a hotter cam too. I don't want to get into such a slippery slope that next time I look up, I've spent $4000 and could have started over.... |
The valves are in line, right? Are the valves the same size? If so, I don't see where you'd need different pistons unless you went with a wilder cam.
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I know a couple guys that swithed to the AFR's on their crate 392 (1 switched to 185's and the other to 205's) and they never said anything about valve clearance issues.
BTW, that switch will really wake that engine up. My buddy with the 205's said with that switch alone (no cam change) his engine now puts out over 500HP. |
The 205's bolt right on to a 351W but the exhaust ports are slightly higher. The valve to piston clearance depends on your cam and valve train geometry. Call AFR and discuss it with them. I had to go to a dished piston to get enough clearance on mine but my cam is "frisky".
Bill stradtner |
Miles,
I first had a 2001-2002 crate FMS 392. I had heard great things about the horsepower gain with a AFR switch,here on CC.I went and talked with them at Keith Craft in Plano about it. I was told by them that the pistons would need to be flycut because of the bigger valves in the AFR. Like what is being said here,others said it wasn't needed. With that and rebalancing and no telling what else,I decided not to. Later on I went with a KC 418". Great engine. |
Madmiles442, Dont know about about the pistons but the mating flange is slightly different I had to do alot of grinding on my coated headers to get them to fit . I hope the angle is the same as stock , beware that changing any part can be a whole snowball effect down the line.
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Madmiles,
Don't know about the piston clearance. The headers will bolt on to the spf headers though. |
Fred, did you say something? I was so distracted by your new Avatar, I didn't hear a word you said.....
Boing boing boing |
I'm sure about the particulars, but my Roush 427R has AFR 205 heads built for Roush. It may have some to do with cam and carb and intake too, but they flow really good with my set up.
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Miles, what are your cam specs right now? If it is not too wild on lift and duration, There is little risk that it will not fit. On the exhaust, the ports are raised about 1/8", so your side pipes will be that much closer to the top edge where they exit the body, not enough to mess with your mounting supports for the pipes.
You could go ahead and buy the heads, then mock them up to measure piston clearance with your current cam. You need to check pushrod length again too. Then you have a choice (while the top half is already disassembled) to keep the current cam if clearance is tight, or buy a new one if there is enough clearance. Either way you should get some more power out of the deal. |
My son has a set of AFR heads about 1 year old with about 5000 miles on them.
Please give me a call if you have any intrest. Thanks, Dave 215 896 0650 |
Thanks for the info, no decision yet. And no clear answer.
I don't want to end up like the "When Stroker Motors Go Bad" with valves dancing all over the piston faces. Maybe next winter I'll swap the heads if I find definitively that they'll work. Thanks again for the feedback. |
If you have narrowed the field down to AFR's you may want to consider a pair of AFR's new 185 Comp version heads. The CNC program has been revised and just based on flow bench numbers they are very comparable to the 205's. I believe the 185 Comp version will be available in the next 60 day or so.
I too am running a 392 and have look at the numbers for new 351 (larger SPF headers), gaskets, and 185 comp heads... the cost per estimated horsepower is pretty steep. I would suggest getting your cam spec's from FMS and calling AFR and asking them to run the numbers matching your goals with a specific pair of their heads. A good back check would be call the cam manufacturer and confirming the heads selected match your goals and their cam. Before I do anything I plan to have my current setup dyno’ed to confirm the baseline RWHP and more importantly the air/fuel ratio through the rpm range. The baseline will give me the ability to confirm any gains and the cost per horsepower after such major modifications. Good luck and keep us posted. Ed |
Ed,
Call Dennis at Olthoff Racing (spf Dealer) and ask him about the larger 351 headers. When I talked to him, he said there isn't a large difference in power (about 10hp at 5500rpm, but loss of tq down low). He was the one making the headers. Dennis is very pleasant to talk too and very informative with these types of questions. |
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In short I have done nothing but enjoy my machine. As mention earlier I do plan to have the car dyno'ed to confirm the air/fuel ratio over the rpm range. The side benefit will confirm the drive train losses based on the engine dyno number from Roush. I’m still following the head swap articles with great interest. Thanks again, Ed |
Ed,
Your Roush heads flow a lot better than my Ford Motorsport GT-40 heads. Your HP gains might not be as large as what I would get. I anticipate a gain of 50-60 HP going to the AFR 205's. Then if I was to redo the headers and sidepipe, get another 30-40. Heads $2000/60 = $33.33/hp Exhaust $2000/40 = $50.00/hp Of course, spending $4k is nearly halfway to a Keith Craft 408 with 525 horse and a stronger bottom end. |
Madmiles I have also wondered the same thing about the heads, you would think someone has put a set of AFR's on a Ford Racing Crate 392 by now.
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My thoughts exactly on the new engine.... I'm going to sit on the sidelines for now and enjoy the 448hp/484tq of my current engine. More is always better but the capabilities of this setup far exceed my ability to drive. A performance driving school is definitely in my future. Just keeping it pointed straight and between the ditches is the goal for now. Ed |
Always check the Valve clearance!!!!!! You can read my posts in the small block forum when I put AFR 185 heads on my 2006 FMS392. Ran into lots of problems. But, in the end they added over 100hp.
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Without removing them, you can notch pistons......
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