Hi Everybody, I'm new to the board and starting a new project. I have a 1930 model A roadster, I'm planning on putting a flathead motor and possibly with a blower optimistically 300 hp. I'm debating on the frame, I know I need to add some cross bracing but is it necessary to box the frame rails as well. I searched the site but only found threads where everybody is boxing their frames, maybe that's my answer. Anyways, are there guys running 300hp motors without boxed rails and if there are previous threads on the subject please help me out and direct me to them. Thanks in advance.
Anything more than stock necitates frame boxing. Also, you will most likely need to straighten the frame first. They sag in the middle, at least all the ones I've had.
I was taking the running board braces off yesterday and was surprised at how much the frame flexed. Boxing it is I guess.
Get yourself a 6 foot level, if your doing frame work it is going to come in handy! Place it on the frame along the frame rails in different spots and you will see quick enough if it has sagged. Check it across the frame from side to side in different areas. Also measure it from a point at the right front to a point at the left rear. Repeat for the other side to see if it is out of square. I felt regardless of what horsepower the flathead is going to make it is WAY heavier than the original 4 banger so boxing to me is just a common sense thing to do. Especially if you think your motor could possibly twist it. I am also doing a 31 roadster with a flathead.
Box the frame and add a decent K-member to stop flex and enhance the torsional rigidity. You won't regret it.Easy to mount a transmission cross member to it.
I built my frame up with new A rails and X member, plenty stiff enough for the flatty I'm runing (from Dagel's http://www.dagelsstreetrods.com/super_x_crossmember.htm ) . 300Hp is going to be a challenge but not impossible. Joe Abbin should be able to help.
My '31 roadster frame, unboxed, has been carrying a 331 Cad and early Hydro around for the last 50 years or so. Seems to have held up fine; but when I go through it again the first thing to happen will be straightening and boxing the frame...
I don't know the original source, I had a photo copy from a while back, came across it again, scanned it, and cleaned it up a little. I've posted it a few times when the subject has come up. Post up a thread on how it went; when you get it going.
I've boxed the frames in all of my cars and always thought it was the way to go but I recently looked over organgrinders coupe at the hamb drags and it runs an unboxed model A frame with a monster of a big block pulling wheelies and I left scratching my head wondering if my gutless small block really needed a boxed frame to hold it together.
Take a bare Model A frame and put a concrete block under the front right frame horn and sit the back of the frame on the other block on the left side,then you and a buddy stand on the unblocked sides and it will amaze you just how much the frame twist. The frames were built to flex and twist because the roads were mostly unpaved and extremely rough & rutted. I prefer to box the frame. HRP
I don't think anybody has mentioned it; but if you plan to use a cross steer set-up, you probably will need to box the frame. Cross steer really torques on the frame.
Also helps keep doors shut on inclines... Went in the driveway in my old bud's channeled 'A' Coupe, un-boxed Model A frame, 21 stud flathead and '36 box, F-1 center crossmember. Passenger door opened on the slightest twist. I had picked up his grandmother walking home from the store...she didn't like me, but accepted the grocery-saving ride. Her story: "That hoodlum Mike picked me up in your car, all polite, then turned in the driveway and tried to dump me out!" She was an old 'country type'...
There are a lot of good reasons to box a frame, and if it was my car, and I ran and original Ol' Henry frame, that seem a lifetime of use/abuse between you and Dearborn, I would box it. The reason to box a frame to make it live up too it's best under load AND cornering. In a drag car it's a matter of load and stability, but mostly in a straight line, and coming down from that highed, flexibility means soft landing, and less cracking. There has been almost endless debates on here about the boxing and how. I've even heard talk about good looking frames that when put on 4 stands and someone stepping on to it can make it flex out of shape, and that old rivets that looks tight can even wiggle. One guy even claim, that welding all the joints between crossmember and framerails makes the car handle better. EDIT, it might have been HRP, I just wasn't sure, but after reading his post it all comes back. Welding up the crossmember idea, was that also you Danny? End of edit. I would remove all rivets, sand blast, line up with good bolts, install boxing plates and then weld it up very slowly (Boxing plates and crossmember), but only "chain link" weld the frame (slowly and far apart to prevent it go out of shape). Reblast, powder coat and fill inside with linseed oil or undercoating wax. And never ever have second doubts about not doing it. Because the extra weight doesn't matter that much and even if it only makes a small bettering, it gives piece in mind!!
300 hp would certainly warrant boxing and bracing IMO. You might do OK with a stock flathead and no boxing but most folks will tell you better safe than sorry.
I read the 300 hp as an example of Fast/full race (by 1954 standard) and then 10% on top for safety/good measure, not a firm value!!
That picture is from California Bill's Ford Speed Manual...about 1952, but available in reprint. A frame straightening tech for basically stock frame: http://www.fordbarn.com/forum/showthread.php?t=26355&highlight=frame+heat&showall=1 look at post 21 for starters
I am running an unboxed frame with a 32 center cross member and torque tube. no flex!! without the closed driveline defiantly box the frame. Walter
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