Howdy gang, I'm in the process of rebuilding my flathead. It's a '49 block that checked out OK at the machine shop. I'm having Keller Machine in Medford Oregon do the machine work by the way. It's getting bored to 3 5/16", using NOS Jahn's pistons. 4" Mercury crank, Joe Hunt magneto and Offy heads. What I'm looking into doing is to use: Chevy valves 1.6 x 4.935" or 5.005" (longer then the Ford ones 4.915") Isky MAX-1 cam or 77-B Stock Ford lifters. #6500. Anybody have NEW ones? I'm waiting for cam base circle dimensions from Isky. Ron Isky off the top of his head was thinking that the 77-B may do it. My intentions are to not have to use adjustable lifters. Stock ones are very light. Seems like there are several horror stories out there from them loosing up and ruining cams etc. Anybody else on here done this or tried or done this and died?. thanks for listening, Gary
Gary, Sure, that is doable; I've used the same cam grind/ stock lifter combo, but with stock Ford valves. If your stems are still too short you just build them up to give yourself sufficient material to grind! good luck, Tooratly
Tooratly- If I'm not mistaken the end of the valve stem is a "cap" of harder material. At least on the SS ones I'm looking at using. Wouldn't welding on it give you a softer material? Besides that though. I'm glad to hear somebody has done it. I should go play the lottery the way things are going with this motor so far. Anybody else???
In 1942 the speed shop welded on Stellite to the bottom of the valves to lengthen them for me. There were no adjustables then. looking at a book (DRAKE) it said that one builder had 1.75 valves on the intake! traderjack
Here in New Zealand adjustables were not available in the 50s and 60s. It was common practice to build up the base of the stem and grind it to the required gap.
Hmmm . . . seems to me that you're going through a whole lot of trouble to end up running a cam that is very mild. You're building a 276 cube motor - and both of those cams are nothing to get too excited about. If it was my motor, I'd run a bigger cam, adjustables and be done with it. You're not going to be spinning the thing up to 6,000 RPM, so who really cares about the extra weight of the adjustables. Buy a good set of hollow adjustables (about $200) and put in a cam that has the lift and duration that your motor needs. If you're partial to Isky, maybe a 400 jr, of a Potvin 3/8 from Moon, or L100, or a Winfield SU1A . . . there are so many good cams that you'll have much more fun with than a MAX 1 (which isn't a bad cam, just a bit mild). Anyway . . . just another opinion . . .
You need more cam than a 77B for that engine...A 1007B would be about right...Very slight idle lope and excellent mid range... Forget the adjustable lifters and their inherent faults of being heavy and screws that loosen....Even some brand new ones come with loose screws. Find a used set of original hollow steel lifters and have them refaced and polished. Pete "Been in the cam business 53 years"
Well there's something to think about, cam choice that is. I was thinking on the mild side, sounds like too mild. I didn't want to lose the mid range of the motor. I'm not partial to any of the manufacturers really. I'll look into the others mentioned. Pete1, got any hollows for sale? Thanks, I really appreciate the input, Gary
I've never used adjustable lifters in a flatmotor. The added weight means higher weight springs are required to control the added weight....that means more wear on the cam. Screw that, I spend the extra time grinding to get correct clearance. With the light springs, there's less pressure on the valvetrain to cause wear, requiring longer intervals between valve adjustments. I haven't tried using the chevy valves but I'd want to be sure I didn't grind through the hard facing on the chevy valve tips. If there's a 0.020" difference, you should be able to build the chevyvalve tips up and have them hardened...should work.
I like the grinding to fit process. Done it before for a stock build. The Chevy valves I looked at had hardened tips that measured about .100 long. There is material to work with. Maybe .050" or so? Haven't heard back from Isky yet to find out the cam base dimension for the cams I was wondering about. With the cams that have been suggested I should plan on subtracting another .020-.030" or so for base dimensions by the sounds of it. To be on the safe side. Rocky, Can you recall what cams you've used with the stock lifters?
Looks like I'm going to need more length to compensate for the cam lift then my original cam choices. The cam is a Schneider 400sr. with .386" lift. The cam I chose has a base circle difference of .148" from the stock one, which means the lifter and/or valve need to be about .074" longer then the OE ones. Anybody welded up that much on the stock valves or welded on the Stainless ones? Sounding like I may need adjustable ones.
Another common method was to weld or braze a disc to top of lifter...many grinders have a lifter fixture to get this ground flat. I think Red's (before new owner) did a lot of investigating of available post-Johnson adjustables, and there is a tech article there. Presumably they have figured out the best of the current crop. The old Johnsons were quite reliable. I think with a mild cammed street flathead, weight is not a real issue. Most hotrod springs are stiffer than needed for this level of engine. Still, the heavy lifters are most unappealing and un-hotrod like. I remember my own horror when the Johnson supply ran out and Joblot sent me a box of the damn things...they are still sitting unused waaaaay in the back of the basement. I went and derusted some old Johnsons when I saw the new ones!
I built a flathead merc crank, crower87f track cam, a set of nos hollow johnson lifters, 1.60 valves int & ex, get a copy of Mike Davidsons FLATHEAD FEVER, you will need this when you clean up your ports. built my car 10yr ago drove from kankakee IL to so cal 2 times 21mi to the gal running 75-80 mph, on two carbs. dave
And after a few hundred miles, when your valves have settled in the seats, you can take it all apart and do it all over again. If you don't like that, just subtract .010" from all the lengths - and have a noisy engine and extra cam and lifter wear. You can also be sure that the valves will not all settle to the same height. BTW: you're comparing the valve lengths? How do you know the assembled height of an oversize valve before the seat is actually cut? Answer: you don't - but it's not the measurement you're making. The larger head always seats higher in the chamber (shortens the stem), but how much depends on how bad the original seat was, how big an oversize etc. Don't.
Although I like to use stock lifters for a stock engine it really isn't practical if you are going to use a regrind. You may have to reset them after run-in. The weight really isn't much of an issue with the flathead. Go ahead and use adjustables. More 2 cents, Jahns pistons are really heavy. Oh yeah, The 77B is about the same as running a late Merc cam. Not even noticable. Try an L-100. It will make you smile
I've been running almost 15 years on a set of adjustables. Still running fine. Also, ditch those old Jahns pistons and get a decent modern design piston. Jahns are heavy and require quite a bit of clearance.
Welding supply stores at least a good one will have some hardface rod for tig welding.Done this on several occations for custom valve lengths on motorcycle applications.Less of a ware factor in the flathead design and should be fine. When installing larger valves,try not to sink the valve too much to make adjustments,your making the height of the port shorter so any gain will be lost or a ton of work to get you back were you started. Gary
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