Technical Flathead valve to head clearance?

Sounds good, thanks!!!

 

What seat pressure should I be aiming for? With an Isky max 1 cam

 

bored and stroked set you up on the previous page with ~75lbs lots of guys run even less. stock ford valves will be about 2" installed height with no shims. you can check the spring rate on a drill press and a bathroom scale. use a long bolt and nut with a washer thread the bolt so the distance from the washer to the head of the bolt is 2". put the end of the bolt in the drill press, the spring on the bathroom scale and push the spring down with the drill press until the bolt head just touches. check the scale for pressure without shims.

 

RevKev6 has it right --> you need to test the spring in a measuring device to figure out at what exact height, it measures the recommended/desired pounds.


They should also, then go PAST that point and compress the spring further --- additional distance = the height of the cam profile - minus the lash + .060 . . . there should be no coil bind at that height. If there is coil bind, then this cam/valve/spring combination can't be used. With 70 - 75 lbs on the seat, you should not have a coil bind problem - unless the springs are mighty weak . . . which should not be a problem with the 185G springs or Zephyr type springs.

Now, you know the installed height of the springs - when each valve is in the block - sitting on the seat. I usually get a couple light springs to then use during the "tuning" process. You'll find that if you just installed the valve/guide/spring/retainer/keeper package, that your installed spring length will probably be TOO long. This means you'll not have enough LBs on the seat - and you risk floating the valves!

Given the measurement on each guide/valve/spring/retainer package - you'll need to shim the valve guide end of the spring with shims --> they normally come in .060, .030 and .015 thicknesses (and they must be the ones designed to fit the flathead guides and springs). You determine the 'shim package' needed for every valve - testing them one by one. Your goal is to get all installed valve spring heights to plus/minus about .020 or so.

Here is a picture of how to measure in the block (with a test spring) - you'll need a small set of machinist dividers - to measure the distance between the valve guide side and the top of the retainer (the ID dimension - the installed spring height). Note, the retainers shown are a special set of moly ones that I used in race motors - they are much thicker than stock retainers (just so you know what you're looking at).



Dividers: You'll need a small pair - like 3" ones similar to this:


In the end, my guess is that you'll have 1 or more shims on every valve setup - the result will look similar to this one (which has a .060 and a .030 on it):

 

Well freezing my butt off on,the driveway today, I got the new cam in, and have 6 of the valves done, they lapped nicely with very little effort and theses valves are a lot lower in profile so....I wish I would have gotten these in the first place.

I Did the damaged valve first and no damage to the valve seat !!!!!

So far i needed one 0.060 shim on each valve to get 75 pounds. So 6 done and lash set.... 10 more to go on another day. Gotta load up the band equipment for a gig tonight.




Also a fellow hamber bought the old cam and liftersboff me to regrind, so my "lesson" is costing a tiny bit less.

 

Great News! I've quite happy to see you out there getting it all put back together - with some good parts in it. Make sure you clay the heads and figure out if you need some hand work in the top valve pocket corners - you surely don't want to repeat the lasts drama!

What springs did you end up getting?

 

Isky 185g

 

Well I spent 8 hours in the driveway working on it, and it is running great (hopefully it stays the way), with nice dead even compression on all cylinders.

Lots of clearance as well...... .060 more than the thicker cheap stainless valves.

I took it for a nice 25 degree snowy drive and all seems well for now, Hope it stays that way!!

 

Was doing some research on cutting for valve clearance on flathead ford
Found this old thread
Very good information for anyone building there own motors or just want to educate themselves

 

Keep in mind that for most street engines and most performance cams, having 60 - 65 lbs on the seat is more than enough. Very few folks rev their engines much above 5,000 RPM (on the street), so there is no reason to have heavy valve seat pressure if this is all you're doing and you want the cam to last. The more pressure you put on the cam lobes, the more they tend to wear - as 99.9% of flathead cams are cast iron, not hardened steel billets.

 

Thanks
My experience has been setting up spring pressure on ohv motors I know flatheads are different just because of more direct operation of the valve
I was just wondering if I do have to cut for valve clearance do you do it on the valve angle and of course the flathead has different angles on each bank
I will also be running a max 1 cam with zephyr springs but in a 221 ci motor but I am looking at 3500 rpm max (Av8 speedster)
I thought the 4500 rpm in this thread was a little high for a flathead
But all the basic methods in this thread are great

 

Not sure what you're talking about? Are you talking about clearance to the HEAD or tappet clearance?

 

Valve to head clearance
Referring back to your post on page 1
Nice to be talking to one of the original posters

 

You only need about .060 or so above the valve . . . the only way it is going to hit is if you float the valves and this will only happen if you over-rev the thing (and you're not hitting a piston anyway). Check the clearance with clay and with a head gasket on.

If you have too little clearance, you don't touch the valve or the seats, you modify the head chambers with an air porting tool. Given the valve angles, the only place that might need work is up at the top in the valve pocket eyebrows . . . as the valve in angled and the head chambers are not. The valves will only hit up at the very top.

 

I have a basically stock '51 Merc (massaged Edmunds heads, improved carburetion, and a Mallory dual point) with the stock mercury cam in my '51 Ford. It will turn 4500 RPM easily, and accelerates best when shifted at slightly over 4000 RPM. I think you are doing yourself a disserve by limiting yourself to 3500 RPM, especially in a Speedster with a MAX-1 cam.

I always rework my heads to yield .050" clearance over the dome for improved combustion and compression. I also check the clearance over the valves, and have never encountered a situation where any head modification was required.

 

Hell, I went to 6200 the last time I was on a chassis dyno - but this was with a very heavily modified engine with two steel main caps. But hey, the 21A rods held up! LOL

 

Thanks for the information

 

This is a Babbitt bearing 21 stud with single carb ported intake manifold
Was going for the .050 over pistons clearance but was worried about the extra valve lift

 

I have always thought that the engines with poured mains were as good as the later insert engines if done right. In addition, the "full-floaters" on the rods are considered to be superior.

I have a MAX-1 in my "Hot Rod" engine (also with reworked Edmunds heads) and had no problem with valve clearance.

 

Good to know
Hope to assemble motor this winter
All other measurements have already been done just looking ahead to potential problems

 

I got a notification that someone liked a post on this thread (and that reminded me about this....and my appreciation of the wonderful guidance I recieved) so I figured I would post a 6 year later update on my engine / car.

Thus far I have NOT had to dig back into the engine!!!! Furthermore I have put a lot of miles on it including quite a few exhibition races on the dirt track with occasional pretty high rpms when pushing it hard to get around someone on the track that doesn't want passed.

I have busted a few axles, wore out a used 3 speed tranny and wore out a used f1 steering box but so far (knock on wood) the engine has been great.

And as an added bonus I finally bought a garage... a big old ww2 garage with a coal furnace so I don't have assemble my cars outside in the snow anymore!!!

 

I rarely read old threads, but read every post in this one. Hats off to @Bored&Stroked for his assistance and information provided.
I most likely will never have a FH in my possession again, but this was such a good read I couldn’t stop.
Lastly, happy to read your update and everything worked out for ya!