some advice for adjusting valves
- Thread starter felix37
- Start date
pineapple
Member
I'm wrapping my 8ba build with an L100 cam, while I had the block bare, pre-hot tanking, I ground around 1/8" off the top of the lifter bores as well as drilled them as low as I could at 5/32 dia. as per Ol Rons book, did all the exhaust and intake port work needed, then took it to the machine shop for cleaning. I did end up putting the crank in without the rods etc. to turn the cam to adjust for valve clearance(as I did'nt feel like building a fixture to turn the cam). I had a set of original johnsons refaced by Dave in Florida for this cam, while setting up the valves, I now realize that Pete and Walt are correct,I had to remove screws from 2 different sets of other beat up johnsons I had in other engines to get them where I felt they would hold adjustment for a while..a couple of them, I even dinged up the threads to try snugging them up. I have not fired this engine up yet, but I have little faith that clearance will remain consistent..The next engine I will grind stems to length for clearance and use original ford lifters. Another thing I noticed is that once clearance is set on both valves on any given cylinder while closed the clearance will change on one of those valves when the adjcent valve opens,I'm guessing that the cam is deflecting due to removal of material during regrind? Anyhow, these are my observations..I may be off a bit due to inexperience, but this may increase discussion enough to help more first timers...I cant say enough about the information in JWL and OL Rons books as well...
Matt
Matt
Ol' Ron
Well-known member
I doubt like heck that the cam would deflect with only 50/60 lb springs. I also use SBC valves with the longer stems and this keeps the screws deep in the lifter. Of ALL the engines I've built I've never had a problem with lifters or valve float. BUT I've never turned them much over 5000 rpm These are street engines.
Pete
BANNED
For all practical purposes the cam does NOT deflect, even with an .820 diameter relief between lobes as with a 404. This is with valves at 100 lb. on the seat.
I have watched a 404 with a strobe running in a test fixture at 6500 rpm and all you can see is very slight flutter. Almost imperceptible. This was a cast iron core. The steel ones have even less flutter.
"Been in the cam business 60 years"
I have watched a 404 with a strobe running in a test fixture at 6500 rpm and all you can see is very slight flutter. Almost imperceptible. This was a cast iron core. The steel ones have even less flutter.
"Been in the cam business 60 years"
Walt Dupont--Me.
Well-known member
Well Andy. I don't know if it deflects or just even the cam out after all the springs are hooked up. But I've always real fussey with my valve setting. Take a max-1 cam, the setting is .014 straight through. I set all the valve with no spring at .012, then I hook em all up with the springs set at 50-55 seat pressure. Then I check the clearance, usually have to remove most of them one at a time and fine tune the setting 1-2-3-.000 That's with butt grinding. I spend more time setting up the valve train that building the rest of the engine. Walt
pineapple
Member
Admittedly I am in over my head on this subject, as this is my first flathead build, the deflection theory was my only thought regarding the clearance changing.I'm using original ford valves that I refaced etc. , so that may explain the lifter issue as these valves have probably had the stems ground once or more before I got to them, so my adjusters are probably out more than they should be.. If I end up with the lifters losing adjustment, I will use chevy valves next.. Anyone have a part # for them? Sorry Felix for hijacking your thread.. Thanks for all the input fellas!
Matt.
Matt.
Karl Wolf
Well-known member
Chev exhaust valves have all been the same, from the 1955 Chev 265, 283, 327, through the 350's...
The TRW # is s2090, but I'm running Manley's cause I like the cut down stem and the shape...
That said, If you're running a stock cam, the Chev valve is 1/16" longer, and that's a lot... I've used them with a reground cam and they're just right.
Karl