Hi guys new new member here. I am info gathering for a 46 motor that I am for building my 27 tudor, it will have a 4 1/4" crank 3 5/16 pistons and a Kiwi L100 cam so far. My question is valve sizes,I have read that I should use the longer chevy valve for a reground cam. I have seen all sorts of combinations of 1.5 and 1.6 valves I will be doing a mild port of both intake and exhaust.so do I stay with 1.5 or go to 1.6 and if I use 1.6 do I do Both. Input Please.
valve size question
- Thread starter 27lizzie
- Start date
Bored&Stroked
Well-known member
You will not see any appreciable difference in going to 1.6" valves over the 1.5" valves - especially if you're doing mild port work (which is probably just cleanup and polishing). It is not really worth the added expense of swapping out all the hard seats just for .050 width on each side.
If you are talking about length, then the stock Chevy length (which is longer than stock Ford valves is a plus). The reason is the base circle on the cam will be smaller, which demands a longer lifter or a longer valve. Since nobody really makes longer lifters (and you don't want the adjuster too far out - if running adjustables), then having a longer valve will help.
Here is some information that I wrote on the HAMB - it will probably help you:
Those of us who have built hot flatheads have probably heard about 'Zephyr' springs, Isky 185G single springs and maybe even the "hot setup" for big cams . . . the Isky dual valve springs. How many of you have ever actually tested them on a valve spring compressor or ran them?
1) Engine Style and Spring Pressure: It if very easy to NOT think about how simple the flathead valve train is -- there are very few moving parts . . . no rockers, no pushrods and not much weight (unless you're running those crap SOLID adjustable lifters). Due to this, you really don't need and don't want much spring pressure on the street - even for a .400 lift cam like the Isky 400 Jr., Potvin 3/8, etc.. This is especially true if you're being conservative on your RPM range and not pushing the top-end past 5500 (which very few people do). Also, the flathead only has 3 cam bearings, so putting a bunch of spring pressure puts unnecessary pressure on the cam -- and on a high-lift cam (which has a small shank diameter or base circle), it wants to deflect/flex all the more.
Putting your 'Cam in the Oil Pan': Lastly, the more spring pressure you run on a flat tappet, mushroom or radius cam - the more valve train wear you get. Want to wear that cast iron regrind out really fast??? - put a bunch of spring pressure on it! Roller cams can take much more, but they are made out of 8620 or 9310 billet steel and are heat treated!
So how much is enough? Well . . . as usual, it kind of depends. For MOST even hot street flatheads, you'll probably not need more than 60 - 70 lbs on the seat. For even more radical cams (not really street cams) - like the Potvin 425, you'll probably not need more than 80 - 85 lbs (with the above rpm range). Even on my blown flathead with a very radical .450 lift cam and steep fast opening ramps, I only ran 90 lbs on the seat . . . ran to 6800 RPM and didn't float a valve.
My good friend (no longer with us) 'Flatdog' with his Crower roller cam only ran about 90 - 100 on the seat . . . with 10 lbs boost in a full drag-race application (.450 lift as well).
2) Testing Installed Heights and Spring Pressure: You can buy a nice hydraulic tester that will work on a drill press or a lathe for somewhere around $80 (I think that is correct - checkout Jegs). It works great:
3) Sample Spring Pressures and Flathead Myths: Here are some numbers to review on spring type, pressure and installed heights. I wanted to check it with a reasonable seat pressure and a "nose" pressure - assuming a Potvin 3/8 cam - .375 or so lift (gross).
a) New Lincoln Zephyr Springs (new) - Reds:
Height: Pounds:
1.950 80
1.575 170
b) Isky 185G (new) - One of my favorite flathead single springs:
Height: Pounds:
1.980 80
1.605 180
c) Isky Dual Springs (new) - What many swear they need on cams like the 404-A, rollers, etc:
Height: Pounds:
1.765 80
1.390 180 lbs
d) Lincoln Zephyr (used) - came out of a 404-A radius cam setup
Height: Pounds:
1.820 80
1.445 150
Here is a picture - with the used Zephyrs on the left, then the new Zephyrs, then the 185G, then the Isky Duals:
So . . . did you notice anything funny in the numbers ?????????????????
How about those trick Isky dual springs? First of all did you notice how SHORT the installed height needed to be to just get 80 lbs? How the heck are you going to end up with a spring height of 1.765? - to do that, you'd need about .200 - .300 of spring shims (unless you ran shortened valves). This is especially true since many of you are using SBC valves in your flatheads . . . everybody is selling them and they are a bit longer than a flathead anyway.
Even when you install the dual springs at the necessary height to achieve 80 lbs on the seat . . . they still have the SAME spring pressure as the single 185G springs on the nose. Also, they are a royal pain in the *** to install - as the outer spring will NOT fit through the guide bore . . . so you "assemble" them with the valve/guide in the block . . . now that REALLY sucks! Talk about one big cussing/swearing fest -- and a lot of bloody knuckles . . . (even with the necessary tools).
If you have a fairly stout street engine - run the Zephyrs, if you have a really big cam and/or a blower, run the 185Gs. Use the approximate spring pressures listed above . . . or not, whatever makes you happy
Installed Spring Height is Key! The numbers that I posted on the previous installment showed that you need to achieve an installed spring height of about 1.950 - 1.980 (depending on which spring you're using and how many lbs you want/need on the seat). If you're running the typical SBC 1.5" pro-flow, better than a Ginzu frigging valves . . . that anybody can buy from anyplace . . . but the flathead web sites sell as if they have a "special part" just for you . . . then you're running a valve that is about 4.910 or so in length. The stock flathead valve (if I remember correctly
) is 4.810 in length - so you're already .100 longer . . . which means MORE spring shims.
So lets take a typical combination of SBC 1.5" or 1.6" 4.910 valves, Lincoln Zephyr springs and a desired installation height of say 1.950 or so. Well, without ANY spring shims, running stock retainers . . . you'll have an installed spring height of over 2.1 inches - this is WAY too weak! (I know - depends on your engine, the one I just did was about 2.150). That means you need three .060 shims and one .030 shims . . . lots of them stacked up like a bunch of nickles. If you buy the Zephyr springs and complete valve package from places like Reds . . . they throw in one .060 shim per valve -- not even close . . . (you'd think they'd know the issue . . . guess not!)
Solving the Spring Height/Retainer Problem: Don't just slap the damn valves, springs, retainers together . . . cause you bought the kit and that is all your have to use . . . get off your butt and buy some aftermarket chrome moly retainers (Comp Cams: 743-16) - and turn them down on a lathe to end up with the following:
a) The correct installed height - with probably NO shims
b) A nice chrome moly retainer . . . much better than the stock stuff.
c) A much cleaner valve setup with a nice tight fit between the valve spring and the retainer. The inner valve spring area of these cut-down retainers fits a flathead Zephyr or 185G spring perfectly!
Here are some examples of what I do - using the Comp Camps chrome moly retainers -- part number "743-16"
a) Mount them in a lathe
b) Turn the OD down to match the OD of your Zephyr or 185G springs
c) The spring will have a tight fit on the inner spring location of the retainer.
d) Put a valve, guide, spring, retainer, lock assembly together.
e) Install it in your block and measure the installed height - adjust as necessary. The thicker retainer will be equal to 2 - 3 thick shims . . . you may still need some, just depends on the lbs you want on the seat!
f) Tip: It is nice to have a weak 'test spring' - that you can just compress by hand during the 'fit up' stage . . . makes life easier.
Here are some pictures:
Here are pictures of a stock, modified and Comp-Cams moly retainer - see how they've been turned down:
Here is the complete assembly - ready to go . . . nice and clean. I still needed one thick shim .060 and one .015 shim . . . better than 5!
This should help yah!
B&S
If you are talking about length, then the stock Chevy length (which is longer than stock Ford valves is a plus). The reason is the base circle on the cam will be smaller, which demands a longer lifter or a longer valve. Since nobody really makes longer lifters (and you don't want the adjuster too far out - if running adjustables), then having a longer valve will help.
Here is some information that I wrote on the HAMB - it will probably help you:
Those of us who have built hot flatheads have probably heard about 'Zephyr' springs, Isky 185G single springs and maybe even the "hot setup" for big cams . . . the Isky dual valve springs. How many of you have ever actually tested them on a valve spring compressor or ran them?
1) Engine Style and Spring Pressure: It if very easy to NOT think about how simple the flathead valve train is -- there are very few moving parts . . . no rockers, no pushrods and not much weight (unless you're running those crap SOLID adjustable lifters). Due to this, you really don't need and don't want much spring pressure on the street - even for a .400 lift cam like the Isky 400 Jr., Potvin 3/8, etc.. This is especially true if you're being conservative on your RPM range and not pushing the top-end past 5500 (which very few people do). Also, the flathead only has 3 cam bearings, so putting a bunch of spring pressure puts unnecessary pressure on the cam -- and on a high-lift cam (which has a small shank diameter or base circle), it wants to deflect/flex all the more.
Putting your 'Cam in the Oil Pan': Lastly, the more spring pressure you run on a flat tappet, mushroom or radius cam - the more valve train wear you get. Want to wear that cast iron regrind out really fast??? - put a bunch of spring pressure on it! Roller cams can take much more, but they are made out of 8620 or 9310 billet steel and are heat treated!
So how much is enough? Well . . . as usual, it kind of depends. For MOST even hot street flatheads, you'll probably not need more than 60 - 70 lbs on the seat. For even more radical cams (not really street cams) - like the Potvin 425, you'll probably not need more than 80 - 85 lbs (with the above rpm range). Even on my blown flathead with a very radical .450 lift cam and steep fast opening ramps, I only ran 90 lbs on the seat . . . ran to 6800 RPM and didn't float a valve.
My good friend (no longer with us) 'Flatdog' with his Crower roller cam only ran about 90 - 100 on the seat . . . with 10 lbs boost in a full drag-race application (.450 lift as well).
2) Testing Installed Heights and Spring Pressure: You can buy a nice hydraulic tester that will work on a drill press or a lathe for somewhere around $80 (I think that is correct - checkout Jegs). It works great:
3) Sample Spring Pressures and Flathead Myths: Here are some numbers to review on spring type, pressure and installed heights. I wanted to check it with a reasonable seat pressure and a "nose" pressure - assuming a Potvin 3/8 cam - .375 or so lift (gross).
a) New Lincoln Zephyr Springs (new) - Reds:
Height: Pounds:
1.950 80
1.575 170
b) Isky 185G (new) - One of my favorite flathead single springs:
Height: Pounds:
1.980 80
1.605 180
c) Isky Dual Springs (new) - What many swear they need on cams like the 404-A, rollers, etc:
Height: Pounds:
1.765 80
1.390 180 lbs
d) Lincoln Zephyr (used) - came out of a 404-A radius cam setup
Height: Pounds:
1.820 80
1.445 150
Here is a picture - with the used Zephyrs on the left, then the new Zephyrs, then the 185G, then the Isky Duals:
So . . . did you notice anything funny in the numbers ?????????????????
How about those trick Isky dual springs? First of all did you notice how SHORT the installed height needed to be to just get 80 lbs? How the heck are you going to end up with a spring height of 1.765? - to do that, you'd need about .200 - .300 of spring shims (unless you ran shortened valves). This is especially true since many of you are using SBC valves in your flatheads . . . everybody is selling them and they are a bit longer than a flathead anyway.
Even when you install the dual springs at the necessary height to achieve 80 lbs on the seat . . . they still have the SAME spring pressure as the single 185G springs on the nose. Also, they are a royal pain in the *** to install - as the outer spring will NOT fit through the guide bore . . . so you "assemble" them with the valve/guide in the block . . . now that REALLY sucks! Talk about one big cussing/swearing fest -- and a lot of bloody knuckles . . . (even with the necessary tools).
If you have a fairly stout street engine - run the Zephyrs, if you have a really big cam and/or a blower, run the 185Gs. Use the approximate spring pressures listed above . . . or not, whatever makes you happy
Installed Spring Height is Key! The numbers that I posted on the previous installment showed that you need to achieve an installed spring height of about 1.950 - 1.980 (depending on which spring you're using and how many lbs you want/need on the seat). If you're running the typical SBC 1.5" pro-flow, better than a Ginzu frigging valves . . . that anybody can buy from anyplace . . . but the flathead web sites sell as if they have a "special part" just for you . . . then you're running a valve that is about 4.910 or so in length. The stock flathead valve (if I remember correctly
) is 4.810 in length - so you're already .100 longer . . . which means MORE spring shims.So lets take a typical combination of SBC 1.5" or 1.6" 4.910 valves, Lincoln Zephyr springs and a desired installation height of say 1.950 or so. Well, without ANY spring shims, running stock retainers . . . you'll have an installed spring height of over 2.1 inches - this is WAY too weak! (I know - depends on your engine, the one I just did was about 2.150). That means you need three .060 shims and one .030 shims . . . lots of them stacked up like a bunch of nickles. If you buy the Zephyr springs and complete valve package from places like Reds . . . they throw in one .060 shim per valve -- not even close . . . (you'd think they'd know the issue . . . guess not!)
Solving the Spring Height/Retainer Problem: Don't just slap the damn valves, springs, retainers together . . . cause you bought the kit and that is all your have to use
. . . get off your butt and buy some aftermarket chrome moly retainers (Comp Cams: 743-16) - and turn them down on a lathe to end up with the following:a) The correct installed height - with probably NO shims
b) A nice chrome moly retainer . . . much better than the stock stuff.
c) A much cleaner valve setup with a nice tight fit between the valve spring and the retainer. The inner valve spring area of these cut-down retainers fits a flathead Zephyr or 185G spring perfectly!
Here are some examples of what I do - using the Comp Camps chrome moly retainers -- part number "743-16"
a) Mount them in a lathe
b) Turn the OD down to match the OD of your Zephyr or 185G springs
c) The spring will have a tight fit on the inner spring location of the retainer.
d) Put a valve, guide, spring, retainer, lock assembly together.
e) Install it in your block and measure the installed height - adjust as necessary. The thicker retainer will be equal to 2 - 3 thick shims . . . you may still need some, just depends on the lbs you want on the seat!
f) Tip: It is nice to have a weak 'test spring' - that you can just compress by hand during the 'fit up' stage . . . makes life easier.
Here are some pictures:
Here are pictures of a stock, modified and Comp-Cams moly retainer - see how they've been turned down:
Here is the complete assembly - ready to go . . . nice and clean. I still needed one thick shim .060 and one .015 shim . . . better than 5!
This should help yah!
B&S
tubman
Well-known member
I swear that within the last week that I read either here or on the H.A.M.B. that the later model 8BA's with rotating valves had slightly longer lifters than the earlier engines and would be the thing to use with reground cams and regular valves. Anyone else remember seeing this? If it's true, it's a handy thing to know. I checked a few places to see if the listed different part numbers for early vs. late 8BA's, but most folks only list the Sealed Power adjustables, which leads me to believe this may be true.
Edit - Found the post from Walt Dupont.
No, on the adjustables. But I'll give you a little tip, all the stock flathead lifters up to 51 are 1.720 long, the 52-53 EAB lifters are 1.750 long, as are the 49-53 Merc lifters. NOW, the extra .030 is a big help when using reground cam with a lower bass circle. This tip is when your butt grind valve stems. Walt
Edit - Found the post from Walt Dupont.
No, on the adjustables. But I'll give you a little tip, all the stock flathead lifters up to 51 are 1.720 long, the 52-53 EAB lifters are 1.750 long, as are the 49-53 Merc lifters. NOW, the extra .030 is a big help when using reground cam with a lower bass circle. This tip is when your butt grind valve stems. Walt
Last edited:
Ol' Ron
Well-known member
Thanks B&S for this information. Having been running Flatheads for almost 60 years, it's nice to go back in time and realize the mistakes we've made now that we have more experience. Having been there done that, I had to rething the trem street engine. Tighter clearances and lower RPM's When building my engines I told the customer to red line at 4500 rpm, set all my valve springs at 50lbs on most cams regardless of type of lifter. Using the L-100 as an example, I never observed valve float up to and including 5000 RPM. Experimenting is the answer here. Why run a high valve spring pressure?? to Keep the valves from floating, right. My 400jr in the stock car was a mess after one season of racing with 80 lbs of pressure. My next cam an Errson D410 survived a season with only 60 lbs on the seat and the engine preformed better than with the 400 jr. I don't want the people here reading this to think I have the answers to these kind of questions, because I don't. However ther are some areas where I've had to learn the hard way ($$$$). There is a BIG difference between racing and street use. So give some thought on the application. Most cam grinders will spec the spring pressure for maximum preformance
GOSFAST
Well-known member
While on the subject of valve guides/spring heights I would add this, when using the aftermarket shims (part #A/B/C 101) that are available for this platform (cars, trucks, tractors) closely examine the spring seat area, the shims do not sit properly. (See the photo below)
This is a minor issue we've more recently discovered. You either have to chamfer the shims or "relieve" the small radius on the guide. Easier to do the guides.
When the shims are lying in position, with minimal pressure, you will see a fair sized "gap" between it and the spring seat section on the guides.
Thanks, Gary in N.Y.
P.S. Missing this item may affect the spring pressure you think you have, it could really end up being off some on the final ***'y of the springs!
This is a minor issue we've more recently discovered. You either have to chamfer the shims or "relieve" the small radius on the guide. Easier to do the guides.
When the shims are lying in position, with minimal pressure, you will see a fair sized "gap" between it and the spring seat section on the guides.
Thanks, Gary in N.Y.
P.S. Missing this item may affect the spring pressure you think you have, it could really end up being off some on the final ***'y of the springs!
Attachments
Ol' Ron
Well-known member
Hay Gary, finally got that 294 running of Robs after the second rebuild. Have it tuned pretty well, and when the 2 97 secondaries kick in, things happen very quick. Nice job on the assy, had to go to .005" on the piston clearance. Running 180 stats to keep it tight. so far so good.
Getting back to your original question-----there will be performance advantages with the use of 1.6 or even 1.7 valves with the engine sized as mentioned and with reasonable port work. Whether or not your application will utilize the available performance is open for you to decide.
There is no problem with adapting the standard Ford valve seat rings to the 1.6 valves. Another myth exploded.
It is true larger valves need extensive port and head revisions to make significant flow increases at the higher lift numbers. However, larger valves increase low lift flow very dramatically when combined with reduced rod length/stroke ratios.
Again, each individual will have to decide what is best for his or her application.
There is no problem with adapting the standard Ford valve seat rings to the 1.6 valves. Another myth exploded.
It is true larger valves need extensive port and head revisions to make significant flow increases at the higher lift numbers. However, larger valves increase low lift flow very dramatically when combined with reduced rod length/stroke ratios.
Again, each individual will have to decide what is best for his or her application.
Thanks everyone for your input, it's given me something to think about. One of the items mentioned is valve train weight and spring pressure on a reground cam. The Use hollow adjustable lifters (lighter than the solids) makes sense. What about hollow stem valve are the any lighter than solid stem. Has anyone gone done this road.
GOSFAST
Well-known member
With respect to the overall valve sizes and "streeters", most times the larger valves will not have any add'l "seat-of-the-pants" feeling. It may show some slight gains on the dyno however.
You always have another option by going in between the stock size valves and the 1.600" Chevs, you can use a 1.560" Ford 240" truck exh valve. This has saved many an original insert for us! (See photo below)
An all-out race build would benefit more from the larger valves. One more procedure that may really help with overall "breathing" is having the block extrude-honed. Not for the faint-hearted pricewise though! (I have never done a Flathead using this method, have done some conventional V-8 exh manifolds)
If the valves have fairly wide 45* "margins", locating the seat at the outer valve edge and a 30* (nominal) back-cut on the valves will be a large plus also! This also helps low-end flow.
Thanks, Gary in N.Y.
P.S. Hi Ron, excellent, I knew there was an issue of some sort but didn't have any of the particulars?? He had ordered some add'l parts after the fact. He's really a genuinely nice guy. Nice family also! I'm glad he's finally up and running! I'm sure he appreciates all the help/time you gave him also! Piston-to-wall with those Ross pieces will be no issue. We send them out between .004" and .005".
You always have another option by going in between the stock size valves and the 1.600" Chevs, you can use a 1.560" Ford 240" truck exh valve. This has saved many an original insert for us! (See photo below)
An all-out race build would benefit more from the larger valves. One more procedure that may really help with overall "breathing" is having the block extrude-honed. Not for the faint-hearted pricewise though! (I have never done a Flathead using this method, have done some conventional V-8 exh manifolds)
If the valves have fairly wide 45* "margins", locating the seat at the outer valve edge and a 30* (nominal) back-cut on the valves will be a large plus also! This also helps low-end flow.
Thanks, Gary in N.Y.
P.S. Hi Ron, excellent, I knew there was an issue of some sort but didn't have any of the particulars?? He had ordered some add'l parts after the fact. He's really a genuinely nice guy. Nice family also! I'm glad he's finally up and running! I'm sure he appreciates all the help/time you gave him also! Piston-to-wall with those Ross pieces will be no issue. We send them out between .004" and .005".
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Ol' Ron
Well-known member
The issue was an oil rail had bent over during instillation. The engine was subjected to major detonation ,due to improper ignition advance. Removing the heads to check pistons I found the wall in #5 cyl grove near the wrist pin location. Removal of the piston showed the ring problem. Ross wouldn't make a 10 or20 over piston unless we bought 4?? so we sleeved the cylinder. All this took time and expense. So No mater how careful you are you can still Fu** up. Have alittle over 1000 miles on it now. So far,So good. She's a real torquer.
Kahuna
Well-known member
I take a different approach to the valve sizing issue. I am a firm believer that you cannot make the valve too big. Here's my thoughts:
Because of the valve chamber in the head (no matter what brand), only about 75% of the area is actually used. If you then increase the valve size, you increase the useable area. This can't be anything but GOOD.
Now, if you increase the LIFT of the valve thru a new cam (even without adding duration), you will increase performance without durability problems.
Of course, no one does this because a new cam will always have more duration than any stock Ford cam.
Just my thoughts
Jim
Because of the valve chamber in the head (no matter what brand), only about 75% of the area is actually used. If you then increase the valve size, you increase the useable area. This can't be anything but GOOD.
Now, if you increase the LIFT of the valve thru a new cam (even without adding duration), you will increase performance without durability problems.
Of course, no one does this because a new cam will always have more duration than any stock Ford cam.
Just my thoughts
Jim