Evolving the Side valve flat head design idea

Engine tech, for those engines, products, and technologies of yesteryear.

Moderator: Team

Truckedup
Guru
Guru
Posts: 2728
Joined: Mon Jan 21, 2013 2:41 pm
Location: Finger Lakes

Re: Evolving the Side valve flat head design idea

Post by Truckedup »

Big HP numbers at the expense of a wider power band might not be the best for dirt flat racing done in one gear...
jed
HotPass
HotPass
Posts: 875
Joined: Tue Nov 18, 2008 4:18 pm
Location: Dallas

Re: Evolving the Side valve flat head design idea

Post by jed »

I was thinking the same thing. Large intake ports and valves would work good at Bonneville but not so well on a short
track engine.
Pete1
Member
Member
Posts: 81
Joined: Sun Nov 10, 2013 9:41 pm
Location:

Re: Evolving the Side valve flat head design idea

Post by Pete1 »

jed wrote: Sun Aug 02, 2020 5:21 pm I was thinking the same thing. Large intake ports and valves would work good at Bonneville but not so well on a short
track engine.
I would agree normally but I only have data on large flatheads, 315 ci or more. Nowdays 321. It works.
jed
HotPass
HotPass
Posts: 875
Joined: Tue Nov 18, 2008 4:18 pm
Location: Dallas

Re: Evolving the Side valve flat head design idea

Post by jed »

Are these engines NA??? From the data you have you give us a us intake valve size, the throat size, where is the choke point,
the adverage CSA, how big in cc's are the intake block ports, the length of the intake port from intake seat to the plenum
or the end if the injector stack, are the valve seats sunk or raised, a 45' seat angle, gas or alcohol, compression.
what about exhaust valves, ports ECT. Are the Pistons dome and what shape.
I know lots of questions just thought I would ask. lol
User avatar
frnkeore
Expert
Expert
Posts: 825
Joined: Wed Dec 25, 2019 3:06 am
Location: Oregon

Re: Evolving the Side valve flat head design idea

Post by frnkeore »

I've got a question about the FH Ford engines:

Knowing that the flow is blocked to the rear of the valve and that to keep compression up, that you need to have no more than .040, from the top of the valve, to the top of the cyl head, the valve curtain won't have much more than a 180 deg, effective area, because of the contour of the rear part of the head, that wraps around the valve.

It's common to put 1.6 in & ex valves, in these engines BUT, the intake ports are very hard to increase flow. The ports are only 1.312, in diameter and very hard to open up, in the middle area. The bottom of the bowl, is only about 1" in diameter but it an be opened a little.

The actual question is, if you install 1.72 SBC valves on the intake side and open the bowl, as much as is practical, will the larger diameter of the curtain, make up for some of the lack of flow, around the back side of the valve. Will it make a noticeable increase in flow, just because it has more curtain area?

I know that it won't increase the CSA of the port, itself but, would it allow the port to flow more of it's potential with it's wider curtain?

1.72 valves, have been put into these engine but, I have never seen or heard of HP or flow improvements with their use. I had always though of it as useless, because of the CSA of the port but, now I wonder if the curtain improvement, by itself will help flow.
Ks Fats
Pro
Pro
Posts: 375
Joined: Wed Feb 12, 2014 12:39 pm
Location:

Re: Evolving the Side valve flat head design idea

Post by Ks Fats »

I'll start with the caveat of: I don't build big inch flatheads that operate in the same rpm range as Pete's engines, but I do know that he normally operates in ranges well above what most of us would call "safe" for a flathead. All of the stuff I build is 296 and below; some at 248, most circle track, all n.a. If you flow a stock block you will find that the exhaust flows 85 to 87% of the intake; that is really an indicator of how poor the intake is not how good the exhaust is. Putting 1.6 valves in both never made sense to me so I try to maintain some split between intake and exhaust valves. I don't use chevy exhaust valves on the intake side, I don't like the radius between the stem and head. Thompson from way back when made some replacement valves for the split guide engines that were also swirl polished, that head shape is a good model to copy for the intake side. On the small cubic inch engines using a 302 ford exhaust valve (1.450 I think) will allow you to drop the exhaust seat relative to the intake and still maintain good flow. On the intake side turning down 1.72 valve will allow you to shape the head of the valve relative to the cylinder head and the seat form you are using, typically 1.650 to 1.675 depending on the margin width you start with. Have had the pleasure of working with a couple of fellows running nitro nostalgia cars and they require completely different thinking but they are not limited by having to run coolant in the block. Some years back on the forum a fellow called "Kahuna" built a flathead using 1.72 intakes (n.a. on gas) that made between 165 t0 170 I think but I don't remember anything about the ports; that info should be available. The nitro stuff is the only engines that I've been associated with that used 1.72 + intakes so that is not really a fair comparison. As mentioned before: port velocity relative to engine size is important for driveability; Bobby Meeks (worked for edelbrock) has been quoted as saying about flathead ports:" You can't get them too big for Bonneville but you can damn sure get them too big to pull the hat off your head coming off a corner", I try to remember that.
pdq67
Guru
Guru
Posts: 9841
Joined: Thu Mar 04, 2010 8:05 pm
Location:

Re: Evolving the Side valve flat head design idea

Post by pdq67 »

I have to ask?

What is wrong with running as high a lift by sinking the head so that the valves can have such a high lift? Put the heads of both valves up into the head, but still hold the needed hot valve to deck clearance. ".040"??

And then just using the 180 degree curtain that you will end up with.. Double the lift and you will still have the needed curtain area...

What am I missing? Cams and, "valve-train", if you will, being able to operate at twice the lift??

pdq67
User avatar
frnkeore
Expert
Expert
Posts: 825
Joined: Wed Dec 25, 2019 3:06 am
Location: Oregon

Re: Evolving the Side valve flat head design idea

Post by frnkeore »

Compression.

Not to mention that the head isn't thick enough to do that.
Ks Fats
Pro
Pro
Posts: 375
Joined: Wed Feb 12, 2014 12:39 pm
Location:

Re: Evolving the Side valve flat head design idea

Post by Ks Fats »

The cam core is not large enough to allow that kind of lift also; the cam tunnel would need to be bored out for larger bearings and a larger diameter cam core fabricated. It has all been done but its pricey on anything but an all out engine. A 32 billet core can be undercut for more lift but it is still limited. I see from my post above I missed answering the question directly; no a 1.72 valve will not be worth the effort without a lot of additional port work. The bowl on the cylinder wall side needs to be filled and a 1&5/8 radius formed. Since the short side radius is at the top of the port it needs to be widened and enhanced to the point where you'll probably be into the stupid water passage between the port and the manifold face. Not a problem on a dry block but requires some tricky brazing on a water block; right about this time the fun meter goes down the tubes.
User avatar
frnkeore
Expert
Expert
Posts: 825
Joined: Wed Dec 25, 2019 3:06 am
Location: Oregon

Re: Evolving the Side valve flat head design idea

Post by frnkeore »

KS, I think you are missing my point. The actual flow, in the port, can't be improved, very much, because of it's physical size and shape. Like other OEM ports, if you only increase the bowl, it doesn't have that much effect on the flow, itself.

I think filling the back side of the chamber, behind the valve head, may help to bias the flow, forward and you can't get any additional flow, over the top of the because of physical limits on combustion chamber thickness and compression drop. Increasing the diameter of the valve head, itself won't gain much because the port size is limited. The port is only 1.312" in diameter, the appox. best size, for a 1.5" intake, that comes stock.

The mid part of the port, is problematic, to increase evenly, over 8 ports, w/o a LOT or dedicated porting effort equaling money. A 1.56-1.6" valve is about max for port improvement.

I'm not suggesting that the bowl, be maxed out, beyond what a 1.56-1.6 needs but, the use of a 1.72 valve, on that same bowl, by extending the seat to match the 1.72 (maybe 1.68) valve or changing the valve seat to 30 deg and using the 45 deg seat area, as a transition angle, such as 60-45-30. That might pull a little harder on the port.

The main reason to use the larger valve, would be to increase the circumference of the curtain area i.e 1.6 = 5.027 and 1.72 = 5.403. Multiply both by what ever % curtain is available, to flow towards the cylinder and you get more curtain, with the larger diameter valve.

Not a great deal more curtain area but, on a FH, every, little bit counts. 30 deg seats help flow at low lift and a FH's lift range, is mostly low lift.

This is the actual FoMoCo drawing of the intake port. As you can see, there is not much that can be done with it. Note the pinch point (less than 1") next to the valve guild and the thickness of the valve pocket.

The mods that I'm suggesting aren't for all out racing but, something that could still be driven on the street and not be any more difficult than what the average hot rodder could do.
You do not have the required permissions to view the files attached to this post.
Ks Fats
Pro
Pro
Posts: 375
Joined: Wed Feb 12, 2014 12:39 pm
Location:

Re: Evolving the Side valve flat head design idea

Post by Ks Fats »

Now we are on the same page. In that instance I think a 30 degree profile would be a necessity for the 1.72 but the seat geometry should be more refined. Think about a 22 top on the 30 seat along with a 37 below the 30 to blend into the existing dressed 45. Use a 55 below the 45 and then hand blend to the bowl. In this case grinding the 45 face on the valve to a 30 might best be left wide. The whole seat form will be raised in relation to the deck and the progression of angles in relation to the valve face will bias toward the bore. Are you thinking in the 330-350 lift range? I'm aware of the ford drawing but I wouldn't take it as gospel; I've cut up junk blocks through the ports and find that the location of the cooling passage above the port and the thickness of the bowl (on the cylinder wall side especially) varies significantly. Years of rust and neglect compound the problems.
User avatar
frnkeore
Expert
Expert
Posts: 825
Joined: Wed Dec 25, 2019 3:06 am
Location: Oregon

Re: Evolving the Side valve flat head design idea

Post by frnkeore »

Yes, those conditions and also, core shift. The drawing is to let people know, what the shape is and what you can expect as a maximum amount you might have to work with.

The cam that I think would be best for a strong engine, of 270 CI, or more, in a light weight car, would be the Isky 400 Jr but, for a class racer, in say, H/Gas (11 lb per CI) Howards makes cams, up to .440 x 262 @ .050, including 2, that are close to the Isky's Track 431 Accelerator.

Another way you might go, knowing that the port is limited and it will do a better job filling a smaller cylinder, is to run a 221 CI block, bored as little as possible and offset grind the crank to 3.625 and see what you could do with a FH, under 240 CI.

Compression is what is so important with these engines and you need to get the piston and valve clearance as close to that .038/.040 as you can. FT pistons, with FT heads, can also help with that.

I would also like to hear about any transfer area porting that has been done on the Ford FH, to gain flow w/o loosing compression.
jed
HotPass
HotPass
Posts: 875
Joined: Tue Nov 18, 2008 4:18 pm
Location: Dallas

Re: Evolving the Side valve flat head design idea

Post by jed »

I was just wondering if any one has tried a 2 plugs in the head. I have been reading the thread about dual plugs
or squish. Being aquatinted with Ron Kelly he sometimes runs lots of timming advance, some time as much as 60'/70'.
my thought is a dual plug set up might help with lowering the timming.
His engines are basically NA and run pump gas. No alachol, no nitrous no nitro.
Post Reply