4 banger valve train thoughts/questions

ThosD

ThosD

Member
I'm several months away from pulling and rebuilding my 1930 engine. But I am collecting ideas for the build in my idle hours.
1. Valve seats. Has anyone used a 3 angle grind? Notice a difference? Might improved flow from the 3 angle grind be equivalent to additional cam lift?
2. Light weight tappets. Do any exist for the 4 bangers? I'm interested reducing valve train weight to improve rev up response and reduce wear on cam lobes.
3. Valve springs. If valve train weight can be reduced, then it seems that a lighter spring could be used to control valve float and further reduce cam lobe wear.
Thanks for your comments.
Tom
 
Ford engineered a well thought out four banger. You change one thing and you're going to open a Pandora's Box. Get hardened seats, correct adjustable tappets, and good quality parts and she'll run another 90 years (or until they ban gasoline!) LRF
 
The Model A engine does not really turn high enough RPM to worry too much about valve float. Unless you are building a race engine you will have a maximum RPM of about 2,500. The Ford engineers designed the valve train for the engine RPM. Hardened seats are a good idea.

The 3 angle grind on the valve seats is standard procedure and should be followed, even in a Model T. Just make sure that the guide for the grinder is tight in the valve guide so that you get a concentric grind, and grind the valves too. If everything is done correctly you will not need to lap the valves. Check with some bluing.
 
nkaminar said:
The Model A engine does not really turn high enough RPM to worry too much about valve float. Unless you are building a race engine you will have a maximum RPM of about 2,500. The Ford engineers designed the valve train for the engine RPM. Hardened seats are a good idea.

The 3 angle grind on the valve seats is standard procedure and should be followed, even in a Model T. Just make sure that the guide for the grinder is tight in the valve guide so that you get a concentric grind, and grind the valves too. If everything is done correctly you will not need to lap the valves. Check with some bluing.
Click to expand...



Yep, I use pencil to check the width and placement.
The purpose of the 3 angles is the seat contact width and its placement on the valve face. Additional angles can be made inside the port or combustion chamber, but, I doubt they're needed in one of these engines. I'm not a big fan of lapping either if the job is correct. .060-.080" intake, .080-.090" exhaust.
 
Thanks for the input. I was under the impression that 3 angle valve seats became a standard production item in the late 1980s. I guess that the 3 angle job is common because all of the machine shops have the equipment to cut the three angles. I want to build a 4 banger that is capable of sustaining 60 mph. It seems that my goal is doable, but not with a bone stock engine. 3000/3500 rpm also seems reasonable with changes to the bearings and oiling system.

Cheers!
 
ThosD said:
I'm several months away from pulling and rebuilding my 1930 engine. But I am collecting ideas for the build in my idle hours.
1. Valve seats. Has anyone used a 3 angle grind?

> Standard OEM practice.

Notice a difference? Might improved flow from the 3 angle grind be equivalent to additional cam lift?

> 3 angle is standard. A 5 angle or radius seat will improve flow. Usually
not worth the cost or effort for a street engine. Yes, it does have the effect
of more cam lift.

2. Light weight tappets. Do any exist for the 4 bangers?

> Home made items for race engines. Non adjustable and made from
titanium.

I'm interested reducing valve train weight to improve rev up response and reduce wear on cam lobes.

> Valve train weight can be greatly reduced by using titanium valves.
Another race item that is very expensive and needs special procedures
for installing. Stock valves can be lightened slightly. Not enough to notice
in a street engine.
Spool up response is mainly a function of crank assembly weight
including the flywheel and damper.


3. Valve springs. If valve train weight can be reduced, then it seems that a lighter spring could be used to control valve float and further reduce cam lobe wear.

> Valve springs are specified for the particular cam grind. Wear is usually
not a problem if these specs are followed.

> Flathead model B engines modified for vintage circle track or Bonneville
racing will typically turn 6500 rpm and make about 250 hp on alcohol.

Thanks for your comments.
Tom
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...
 
My heavy 30 Fordor cruises down the interstate at 65 at 2,500 rpm. It has the Mitchell overdrive and the engine has a number to changes that reportedly jump the power to 90 hp, but I think it is more around 80. It will turn 3,500 rpm but why? Flat head engines don't breath well enough for the higher rpm. I have accidentally hit 75 when I was not paying attention. Speed by GPS not the speedometer which reads about 10% high.

The engine has a high compression head, I think 5.5:1, a Weber two barrel carburetor, a dynamic balanced crankshaft, a GAZ camshaft, oversize intake valves, pressure mains, insert bearings, a high pressure oil pump, an oil filter, the stock distributor with V8 points, a lightened flywheel with a V8 clutch, and some other stuff.

So the point being is that you don't have to rev the s**t out of it to go at highway speeds. The engine will thank you. That said, I still like to take back roads and cruise along at 55 mph. Remember that along with speed you have to have excellent brakes, tires, and steering as well as the rest of the car in tip top shape.
 
NKAMINAR is right. I have a great radiator with a six blade fan, an overdrive, improved brakes (cast iron with equalizing), and a few improvements to the engine. One without others really doesn't get you much.

I will say this. Once you get everything addressed, a nice body, and interior your car is so desirable that you will likely never want to sell it. It's just a joy to drive. People have no idea how great the particular car is, but no matter because the joy of having it all done, reliable, and usable makes all the satisfaction that one needs.
 

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ThosD said:
I'm several months away from pulling and rebuilding my 1930 engine. But I am collecting ideas for the build in my idle hours.
1. Valve seats. Has anyone used a 3 angle grind? Notice a difference? Might improved flow from the 3 angle grind be equivalent to additional cam lift?
2. Light weight tappets. Do any exist for the 4 bangers? I'm interested reducing valve train weight to improve rev up response and reduce wear on cam lobes.
3. Valve springs. If valve train weight can be reduced, then it seems that a lighter spring could be used to control valve float and further reduce cam lobe wear.
Thanks for your comments.
Tom
Click to expand...

Back to original questions;

1, yes seats can be put in, IMHO, not recommended, must be done correctly, no advantage unless saving block.
2. not necessary, the engine does not have an issue with valve train weight.

3. again, not necessary, if you are going to rev the motor higher you can use springs with more preload and spring rate. cam wear is not issue if properly lubricated.

FWIW, the largest gain in response, ability to accelerate quicker is to reduce the MOI of the flywheel and clutch assembly.
And, IMHO, if you are thinking about hot rodding the motor, you are better off starting with a "B" motor, just from the strength aspect.

John
 
Appreciate all of the responses. I have owned my A for 4 months and I am presently rebuilding the front suspension and steering. The balls of the steering arms were egg shaped, the radius rod ball had flat sides. I'm putting in an F100 steering box conversion to hopefully tighten the steering response and ease the steering effort.
In the mean time, I'm looking forward to rebuilding the engine with reliability and endurance being 1st priority. My wallet will determine what I can do performance wise. So, I share some blue sky ideas to gather info from experienced owners in order to receive feed back. Thanks again for the responses.
Tom
 
ThosD said:
Appreciate all of the responses. I have owned my A for 4 months and I am presently rebuilding the front suspension and steering. The balls of the steering arms were egg shaped, the radius rod ball had flat sides. I'm putting in an F100 steering box conversion to hopefully tighten the steering response and ease the steering effort.
In the mean time, I'm looking forward to rebuilding the engine with reliability and endurance being 1st priority. My wallet will determine what I can do performance wise. So, I share some blue sky ideas to gather info from experienced owners in order to receive feed back. Thanks again for the responses.
Tom
Click to expand...


pick up Jim Brierley's 4-Bangers! and me, book there is wealth of good info is his book
Jim Brierley (jimb4e4@gmail.com)
sent him an e-mail and order the book from him directly well worth the money
Terry
 
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