A local fellow is up against something that has us both stumped. Car is a '73? Scamp, 225 auto. Valve seats were shot, so we picked up a '64 head, that had been rebuilt with what I was told are Furd 300 valves. Only problem is, they are about 1/4" longer than slant valves. We can't back the adjusters out far enough to set the valve lash. The head came off a running motor, with stock rocker arms and pushrods. What are we missing?

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Shorter pushrods.

Valves can be cut down too. In addition, if the valve seats receded, there will be a problem.

Interesting. I run 300 Ford Valves, with diameter cut down a bit. They are too big stock unless you run a larger bore than 0.060" over.

Shoot some photos, if you took them prior to installation.

If the valves didn't look like they were close to touching when closed, they probably aren't Ford 300 Valves. The stems are also smaller diameter than the mopar valves.

2¢

CJ

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Part of Tyrde-Browne Racing

Yup, ditto what Ceej said. When I had a slant head rebuilt and modified to use Ford 300 valves, the valve guides were bored out and re-sleeved to match the diameter of the valves and the valve stems were shortened and re-notched for the retainers. At this point it would probably be easiest for your friend to get some custom length pushrods.

My Ford 300 valves aren't cut down, and it is a TIGHT fit inside the combustion chamber. The head is currently installed on my brother's 83 Dodge van that has a .060 overbore.

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Casually looking for a Clifford hyperpak intake for cheap.

The 300 Ford valves are .10 longer than stock valves. What is the CC of the head you are trying to run? My head is cut .10 and with the Ford valves is 42 CC, I run stock pushrods and have adjustment.

Richard

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Part of Tyrde-Browne Racing

That's alot of valve for a tiny bore! I would think your gains from the increased diameter would be offset by losses from shrouding by the cylinder wall. If you do bore notches, then where did you get head gasket?

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63 Valiant Wagon
225 - 4 bbl

The fire ring is 3.50" bore notching doesn't interfere with the fire ring unless you go overboard with it. Not necessary.
Even with turned down 300 valves, it can be required to bore notch. This is due to the combustion chambers not lining up with the bores. Make certain that the combustion chamber is aligned over the bores. Offset dowls are sometimes needed. Lots of variations in manufacturing were the culprit.
With anything less than a 0.060" Overbore, the bores will shroud the valves. If you go with a 0.104" Overbore, this will be minimal. That would require going K-1 or some other metric piston.

I'm running with bore notches on a 0.045" overbore. I've turned the exhaust valves down. The valve stem center is much closer to the cylinder wall than the intake valve. The intake valve is full size. The valves are still extremely close together. Fopar has better chamber shape. My next engine has 300 ford valves turned down to 1.77/1.44. This is more ideal for a small bore, and still takes advantage of the small stem size.

CJ

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Part of Tyrde-Browne Racing

You could just shim the shafts up, which really will probably give you better valve/rocker geometry and give you more lift with less stress on the valve guides. They sale these for the Big and small blocks, they should fit the slant. If not it would not be much to make them. The ones they sale come in different thicknesses to help get your rocker at the right height. There really is more to it than just getting the pushrod to fit in there. Set your rocker where it needs to be, then get a pushrod the lenth to work with getting your ajuster where it needs to be. All these angles will effect the valves movement in a hugh way.


Jess

I know shorter pushrods can be made if need be, it just has me baffled that they weren't necessary on the motor the head came off of?

Anyway, I'll cut to the chase here. Would he be better off just having the original head rebuilt with hardened seats? The bottom end is still all stock, the big valve head was not for performance, it is just what I happened to have laying around with hardened seats already in it. Trying to get this thing done and back on the road quick/cheap.

In response to various inquiries: Reeds picture looks familiar, so I'm going with them being 300 valves. Don't know how much head was cut, but it was pretty minor. 20k on a fresh build with hardened seats, so receding shouldn't be an issue. Motor the head came off of was 0.030 or 0.040 over.

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did the other engine have a high lift cam. if so the base circle of the cam is smaller.

yea and split the stands...

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1965 Plymouth A/FX 512ci (under construction)
1968 Dodge Dart SL6 14.25 @ 91.5 1.91 60'
1973 Dodge Dart SL6 Stock
Killer Bee's Member Since 09'
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Been there, done that (gotta taper the shims so the sides are much thinner than the bottom)

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63 Valiant Wagon
225 - 4 bbl

Dang! Just reminded me. I need to drop a junk head off at the machine shop. We're cutting the towers off of it, The towers are going to be cut off the good head. Install guide pins, and machine to create a tower of the right height to correct the valve geometry.

Another option..

CJ

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Part of Tyrde-Browne Racing