V-8 valve guides

[IMJ]

I am curious why Studebaker used longer valve guides for the intake than for the exhaust. Since the flow can be improved with the intake guides flush like the exhaust is there any advantage to have them longer. I guess there must be a theory to the longer guide otherwise it could have been one less part number to carry.

regards,

Jay

[Bud]

My theory is the Stude engineers figured that a longer intake guide would allow less oil into the cylinders on the intake stroke due to vacuum pulling less oil through the longer guide. Bud

[Mike Van Veghten]

The only real value is more valve support. Many of the 50's and 60's heads were that way. As to the intakes only...no clue, none of those designers are around any longer!
The oil theory doesn't hold oil(!) because the oil comes from the top of the stem/valve, not the bottom to the bottom. And it would then not matter how long the guide was...the oil would flow the full distance of the guide!

As far as need, when I port a set of Stude heads and guides are needed, I buy 16 exhaust guides. If guides aren't required, the machinest will remove the guide to the cast iron for me...which essentially ends up the same length as the exhaust giudes.

Removing the extra material "will" help air flow. If they were smaller in diameter, more like modern guides, the air/fuel flow would not be as effected as badly as the large diameter as the big Stude (Buick, Olds, Cad) guides are.

Mike

[PackardV8]

"I am curious why Studebaker used longer valve guides for the intake than for the exhaust."

In terms of wear, a longer guide is better. Stude engineers weren't concerned with high RPM intake flow. They were designing a low-RPM 2-bbl single-exhaust engine to take farmers to church. However, they did everything for a reason. Wish they had told us what were their reasons.

Maybe, the explanation is on the exhaust side. When an exhaust guide protrudes into the port, it is subjected to the full heat of the exhaust gas stream and could become red hot on a long, hard pull. If the engine were shut off suddenly and the exhaust guide cooled quickly, it might seize the exhaust valve stem. With the guide flush with the head, it doesn't have a thin section exposed to as much heat and is closer to the coolant.

thnx, jack vines

PackardV8

[Milaca]

Speaking of valve guides....when I am driving my Hawk downhill and let off of the accelerator, I get LOTS of oil smoke being that the oil apparently rushes to the front of the heads (where there are no drain holes to the block) and the oil gets sucked into the very front cylinders through the intake guides. I recently removed all of the spark plugs and the front plug from each head had large amounts of crust & oil buildup whereas the other plugs looked great.


"South Bend or Burst!"
In the middle of Minnestudea

[Skinnys Garage]

quote:Originally posted by Milaca

Speaking of valve guides....when I am driving my Hawk downhill and let off of the accelerator, I get LOTS of oil smoke being that the oil apparently rushes to the front of the heads (where there are no drain holes to the block) and the oil gets sucked into the very front cylinders through the intake guides. I recently removed all of the spark plugs and the front plug from each head had large amounts of crust & oil buildup whereas the other plugs looked great.

I'd say the oil drain back is only a minor part of the problem. I would say the problem is worn guides or bad seals. With your foot off the throttle, combined with some engine braking going downhill, you're getting the maximum cylinder vacuum. Any weak link, bad guide, seal, gasket, ring or bad piston will show up under different conditions. If your drain back holes can't keep up, I won't say that can't be a factor, but at the angle Stude motors sit, I'd say more than the front two would be flooded. My old 259 smoked on or off the throttle, up or down a hill and just to spite me, it would leak when I shut it off![8D]