milling iron heads

[Ol' Ron]

The original CT L-100 had .375 for both intake and exhaust. with .016 clearance, Thus aprox .360 net lift. However, on a reground stock cam, allot of material is removed from the base circle to get that much lift. I consider any cam over .350 net lift a hi lift cam. again the Isky 400jr ground on a billet would still have allot removed from he base circle due to the fact it must fit through the cam bearings. I'm also Conservative when I build a street engine. I look for reliability and economy, anlong with long life. Thus 50 lbs of valve spring pressure.

[Ol' Ron]

The original CT L-100 had .375 for both intake and exhaust. with .016 clearance, Thus aprox .360 net lift. However, on a reground stock cam, allot of material is removed from the base circle to get that much lift. I consider any cam over .350 net lift a hi lift cam. again the Isky 400jr ground on a billet would still have allot removed from he base circle due to the fact it must fit through the cam bearings. I'm also Conservative when I build a street engine. I look for reliability and economy, anlong with long life. Thus 50 lbs of valve spring pressure.

[hardtimes]

Originally Posted by Ol' Ron

The original CT L-100 had .375 for both intake and exhaust. with .016 clearance, Thus aprox .360 net lift. However, on a reground stock cam, allot of material is removed from the base circle to get that much lift. I consider any cam over .350 net lift a hi lift cam. again the Isky 400jr ground on a billet would still have allot removed from he base circle due to the fact it must fit through the cam bearings. I'm also Conservative when I build a street engine. I look for reliability and economy, anlong with long life. Thus 50 lbs of valve spring pressure.

Hey Ron,
Was 50 lbs stock seat pressure on a factory engine ?

[B-O-B]

Here is the spec sheet on my cam grind L100

[flatjack9]

The sheet specs lobe lift, so you need to subtract .014 to get actual lift at the valve.

[JSeery]

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Originally Posted by hardtimes

Hey Ron,
Was 50 lbs stock seat pressure on a factory engine ?

Bob C posted the factory specs a day or two ago.

"I found these valve specs in the Ford truck service manual, I think the car
would be similar.
1949-50 Test Length 2.13" 37-40 lbs
1951 Test Length 1.89" 40-43 lbs"

Don't believe any factory spec was in the 50lb range, that would have been a "Hot Rod" number.

[Ol' Ron]

use a stock spring with a .060-" shim, this gives between 50/55 lbs

[hardtimes]

Originally Posted by JSeery

Bob C posted the factory specs a day or two ago.

"I found these valve specs in the Ford truck service manual, I think the car
would be similar.
1949-50 Test Length 2.13" 37-40 lbs
1951 Test Length 1.89" 40-43 lbs"

Don't believe any factory spec was in the 50lb range, that would have been a "Hot Rod" number.

Very good specs, thanks much !

[hardtimes]

Originally Posted by Ol' Ron

use a stock spring with a .060-" shim, this gives between 50/55 lbs

Thanks much for sharing this information !

[51 MERC-CT]

Originally Posted by Ol' Ron

use a stock spring with a .060-" shim, this gives between 50/55 lbs

Just to clarify, would that be with the longer (Chev.) valves?

[40cpe]

Originally Posted by 51 MERC-CT

Just to clarify, would that be with the longer (Chev.) valves?

My experience: I used the chevy valve and LZ springs from Red's Headers with the keeper in the bottom slot. Jim said the springs would give about 80# on a stock valve. I used one .060 shim all the valves and an additional .010" on some to get 45# to 52#.

[flatjack9]

That's been my experience also.

[Kahuna]

I was able to find a new set of Canadian aluminum heads, as I wanted the appearance of stock heads. Then had them modified after a lot of measuring to accommodate a high-lift
Potvin 425 cam. They seem great, but now I think I would rather have the finned heads for the appearance.
Jim