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Forum: Hot Heads Tech Talk

Forums->Hot Heads Tech Talk->lash cold , solids

jgrady
lash cold , solids


I am unsure if aluminum heads change lash ? should not given head studs are in great clamp tension firmly hold distance deck to rocker ?
related , I saw old hot rod article about P and G , valve gapper , Billy Rasmussen running C/A won nats 5 years in a row with 270 hemi dodge / old ford . in 12 ‘s in late 50’s . one smart guy , homemade ram manifold .
Anyway he swore by .018 cold , ( both !) and 1955 300 service bulletin called for .022 both . Then later 300 opened up exhaust to as much as .028 . As an engineer , the delta ( change) due to temp change in a given engine should be constant , repeatable, certainly within .001 , so hot settings are a joke from cam guys covering tail when hot ( imho) . some constant number added or subtracted should get you cold set .
But exhaust stem gets hotter , one would expect if done right exhaust would be set looser a few thou ? maybe more — but not .006 ?
personally , despite fanatics about this , it seems a few thou one way or another makes no difference to performance in .500 lift , but gap should align with cam designer’s take up ramp . Much more important ? new
comp flat tappert cam , 392 , hot heads , what is cold gap ? comments ?

2) using LA block pump , oil shaft changes length , anyone know numbers?
3) Arp studs hit stock valve cover , ok if cut at bottom , but nut still taller ? was thinking space up cover ( anyone make that ?) but then plug tubes wrong . Thanks for any input , be safe, John

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on: Sun 03 of Jan, 2021 [17:58 UTC] reads: 333

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Webmaster
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Re: lash cold , solids
on: Thu 14 of Jan, 2021 [20:28 UTC] score: 0.00
>John:
On my last one I set the intakes @ .007 and exh @ .009. When hot, I got .012 & .016. Start from there and fine tune. Have fun,
Bob



I am unsure if aluminum heads change lash ? should not given head studs are in great clamp tension firmly hold distance deck to rocker ?
> related , I saw old hot rod article about P and G , valve gapper , Billy Rasmussen running C/A won nats 5 years in a row with 270 hemi dodge / old ford . in 12 ‘s in late 50’s . one smart guy , homemade ram manifold .
> Anyway he swore by .018 cold , ( both !) and 1955 300 service bulletin called for .022 both . Then later 300 opened up exhaust to as much as .028 . As an engineer , the delta ( change) due to temp change in a given engine should be constant , repeatable, certainly within .001 , so hot settings are a joke from cam guys covering tail when hot ( imho) . some constant number added or subtracted should get you cold set .
> But exhaust stem gets hotter , one would expect if done right exhaust would be set looser a few thou ? maybe more — but not .006 ?
> personally , despite fanatics about this , it seems a few thou one way or another makes no difference to performance in .500 lift , but gap should align with cam designer’s take up ramp . Much more important ? new
> comp flat tappert cam , 392 , hot heads , what is cold gap ? comments ?
>
> 2) using LA block pump , oil shaft changes length , anyone know numbers?
> 3) Arp studs hit stock valve cover , ok if cut at bottom , but nut still taller ? was thinking space up cover ( anyone make that ?) but then plug tubes wrong . Thanks for any input , be safe, John
>

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George
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Re: lash cold , solids
on: Tue 05 of Jan, 2021 [16:28 UTC] score: 0.00

If they are HH alloy heads you should probably call HH & ask. Int shaft length will depend on weather you are using the OEM or LA dizzy with the oil pump. On the 392 the Melling oil pump is available new, just bolt it on! Then you just need to decide on the Dizzy as to int shaft length. On my 331 the OEM valve covers cleared the ARP head studs.

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jgrady
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Re: lash cold , solids
on: Sun 03 of Jan, 2021 [17:59 UTC] score: 0.00
> I am unsure if aluminum heads change lash ? should not given head studs are in great clamp tension firmly hold distance deck to rocker ?
> related , I saw old hot rod article about P and G , valve gapper , Billy Rasmussen running C/A won nats 5 years in a row with 270 hemi dodge / old ford . in 12 ‘s in late 50’s . one smart guy , homemade ram manifold .
> Anyway he swore by .018 cold , ( both !) and 1955 300 service bulletin called for .022 both . Then later 300 opened up exhaust to as much as .028 . As an engineer , the delta ( change) due to temp change in a given engine should be constant , repeatable, certainly within .001 , so hot settings are a joke from cam guys covering tail when hot ( imho) . some constant number added or subtracted should get you cold set .
> But exhaust stem gets hotter , one would expect if done right exhaust would be set looser a few thou ? maybe more — but not .006 ?
> personally , despite fanatics about this , it seems a few thou one way or another makes no difference to performance in .500 lift , but gap should align with cam designer’s take up ramp . Much more important ? new
> comp flat tappert cam , 392 , hot heads , what is cold gap ? comments ?
>
> 2) using LA block pump , oil shaft changes length , anyone know numbers?
> 3) Arp studs hit stock valve cover , ok if cut at bottom , but nut still taller ? was thinking space up cover ( anyone make that ?) but then plug tubes wrong . Thanks for any input , be safe, John
>


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