Crusader 454 Model 350

"Freshing up the top end (

"Freshing up the top end (cam lifters, freshened heads) of a 1985 Model 350 454. Does anyone know the tap size needed for cleaning out the head bolts in oder to get a good torque setting? I would like to pick one up on the way to the marina. Also, any other reccomendations other then the basic for putting it back together?"

"IIRC, 7/16". Many of th

"IIRC, 7/16". Many of those bolts will need thread sealant, going into coolant passages. PST or similar, not rtv."

get a good break-in lub for th

get a good break-in lub for the cam and use it. Make sure to use a marine head gasket set.

"And run the motor at 2,000 rp

"And run the motor at 2,000 rpms plus for at least 20 minutes at start up. Do not let it idle or those flat tappets will round out the cam lobes.

Jeff"

jeff you said run engine at 20

jeff you said run engine at 2000 rpm for 20 min when puting new cam and lifters to save the lobes from rounding off why. and also puled the heads of my RH 454 crusader and i was suprised to see pistons were facing to rear of engine why thanks

"The 2000 rpm for 20 minutes m

"The 2000 rpm for 20 minutes may vary, based on camshaft mfg's recommendation. Biggest driver is to ensure adequate oil flow as each lifter and its cam lobe 'mates'. Some will ask you to go as long as 30 minutes and some will ask you to vary rpm up to 3000. They all recommend a break-in lub and natural petroleum oil too.

The 'notches' on the RH engine are reversed as the crank rotates opposite a 'normal engine'. The notches are there to ensure the 'thrust bearing' side of the piston is aligned correctly to the block."

this is my first RH overhaul i

this is my first RH overhaul it makes sense thanks a lot

"The cam to lifter loads at 20

"The cam to lifter loads at 2000 rpm are less than at 700rpm. So, breakin is done at 1800 to 2000 rpm for about a half hour, using break in lube on all wiping surfaces. Also, precharge the engine with oil, using a drill mounted drive that sits in place of the distributor. "

"Dave:

What's the basis

"Dave:

What's the basis for the load at the cam-lifter interface is less at 2000 than 700?

The springs' k-constant is fixed so the force it needs to compress it is fixed, at least statically...is it one of those fluid dynamics things going on that offsets the static case?

tnx mark"

Flat tappets need high speed w

Flat tappets need high speed when being broken in since the main way they are lubricated is from oil flung off the crank.

Jeff

"Here ya go:

"Notice

"Here ya go:

"Notice that the contact stress between the lifter and the nose (peak) of the cam lobe (dark line) is very high at idle speeds and DECREASES as engine speed increases (green line).

Why is that? As the engine speed increases, more and more of the spring force is being used to provide the negative acceleration required to reduce to zero the speed of the lifter, pushrod, rocker, valve and retainer, so that it can reverse direction at peak lift and keep the lifter in contact with the cam lobe. Therefore the contact stress over the nose of the cam lobe decreases as engine speed increases (shown by the green line in the graph above).

At low speeds, the maximum valve velocity is relatively low, therefore there is not much kinetic energy in the valvetrain motion. When there is less kinetic energy, then less of the valve spring's energy is used to produce negative valve acceleration (slow the components down to zero velocity over the nose of the lobe), so more spring pressure is available to be applied to the cam-lifter interface. To make it worse, while the engine is being cranked by the starter, there is virtually no lubrication at that interface. (see Valve Train Dynamics in the Engine Technology section)."
from : http://www.epi-eng.com/rotorway_helicopter/rotor_drive_system/engine_issues.htm

and others as well. In laymans terms, at high rotary speeds, the lifter is being "thrown off" the cam where the max contact pressure exists at low speeds."

"mechanical dynamics of the va

"mechanical dynamics of the valvetrain would have been adequate....thanks for the link, now i have another detailed lesson(s) to learn."

First time user, i have twin 454 xli 1999 engines. The starboard engine lost power to the fuel pump and the starboard fuel gauge at the same time. I jumped power from the battery to the fuel pump and it worked fine. Any advise would be helpful. Vr d.

My brain is filled with so much S#!t just to keep my life going, I don't think I have any room for "mechanical dynamics"