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37 Zephyr


peter_smith
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Hello all

It's a while since I have posted on here, been a bit busy

I have just had the 37 Zephyr out today for a short run,

after having the engine out over the winter,I fitted new

stainless valves, new guides,Mercedes valve stem seals on

the inlets, and I wanted to make the valves adjustable, I

thought about buying adjustable lifters, but then thought

why not go the whole way and make up some roller adjustable

lifters, the basis of these were 2 sets of GM V6 hydraulic

lifters, with the hydraulic part machined off

($50 a set on ebay) there was no point in buying bearings

at $14 each, I then had to make 24 hollow barrels

with adjusters to press these into, finished off with a couple

of spot welds on the bottoms for insurance, these were then

ground to suit the bores, these are guided to stay in line

camshaft, and I was not very happy with the V8 idea of a tiny

screw to locate them, I also wanted something that would stop

the lifter turning when adjusting the clearances, so I went

for flats on the lifters, with hardened and ground plate

between each pair, this involved creating a bridge framework

the full length of the valve chest to carry the plates, this

is fastened by a bolt at each end, I added a spring in the

middle which butts onto the underside of the inlet manifold

just in case it vibrates in the middle, but I don't think

it will.

the stainless valves which are a V8

part had to be cut to length and regrooved for the keepers, I

also had to use shorter valve springs, but managed to find

some 2"long with a similar spring rate 50lbs closed, 105 lbs

open, which allowed me the room for the adjusters.

Also fitted a new rotor, and high volume oil pump modified to

a full flow oil filter, this involved making up a new bottom

plate for the pump which takes the oil through the bottom of

the oil pan via an O ring joint up to the filter, then back

out, and into the block where the old oil filter fitting

was, the original outlet on this new pump was just under 7/16"

dia, so I made the pipework 7/16dia right through, and opened

the block out to suit.

I also fitted a prelube kit, don't know if any of you have

seen these, its from autoenginelube Co Las vegas, as you know

most crankshaft wear takes place when you start up, especialy

if the motor has stood idle for a while, as ours do, the

bearings are dry, and the oil system drains into the pan.

All this does is pressurize the oil system before starting

the engine, it then charges itself back up when the engine

starts, the canister is a bit bulky but could be hidden a bit

better, I just put it thier for convenience. this is a 3 quart

cannister, there are 1 and 2 quart sizes.

It seems to work very well, you can see the oil pressure gauge

rising when it's turned on before starting.

I also made up and fitted twin stainless steel exhausts, I

had been collecting the parts for this for some time, and

managed to get 2x18" stainless mufflers which fit nicely

fore and aft, instead of accross the rear end

Hopefully I will be putting a few miles on this car now, so I

will keep you updated as to how it goes, it may all end in

disaster, who knows,no pain, no gain, but for now it seems

to be running well.

Peter Smith

UK

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Hello Dee

Yes you are right, some roller cams have a steeper profile with a flatter top so that the valve opens faster and for longer, the zephyr cam profile is much softer than that, as I was not looking for extra performance, more for reliability,(re reduction of anti scuffing aditives in oils) I tried the original cam in with these lifters with the following results, 0.013" clearance.

inlet opens 21deg BTDC.

closes 54deg ABDC.

exhaust opens 50deg BBDC.

closes 9deg ATDC.

These are not to far away from the original settings going by the book I have got, I did not measure them before stripping the engine (I should have for comparison), the book states them as.

inlet opens 19.5deg BTDC.

closes 54.5deg ATDC.

exhaust opens 57.5deg BBDC.

closes 16.5deg ATDC.

Looking at some of the V8 settings, which were very different from these, I was happy to go with the above results for lead, lag, and overlap, what concerned me more was that the rollers being only 0.375" wide might roll up the hard facing on the cam, but by keeping a similar spring rate, I hope this is not the case, time will tell, it is all a bit experimental anyway.

Peter Smith

UK

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I know the cam lobes are slightly off center to induce lifter spin but it appears you still have full contact between the roller and lobe. Should run very smooth and quiet with that lobe profile. Wear between the top of the tappet adjuster and the valve stem should also be reduced without the tappet spinning. It'll be interesting to see if there is any really noticeable performance difference with the modified valve action. I don't know about the UK or Europe but oils here still contain a reduced amount of ZDDP so these old engines will probably survive. Good luck Peter

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Hello Dee

Yes I have got full roller contact, with a bit of cam to one side doing nothing, there was about 0.020" endfloat on the camshaft, I took this down to 0.005" by machining the front cover, as far as the oil additives are concerned, I would not have done this for that sole reason, but as I was in there anyway why not give it a try.

This engine is on standard bores, it must have had the block replaced at sometime in it's life, unfortunately the crank is the early small journal one, and it has been ground to it's limit, although it is in good usable condition, I might look out for a later crank and a set of rods, (got to keep busy)

As far as any increase in performance, there is a company near me who could do a dyno test on this, what do you think would be a reasonable BHP figure for a standard engine in good condition?

Regards

Peter smith

UK

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Peter, these engines were rated at 110 Hp but who knows at what state of "assembly" the engine was in at that time in history or even how approximate that rating might have been? With the somewhat slower valve opening I suspect the throttle response might change (?) but the overall power output may stay as it is? I guess you'll find out when you drive it.

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