1966 Toronado 425 V8 engine overhaul need help

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Otto Skorzeny
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Re: 1966 Toronado 425 V8 engine overhaul need help

Postby Otto Skorzeny » Tue Mar 30, 2021 11:12 am

That's great news. No lasting damage done, I trust.

By the way, there's nothing wrong with installing hardened valve seats when rebuilding an engine but it really isn't necessary. Any extra wear on the exhaust valves will be so minute as to be unnoticeable. If and when you ever experience a problem, it will most likely be time to rebuild the entire engine again anyway.

If you're racing it or auto-crossing it or running it at high revs all the time then hardened valve seats are a must.

I've never owned a modern car. None of my vehicles has ever suffered a burned exhaust valve due to using unleaded fuel. This includes a bunch of 60s Mustangs, '68 Camaro, '72 Monte Carlo, '56 Cadillac, '64 Galaxie, '56 Ford pickup, etc. They all got or get driven as daily drivers.

ochaffard
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Re: 1966 Toronado 425 V8 engine overhaul need help

Postby ochaffard » Wed Mar 31, 2021 3:38 am

Otto,

I am with you , but as the engine needed a complete rebuilding .. it was quite a small operation at that time ... by the way talking to Mondello yesterday evening over the phone they told me they have now in stock "brilliant" SS exhaust valves which are good for service under new gasoline and that doesn't need any hardened seat ...

To be frank , I also never experienced an issue with regular valve seat, never use lead-like additive .. and never faces too an issue on my U.S cars but just on some French cars from the early 60's (Peugeot 404) which are well-known for quite fragile valve seats ... whatever gasoline you use !

Olivier
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Otto Skorzeny
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Re: 1966 Toronado 425 V8 engine overhaul need help

Postby Otto Skorzeny » Wed Mar 31, 2021 6:22 am

The whole leaded vs unleaded gas debate was exaggerated from the get go.

AMOCO introduced its famous super unleaded "white gas" in 1923. So even when unleaded fuel was mandated in 1974, it had already been around for 50 years without damaging peoples' cars.

bcroe
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Re: 1966 Toronado 425 V8 engine overhaul need help

Postby bcroe » Wed Mar 31, 2021 6:44 am

I do not doubt these "hobby cars" can be driven limited miles without
hardened seats. But my 60s cars were of the age when ring and valve
jobs were common, a car with overt 100,000 miles was considered
worn out. But with the late 70s engines all that stopped, end of the
constant maintenance (that should have happened a decade sooner).
I have driven so many late 70s Olds small blocks well past 200,000
miles and they still check out to new specs, oil use only slightly up.
Those valve rotators and hard seats work, there are several over
300,000 miles and honestly with proper oil changes, I have never
managed to wear one out. 403s are the engine of choice here. Bruce Roe

ochaffard
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Re: 1966 Toronado 425 V8 engine overhaul need help

Postby ochaffard » Wed Mar 31, 2021 11:25 am

To the 425 Team ... without waiting the Mondello valve stem height gauge I have ordered , is someone able to give me the dimensions of that gauge ( original tool was BT-6428) ?

ochaffard
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Re: 1966 Toronado 425 V8 engine overhaul need help

Postby ochaffard » Wed Apr 14, 2021 12:15 am

We just received the Mondello tool ... so we now can begin to set up the valves at the correct height and control also springs position vs. valve stem top ... what worries us a bit is that as we surfaced both the heads and the engine block , this will have an impact ... probably not compensated enough by the new head gaskets , which we know are thicker than the originals in metal ... if by any chance somebody has an opinion on this specific point if will be welcome !

bcroe
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Re: 1966 Toronado 425 V8 engine overhaul need help

Postby bcroe » Wed Apr 14, 2021 6:42 am

ochaffard wrote:We just received the Mondello tool ... so we now can begin to set up the valves at the correct height and control also springs position vs. valve stem top ... what worries us a bit is that as we surfaced both the heads and the engine block , this will have an impact ... probably not compensated enough by the new head gaskets , which we know are thicker than the originals in metal ... if by any chance somebody has an opinion on this specific point if will be welcome !


In theory if you spaced the rocker support up the average of the head
and block cut, it would put the geometry back where it was before. I
have not done it yet, but would to help a wear situation. Bruce Roe

ochaffard
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Re: 1966 Toronado 425 V8 engine overhaul need help

Postby ochaffard » Thu Apr 15, 2021 4:13 pm

Dear Bruce, after exchanging with engineers and experienced motor rebuilders , we concluded the best way to restore initial valve train geometry to take into account the significant alteration due to block surfacing, head surfacing and finally modern gasket additional height ,WITHOUT changing the valves stem top height factory settings and springs is to reduce the length of the pushrods, through machining or just finding the closest length available vs. theoretical calculation.
Why ? ... just because the pushrods are of the same angle of the V and consequently « one inch » less of metal taken out from both the block and head is equal to « one inch » of length of the pushrod.
So no impact on the geometry of the rocker arms on their pivot or/and any other side impact.
Doing so it ensures the BT-6428 original gauge tool, or the Mondello replacement , stays fully operational, as if you had a fresh factory no miles engine.
Now we have to calculate that correct pushrod length ... to follow the job we just carefully completed on the heads ... now all valve stem tops are at the same height ... with correct springs height too ... and in line with the gauge requirements.

bcroe
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1966 Toronado 425 V8 engine overhaul need help

Postby bcroe » Mon Apr 19, 2021 2:31 pm

There is more than one way to skin a cat, and I am no valve expert. Adjustable
push rods exist, I have not put any into service. I would define "best way"
as one which is affordable and achieves a long service life. What I described
is exactly equivalent to the adjustable nut used on some roller rocker setups.
good luck,, Bruce Roe

ochaffard
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Re: 1966 Toronado 425 V8 engine overhaul need help

Postby ochaffard » Sat May 15, 2021 4:37 pm

To all the Toronado engine afficionados .

I owe to all of you who helped and gave advices an update.
We installed everything back together, using adjustable pushrod to calculate correct length for each pushrod and made the necessary adaptation (in the range of 0,004 to 0,01’’ of height decrease) ... one by one to obtain the correct initial preload.
To avoid any issue, we mounted back the lifter not being primed (only a bit of oil bath to ensure safe mouvement inside their bore).
We had some fear at first as the engine didn’t want to start as it should ... as always problems are not flying alone !
We just faced a flooded carb. ... the needle obviously didn’t like the new fuel pump pressure, which shows to be above standard ... corrected with a pressure regulator and a brand new carb kit from Daytona Carb. which includes an enhanced needle design ... and everything is now fine ! Very silent engine ... balanced idle ... perfect !
Thanks again to all for your support,

Olivier
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