Thanks Bill,
I stand corrected! Maybe I was the one who didn't get enough sleep, my
memory playing tricks on me! As a European I haven't seen a V8 crank in a
long time. Your absolutely right!
The principal still holds though.
Matthew Tinker
> I don't want to beat this to death, but it's important enough to write
> at least one more time. We agree in the basic principle, that when one
> cylinder is at TDC firing its opposite will be at TDC overlap. Thus we
> agree on the inline 6. Where we don't agree is as to how a V8 crankshaft
> is constructed. I'm talking even firing engines here, nothing weird
> like "180 degree" oddballs. And small block Chevy firing order,
> 1-8-4-3-6-5-7-2. The Chevy cylinders are numbered like this (I hope
> this looks OK after it's been mailed):
>
> Front
> 1 2
> 3 4
> 5 6
> 7 8
>
> The crank has 5 main bearings separating 4 throws, each throw is 90
> degrees apart. 1 and 2 are on the same throw, 3&4, 5&6, 7&8 on the
> others. They are paired but 90 degrees out of phase due to the angle
> between cylinder banks. So what the positions look like when you've got
> #1 at TDC firing is:
>
> Front
> 1 (TDC firing) 2 (270 before TDC overlap)
> 3 (270 before TDC firing) 4 (180 before TDC firing,BDC)
> 5 (90 before TDC overlap) 6 (TDC, overlap)
> 7 (180 before TDC overlap, BDC) 8 (90 before TDC firing)
>
> Note "overlap" = "on the hard".
> Note also this engine turns CCW from the rear.
>
> So what you'd do is get the engine to #1 TDC firing. Both #1 valves are
> closed and #6 are on overlap. Set lash on #1. Rotate in running
> direction until #5 is on overlap, about 90 degrees. Set lash on #8.
> Rotate until 7 is on overlap, another 90 degrees, set lash on 4, etc.
>
> Cautions:
> On the 348/409 Chevy and most or all Fords the same principle
> applies but the numbering and firing order are different. Make sure you
> know what you've got before trying this. Or any other lash setting
> scheme.
> This only applies to even firing engines; equal degrees
> between firing events. Doesn't work on singles (obviously), Harley or
> Indian V twins, "180 degree crank" flathead Fords, uneven firing Buick
> V6s. Will work backwards on left hand engines (on marine twin
> installations the port side engine usually spins backwards).
>
> And yes, this will work on even firing V6s; 1st and 4th in firing order
> are paired, 2nd & 5th, 3rd & 6th.
>
> Bill Gray william.gray@snet.net
>
>
> -----Original Message-----
> From: Tinker [mailto:tinker@wanadoo.fr]
> Sent: Thursday, January 31, 2002 2:08 PM
> To: William Gray
> Subject: Re: [oletrucks] Adjusting valves
>
>
> The V8 crank is the same shape as four cylinder. In the four cylinder
> engine the first and last pistons are up when the middle ones are down.
> It doesn9t matter whether the firing order is 1342 or as fords (europe)
> used to be1243, the pairs are the same, only the cam and high tension
> leads order change. I took the firing order and cylinder numbering out
> of the Haynes manual, but it doesn9t change anything. The first cylinder
> on the left bank is paired with the last cylinder on the left bank. The
> second cylinder on the left bank is paired with the third cylinder on
> the left bank. The same is true for the for the right bank. Each bank
> being like a four cylinder engine. You've got the in line six spot on,
> but what about the V6? I have never seen a five cylinder audi engine,
> and the my v twin Moto Guzzi bike engine dosen't pair up!. When setting
> high performance engine tappets, one adjusts one valve at a time, inlet
> fully open, adjust the inlet on it's opposite cylinder, this means that
> the cam is at it's absolute lowest point! But that's a wild cam shaft
> story!
>
>
>
> Matthew Tinker
>> Neat Trick!! I think the pairings listed are wrong, though (or maybe
>> I didn't get enough sleep?). Pairs should be opposite in the firing
>> order; for the 1-8-4-3-6-5-7-2 order, I think the pairs would be 1&6 -
>
>> 8&5 - 4&7 - 3&2. The 235's firing order is 1-5-3-6-2-4, so the pairs
>> would be 1&6 - 5&2 - 3&4.
>>
>> Bill Gray
>> william.gray@snet.net
>>
>>
>> -----Original Message-----
>> From: owner-oletrucks@autox.team.net
>> [mailto:owner-oletrucks@autox.team.net] On Behalf Of Tinker
>> Sent: Wednesday, January 30, 2002 7:40 PM
>> To: oletrucks@autox.team.net
>> Subject: Re: [oletrucks] Adjusting valves
>>
>>
>> The easiest way I know for finding out when a cylinder is at TDC
>> ignition stroke is when it's opposite cylinder is "on the rock" (I'm a
>
>> Brit, you may have another term, it means that both valves are
>> slightly open, valve
>> overlap) both push-rods are "tight", under pressure. To establish that
>
>> no 1 on a V8 is on TDC ignition, No 7 cylinder is also on TDC but "on
>> the rock"(the push-rods won't turn easily).
>>
>> N01cylinder tdc->n07cylinder"on the rock" adjust N01cylinder
>> N02tdc-> N08"on the rock"adjust N02cylinder
>> N03tdc-> N05"on the rock"adjust N03cylinder
>> N04tdc-> N06"on the rock"adjust N04cylinder
>> N05tdc-> N03"on the rock"adjust N05cylinder
>> N06tdc-> N04"on the rock"adjust N06cylinder
>> N07tdc-> N01"on the rock"adjust N07cylinder
>> N08tdc-> N02"on the rock"adjust N08cylinder
>>
>> This is for a firing order of 1-8-4-3-6-5-7-2
>>
>> Does this make sense?
>> Matthew Tinker
>>
>>
>>> I know I should know this, but need a refresher. How do I adjust the
>>> rocker arms to set my valves on my '58 235? I know I need to get
>>> them
>>
>>> when each piston is at its own TDC, but don't remember how to find it
>>> for any but #1. I can find TDC for #1, but don't remember how to
>>> take
>>
>>> it from there. I know I will set them initially when cold to get
>>> close, and then bring engine to operating temp, and adjust them to
>>> hot
>>
>>> while the engine is running. So, can anyone give me a refresher in
>>> valve adjusting 101? OH, yeah...I have solid lifters.
>>>
>>> Thanks,
>>>
>>> Rob
>>>
>>> My Zen Moment for the Day: Always remember, you're unique! Just
>>> like
>>
>>> everyone else. oletrucks is devoted to Chevy and GM trucks built
>>> between 1941 and 1959
>> oletrucks is devoted to Chevy and GM trucks built between 1941 and
>> 1959 oletrucks is devoted to Chevy and GM trucks built between 1941
>> and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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