[DeTomaso] Pushrod guideplate adjustment?
wkooiman at earthlink.net
wkooiman at earthlink.net
Tue Apr 13 21:54:16 EDT 2010
At least you got to the bottom of it. My guess is the shop screwed up when they did the screw-in studs.
My 2nd guess is you're okay as long as you have enough thread engagement and everything is lined up. That's only a guess, though. You want to get advice from someone else (not me) on this one.
-----Original Message-----
>From: Dave Londry <davel at emspace.com>
>Sent: Apr 13, 2010 6:36 PM
>To: wkooiman at earthlink.net
>Cc: detomaso Forum <detomaso at realbig.com>
>Subject: Re: [DeTomaso] Pushrod guideplate adjustment?
>
>This is more interesting still, Will.
>- the shop who did it was somewhere around Portland - before my time.
>- of course I have the heads on now with $100 of gaskets under them
>- the spacing of the top of the studs is hard to measure repeatably.
> I ended up running nuts on 2 turns and measuring inside to inside of
>the nuts
> 5 - 2.457 1 - 2.456
> 6 - 2.453 2 - 2.425
> 7 - 2.416 3 - 2.401
> 8 - 2.422 4 - 2.417
> So # 8 doesn't stand out - but the new rockers are far from centering
>on the valvestems.
>- I went to change out the all the rockerstuds to CompCams Magnums
> and found that some greasehole had nicely cut the head-side of the
>stud to 0.615 from 0.800.
> This is because the tapped hole is only about 0.650.
> This leaves 0.540 engaged in the head - or 1.24 diameters, down from
>1.66.
>- So I could only change the exhaust rockerstud.
>- I found that both #8 studs had wear patches down the shank.
> Small on intake & big on exhaust.
>Here's where it gets ******weird******
>- I decided to see if the misalignment tracked the pushrod guideplate so
>I swapped the guideplates for #7 & #8
>- Now #8 lines up fine AND #7 DOES TOO.
> #7 alignment wasn't good before - but #8 was very bad
>
>So I think I can get some more depth in the hole for #8I by using a
>blind tap,
> trim my new rockerstud to about 0.700 and put it in with a hi-test
>threadlocker.
>Then if I can get a decent witness print on the stems, get on with it.
>
>What do all y'all think?
>dave
>
>
>wkooiman at earthlink.net wrote:
>> Measuring the distance from the studs sounds like a good idea.
>>
>> You might also consider taking the heads to a different machine shop. i.e. not the one that converted the heads to screw-in studs.
>>
>> Someone mentioned that the rocker studs might have been tapped off center (or crooked).
>>
>> Regardless, a decent machine shop should be able to tell if the studs are where they're supposed to be.
>>
>> The bottom line is if the studs are bent or crooked, the rocker will be crooked too, and even if you cut/reweld the guide plates, you're still going to have a rocker related failure.
>>
>>
>> -----Original Message-----
>>
>>> From: Dave Londry <davel at emspace.com>
>>> Sent: Apr 6, 2010 12:17 AM
>>> To: wkooiman at earthlink.net
>>> Cc: detomaso Forum <detomaso at realbig.com>
>>> Subject: Re: [DeTomaso] Pushrod guideplate adjustment?? [Re-trying to get this post.]
>>>
>>> No pain Will;
>>> that's a bonus question Will - and I haven't.
>>> You can tell I'm used to rockershafts or direct acting.
>>> I guess I should be able to measure the centre to centre distance of the
>>> studs on #8 and compare them to 2 or3 other cylinders.
>>> (unless the pedestals were bored skewed)
>>> I'm guessing that they're compcams magnum, everything else is,
>>> so for $53 for a set plus another $35 to get them here, I can just try
>>> a new pair.
>>> And I'll need some hi-temp threadlock I guess.
>>>
>>> You're right.
>>> I'd really like to get rid of the problem without extra clanging noises.
>>> dave
>>>
>>> wkooiman at earthlink.net wrote:
>>>
>>>> What about the rocker stud? Have you verified it isn't bent?
>>>>
>>>> Sorry to be a pain. I'd just hate for you to spend lots of time getting it back together only to bend something else.
>>>>
>>>>
>>>> -----Original Message-----
>>>>
>>>>
>>>>> From: Dave Londry <davel at emspace.com>
>>>>> Sent: Apr 5, 2010 7:11 PM
>>>>> To: detomaso Forum <detomaso at realbig.com>
>>>>> Subject: Re: [DeTomaso] Pushrod guideplate adjustment?? [Re-trying to get this post.]
>>>>>
>>>>>
>>>>> OK I get it. Thanks guys.
>>>>> Sounds like a "measure lots - tack once" job.
>>>>>
>>>>> Will & Jack
>>>>> - both #8 rockers, all the valves and all the valve springs have been
>>>>> replaced.
>>>>> The pushrods are as straight as my granite flat and I still need to move
>>>>> them about 0.110 closer together.
>>>>> (but that's quite a bit less than when the bent rocker was still there)
>>>>>
>>>>> dave
>>>>>
>>>>> -------------------------------------------------------------------
>>>>> Dave,
>>>>>
>>>>> I think most people actually cut the guideplates in two and retack them back together once they have the correct alignment.
>>>>> Julian (Kift)
>>>>>
>>>>> ----------------------------------------------------------------------
>>>>> Actually from that picture it looks like something is bent. It shouldn't be off by that much.
>>>>> (Will Kooiman)
>>>>>
>>>>> --------------------------------------------------------------------
>>>>>
>>>>> hemipanter at hemipanter.se wrote:
>>>>>
>>>>> Cut the guidelate in the middle and weld a washer over the connection.
>>>>> I did this 100:eds of times.
>>>>> Goran
>>>>>
>>>>> JDeRyke at aol.com wrote:
>>>>>
>>>>>
>>>>>> rockers, guide plates and pushrods- are hardened steel and cannot be
>>>>>> straightened if even slightly bent. Matter of fact, if anything IS bent, throw it
>>>>>> away before it breaks in two and takes out the top end or worse. It may only
>>>>>> be a matter of visual perspective, but better to spend a couple of hours
>>>>>> checking than find out the hard expensive way. good luck- J DeRyke
>>>>>> _______________________________________________
>>>>>>
>>>>>> Check everything. All the parts involved- the valve stems, pivot
>>>>>> studs, the
>>>>>>
>>>>>>
>>>>> -------------------------------------------------------------------------------------------------------------
>>>>>
>>>>>
>>>>>> I'm re-assembling #6143's valvetrain now and I don't see how to do
>>>>>> guideplate adjustment.
>>>>>>
>>>>>> http://www.poca.com/index.php/gallery/?g2_itemId=15138
>>>>>> The is a pre-teardown pic but it shows my question nicely.
>>>>>>
>>>>>> The roller-end of both intake and exhaust need to be moved outward
>>>>>> (from the bore centre).
>>>>>> That means the pushrods need to be closer together.
>>>>>> Do I put more bend in the guideplate to do that?
>>>>>>
>>>>>> thanks in advance
>>>>>> dave
>>>>>> (never did pedestals before)
>>>>>>
>>>>>> --
>>>>>> Dave Londry
>>>>>> davel at emspace.com
>>>>>>
>>>>>>
>>>>>>
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