OST-075: Blue(top) Hawaii

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oldeskewltoy
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OST-075: Blue(top) Hawaii

Postby oldeskewltoy » Tue May 04, 2021 8:36 am

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After discussing this build with my client, he sent me his largeport head, and his Crower cams.

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Unpacked...

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cam covers removed....

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and fully disassembled, prior to getting cleaned, pressure checked, and tumbled

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more to come....... :D
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

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oldeskewltoy
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Re: OST-075: Blue(top) Hawaii

Postby oldeskewltoy » Wed May 05, 2021 1:10 pm

A closer look at the valves......

Once you get past the really bad one... do you see it?

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The TVIS effect.... Valves 1, 4,5, and 8, the valves w/o the TVIS butterflies have far more build up.



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... and this head has been serviced at least once before... head machined...


... and valve job?? :roll:

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more to come..... :D
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

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oldeskewltoy
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Re: OST-075: Blue(top) Hawaii

Postby oldeskewltoy » Thu May 06, 2021 10:04 am

from another forum wrote:Are those valve seats machined crookedly?


Why yes.... yes they are :cry: . And don't ask how they did it... cause I don't even know.....

This is just another reason to get the head properly rebuilt....


So, on to deburring the head, and I found this :shock:

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simply amazing......................


Now, this is the cam card that came with my client's cams.....

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anyone tell me what seems to be wrong???



More to come...... :D
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

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oldeskewltoy
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Re: OST-075: Blue(top) Hawaii

Postby oldeskewltoy » Mon May 10, 2021 9:36 am

from another froum1 wrote:I'll venture an uneducated guess. A negative number for the exhaust valve closure, i.e. -8.0 BTDC. Perhaps a negative "before" degree reading equals "after"?

PS: Are you keeping the fishing line weight or returning it to the client?



from another forum2 wrote:The nomenclature is very strange to begin with and the visual aid isn't helping at all with the intake going full circle.

The duration @0.05 lift and the opening closing degrees don't add up for me. The intake calcutes to 212 but the exhaust ends up at 228. If I interpret the minus sign for the exhaust wrong I can get it to 212 but then there wouldn't be any overlap (on the contrary all valves would be closed for 8°). Also the ramp seems to be very slow/wide but that might just be me as I'm comparing it to Catcams which are known for a rather aggressive ramp angle.

I haven't wrapped my brain around engine related things for years and it's very late so I might be completely off :D




In this case it is 8 degrees BTDC, otherwise as "from another forum2" mentioned we would be @ 228 if it were after TDC. A few things to remember most of the mild cams will close the exhaust valve BTDC, or close to TDC, while still at a certain lift point (either .040"/1mm, or .050"), seat to seat the valve still usually closes after top dead center - dependent on cam timing.

agreed, their timing wheel/diagram doesn't help either......

As to comparing them to Cat cams - yes, the Crower are far more mild a ramp, and offer only a minimal lift increase (7.75mm lift) over stock cams. The Cat cams I typically recommend for mild builds are 212 @ .040" (likely around 208-210@.050"), but with 8mm lift. So the Cat cams are a tiny bit shorter in duration @, much shorter in duration overall, and offer more lift. The Crowers will twist a few hundred more rpm.


But while all that is pertinent, that wasn't what I was after.....


This is what I was focused on..... Crower had HOT clearances... something you just don't get, and the FSM only has a reference for.... AND the reference is looser then Crower's spec - possibly making clearances too tight on the Crower cams.... Image

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more to come....... :D

PS - didn't keep the weight.... ;)
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

Sepheroth86
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Re: OST-075: Blue(top) Hawaii

Postby Sepheroth86 » Tue May 11, 2021 5:43 am

I enjoy reading these posts.

I wish this forum was as active as it was back in the late 1990's.

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oldeskewltoy
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Re: OST-075: Blue(top) Hawaii

Postby oldeskewltoy » Thu May 13, 2021 1:19 pm

Sepheroth86 wrote:I enjoy reading these posts.

I wish this forum was as active as it was back in the late 1990's.


Thank you.... I'm doing my part in keeping the forum alive..... ;)


from another forum wrote:I seen the clearance thing but disregarded the 'hot' part entirely as the seemed in the ballpark for 'cold' - maybe another typo?

Have you tried contacting Crower - as there's some blurb about changed specs and stuff?


I called, and left a message, as well as emailing them. No answer.....

Then I got the brilliant idea of doing a search on their website.... bingo.

Some changes - clearances no longer specified hot, some absent info - TRD single springs are no longer available, so no spring listed. Timing wheel better... but still inaccurate, or at least it doesn't represent actual timing.

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full size view - http://gallery.ostportworks.com/albums/userpics/10005/Cam_card_2021_complete~0.jpg



now 2 down.....

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from a slightly different perspective

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more to come..... :D
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

User avatar
oldeskewltoy
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Re: OST-075: Blue(top) Hawaii

Postby oldeskewltoy » Fri May 21, 2021 4:38 pm

from another forum wrote:I know it's tedious but in my opinion you would be best off to measure it yourself - if they did change the specs at one point who knows what version you have in hand.

EDIT: as for the illustration it looks intended as an abstract and not to the actual degree as 8° ATDC isn't anywhere close to what is pictured in either of the two drawings


Agreed, I set clearances to .006" on the intake side, and .008" on the exhaust side.

As far as cam timing, that is in my client's hands - I did send him both cam cards - so he should be able to set them up.


From 3 down to 4 down.......

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And off to the machine shop where that horrible valve job went away....

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Once back in my hands, a quick re-assembly... and checking clearances....

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A big swing is needed... 10 of 16 valves I can't get a clearance on.... so back to the shop to get them tipped - If you look to the far left you can see how much I had the intake valves tipped....


Now with clearances set - a set of faux cams is fitted to keep the shims/buckets in place during return shipping.

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OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!