#181  
Old 10-19-2023, 07:48 AM
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HWYSTR455 HWYSTR455 is offline
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Interesting. I think I saw somewhere that one is 7/8" diameter, and another is 15/16" diameter, but didn't save the source. I flipped around yesterday for a short digging on this some but found no conclusive info.


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1970 GTO Judge Tribute Pro-Tour Project 535 IA2
http://forums.maxperformanceinc.com/...d.php?t=760624
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  #182  
Old 11-15-2023, 08:23 PM
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Scarebird Scarebird is offline
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Last month the engine tossed the belt - again. So after I returned from vacation I examined it closer. A straight edge across the power steering pulley showed it to be 1/2 off, and a chip in the composite pulley.

So I bought a pulley installer/puller and a new GM pulley, shimmed one of the legs 0.054" and will see what happens this time. I wanted to use the 3/4 ton mount but they are out of stock everywhere.

  #183  
Old 11-18-2023, 01:24 PM
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Belt seems ok so far.

15-1/2 mpg, in town driving only. Once belt shows to be reliable will try a run up to Santa Fe.

  #184  
Old 11-21-2023, 08:34 PM
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Another PY'er had asked about the cam I am currently running - GM# 12664572. It was touted as a non-DOD LT1 cam, 200/207 @116.5.

Greaseball noted to me to check this cam out again. I was horrified to discover somebody at GM goofed, the real spec's are 189/223 at 120 separation!

I emailed the vendor, Michigan Motorsports, about this issue. This was their reply:


Good morning,

Back when you purchased that camshaft, everybody (including ourselves and several large GM parts retailers) who was selling that LT5 camshaft had it listed as being similar specs to the L86/LT1 camshaft, as that is what the information everybody had at the time showed the specs as being. I'm not sure if GM changed the camshaft now that the LT5 is just a crate engine rather than a production car engine, or if the information everybody had was wrong all along, but it was later discovered when one of the larger companies selling that camshaft measured it on one of their Andrews camshaft machines that the specs were quite a bit different than thought and we all updated our listings to show the 188/223 specs that they informed us of.

At that time we went ahead and stopped selling that camshaft since it wouldn't be a good fit for most of our truck/SUV customers even though we hadn't heard any complaints from anybody about how it ran in those engines at all.

We now sell the Texas Speed camshaft in the link below for the L86/LT1/LT4 DOD deletes. To use that camshaft on an L84, you would need to upgrade to LT1 style valve springs as well.

If you don't want to run the LT5 camshaft, you can return it to the address below for a refund or store credit.

The LeMans has of course been running for the last 6 months with this wrong cam. Other than the wide separation, it seems to be a Gen V version of Comp's Thumper.

Yuck.

So I will replace it and now am leaning towards the L8T cam, which is the same as the 5.3 (193/199) but with DOD delete. The L8T is a 3/4 and 1 ton truck version of the Gen V but in 6.6 liter. The smaller 189 does indeed move the LeMans briskly and with less exhaust duration should get better power and mileage.


Last edited by Scarebird; 11-21-2023 at 08:39 PM.
  #185  
Old 11-21-2023, 11:34 PM
greaseball greaseball is offline
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Quote:
Originally Posted by Scarebird View Post
Another PY'er had asked about the cam I am currently running - GM# 12664572. It was touted as a non-DOD LT1 cam, 200/207 @116.5.

Greaseball noted to me to check this cam out again. I was horrified to discover somebody at GM goofed, the real spec's are 189/223 at 120 separation!

I emailed the vendor, Michigan Motorsports, about this issue. This was their reply:

Thank you for helping me confirm what I feared, Scarebird. Also, thank you for posting the reply from the vendor that you used for your LT5 cam.

Ive started a new thread on this subject:

https://forums.maxperformanceinc.com...d.php?t=870470

The Following User Says Thank You to greaseball For This Useful Post:
  #186  
Old 11-22-2023, 07:37 AM
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In the later years, Pontiac had some wide LSA cams, 116-118 or so, and suspect it was due to plugged up exhausts with cats, but there was not much trade off on power without other mods, so...

Some of the earlier Crane cams used 114-116 LSAs and were good performers, but sure there were specific reasons for those numbers.

On what is basically a 327, with tall intake ports, I suspect there was some concern about intake velocity, and sure they did a ton of testing. (for all-around performance).

As for documentation, engineers are pretty terrible at docs, and generally dread doing them. Most are rushed, lack grammar, and things (tech/assembly) change along the way. Discernment is always advised.

Nice catch by the way, and the discovery & sharing will live forever on the internet.


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1970 GTO Judge Tribute Pro-Tour Project 535 IA2
http://forums.maxperformanceinc.com/...d.php?t=760624
1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car
https://forums.maxperformanceinc.com...ght=procharger
Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be
  #187  
Old 11-22-2023, 10:22 AM
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Greaseball brought this to my attention.

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