FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#221
|
||||
|
||||
Quote:
I think the factory used a tighter tolerances for individual measurements and the parts to fit in them compared to other companies like Chevy. They are on the deck/bores sometimes too. The line worker would know to use a different piston for an 'M' compared to an 'L'. (same for crank, use different size main bearing according to the letter) These were not big numbers. Something like .0005" different. (or maybe even less) I have a bulletin where they changed the letters to 'L' and 'M'. (possibly around 1971? have to look it up) Thanks for the pics, they are awesome!
__________________
John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
#222
|
||||
|
||||
Definitely..
Quote:
What I've found is that finding a Block that can go over 4.200" is kinda' rare. Unless you want Bores that are less than 0.095" in Thickness. I try to stay above 0.100" in "Non Thrust" Areas of the Bore and above 0.150" in the Thrust Areas. If you're Racing, then "Hard Block" is Your Friend. Have a Good One, Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#223
|
||||
|
||||
"Select Fit" Bearing Clearances.
Quote:
I've worked on Engines that were Coded that way and the Factory Shop Manual actually deciphered the Codes for the Technician. It's all about "Select Fitting" the Bearings, which is still a Common Practice. I just wondered if anyone actually could decipher those codes on a Pontiac Block. I do realize that it doesn't matter if you're Align Honing or Align Boring the Block and Machining the Crankshaft. I was just curious. Thanks Again, Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#224
|
||||
|
||||
Great Work Larry! Nice documenting the obvious dimension differences.
Did you look at one of the most critical indicators of the strength of the block (where the two casting segments come together). The 67 400 block comes very close to the actual bores. The later blocks and the 455 block have the casting split line in the middle of the main webs where they see the most stress. (Typically where cracks start like the ones in the other posters thread). Food for thought. But everyone has their own thoughts on where the strength come from in a block. Tom V.
__________________
"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#225
|
||||
|
||||
Post #217
Quote:
I briefly made mention of the Casting Line Difference back at Post 217. You're correct about the Casting/Parting Line Differences and that is Definitely something that needs to be Considered. Especially when the Casting Thickness in that Area is Thin, much the way that most, but not all, Later 70's Block are. In this Case though, I was pointing out the Differences in what "I Consider" to be some of the Better Blocks that are out there. These Blocks could be Modified for the Intended Application without the Risk of Ruining a "Rare Pontiac" Block that would be best Suited for a "Numbers Matching" Restoration. Let me say this about the Casting Line Location in the 455 Cast #485428 Main Webbing. I can Honestly say that I've never seen a #485428 Casting break there. Maybe it's due to the Thickness of the Main Webbing and Maybe it's due to the Quality of the Casting. If you'll notice in the photos that I've posted, the (1972) Cast #485428 455 Block is a Nice Looking Casting. Thanks, Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#226
|
||||
|
||||
Thank you Larry for all the info and pics you just posted. Even more reason to sticky.
Charles
__________________
68 Firebird. IA2 block, 505 cu in, E-head, Solid roller 3650 weight. Reid TH400 4:11 gear. 29" slick. Best so far 10.12@133 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
#227
|
||||
|
||||
So, where does that leave us?
Quote:
I didn't plan to spend My ENTIRE Saturday doing that, but what the Heck... I'll tell you Guys what I'm going to use for My Next (Personal) "Stock Block" Performance Build. A Late 1971 to Late 1974 #481988 400 2-Bolt, 2-Bbl. (No Cylinder Bore Chamfers), with Splayed Caps on the Center Three and 7/16" Fasteners on the Outer Bolt Position. This Block is Very Similar to the (1972) Cast #485428 455 Block that I Illustrated. (Now I've got to find one with sufficient Cylinder Wall Thickness.) "Screaming Chief" shows what this Block looks like in His Posts #171 and #172. (Thanks for Showing that 1977/78 Block with the 1974 Casting. I was Totally Unaware of that. Once again showing that there are No "Set Rules" Pertaining to Casting Numbers and Date Codes.) Have a Good One, Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#228
|
||||
|
||||
IMO, you can't beat the early 389 blocks . '58 to '60 are the best but are probably a bit limited on bore size . If you want a smaller cube engine the 2 bolt block can be fitted with splayed 4 bolt caps and they are very thick in almost all dimensions going by the one I sonic'd. I also have a '61 389 block to use in my next n/a build,although this doesn't have the lengthways stiffening rib that the '58 to '60 blocks do, it is also very thick dimensionally and has the 1/4" taller main caps too. Although these blocks need an adapter to fit them to a TH400 pattern gearbox, this isn't too difficult to make. Now if someone could start manufacturing these adapters cheaply in 1/4" steel........ (The ali Wilcap adapters are a bit thick for my liking and quite pricey too)
Thanks go to Steve Barcak for bringing the virtues of these early blocks to the attention of the Pontiac world. |
#229
|
||||
|
||||
I Agree...
Quote:
I agree with All of that. As you have mentioned, the Bore Size is the limiting factor. IMO, for a Racing Application, I don't want a Bore Size any Smaller than 4.185". I prefer 4.210" or Larger. Therefore I believe that the trouble associated with the Early 389 Blocks just isn't worth it. That's My ... On the other hand, the CV-1 Cylinder Head with the Correct Ports could change all of that. The Bore Size would be less of a factor, for sure........ The Jury is Still Out on that one. Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#230
|
||||
|
||||
Larry
Thanks for Putting the time into this! These pictures are awesome! Im using a 70 400 2 bolt block, that is using the program splayed blocks.
__________________
Darby 74 Grandville 2Dr 455 c.i 4550# 2011 1.60 60 ft,7.33@94.55-11.502@117.74 2017, 74 firebird -3600 lbs (all bests) 1.33 60 ft, 6.314@108.39 9.950@134.32 M/T 275/60 ET SS Drag Radial 2023,(Pontiac 505) 1.27 60 ft, 5.97@112.86, 9.48@139.31.... 275/60 Radial Pro's Last edited by grandville455; 01-12-2015 at 09:44 AM. |
#231
|
||||
|
||||
Program Caps Question....
Quote:
Did your Program Splayed Caps come Drilled for 7/16" Outer Fasteners or 1/2" Outer Fasteners? I ask because I just received a "Splayed 400" set that were Drilled for 1/2". I've always gotten Caps from Program Engineering that were Drilled for 7/16" when the Caps were Splayed. I haven't called them yet because I just noticed it yesterday. NOTE: Of course the Factory Style (Straight not Splayed) Program Caps are Drilled 1/2" for the Outer Fasteners. That matches the factory Drilled Holes in the Block. Thanks, Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#232
|
||||
|
||||
Quote:
__________________
Darby 74 Grandville 2Dr 455 c.i 4550# 2011 1.60 60 ft,7.33@94.55-11.502@117.74 2017, 74 firebird -3600 lbs (all bests) 1.33 60 ft, 6.314@108.39 9.950@134.32 M/T 275/60 ET SS Drag Radial 2023,(Pontiac 505) 1.27 60 ft, 5.97@112.86, 9.48@139.31.... 275/60 Radial Pro's |
#233
|
||||
|
||||
Woops..
Quote:
I sent them Back Already. They'll be sending out a New Set as soon as they receive them. Check Everything, Every Time.... Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#234
|
||||
|
||||
Quote:
Tom V.
__________________
"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#235
|
||||
|
||||
I checked my program splayed caps and they are drilled for 1/2 in as well. Looks like it would still work for the 59 block I have though. I have had these for awhile and just noticed it. Wonder if I should try to send them back or use them?
|
#236
|
||||
|
||||
Let's Keep it Going..
Thanks for the Acknowledgement Tom.
I would say that ALL of this information (Not Just what I Posted) is applicable to the Majority of Racers or Fast Street Car Owners. I'd say any Build in the 600ish to 750ish Horsepower Range for sure. I appreciate the others that have taken their time to post and am just "Paying it Forward". Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#237
|
||||
|
||||
It's your Call.
Quote:
My Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#238
|
||||
|
||||
Let Me Elaborate a Little.
Quote:
While rereading My Posts last night I realized that this information may be a little misleading. I PREFER to have a minimum of 0.125" of Wall Thickness on the "Non Thrust" (Front and Rear) Portions/Surfaces of the Cylinder Bore and a minimum of 0.185" on the "Piston Skirt Loaded" (Inner and Outer) Portions/Surfaces (Not just the Thrust Surface) of the Cylinder Bores as a MINIMUM. That's what I PREFER. BUT, what I have found over the years is that I have had a lot of trouble finding Blocks that could be Overbored more than 0.030" with that much Wall Thickness Remaining. So, because of that, I've had to adjust what I would accept as a "BARE MINIMUM". That's where the previous specs. of 0.100" and 0.150" came from. I hope that makes more sense, Larry S.
__________________
---------- http://www.pas4performance.com Proud to Say, "Made in the USA" ---------- |
#239
|
||||
|
||||
Quote:
__________________
Darby 74 Grandville 2Dr 455 c.i 4550# 2011 1.60 60 ft,7.33@94.55-11.502@117.74 2017, 74 firebird -3600 lbs (all bests) 1.33 60 ft, 6.314@108.39 9.950@134.32 M/T 275/60 ET SS Drag Radial 2023,(Pontiac 505) 1.27 60 ft, 5.97@112.86, 9.48@139.31.... 275/60 Radial Pro's |
#240
|
||||
|
||||
I thought 7/16 would be fine as well. So should I send these back and get the 7/16 drilled caps? Or can I use these 1/2 in drilled caps and have the block drilled for 7/16? I think you can get arp bolts with a bigger head.
|
Reply |
|
|