Big block parts interchange PITA

DJ Dep

DJ Dep

refugee from the other place
Joined
Mar 23, 2008
Messages
718
Location
Silver City, NM
Thank you gubment motors for "improving" the Mark IV engine and making all kinds of incompatible headaches for everyone. :(

Are there any aftermarket blocks being produced that DO use all the Mark IV parts and DON'T have compatibility issues with them?

Also, some of the aftermarket blocks "feature" that they have bosses installed for the clutch pivot, but they are NOT drilled and tapped. Any aftermarket blocks that have those holes drilled and tapped?
 
redvetracr said:
you can buy a nice pivot ball bracket from Scoggin-Dickey...I did and it works fine.
Click to expand...

I saw that. That solves that problem. But unfortunately ALL the blocks including Dart and Merlin can't use the Mark IV Vette oil pan. :(

Gen 6: GM recognized that it did not make any friends when it designed the Gen 5, and so they chose to revise the coolant passages again when designing the Gen 6, allowing the older heads to be used without coolant seepage problems. The boss for the clutch bracket returned, but was generally not drilled and tapped. The non-adjustable valvetrain remained,
[this is an improvement????] as did the one-piece rear main seal. Some but not all Gen 6 454 (and not 502) blocks regained a mechanical fuel pump provision [I need that]. Production engines installed in pickup trucks got a high-efficiency cylinder head, still canted-valve, but with a modern heart-shaped combustion chamber of about 100cc. The intake port has a "ski jump" cast into it to promote swirling of the intake air flow. All production vehicles with a Gen 6 used a 454 version, but over-the-counter 502s are available. The Gen 6 is sometimes referred to as the "Gen Fix" because it fixed a number of issues that disappointed enthusiasts when the Gen 5 was released. As an added bonus, most if not all Gen 6 engines use hydraulic roller lifters [which I DON'T need].

It looks like I will be shopping for an original/used/rebuilt Mark IV block. Less hassle than converting a new engine to old specs.

:huh2:
 
Just got e-mail reply back from Scoggin. The pivot ball bracket works for both small blocks and big blocks. Gonna order one now.
 
Dep, seriously, go roller. At this point, I just don't see any good reason to stick with a flat tappet cam. For a modest additional expense, you get more power and less wear. It's nothing but win/win. I don't ever want to build another flat tappet engine so long as I live.
 
clutchdust said:
Dep, seriously, go roller.
Click to expand...

I think his point was he didn't want hydraulic rollers. This still leaves an option for solid rollers. But I've read that high lift, large spring pressure rollers don't last too long.i

If somehow you can get a blower onto the engine, building up the engine works out better. Pick a low compression ratio, (8.00:1), a minimal overlap duration cam shaft, moderate spring pressures and hydraulic rollers, mufflers that are quiet, etc and you've an engine that idles smoothly, is quiet, and is docile at low rpms.....it's just getting the bower on that's difficult for a custom installation.
 
Last edited:
clutchdust said:
Dep, seriously, go roller. At this point, I just don't see any good reason to stick with a flat tappet cam. For a modest additional expense, you get more power and less wear. It's nothing but win/win. I don't ever want to build another flat tappet engine so long as I live.
Click to expand...

Never happen. It will be flat tappet/solid lifters. Proabaly the 1971 LS-6 cam.
Also the low rise LS-6 manifold.

68/70Vette is correct. I don't want roller anything including roller rockers. I will probably buy a bare block and work from there. Get aluminum heads that have adjustable rockers. Buy a balanced rotating assembly. I will probably end up with either a Milodon or Moroso oil pan. I looked at them and there are some decent ones available. I just ordered the clutch gizmo Redvetracr mentioned. Not cheap but better and easier than trying to drill a hole and screwing it up.

A blower? LOL...before I did that I'd buy Hilborn injection and run 8 tubes through the hood. I plan on 11 or 12-1 compression. This is NOT going to be a daily driver. And yes, I have access to racing gas.
 
Last edited:
I WAS under the ASSumption that a roller cam was almost impossible to wear out.....BUT, the one in my engine did.....the TPIS ZZ4 500 buck cam wore out, the hardening was not worth crap, the stock style lifters were untouched, and in the car running fine....

just WTF is going on with modern replacement cams that they are crapping out on guys....?? seems like most of the complaints are on the flat tappet side, but then there is ME....WTF??

I blame China, myself....no other choice....

:mad::flash:
 
turtlevette said:
can you take some pictures. It's hard to believe the lifters are still good. start another thread.
Click to expand...

Jim, ME? I think I posted a thread here on that cam/lifters some time ago, I know there is nowhere else I post about this, and I did take pix of the cam anyway...the lifters are fine....I looked at them with a mag glass under bright light, smooth as glass and not the least bit rough on rolling....but that cam was JUNK from the git go....oil pressures been fine for years now...

engine smooth as silk since cam change and chip replacement with stock program L98....

:cussing:
 
Dep, I'm curious, what's your resistance to rollers? Not trying to change your opinion but you're obviously not averse to mods. So why not roller? You know something I don't (GENE not withstanding)?
 
You must log in or register to reply here.

Latest posts

Back
Top