V6 Discussion and questions about the base carbureted or MPFI V6's and the rare SFI Turbo V6.

Hmmm, decision time...

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Old Apr 6, 2007 | 03:41 PM
  #1  
Six_Shooter's Avatar
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Car: 1973 Datsun 240Z/ 1985 S-15 Jimmy
Engine: Turbo LX9/To be decided
Transmission: 5-speed/T-5
Axle/Gears: R200 3.90/7.5" 3.73
Hmmm, decision time...

Alright well I pulled the heads off of James (1985 GMC Jimmy), that has been loosely bolted on for about a year or so now, probably longer, just to keep it somewhat sealed up, There were no spark plugs in teh heads, I know I'm a dumbass.

Now, I was expecting at least some light rust on the cylinder walls, since I didn't coat them in anything before I moved it to a previous location and then to where it is now, at the previous location it sat outside for about 6 months. Overall it's not too bad and even the cylinder that is bad IMO, could probably be cleaned up with a light hone or maybe just some elbow grease and a rag, but it looks worse than that right now, you know that black corrosion that forms, yeah it looks like that.

Now here are my two choices:
I have another genI (2.8) block that I could have bored and prepped and basically put it back together the way I was planning on putting this one back together, all new bearings etc, etc.

Or I could use a 3400 block, re-drill the starter holes (will have to make a jig for that), and a new driver side mount, along with a modified oil pan and maybe crossmember, I believe I could do it with just a modified oil pan.

GenI block would allow me to retain my 260-2 bumpstick, which works very well, keep my current pistons (Federal Mogul Hyper Eutectic FWD stock replacement 3.1 pistons .030" overbore). It will bolt right in, with out ANY worries.

GenIII block would give me full roller bumpstick, better oiling, and more displacement, but cam selection is next to nil, especially for a turbo grind, more actual work getting it in there, and would need new pistons, I don't trust the stock cast pistons, would at least like hyper eutectics, since the ones in the current block still look almost new after 20 000+ KMs of HARD abuse.

I had intended to keep this simple if it came to a decsion like this and keep the block the way it was as a genI block, for ease of install and current parts swap-ability, but I'm at a crossroads, where I could possibly gain an easy 25 to 50 HP, just by going the 3400 route, if not more.

What would you do?
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Old Apr 6, 2007 | 08:12 PM
  #2  
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From: Sayreville NJ
Re: Hmmm, decision time...

id keep the gen 1 block, i think the better cam choices are worth more then better oiling,ive spun my motors to 7k,run sever amounts of boost on them and have yet to hurt a main or rod bearing.lol well except fo rin the begining of the winter when i wa sputting off changing out the 50 wieght oil in the car for some lighter stuff and snapped the oil pump drive.

ur already at 3.2L so ur talkign what 5ci or something to goto the 3.4
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Old Apr 6, 2007 | 09:10 PM
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Car: 1973 Datsun 240Z/ 1985 S-15 Jimmy
Engine: Turbo LX9/To be decided
Transmission: 5-speed/T-5
Axle/Gears: R200 3.90/7.5" 3.73
Re: Hmmm, decision time...

Originally Posted by daves12secV6
id keep the gen 1 block, i think the better cam choices are worth more then better oiling,ive spun my motors to 7k,run sever amounts of boost on them and have yet to hurt a main or rod bearing.lol well except fo rin the begining of the winter when i wa sputting off changing out the 50 wieght oil in the car for some lighter stuff and snapped the oil pump drive.

ur already at 3.2L so ur talkign what 5ci or something to goto the 3.4
Yeah I know the displacment isn't huge, but the valves do have less shrouding in the larger bore, plus the roller cam and better oiling make it more desirable.
The cam "choices" would be limited to the 260-2 that I have in there already, I don't want to buy a new cam for this, and if I'm going that far, I will just go 3400 block then. I inspected my lifters tonight and one seems to have a slight mushroom on it, it gets tight in the bore when the bottom is pushed into teh lifter bore, all the others were fine.

Plus if I do this, I'll be able to offer swap mounts, and possibly modified oil pans, for others to be able to use these engines, since there is a lot of interest in this swap.

I'm going to check on some pricing in the next few days, maybe that will help me decide.
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Old Apr 6, 2007 | 11:04 PM
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From: Casselberry, FLA
Car: 88 V6 'bird/89TBI bird/85 T/A
Engine: 2.8/TBI/TPI
Transmission: V8 T-5/700R4 x2
Axle/Gears: 3.42 open/2.73 open/ 3.27 9 bolt
Re: Hmmm, decision time...

I have already seen the gen III 3.5 engines in the wrecking yards up north...

It's just something to think about if you're looking to start with a maxed out displacement. The two I saw were from a Buick Rendevous and a Pontiac Montana. The intake looks just like my gen III intake from my sister's 96 Cutlass 3400 sfi engine.
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Old Apr 6, 2007 | 11:25 PM
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Car: 1973 Datsun 240Z/ 1985 S-15 Jimmy
Engine: Turbo LX9/To be decided
Transmission: 5-speed/T-5
Axle/Gears: R200 3.90/7.5" 3.73
Re: Hmmm, decision time...

I'm looking to use what I already have, no buying of new blocks here. I have another genI 2.8 block and two 3400 blocks.
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