Talk me out of (or into) it, Oppo

"MM54" (mm54mk2)
04/13/2018 at 20:38 • Filed to: '71Chevelle

The Oppo Half-Massed Rally is July 28. The Chevelle needs the engine rebuilt. Can I / Should I try to get it done in time?

The engine desperately needs rebuilt, which I have been planning to do this summer for quite a while. I have a really bad chronic case of while-I’m-in-there-itus which means I’m also going to clean up the whole engine bay while it’s apart (need something to do while the block is getting machined, right?) and knock out some of the rust I’m sure is hiding behind the fenders.

I had been planning on starting this work in June-ish, but with the motivation of the Oppo Rally coming up, maybe I should get started late this month or early May, and target to be done by mid July? Is this stupid? As a friend told me, “Worst case you get a lot done, then take another car, right?”

Talk some sense into me, Oppo (or push me over the edge, either way).

DISCUSSION (17)

Noah - Now with more boost. > MM54
04/13/2018 at 21:01

Well... that would be pretty epic. And you have quite a long time.

(Says the guy who has been working on a simple big brakes/intake/exhaust/bearing replacement job for two months...)

If only EssExTee could be so grossly incandescent > MM54
04/13/2018 at 21:13

You can be this year’s Pixel.

merged-5876237249235911857-hrw8uc > MM54
04/13/2018 at 21:16

I think your friend is right. Give it a shot, at least you’ll get a bunch done. But if you pull the motor and the engine bay is all rotted out, maybe look for a plan B, but I would imagine you know roughly how good/bad it all is already so hopefully no surprises.

Noah - Now with more boost. > If only EssExTee could be so grossly incandescent
04/13/2018 at 21:47

Hopefully Pixel will Pixel again though. Running into that thing in the middle of a graveyard in the ghetto was totally outrageous.

Die-Trying > MM54
04/13/2018 at 21:48

what engine/size?

If only EssExTee could be so grossly incandescent > Noah - Now with more boost.
04/13/2018 at 21:55

I actually dropped by his place on my way out to my overnight stop the day before and helped out with the truck a bit.

Duck Duck Grey Duck FTMFW! > MM54
04/13/2018 at 22:53

DO IT!!!!!!!! There, glad we got that out of the way.

MM54 > Die-Trying
04/13/2018 at 23:01

Chevy 307. If the block/crank/rods magnaflux good then I’ll rebuild it, if I need a block or crank/rods I’ll find a 350 to build. I’ll need pistons for the bore either way.

MM54 > merged-5876237249235911857-hrw8uc
04/13/2018 at 23:03

There shouldn’t be any rust-related surprised, other than possible some stuck fasteners on the engine. I think the big thing that would slow me down would be the machine work on the engine and any sort of surprise getting things assembled.

MM54 > Noah - Now with more boost.
04/13/2018 at 23:08

Yeah it should be easily done in a couple months, but the trans swap (PG to Muncie) was also theoretically a project that should have taken a week that took a couple months.

MM54 > Duck Duck Grey Duck FTMFW!
04/13/2018 at 23:09

Thanks I guess

Noah - Now with more boost. > MM54
04/13/2018 at 23:12

Yep that sounds about right. Car projects are so hard to estimate. The endless trips to the parts store, the machine shop taking forever, etc...

Die-Trying > MM54
04/13/2018 at 23:16

just asking, because it would cost ALMOST as much ....... to just build a 350, and get a good deal more power out of it. just something to think about. its another one of those “while you are already there”, scope creep...... 350 cores are cheap.

and you could build a 350 replacement while driving the 307......

MM54 > Die-Trying
04/13/2018 at 23:57

I want to build the 307, would be fun (though I’m already getting tired of people telling me it’s dumb to do so - not talking about you). The catch though is (as above) if it gets to be too costly (crank / rods) then I’ll get a 350 short block and build it at the same cost as the 307. If I’m buying a crank, it’s going to be a 400 crank to stick in a 350...

Die-Trying > MM54
04/14/2018 at 18:18

there is nothing WRONG with 307s..........

its just that you are leaving a lot of power potential on the table by not building more cubes at almost the same price....... think of it this way. you can get RIGHT AROUND 1.25 hp PER cubic inch*, if you pay attention to all your details, and match parts fairly well.(*ball park numbers, slightly optimistic)...... AT 1.25 hp from a 307, is going to be around say 375, best case. building an additional 43 cubes(350), gives you an almost instant 50hp addition, just in volume potential.

fun facts........ the 307 crank has the same stroke as a 327....... the 327 has the same bore as a 350......... most 307 cranks had the medium sized main bearings, like the 1969 and later 350s........ more stroke, provides more torque, and torque is good for getting heavier cars rolling from a standstill.......

smaller cubes usually get better fuel economy...... gas is still going up....... its fun to be able to cruise the car around the block a lot, because you can afford to........

just stuff to think about.......

MM54 > Die-Trying
04/14/2018 at 18:26

This is all good info - I’ve done a lot of research into it; the 307 is basically a 283 with a 327 crank. I want to say that the ‘71 307 has the small-journal crank though. I’m not going for crazy power, bore/hone, heads, and a cam should be good (I’ve already got a decent intake, headers, and a holley on it). Something to drive around, have fun, and not be constantly breaking parts :)

What it does all boil down to though is the reusability of parts - I want to rebuild the 307, but not so much that I’m going to spend a ton more on it than I would an equivalent 350.

A semi-alternative I have considered is finding a 350 short block that I can just ball hone and toss in new rings and bearings to cut out the machine shop all together - would save time, but the cost of buying the short block would cancel out with the machine work on the 307.

Die-Trying > MM54
04/14/2018 at 19:11

alot depends on how much you feel comfortable doing yourself, and how much you THINK is worth investing for peace of mind.

more than likely youre going to put a camshaft in it while it is apart.......BUT....... do you just get a near factory replacement flat tappet, and roll the dice that it will keep on lasting with the modern oils(that have less zddp antiwear additives) with the possibility that it COULD go flat in short order. OR do you spend the money on a roller set up, that takes that worry off of your mind for the foreseeable future? one costs around $150-ish, and the other costs around $1100...... a lot just depends on what you are planning to spend already. also how mean you plan to be to it, and how long you INTEND to keep enjoying the car for......... no easy answers here....... power envy is a REAL thing.

before you get started, you ought to decide how you plan to enjoy the car, and what it NEEDS to do to make YOU happy with it. that way you can round up the parts that will work the best together for what you are wanting to do THE FIRST TIME. and be honest with yourself on how you will actually drive it. makes a big difference in the end result.........

projects are (more) fun when you are driving them......

just more dumb stuff to think over while getting your plan ready......