Modified 425 reassembly,i need help

Old May 30th, 2019, 07:38 PM
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Modified 425 reassembly,i need help

Im looking for pointers,tips,resources, overall really just where do i start?
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Old May 31st, 2019, 04:55 AM
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First question would be have you ever done a complete engine before and do you have the proper tools to measure everything and to assemble it ?
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Old May 31st, 2019, 06:18 AM
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Modified? Does that mean machine work? There are lots of videos on YouTube. Put in Oldsmobile. Bill Travado has a series of an Oldsmobile engine assembly. Some tools will be needed.
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Old May 31st, 2019, 01:45 PM
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Machine work yes,No previous experience on this scale. I probably have most of the tools or access to them.

Last edited by JayDee314; May 31st, 2019 at 01:46 PM. Reason: Adding info
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Old May 31st, 2019, 10:40 PM
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Oh boy......this may sound daunting and scary at first, but after many "well-intentioned" machinists got done with our parts, everything would have absolutely screwed up in a matter of 5 minutes or less of firing up the engine for the first time.


VORTECPRO saved our bacon after seeing how much I couldn't properly measure because I didn't have the correct tools (He has a nice Sunnen dial bore gauge and the way to zero it in a fixture for a targeted hole/bore size) for the crankshaft journals, rod big ends, main bores, cylinder bores, and then once those bore sizes were established and repaired by resizing the rod big ends, align honing the mains, verifying piston to cylinder wall clearances and/or honing to correct size, then you install the bearings that you bought for the mains and rods, and take measurements on each bearing i.d. again to verify the clearance to the crank.

I have a cheap dial bore gauge, and it works fine for hard parts, but it doesn't do great on bearings, as it doesn't have large rollers and can mark the bearings a little too much. I could just measure enough to know that I wasn't getting the clearance that I wanted/needed to keep this engine alive.

The next thing that is very difficult to measure without a known/trusted crank grinder helping you out is not only the clearances that can be measured with a micrometer for the ROD and MAIN journal sizes of the crank, but a way to measure the journals for concentricity, runout, sloped journals, a bent crankshaft nose, etc.

As can be seen on our build thread (yes, I know it is long), but it shows two videos, one of the crank showing an Egg-shaped profile (watch the Arnold gauge needle flick back and forth when it is centered on a journal of our crank when it was poorly turned); Once the crank was corrected by VORTECPRO, the Arnold gauge shows ZERO run-out and no concentricity issues.

It is not like Oldsmobiles are some sort of Rocket Science (pun intended), but, the truth is, that most machinists can't/won't do quality work for the common customer. I am sure there are more than just a few Chevy engines that have been screwed up just as bad as these machinists can screw up an Olds engine, but in all honestly, 90% of most engine machinists work is involving Chevrolet engines of some sort, and many of them don't care to learn about another type of engine, especially one that has a reputation for being hard to rebuild successfully (Olds).

I think you really have to first, find a good machinist with a reputation for success with Olds engines or other oddball engines, Secondly, you have to pay this good machinist a decent amount of money to get good work, otherwise, why wouldn't they just hurry through it and take your money with a smile and say "good luck" when you pick up your junk.

This is where you as the "builder" (not just an assembler) come in. Checking clearances and doing the hard work of correcting any flaws before the engine is assembled and ruined by running it, or you are disappointed with the lack of performance, and/or you have extreme oil usage/overheating issues.

As for pointers, You need to know what clearances you have for all of the above mentioned items, and they all need to be measured correctly with the correct tools.

My advice, worth $.02:

1. Main bearing clearances for street/strip with a Big Block Olds - Main bores set to middle of spec range, no oiling restrictors required
Mains 1 through 4 - prefer clearance of .0028-.0032 with a a Speed Pro 2/3 grooved main bearing set
Main number 5 - prefer clearance of .0033-.0037

Keep all bearings numbered to the main bores where they were measured for clearance for Mains and Rods.

2. Rod bearing clearance with rod bores set to middle of spec range - running bearing of choice
All rods should have .0024-.0027 of clearance range

3. Run Durabond rear grooved cam bearings, with the oiling holes positioned at the 3 o'clock position when looking at it from the front of the block

4. Run Restricted Pushrods with .040 orifice holes to limit oil flow from the lifters up through the cylinder heads- this will be fine with stock rocker arms or roller rockers. - Verify pushrod length to order correct pushrods after mocking up all parts. Stock-length pushrods are usually not the correct length once the cylinder heads have received a valve-job or new valves because the valve-tip heights are not correct. Smith Brothers has nice pushrods and they make them in all sizes.

5. Run a Melling High Volume oil pump (verify that it has the pink spring in it). Recommend to disassemble the pump and check clearances of the gears lash and the end play of the gears to the bottom plate, then pack the pump with a good engine assembly lube like CMD or Joe Gibbs engine assembly lube. If you run the restricted pushrods as recommended, you should keep enough oil down low to keep a stock oil pan, but a deeper pan and matching pickup is strongly advised. Buy some Mahle Oil pan gaskets with cork over steel cores for a 350 diesel engine. Verify that the oil pump pickup is between 1/4 and 3/8 from the bottom of the pan (use clay plastic bag and gauge thickness after compressed).
You should be able to happily run good quality 10w40 (Maxima) oil with the bearing clearances recommended and the cam bearings/restricted pushrods. You can go to a 20W50 from Maxima or Gibbs-Driven as well, which will hold a little more hot-idle oil pressure.

6. Ensure that the cylinder heads are flat and true. Pull the heads apart if already assembled and check for guide to valvestem clearance on all valves. Have Valveseats checked for concentricity, and have valve faces checked for concentricity as well. Make sure valves are not bent. Since this is a 425, make sure that hardened exhaust valve seats were installed in the heads. Again, be the builder, not the assembler..... I know it is not easy, but all of these things will make the future success of the engine and the happiness for yourself more guaranteed. FEL Pro or Mahle Head gaskets will work fine for most builds unless you expect nitrous or boost. Go with Cometics if higher cylinder pressure will occur. ARP head bolts work well and head studs are better, but the block needs to be torque plate honed with whatever fastener you plan to install to replicate the true bore distortion caused by the clamping of the fasteners. ARP main bolts are recommended, but cap straps are not yet proven to actually do much (we run them, but I haven't ever ran without them)

7. I strongly recommend a Hydraulic Roller cam setup. If you don't run a Hydraulic Roller, use USA Made Hydraulic-flat tappet lifters and an ISKY, COMP, CRANE, or Engle cam. If you use a Hydraulic Flat Tappet, you must run an engine oil with high ZDDP levels such as the previously recommended MAXIMA or DRIVEN (or Valvoline racing) oils.

8. BUY A BTR TIMING CHAIN SET. Buy or borrow the proper tools to Degree the cam. Degree it again. After you verify the cam duration and timing, Adjust the cam timing gear to get the cam installed in the correct intake centerline placement for the best power for your combination. Do not trust a cam ground by any maker is correct when installed "straight up" (where the marks line up). Our cam was ground over 20 degrees off and required the timing set to be a full tooth different than "straight up" as well as setting the cam gear at 2 degrees advance. You can use a small, cheap degree wheel, but they are harder to use and be sure of your numbers. We used a little 9 inch ISKY degree wheel, and I verified the final numbers 4 times with math calculations and worries that I was reading it wrong. VORTECPRO verified that we got the cam degreed and installed correctly using a huge degree wheel and a much better pointer than we had (we used a bent aluminum wire with a timing cover bolt holding it). Cheap tools worked in this case, but it likely took much longer in some ways for us to be sure it was correct, vs. spending more money on a nicer degree wheel setup and only doing a double check.

9. Pistons - are they forged or cast? What rings are you going to run? Even if they are set as overbore rings, check the end gaps on every set for a bore, and keep them numbered together for each bore. If you are running a higher HP setup and you expect some good power, file-fit the rings to run .005 ring gap per inch on the top ring and .0055 or .006 per inch of bore size on the second ring. Ensure that the oil ring expanders have a gap and are not butted together. Was the assembly balanced already? If not, you need to. Make sure and get a damper that has been properly rebuilt or is new to balance with, as well as a good flexplate/flywheel to match it all up. Olds engines have heavy reciprocal weight, they need to be balanced by a good machinist.

10. clean, clean, and clean some more. Make sure your block was properly cleaned by seeing if the oil galley plugs were removed for cleaning and reinstalled or handed to you for reinstallation. You should be able to look all the way through the blocks oil galleys from end to end. Make sure you use the weird-square tool plug with a clean hole in it to plug the galley end near where the distributor mounts into the block. Install the two hex plugs up front under the timing chain gears, one will have a small hole in it, make sure it is clear.

11. install freeze plugs with a thin wipe of silicone around the edge to assist with sealing. Only use brass freeze plugs. Do not use the incorrect Pipe plugs in the oil galleys that every freeze plug kit comes with. They are wrong, wrong, wrong.



I probably missed something, but that will get you started for now....
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Old June 1st, 2019, 04:57 AM
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Holy s&^%!

Thats a good starting point....... If your not scared then I am

You might wanna just have him do it

Last edited by scrappie; June 1st, 2019 at 05:16 AM.
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Old June 1st, 2019, 07:43 AM
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A few other points;
I’d rather have a smart “Chevy” guy than a dumb “Olds” guy.
Let me explain. The guy I’ve been using for over ten years now was by no means an “Olds” guy prior to me going to him. But I could tell he was smart, and most importantly not too arrogant or close minded to ask questions. He’s now machined over 50 Oldsmobile engines for just me in that time, and he still asks questions. Bottom line is it’s your money, and if he doesn’t know something, ask and then you can both learn together.
Olds engines aren’t any harder to assemble or machine as stated in a prior post. It’s just that your machinist should be aware that an Olds is more like a Buick than a Chevy, with the main difference being bearing size and rigidity, therefore requiring different clearances than most. But again a good, capable machinist will notice those things as you move along.
Also no need to pack the oil pump with assembly lube, in fact too much assembly lube anywhere isn’t good either. You should be priming the pump prior to start up anyway, especially if you’ll be using a flat tappet cam.
And the HV pumps don’t come with the pink spring in them already. It’s usually individually packaged in the pump box.
if using stock rods I’d open up those bearing clearances to .003-.0033 as they’ll flex more than you want to know. And use the P series Clevite bearing there, they’ll be more forgiving.
All engines need to be balanced, regardless of weight.
Finally you have a really good, modern piston now available for the 425. It’s made by Mahle and is the best available by far. Let me know if I can be of any further help.
Thanks.

Last edited by cutlassefi; June 1st, 2019 at 08:02 AM.
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Old June 2nd, 2019, 12:03 AM
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If you have never assembled and engine before, your best bet is to find someone that has experience assembling engines, he does not necessarily have to be an Olds guy, and have him be there when you assemble your engine to help you out on your first one. I am an advocate that I can do anything if I have a good book on how to do it, but no matter how good the book, questions will come up as you are doing this. Do not be afraid to ask questions, and measure everything. I have not done an engine in decades, but a couple of decades ago my best friend was an acomplished Chevy engine builder, and I used to sit with him in the garage and shoot the breeze as he assembled engines, and give him a hand here and there. The amount of times that guy would get pissed off as something had not been machined to spec by a machine shop was unreal. He would get all pissed off and start cursing as he had to pack the parts back up again and go back to the machine shop so that they would do it again. I remeber him doing a 350/370 LT1 engine one day, he had the crank cut .010. when he came back and measured it, it was not done correctly and would now need to be cut to .020 to get it fixed. Takes it back to the machine shop and when it comes back they screwed it up again and he had to end up cutting it to .030, he was pissed!
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Old June 2nd, 2019, 07:02 PM
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Originally Posted by cutlassefi View Post
A few other points;
I’d rather have a smart “Chevy” guy than a dumb “Olds” guy.
Let me explain. The guy I’ve been using for over ten years now was by no means an “Olds” guy prior to me going to him. But I could tell he was smart, and most importantly not too arrogant or close minded to ask questions. He’s now machined over 50 Oldsmobile engines for just me in that time, and he still asks questions. Bottom line is it’s your money, and if he doesn’t know something, ask and then you can both learn together..
That is absolutely the truth. I am not at all afraid to ask about something that I don't know about. I don't care how good of a machinist you are you will NEVER know everything about every type of engine.
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Old June 4th, 2019, 12:28 AM
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Yeah Im scared
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Old June 24th, 2019, 05:07 PM
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So after much debate i decided to sell the engine. I will never have time&money needed. So i would like to clean it up a bit,should i sand blast or wire brush and drill?
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Old June 25th, 2019, 05:46 PM
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Kerosene and a stiff parts cleaning brush.
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Old June 25th, 2019, 06:13 PM
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Originally Posted by JayDee314 View Post
So i would like to clean it up a bit,should i sand blast or wire brush and drill?
Whatever you do . DON'T sandblast engine parts . From what I have seen , this can end badly .
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Old June 25th, 2019, 06:33 PM
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Originally Posted by JayDee314 View Post
Im looking for pointers,tips,resources, overall really just where do i start?
So originally your post stated "425 modified reassembly". Im thinking you modified it or had it modified somehow and now looking to put it together, is that right?
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