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Thread: Donor Engine Teardown

  1. #1
    Member FlyingCobra's Avatar
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    Donor Engine Teardown

    Last week I bought an '88 Mustang "donor car." I put that in quotes because I doubt I'll be using much of anything from the car besides the engine, which is what I bought it for. I'm not even sure I'll reuse the rear end, although I'm leaning towards rebuilding it as the limited slip works and I have a set of 3.73 gears that I could throw in it.

    The engine had a set of Edelbrock Performer aluminum heads. These were the exact heads I wanted, and I bought the car for about what the heads would cost. So I figured it's hard to go wrong there. The car also had a Weiand X-CELerator intake (more or less the predecessor to the Weiand Stealth) that I'd use, and an aft sump Milodon oil pan that I'll use if it will fit in the Mk4.

    When I looked over the engine before I bought it I knew there were a number of things wrong immediately, but the fact that they'd never gotten it running I figured was a positive. And sure enough, I was right. Oh boy, did these guys screw things up. For your entertainment, here is the carnage.

    My helper helped me get the engine pulled in a couple of hours. It helped that the guy didn't hook up most of the things correctly, like the motor mounts. Upon tearing into it I found evidence that parts of the engine had run (exhaust ports had soot in them), and there was coolant in the oil when I drained it. However there was no evidence of oil in the upper section of the heads, so my guess is these heads had been used elsewhere at some point, or it had been run minimally.
    1AB4815E-55EF-4A94-94B1-AE391FC4CFA3.jpg

    Crane 1.7:1 roller rockers, which were factory equipment on the '95 Mustang Cobra. However if you look closely, you'll see that they're not straight on, they're tilted. They were all loose, completely inappropriately adjusted.
    0BA58218-AC8E-42F0-9B80-B2A6D7F6BB38.jpg

    Another one of my helpers helping me to pull the valve covers and pull the rockers and pushrods.
    972BEC39-0FCA-4210-8025-D68A4DEA8E0D.jpg

    Surprise! Two bent pushrods. From what I could tell, because these roller rockers were installed so, so loose, they actually twisted enough to screw up the geometry and bend a pushrod during cranking. I found no evidence of valve-to-piston contact.
    6C556100-70DA-4E18-A4C8-1793A8C8CFB2.jpg

    This picture doesn't do the real view justice, but basically the front 4 cylinders looked much cleaner than the rear 4. None of them were particularly dirty. When I pulled the intake manifold, it looked like they had put that on improperly and that was where the coolant leak probably came from. This is backed up by the fact that the coolant level in the radiator was about at the level of the intake manifold. The pistons were clean enough to get a part number from the SpeedPro hypereutectic pistons.
    BA60A598-4BEB-4355-A9EB-16CB1C3556AC.jpg

    Kids, adjust your rockers properly... you can see the damage where the sides next to the forward roller impacted the valve head. Surprisingly, the rollers all turn and seem to behave just fine. Then again it didn't run much.
    5EAEDBB2-99C2-4BA7-8486-26A4FE5705F1.jpg

    I've seen a lot of screwed up things, but I think this takes the cake. Someone used hose clamps over copper pipe to "fabricate" this oil pickup. The screen was pointed upwards at a 45 degree angle like that. YGBSM
    04B3F345-900B-45AC-86FD-2025A67709C7.jpg

    Bearings were not in good shape. So I don't know if this bottom end had been run previously or if someone had gotten it running briefly at one point, and with no oil pressure just completely screwed up the bearings. Hard to say. From everything else that was wrong I'm sure that this person didn't prime the oil pump at all.
    F3438C44-6DC9-453B-8E07-4B015F3B5D92.jpg

    The bores, not so good. Pistons were 40 over, bores are all 50 over. It appears that the guy honed them using one of those drill hone tools, and kept the thing in one spot too long. No cross-hatching evident at all. And this one had a pretty bad score mark in it.
    A4526C37-41AE-4559-900A-6519412A34AB.jpg

    Bare block with Ford 9N (torn apart) in the background.
    C41EC1EB-9DFC-429F-BE50-5CA7E84A5F39.jpg

    I like tearing apart motors and like I said, I bought the car reasonably enough that I'm still in a decent spot. The block is a D8VE-6015-A3A, which from reading up on it is one of the strongest 302 blocks from the factory. But already being 40-50 over (depending on how you look at it) and having that scoring mark on the one cylinder, I'm thinking I'm probably looking at another block.

    The rods and crank look to be fine. I'm not finding any casting marks on the crank in the locations that they're supposed to be in, which makes me wonder if it's aftermarket. Need to look at that further and see what I can determine about it.

    I need to confirm that the heads aren't cracked and that the valves still are straight and seal correctly. I'm going to put a roller cam in the engine.

    What I'm leaning towards at this point is finding a roller block to rebuild, maybe even a complete roller 302 (with not as good heads) and tear that down to put new pistons of my choosing in. Then figure out what to do with the other components I'm not going to use.

    I'm leaning towards rebuilding the rear end from the Mustang for the Mk4, and doing the 5-lug and disk brake conversion. The limited slip works in it and I have a set of 3.73 gears I can use. More decisions to be made while I wait for the kit to show up next month.

  2. #2
    Member JRD56's Avatar
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    Be careful with the oil pan, you really don't want it hanging down lower than the frame. Rebuild the engine properly and it will last a long time, don't skimp, it costs a lot more to redo something than to do it right the first. I did a solid axle rear with disc brake conversion from Rich Oben at Northern Race cars. Give him a call and listen to what he says, he knows what he taking about.
    Purchased and un-assembled Mk3 in 2016. 5.0, Aluminum heads, Performer RPM Air gap, Quick Fuel 650 carb, BBK headers T5, 3.55 rear solid axle, Koni Shocks, PS with Hydra-boost. Also own two restored vintage Mustangs, two Model A fords, 1941 Chevy truck and several other hot rods.

  3. #3
    Member FlyingCobra's Avatar
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    Quote Originally Posted by JRD56 View Post
    Be careful with the oil pan, you really don't want it hanging down lower than the frame. Rebuild the engine properly and it will last a long time, don't skimp, it costs a lot more to redo something than to do it right the first. I did a solid axle rear with disc brake conversion from Rich Oben at Northern Race cars. Give him a call and listen to what he says, he knows what he taking about.
    Those were my plans on all counts. I figured once I got far enough along to test fit the engine in the Mk4, I'd see how it did with that oil pan. If the oil pan hung under then I wouldn't use it and would switch to something else. But if it will work, then it'd be nice to have the aft sump and the extra capacity. I was also planning on Rich's kit. I'm leaning towards just rebuilding the rear end out of my donor Mustang and converting it to 5-lug with Rich's kit. Although I should probably tear into the rear end before I do that.

    The engine I tore down because I was going to rebuild anyway. Now, I just have to figure out what exactly the best path is for that.

  4. #4
    Brandon #9196 TexasAviator's Avatar
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    I built my own motor too, I decided to stroke it, put TFS 190 Heads and a mild cam. The silly thing went and made 475hp on my first attempt at a V8 engine build. Details in my build thread.

  5. #5
    Senior Member rich grsc's Avatar
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    So you bought a useless donor?? The block is junk if its 50 over, even a 40 overbore is suspect on a 302. You want to use an unknown crank, and with how that was put together, I wouldn't trust the rods till I had them inspected. I think just get a new short block, easier and cheaper in the long run?
    I would advise against 3:73 gears in such a light car, have always found 3:55 to be the most used setup in these cars.

  6. #6
    Member FlyingCobra's Avatar
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    Quote Originally Posted by TexasAviator View Post
    I built my own motor too, I decided to stroke it, put TFS 190 Heads and a mild cam. The silly thing went and made 475hp on my first attempt at a V8 engine build. Details in my build thread.
    Your engine is most impressive. I’ll be happy with 400, really even 375. My real reason for wanting the 302 was a lightweight engine that was happy revving and also quick to rev. That’s why I’m trying to minimize the engine driven accessories to the alternator only.

    But with the price of an ATK 351 being less than a 302, that has me thinking heavily about going that route.

    How do you find the response on your 331?

  7. #7
    Senior Member frankb's Avatar
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    FlyingCobra: Assuming that there no cracks in the main webs in your block, it can be sleeved. But the cost of sleeving is probably at or above the cost of a new block. Something to consider!
    FFR MK4 #8317, 393 Cleveland, Lunati VooDoo solid roller, CHI 3V heads and intake, TKO 600, Std roadster seats, 8.8 3.55 diff, 17" Halibrand replica wheels, Ford "Magnetic Metallic", silver ghost stripe.

  8. #8
    Boydster's Avatar
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    Please consider a taller gear. There's a lot of threads about this.

    You can measure the oil pan depth. With a SBF, you want about a 7.5" oil pan.

    Nice work inspecting that engine.
    ---Boyd---
    MkIV #9042 build thread
    www.boss427.us
    Plan: 427W-X, TKO600, Moser 3.55 rear.
    Delivered Feb 2017, first start Oct 22, 2017, first go-cart Mar 26, 2018

  9. #9
    Senior Member KenWilkinson's Avatar
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    I'm building a 302 from a block I bought from DSS Racing. So far I'm happy with the quality. I've called them a few times with questions, and they have been responsive.
    https://shop.dssracing.com/product_p/lvl%2020%20302.htm

  10. #10
    Member FlyingCobra's Avatar
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    Quote Originally Posted by frankb View Post
    FlyingCobra: Assuming that there no cracks in the main webs in your block, it can be sleeved. But the cost of sleeving is probably at or above the cost of a new block. Something to consider!
    Agreed. I think this block is furniture at this point. Have to decide what to turn it into.

    Quote Originally Posted by Boydster View Post
    Please consider a taller gear. There's a lot of threads about this.

    You can measure the oil pan depth. With a SBF, you want about a 7.5" oil pan.

    Nice work inspecting that engine.
    Thanks. I'll measure and I'm pretty sure it's more than 7.5".

    I'm planning a TKO-600 at this point, which has a 2.95 1st gear and 0.62 5th gear. Those ratios with a 3.73 come out to around the same as a standard T-5 with a 3.55. Between that and having a set of 3.73s (came with the donor car, brand new in box), it makes sense. But I figure I'll get my hands on the TKO first.

    Quote Originally Posted by KenWilkinson View Post
    I'm building a 302 from a block I bought from DSS Racing. So far I'm happy with the quality. I've called them a few times with questions, and they have been responsive.
    https://shop.dssracing.com/product_p/lvl%2020%20302.htm
    I'll check them out, thanks!

  11. #11
    Boydster's Avatar
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    Quote Originally Posted by FlyingCobra View Post
    I'm planning a TKO-600 at this point, which has a 2.95 1st gear and 0.62 5th gear. Those ratios with a 3.73 come out to around the same as a standard T-5 with a 3.55. Between that and having a set of 3.73s (came with the donor car, brand new in box), it makes sense. But I figure I'll get my hands on the TKO first.
    TKO600 1st gear is 2.87 or 3.27
    I know you're into a lot more than gear decisions right now. Just remember that the F5 is +1000 lbs lighter, so doesnt need as much gear. Lots of discussions on here about it.
    ---Boyd---
    MkIV #9042 build thread
    www.boss427.us
    Plan: 427W-X, TKO600, Moser 3.55 rear.
    Delivered Feb 2017, first start Oct 22, 2017, first go-cart Mar 26, 2018

  12. #12
    Member FlyingCobra's Avatar
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    Quote Originally Posted by Boydster View Post
    TKO600 1st gear is 2.87 or 3.27
    I know you're into a lot more than gear decisions right now. Just remember that the F5 is +1000 lbs lighter, so doesnt need as much gear. Lots of discussions on here about it.
    2.87, that’s it. I was going from memory. There’s a particular box I have an opportunity on.

  13. #13
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    I have 3.73s with a 300ish hp 302. It’s obviously pretty snappy but given the choice I would take the taller 3.55. I used this because it was already in my donor axle and didn’t seem worth the cost of swapping it out. If yours is not installed I would think you could sell it for a decent price and buy 3.55s.
    That would be my direction if I was in your shoes right now.

  14. #14
    Member FlyingCobra's Avatar
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    Quote Originally Posted by Murd View Post
    I have 3.73s with a 300ish hp 302. It’s obviously pretty snappy but given the choice I would take the taller 3.55. I used this because it was already in my donor axle and didn’t seem worth the cost of swapping it out. If yours is not installed I would think you could sell it for a decent price and buy 3.55s.
    That would be my direction if I was in your shoes right now.
    With which transmission?

  15. #15
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    Stock T5. Which I blew up. New one built to T5z spec being built now with 2.95 1st which will mean bit taller 2nd and 3rd too. I believe it just hits 60mph at 6000 in 2nd.
    With 300 hp 2nd is traction limited so for what you're planning even more so. I think taller gearing will be great. My opinion is also swayed by the general consensus on here that 3.55 and not 3.73 is the way to go, I’ve never driven to compare.

  16. #16
    Brandon #9196 TexasAviator's Avatar
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    Quote Originally Posted by FlyingCobra View Post
    Your engine is most impressive. I’ll be happy with 400, really even 375. My real reason for wanting the 302 was a lightweight engine that was happy revving and also quick to rev. That’s why I’m trying to minimize the engine driven accessories to the alternator only.

    But with the price of an ATK 351 being less than a 302, that has me thinking heavily about going that route.

    How do you find the response on your 331?
    T5z
    347 not 331
    3.73 gear

    It's incredibly responsive, it revs quick and as you already saw gearing is a big deal. The 351 has bigger bearing surfaces and is slower responding and a lot heavier. I built my hand made t5z and 3.73 gear

  17. #17
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    Quote Originally Posted by KenWilkinson View Post
    I'm building a 302 from a block I bought from DSS Racing. So far I'm happy with the quality. I've called them a few times with questions, and they have been responsive.
    https://shop.dssracing.com/product_p/lvl%2020%20302.htm
    I think these DSS blocks are pretty competitive to buying a good junkyard block and having it machined. DSS has a good reputation and goes one better by doing a CNC job on the stock blocks. If I didn't already have my Mexican 302 block machined and assembled, I would consider going with a DSS machined block.

    I tend to accumulate parts over time for future projects, so the DIY approach is the way I usually go. I take the "Built not Bought" moniker to it's extreme. I have an automotive machine shop and body shop background. Now retired, my previous job was in Aerospace working on big commercial Jets and I've built Kit vehicles and a Cobra from another kit provider in the past, this is my first one from FFR. should be fun.
    Last edited by Megascott; 05-11-2019 at 11:59 PM. Reason: spelling error

  18. #18
    Member FlyingCobra's Avatar
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    I don't come around here much these days and am working away at my project, but since I saw my post from last year got revived I figured I'd update a bit.

    I ended up finishing out that parts car for a total invested of -$50 (yes, negative $50), and that included me keeping the Edelbrock Performer heads, block, and rotating assembly. The heads I plan on using but the block and rotating assembly probably not. Either way, I've essentially gotten $1500 worth of heads for free out of that one so that's pretty good.

    I then bought another parts car, a '95 Mustang with a T-5. I mainly bought that because of the 3.73 rear in it, which I'm going to go through anyway. However if the 302 in it a good block once I tear into it (planning to do that this weekend) I may use that as a base motor. Plan has gone to a 331 stroker and then upgrade the T-5. Keep things light weight and more responsive/free revving vs. a 351/TKO. So far I'm doing well on that parts car and it's tracking towards being "free" like the first one was, with me keeping the parts I want for my build. Ideally I'd like to do the straight cut gears that G-Force used to offer, but from what I've seen they stopped selling those. Their current gear set is still a pretty aggressive low angle helix for 1-4 though.

    The primary thing I've found on this second donor engine is that the flywheel was on loose. Like literally grab it and wiggle it back and forth loose. All I care about is the block and we'll see if that's any good or not.

    Hope is to have first start sometime over the summer although I think that fall or winter is more likely as I continue to push forward on the car as a whole.
    Last edited by FlyingCobra; 05-15-2019 at 11:42 AM.

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