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Building a motor over time to hide it from SWMBO, best starting "Block"?

C

Coupe

Member
Im just thinking out loud here guys, so please humor me..

I am pondering a motor build for my 65 fastback and want to start gathering bits. My only hard line is when done I want it to look period correct to the casual observer.

Should I start with a 5.0 roller or a vintage 289?

I ask because I have a line on a 67ish 289 block (still on the original bore) and rotating assembly that I could get cheap and over time get the machine work done and choose performance parts and a solid lifter cam etc.. but I dont know if I would be better off using a 5.0 roller motor and a roller cam set up ( I honestly dont know much about those) ?

My end goal is a high RPM capable motor with a decent amount of compression to mimic the personality and SOUNDS of the vintage K code Shelby & Cobra racecar motors from back in the day. I plan on a cam thats a bit erratic like a road racer and the edgy performance that goes along with it. I have a nice street motor in the car with a mild cam now that works fine but I think that once I get a few more summers on this car the way it is I will want to pick up some performance. The current motor is a 60 thou over already, so its about done.

Any comments on what to use for a good foundation for a 289/302 motor? I am seriously considering the shorter stroke of the 289 to keep with the quick revving nature of the 289, but a bit more stroke may not ruin my day. I don't know if I want to do something like a 347 build because I just don't know it it will have the sound and feel of those old Le-mans racing motors. The car is a toy, 100% toy. If I had a chance at a tack day I would go for it, but the car has glass and no roll bar so I dont know if I will get much of a chance to do that anywhere near Indy.

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Guidance?
 
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I would imagine you will get opinions that run the gamut!

Me, I like a std 289 built for high rpm's. No roller, no stroking, just pure natural high screaming 289. With that said, I currently have a 302 in the car until I can afford another screamer. It runs great and sounds good, all with a mid 5,000 limit. It will not see any track days though.
If you want to see what my old motor was, go here: http://www.cardomain.com/ride/667160/1966-ford-mustang/page-2/

That 289 lasted me about 7 years of track days before the stock crank broke (last April).
 
So, do you feel the 289 crank failure could have been avoided in some ay or do you think a 5.0 crank would have handled it any better?

I guess I should add that I plan on keeping Tri-Y headers to look period correct, so that may influence the choices somewhat, especially on the choice of heads.
 
"Coupe" said:
So, do you feel the 289 crank failure could have been avoided in some ay or do you think a 5.0 crank would have handled it any better?

I guess I should add that I plan on keeping Tri-Y headers to look period correct, so that may influence the choices somewhat, especially on the choice of heads.
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The crank had 7 years of track days at 7,000+ rpm's. I can't really blame the stock crank for breaking after all that! Had I replaced it with a new, stronger crank I'd probably still be running it today. The thing about track motors is that you're always finding the next weak link. It's the price you pay when spinning these things beyond 6,000.

But they sure sound awesome when they are up there :thu
 
"silverblueBP" said:
The thing about track motors is that you're always finding the next weak link. It's the price you pay when spinning these things beyond 6,000.

But they sure sound awesome when they are up there :thu
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crule but true
 
In your shoes, with what you describe you want, I'd grab that 289 for cheap and start there. While there might be a few benefits to a roller cam set-up you won't really be taking advantage of the real potential with the restrictive exhaust you'll be running. You can still stroke that 289 and pick up some cubes and torque. For the street you would really appreciate it.
 
Well, my current 289 has a 302 crank and I am wondering if I could perceive a difference in how quick it revs compared to a 289 crank.

I dont know that tri-Y's with Shelby side exits would be the bottle neck with any 289 heads, maybe with some better aftermarket aluminum heads @ 5k + rpm's , do you really think they would be that restrictive?

What did the R model GT350 or 289 Cobra track car run back in the day? I dont think they ran mufflers, but I cant remember what headers they typically ran.

At first blush I am leaning towards a Solid lifter 289 Cobra knockoff with big rod bolts and a balance of the entire rotating assembly. I doubt I run that slide on hatchet weight that the Shelby K code motors used since I can just balance everything as a unit. I wonder what that would cost me at the shop?

I may keep the bore stock if its a low mile block, or at least just enough to clean em up. I took the heads off of it last year and put them on my car, they are still running the original FORD valves and looked super clean when I lapped them in to check them, so I am guessing the block is a low mileage piece.

This is gonna be a hoot.
 
Best thing to let it spin up faster (IMHO) is going with an aluminum flywheel instead of a steel unit.
 
I went through a similar process with the original 289 too far gone. I also wanted to replicate a HiPo, horsepower-wise at least. Finding an original bore 289 proved to be difficult and expensive (if you can pick up one reasonably, that would be a consideration.) I went with a 5.0 roller block as making 300 HP is easy. I added a 331 stroker kit and a fairly mild cam (1300 to 5500 rpm.) The result was an engine with a lot torque, very streetable, and would run circles around an original k-code.
 
"Jack1966" said:
I went through a similar process with the original 289 too far gone. I also wanted to replicate a HiPo, horsepower-wise at least. Finding an original bore 289 proved to be difficult and expensive (if you can pick up one reasonably, that would be a consideration.) I went with a 5.0 roller block as making 300 HP is easy. I added a 331 stroker kit and a fairly mild cam (1300 to 5500 rpm.) The result was an engine with a lot torque, very streetable, and would run circles around an original k-code.
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I hear ya, but does it "Sound" like a vintage 289? That visceral appeal is what I am going for, I currently have a 302 rotating assembly and the thing works out to 310cid and it runs really good and makes good power, but it does not have the excitement of a "Boy racer 289" if you know what I mean.

Its all relative anyway, hell a new V6 makes more HP than a 289 K code but you dont see people putting them in these cars. I mean yeah, you may find one but I can also find a guy that wants a diesel mercedes powered hot rod...
 
Ya, just like that.

This all started when a buddy picked up a 66 GT350 that someone hotrodded back in the day, I think it has a lemans cam and longtubes with carb work, it sounds sinister and makes my car sound inadequate at the cruise nights....cant have that.
 
Should I spend the money on the hipo main caps or is there a better option for 289 main caps for the money? The internals will not need to be anything specific, just capable.
 
"Coupe" said:
Should I spend the money on the hipo main caps or is there a better option for 289 main caps for the money? The internals will not need to be anything specific, just capable.
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I ran stock main caps.
 
you should consider replicating one of the lemans 289s to the best of your knowledge. then stick it on an engine dyno (with the added data) to provide a data point for what one of these originals did (just a data point, obviously not exact).

seems like that would match the look, feel and sound it appears you are looking for.

just have your machine shop build the shortblock with better parts than they had 40 years ago.

i would avoid a 50 oz crank setup (actually i would avoid a 28 oz setup too).

with all the available parts today and for a street car, i personally wouldn't do the above if i was looking for better performance, idle, efficiency, longevity, etc.

more cubes = lower rpm = less stress on parts = better idle = less wasted fuel

high compression = race fuel = PITA
 
Great news, I obtained a 289 short block that is still on it's original bore and has no ridge and really looks like new. I will put it on the stand and start to sort out what I have when I get it home.
So the goal is going to be a nasty 289 that makes the noises that I like and can spook the masses.. I think a solid lifter Lemans cam or the like. 10:1 at a minimum.

Some of the build basics I remember from my youth, I will have the block checked out at some point but I will also need to get the crank & connecting rods checked and new bigger con rod bolts, then pick pistons (I am going to go out on a limb here and say the 45 year old pistons may not be the best thing to send into the 6k range?).

Then balance the rotating assembly to a new 28 oz harmonic balancer and flywheel, unless someone can explain a better balance weight? Part of me wants to stay with a 28oz in the event a part ever fails and I need to change it.

I would think a SFI damper would be better than using a repop hi-po style balancer so I guess I should go that route.

I see that Silverblue runs stock main caps, I guess if it holds up for his car they would be OK for this street motor, but perhaps changing to main studs and a girdle would add some strength?

Heads. No idea yet. By the time I build a set of 289 heads I can buy aluminum heads and just paint em black.


Feel free to voice opinions and concerns, I have not built a motor since the 90's and while I could just find a slightly used 347 or the like and have a nice motor, but I seriously doubt it would sound right at 6k? :wor
 
if staying with a stock cast early crank, then stay 28 oz. you won't get to zero.

i sometimes wonder if what appears to be a large number of split 289/302 blocks has anything to do with the added weight on the ends of a crank with external balance (especially 50 oz). couple that weight with the needed rpm for that small inch motor to make the power of a larger inch motor and maybe the harmonic is too much for the caps to take. i have no idea. just my thoughts.

i've read good and bad about a girdle. they create another slip interface between the bolts and the cap which seems bad.

back when i was going to build a 351w with factory rods and crank, the shop felt 6200 would be the comfortable limit assuming i went with lightweight pistons. the rods were truck rods w/o the oiling spout and they were going to get beam polished as well. so i can't imagine 6k being any issue in a 289/302.

personally when it comes to sound, i think exhaust is the #1 impact, followed by the cam. at idle, i don't think people will really be able to tell the difference with cubes. at 6k rpm and full load i still don't think people will really know the difference.

when people say small block and sound, i think what they are really correlating is the sound of a V8 spinning higher rpms which for a street engine with larger cubic engines would be a lot more power than a smaller inch motor. so basically, i think it's going to take an exceptional set of ears to tell the difference between a 418 and a 302 spinning at 6k.
 
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