69 Bottom End Parts

[stinger86]

I was talking to my military mechanic buddy and i've told him what i wanted to do with my pony. New carb, intake manifold, headers. He pretty much told me not to forget about the bottom end or i could blow a gasket or something.

What does the bottom end pretty much make up? Pistons, seals, cam?,

I've thought about this and i am going to just take out the engine and get all the parts i want/need and do it all at once. Probably over a week of just rebuilding. Any strats or concerns on that? Thanx

 

[2+2GT]

Must be a Chevy guy. As long as the crank, pistons, and rods are not worn out, they should be fine.

If you are doing this upgrade, and using the OE iron heads, half of you potential improvement will be lost unless you grind out the smog pump bumps in the exhaust ports, and port-match them to your exhaust manifolds/headers. Stock Ford SB exhaust port were horrible, even on the 289HP. This will add 2-3 hours to your upgrade. Well worth it.

 

[stinger86]

Not a chevy guy just a guy whos tired of having dealers do everything and not know whats going on under the hood. Thanx for the input

 

[2+2GT]

I meant your mechanic buddy, not you.

With inspection and shot-peening, stock 289 rods with good bolts are good up to 7000 rpm.

As long as the bottom end is in good shape, your intake and cam will not be a problem, unless, of course, the new power causes you to drive the tar out of it.

I wasn't kidding about the port-matching, you'll be glad you did it.

 

[stinger86]

Well in that case he is . what are OE iron heads. Anything to do with the iron forged or are they just normal heads?

 

[chubbs1080]

Thanks for the info about the exhaust ports. I have my heads off right now and will see what i can do before i put them back.
I just have the stock bottom end and about to put on a new intake and holly 4 brl. and have some long tube headers

 

[2+2GT]

Well in that case he is . what are OE iron heads. Anything to do with the iron forged or are they just normal heads?

Normal heads. And the ports are bad. Easily fixed, though.

The shaded area around the edge, and the smog "nose" inside the hole gotta go if you want performance.

 

[stinger86]

Looking from my Haynes repair manual,

Diameter:
Color coded red..................4.0004 to 4.0052 in (101.61 to 101.73mm)
Color coded blue.................3.9996 to 4.0002in (101.58 to 101.60mm)
Piston to cylinder bore clearence...........0.0018 to 0.0026 in (0.045 to 0.066mm)

WTF does this mean? When i look at new ones...just browsing....they come something like STD, .010", .020" , .030"......What one whould i get since blue and red are different? Freaking cars and there puzzles

 

[2+2GT]

No, it's the Haynes manual that's confusing. Get a Factory Service Manual and it'll be a lot more complete and clear.

And I go by std., .030, etc., too.

 

[D.Hearne]

Looking from my Haynes repair manual,

Diameter:
Color coded red..................4.0004 to 4.0052 in (101.61 to 101.73mm)
Color coded blue.................3.9996 to 4.0002in (101.58 to 101.60mm)
Piston to cylinder bore clearence...........0.0018 to 0.0026 in (0.045 to 0.066mm)

WTF does this mean? When i look at new ones...just browsing....they come something like STD, .010", .020" , .030"......What one whould i get since blue and red are different? Freaking cars and there puzzles

Those are stock piston diameters. Just ignore that. What you want is to pull the motor, bring it to a good local machine shop and let them do some measurements to determine what size over bore you can go to, to clean up the wear in the cylinders. THEN you can pick the correct size pistons to buy. But when doing this, you also want to pay close attention to the compresion height of the piston, the shorter the height, the lower the compression ratio's going to be. You want the tallest piston to acheive a "zero deck" (piston comes up even with the block deck at TDC) You may even want to take this opportunity to bore and stroke the motor with a stroker kit. That will net you more power across the board, no matter the heads/cam and intake you pick

 

[stinger86]

I hear alot about stroking. What kinds of stroking are there and what changes do i have to do if i decide to stroke.....The benefits and downsides? Great info! I'm learning so much. Thanx again guys

 

[D.Hearne]

For 302 blocks there are two strokers commonly available: 331 and 347. The 331 uses a 3.25" stroke crank (vs the 302's 3.00") the 347 uses a 3.40" crank. Both usually use 5.4" rods (vs the 302's 5.095" rods) The longer stroke increases the torque output (and HP too) of the engine. Torque is what moves the car. More torque= the quicker it'll accellerate. The only real change is you'll need to have the block clearanced for the longer rods. Check with your local machineshop to have this done. Or just buy a ready built stroker shortblock.

 

[rbohm]

Well in that case he is . what are OE iron heads. Anything to do with the iron forged or are they just normal heads?

OE stands for original equipment, otherwise known as factory heads. the factory heads are cast iron, same as the block. as indicated the exhaust ports are quite poor, but with a little time with a die grinder, you can open them up quite nicely and gain a lot of airflow through the ports, which will aid in power production, and improved efficiency overall.

For 302 blocks there are two strokers commonly available: 331 and 347. The 331 uses a 3.25" stroke crank (vs the 302's 3.00") the 347 uses a 3.40" crank. Both usually use 5.4" rods (vs the 302's 5.095" rods) The longer stroke increases the torque output (and HP too) of the engine. Torque is what moves the car. More torque= the quicker it'll accellerate. The only real change is you'll need to have the block clearanced for the longer rods. Check with your local machineshop to have this done. Or just buy a ready built stroker shortblock.

good info here, the only other thing that needs to be added is that you will need shorter pistons as well. stroker kits are available from a number of sources, and are relatively inexpensive, especially if you are rebuilding the bottom end.

 

[stinger86]

If I go ahead and buy an already 347 stroked small block, what am i looking for inparticular? The type of metal or what comes with it? My current engine looks pretty old with minor after parts. WOuld a machine shop be unbiased on the condition of the current engine and if its worth stroking or buying a already stroked one.

I've been reading alot on the 347 stroked. I think it will make a great project. My headers came in recently and my first reall addon that i did myself. I probally should have waited and gotten a gasket set but i still cant decide wether to sroke my current motor or buy another. Thanx guys!

 

[rbohm]

if you want to buy an already built short block stroker engine, then check a number of suppliers, and DO NOT go by price alone. better to pay a bit more for a quality build than have to send a broken engine back to be warrantied. grab a copy of muscle mustangs and fast fords off the magazine rack, and check out the ads for engine builders. there are plenty in the magazine. check out their prices, and research them on the net before you buy. most of these companies will custom build a motor for you if you desire.

 

[D.Hearne]

If I go ahead and buy an already 347 stroked small block, what am i looking for inparticular? The type of metal or what comes with it? My current engine looks pretty old with minor after parts. WOuld a machine shop be unbiased on the condition of the current engine and if its worth stroking or buying a already stroked one.

I've been reading alot on the 347 stroked. I think it will make a great project. My headers came in recently and my first reall addon that i did myself. I probally should have waited and gotten a gasket set but i still cant decide wether to sroke my current motor or buy another. Thanx guys!

What oyu're looking for is one your pocket can afford. And don't be afraid to buy one that's got a cast crank. Forged cranks are not necessary for 90% of applications. Forged rods are, but then again nearly all rods were/are forged. Forged pistons ? Well in a 347, I'd tend to want those forged, but they're not needed for stock length cranks. I built my 331 6 years ago using a stroker kit, consisting of a cast steel Eagle crank, SRP forged rods and pistons and it's still going strong after more floggings to 7 grand than I can recall. It's also been in two diffferent vehicles. My son bought a 347 short block from CHP in California last year. So far it's done OK too.