302 Block Questions

I'm looking into a 302 swap for my Ranger, and have a couple of questions about the 302 block.

1. Is a one-piece rear main seal better than a 2-piece?
2. Any advantage to a new block (old casting) vs. an old block (old casting)?

Thanks.

 

[rookieshooter]

The 2nd question I'm not sure if you mean the same casting new old. If your referring that they're both old castings but one is used and one has never been fired up.
Then you can't go wrong with a block that's been run just as long as it's up to specs. This is called a seasoned block.
The reason is metal is not a true solid and does move.
The block that's been heated by running and stretched due to torque of bolts and drive train will hold the tolerences better after the normal machine work. Now moving around, I'm talking only thousands but that's enough.
I know the Guru of small block Chevy's Bill Grumpy Jenkins would never run a knew block.

 

[swetrid]

Once piece rear main seal is less likely to leak oil.

 

[Turdle]

Scott
When I purchased the FMS "Sportsman" block , brand new and did a side by side comparison of the stock 98 explorer block I found not one single difference, Every casting number was the same, also all measurements matched.

A seasoned (oil baked in) block will generally be a bit better, and resist any structural movement after machining since it has already been through several heat-cool cycles and moved around s much as it probably is going to.

A later explorer engine is already retrofitted for a roller camshaft. The rollers on the lifters greatly increase camshaft lobe life, and, allow for faster valve opening.


For these reasons, IMO if building and engine with a goal of under 450 HP I would just get a used explorer engine and tear it down.

 

[Scott B.]

I have heard about engine "seasoning" - but now fully understand it. I found someone selling several new-old-stock engine blocks, hence the question.

I was thinking about buying a used Mustang engine, but realized I would end up with a pile of unused parts. I am going with aluminum heads, possibly a different intake, new crank, rods, pistons, cam, oil pan (to clear the front
axle.)

I thought I could save some money by buying the block only, and as a bonus, I would not have toss a pile of parts.

Jon - I want a pre-DIS setup (don't think I want to convert the truck to OBDII)

 

[rookieshooter]

Scott, one other thing that you probably already know. Make sure, and especially on a used engine that you take a cleaning tap and go down every head bolt hole and clean those threads. This is extremely important and often over looked. Coupled with the fact that your going to use aluminum heads and the torque readings are relatively light. You do not want the torque readings to be absorbed into dirty threads.
Then after torquing on those heads to final specs, wait 24 hours and do them again.
Then you can physically see what were talking about when we say the metal moves.
The bolts have stretched, the aluminum heads have compressed along with gaskets.
I still check the bolts again after a day of running the engine, but usually find that if I let them set 24 hours before firing that I that they still have the good numbers.
You will also find that the Intake bolts are far looser then when you first torqued them.

On some blocks some of the head bolts penetrate through the water jacket and must have some thread sealer (not Locker) applied to them.

And while I'm rambling on. It is well worth your while to check the wear pattern on top of the valve stems, especially if your using some after market goodies in the valve train dept.
You want the pattern to be centered on the end of the stem. This is the reason they make so many different push rod lengths other then stock. They even make push rod length checking tools.

Here's a little quiz about how metal moves on one of my racing engines back in the 70s.
This particular Mountain motor 427 had tremendous valve spring pressure. I think around 500 #s. This was a non-roller cam. I was running some really high number gears in the rear, around 5.38 and was trying to get the valves from floating, which it did.
But I noticed after checking spark plugs that the further I got to the rear plugs, the richer they burned. It was a very small change but still noticeable. Any guesses to why?

 

[Scott B.]

I know to tap/clean the holes, but didn't realize that about the aluminum heads. Thanks for the tip.

As for your quiz, my only guess is that the front of the engine runs cooler than the rear (due to the path of the coolant) - could that have caused the rich condition?

 

[Turdle]

Can I play?

 

[rookieshooter]

I know to tap/clean the holes, but didn't realize that about the aluminum heads. Thanks for the tip.

As for your quiz, my only guess is that the front of the engine runs cooler than the rear (due to the path of the coolant) - could that have caused the rich condition?

Not on this engine. But that's a good guess.

 

[rookieshooter]

Can I play?

Sure.

 

[Turdle]

OK
Your panties got all twisted up because your camshaft did also.

 

[rookieshooter]

Can I play?

Sure you can play. Remember it's about metal actually moving.

 

[rookieshooter]

Yep, the further from the timing sproket the more out of time the cam shaft became due to twist from all that spring pressure.

 

[Scott B.]

So while we are on the subject of camshafts, should I stroke this to a 331 or a 347, and which cam should I run?