[68lemans462]

If I had a "real" 455 laying around I would never consider building a stroker. OEM parts are far superior to the aftermarket stroker cranks...... Go big or go home!

[ta man]

Originally Posted by 1157 motor head

Ok, the winner is the 455! Thanks guys for your input.
i'll bet this next question might be all over the board. Heads, any and all opinions welcome. I am partial to aluminum heads. Your thoughts?

How much power do you want and what is your budget?

[napster]

Store the 389. Build up the 455. Two bolt mains good up to 600HP. Good advise from previous post.

[hurryinhoosier62]

Originally Posted by i82much

that’s a lot of effort for a street engine just to go to a 3” main block, no? is the juice worth the squeeze?

NOPE. Useable 400 blocks are far more common than 455s these days. ALL stroker cranks will fit in a 400 block with minimal grinding. What you will have is a 3” main 455 with far lower bearing speeds, which is an Achilles’ heel of the 3.25” main Pontiac engines.

[hurryinhoosier62]

Originally Posted by 1157 motor head

I have the original 389 out of my 65 GTO, It is a it has never been taken apart or bored over. I also have a 1971,455 complete engine that has never been bored over or any type of machine work done to it.
I want to build a strong street motor. Aluminum E heads, roller cam and rockers and so on.... The question is, do i buy a stroker kit for the 389 to make a 455? Or do i use the 455 to build the strong high horse power that i want? Is the 71 , 455 block a better / stronger casting than the 65 , 389 block?

Have you had the 455 block and crank magnafluxed? If so, they are the building block for a 500hp street engine that WILL double your tire budget. If you decide to build the 455 take it to a QUALITY machine shop that is familiar with Pontiac engines. Have the block hot tanked, square decked, main saddle and cam bore alignment checked. Align hone both if necessary. I’m an odd bird, so I won’t order pistons until I KNOW what the block deck heigh is going to be. Consider using AutoTec pistons, since they can either raise or lower the piston pin bore center line to achieve a “zero” piston deck height with minimal matching of the decks. Ditch the OE cast steel rods for forged units from SCAT or Molnar. Crower produces fantastic rods, but they are pricey. IMO, both SCAT and Molnar produce rods as strong as Crower but are far more reasonable in price. The crank needs to be check for straightness, ground to the next undersize with the stroke on the rod journals being equalized, then have the crank nitrided and micropolished. Make sure you use a COMPETENT crank grinder who will set the journal spec in the middle of the spec. Also, have the crank grinder perform a good radius “job” on all journals to eliminate the OE “barely there” radius. You will then have a cast nodular crank that can survive 600hp.

[Dragncar]

Originally Posted by 68lemans462

If I had a "real" 455 laying around I would never consider building a stroker. OEM parts are far superior to the aftermarket stroker cranks...... Go big or go home!

They are only better if the aftermarket cranks are cast.
Forged 4340 is superior to cast iron in every way. That said the Scat and Molnar are the only ones I would buy. Have had 3 Scat forgings and all were right within spec. Still have 2 and wish I never sold the other 4" unit.
One Eagle cast and stroke was off and .001 tapper on all journals. Had to be re ground NEW.
Molnar- Scat 4340 best. Molnar will send you a call tag to pick up your crank or rods if off spec any at all. Stand behind their stuff..
Then Eagle forged
Ohio forging.
RPM forging. Had one of those and sold it. Wish I still had it too.
You can push a Scat 4340 crank to 1000 HP. Try that with any OEM cast crank and you will have a lot of scrap metal in short order.

[PunchT37]

I believe a factory 455 crank will last up to the power limits of the 455 block.

[Dragncar]

Originally Posted by hurryinhoosier62

NOPE. Useable 400 blocks are far more common than 455s these days. ALL stroker cranks will fit in a 400 block with minimal grinding. What you will have is a 3” main 455 with far lower bearing speeds, which is an Achilles’ heel of the 3.25” main Pontiac engines.

The 3.25 mains might be the Achilles heel of the big PMD engines but for 95% of users it does not matter at all.
If you are big time drag strip or roundy round racing sure.
I have a 455 over 500 HP for years and years. One of the reasons it has lasted is I have refused to use any main bearings with only the single round oil hole in the middle.
The shot of oil comes from the tab side of the 3 holes that intersect and if you do not drill a hole in your main bearing that oil has to hit the back of the bearing, mover over and go through the stock hole location.
By that time the crank oil hole has gone by. Fine if a stock grandma,s station wagon but in a performance use you will starve your rod bearings at high RPM.
I even drill our the race bearings with a oil slot vs round hole on 3" main bearings.

[Dragncar]

Originally Posted by 1157 motor head

Ok, the winner is the 455! Thanks guys for your input.
i'll bet this next question might be all over the board. Heads, any and all opinions welcome. I am partial to aluminum heads. Your thoughts?

Run the new Edelbrock head with the CNC chamber. same as the High Port. But you will not have to deal with intake being raised 3/4" and air cleaner fitment issues it can cause. And you will not have to deal with crossover not lining up or buy the lowered KRE crossover.
CNC chamber only comes in 72 cc so you will need to buy dished pistons which adds a small cost but worth it. You can run 10.5 CR no big deal.
Even more but you will need the right camshaft, tune is critical.
You can run the 80 cc High Port like I have but for what you are doing no need for raised port.
You best bet might be a nice used set of 87 cc E heads. They are around. Old school chambers, so what. Will get it done.

[Tom Vaught]

Originally Posted by The Champ

My correctly date coded, '64 GTO 78XW coded, 389 is on an engine stand, complete carb to pan.

I found a standard bore 455 complete carb to pan for $500.00 and went that route for a 462.

My original 64 389 Tri-Power engine has been on a engine stand for many years and a basically stock 455 engine (Block and crank with good rods and TRW pistons) has been in the engine bay for most of that 20 year period.
The engine now has aluminum heads on it vs the factory heads. I am going away from the solid lifter stuff and will run a flat tappet Hydraulic cam with Rhoads lifters otherwise I would leave it alone. . The engine has HO Try-Y headers.

Remove the early engine and oil it up and store it away and go with the basic 455 engine. The car will be a enjoyment to drive and still perform a lot better vs the 389 engine.

Tom V.

[77 TRASHCAN]

Originally Posted by Tom Vaught

My original 64 389 Tri-Power engine has been on a engine stand for many years and a basically stock 455 engine (Block and crank with good rods and TRW pistons) has been in the engine bay for most of that 20 year period.
The engine now has aluminum heads on it vs the factory heads. I am going away from the solid lifter stuff and will run a flat tappet Hydraulic cam with Rhoads lifters otherwise I would leave it alone. . The engine has HO Try-Y headers.

Remove the early engine and oil it up and store it away and go with the basic 455 engine. The car will be a enjoyment to drive and still perform a lot better vs the 389 engine.

Tom V.

Tom,
I hope we get to hear about you driving the GTO, here one of these days!!!

[Tom Vaught]

The Virus threw off my timeline for firing the engine.
I want to test the engine on my engine run stand first and make sure all of the systems and gaskets are working fine. The welder, I contracted with, normally would have had it built at the beginning of the year. He is actually barely started on the "run stand"project due to the virus and other $$$ projects at his job. So it will be a this fall fire-up hopefully.

Tom V.