Engine Build

[Buickforlife]

Hey guys I need your help. I just pulled the engine out of my Grand National because it was knockin. Turns out that I had a spun main bearing and two spun rod bearings.

I want to put it back together as cheaply as possible but still gain quite a bit of performance. Somewhere around the 630 RWHP range.

Was thinking about turning the crank and getting forged pistons. Will the crank and rods stand up to that amount of power for a long time? This will be a street car that I plan on driving alot. Also what cam would you recommend? I know that I will need to do some porting and polishing on the intake and heads but are there any other modifications that you would recommend?

I would really appreciate any help part numbers and pricing would also be a great help!

 

[hiboom]

hp

sorry horse power and cheep will not get it done.I've had five and still have 3 109's.I would buy a forged rotating assy. pistons crank and rods like the vendors on here sell at least center two caps for starters then come the machine work That's about 5 grand . Mite get by 3 years if the planets and stars align and a good tune.before you freshing it up or have the need for more power.LOL As Grumpy says cheap fast dependeble pick two, words to live by.

 

[charlief1]

If it spun the main bearing then it will at least need a line bore on the mains. While you're at it have the block decked square to the mains. You're in for more than a cheap rebuild, believe me.

 

[clusolynn]

Rebuild...

There was a board member in central Florida trying to sell a rebuilt short block for $1500 within the last few months. Try searching the for sale section, if I run across it, I send you the link. Good luck, John

 

[Grumpy]

If you want good and fast..... it's not going to be cheap....

If you want good and cheap...... it's not going to be fast

If you want it fast and cheap ...... it's definitely not going to be good!

 

[Buickforlife]

Ok well since it seems I can't get away with going with the stock crank and rods should I do a stroker, or just get a standard forged crank?

 

[jasjamz]

If you have to buy the crank, rods, and pistons, you may want to build a stroker. Add in the Girdle or three steel caps. If you go stroker you will need it clearanced inside the block and other little things done. I dont have a stroker but don't feel I "need" one either. I have seen both strokers and stock stroke engines make a lot of power.

 

[charlief1]

Ok well since it seems I can't get away with going with the stock crank and rods should I do a stroker, or just get a standard forged crank?

No one said you couldn't go back with the stock crank. You need to tear it down to see what happened and what damage has been done first. A good stroker will set you back close to 10K, even if you do a lot of the work yourself.:smile:

 

[Jerryl]

No one said you couldn't go back with the stock crank. You need to tear it down to see what happened and what damage has been done first. A good stroker will set you back close to 10K, even if you do a lot of the work yourself.:smile:

Had a “stroker” discussion with someone last night. .
Here is the thread; http://www.turbobuick.com/forums/general-turbo-buick-tech/331444-stroker-kit-worth.html

OP, Here is a cheap stroker set-up.
GM 3.8L Girdled Turbo Buick V6 Stroker Short Block

 

[Buickforlife]

I tore it down. It spun the rod bearings on #4 and #5 and the main bearing in between them.

Thanks for all of the information guys. I don't think that I will be going with a stroker. Probably going to take the block and crank to the machine shop tomorrow to get it checked out. I will post some pictures of the carnage in a minute.

 

[Buickforlife]

 

[charlief1]

I've got a 4.1 crank here that was worse Ty. It's .120 undersized so it keeps my door open when I need it.:biggrin:

Get it to a machine shop and see how bad it is. I'd go ahead and change to main studs instead of bolts so you have better clamping force on the mains. Have it line bored and decked so everything is square then go from there.:smile:

 

[Buickforlife]

I've got a 4.1 crank here that was worse Ty. It's .120 undersized so it keeps my door open when I need it.:biggrin:

Get it to a machine shop and see how bad it is. I'd go ahead and change to main studs instead of bolts so you have better clamping force on the mains. Have it line bored and decked so everything is square then go from there.:smile:

That is the plan! How far can you turn these cranks and have it still usable? It looks like .010 would clean it up, but I will know more tomorrow.

 

[Buickforlife]

I found some three dot rods for sale. Anybody have some information on these?

 

[charlief1]

That is the plan! How far can you turn these cranks and have it still usable? It looks like .010 would clean it up, but I will know more tomorrow.

It may have to go .020 and it should be good unless you want to go into the 9's.:biggrin:

I found some three dot rods for sale. Anybody have some information on these?

Stick with the 2 dot rods. The 3 dot haven't been proven from what I've read so far.:frown:

 

[Buickforlife]

It may have to go .020 and it should be good unless you want to go into the 9's.:biggrin:



Stick with the 2 dot rods. The 3 dot haven't been proven from what I've read so far.:frown:

Thanks for all the help. I am sure I will have more questions later lol.

 

[bison]

That is the plan! How far can you turn these cranks and have it still usable? It looks like .010 would clean it up, but I will know more tomorrow.

.010 isn't cleaning that up. If you want 630whp you need to spend $5k or more to have a reliable bottom end.

 

[black owned]

.010 isn't cleaning that up. If you want 630whp you need to spend $5k or more to have a reliable bottom end.

what would be a good,proven bottom end combo?

 

[Grumpy]

what would be a good,proven bottom end combo?

thats a trick question. some can do more with less. engine is one thing BUT a bad tune will kill anything. PLUS look everything else over in the car !! Output is only as good as the input

 

[bison]

what would be a good,proven bottom end combo?

Steel crank/rods specific pistons. Steel center caps minimum and a tune by someone competent. stock parts hold up great but I've seen evidence of extreme crank flex over 700hp.