306 Schooling

  • Sponsors (?)


nothing you would notice.
I think that having your block bored and the new parts would bring back some of the engines efficiency, but 4 cui is a drop in the bucket.
 
1 million H.P.
Dr_Evil.jpg
 
A 306 is simply the result of getting your old engine bored a bit and freshened up. You are not going to notice any gain other than that of maybe gaining back some original ponies that were lost due to old age an wear. The engine will run strong and will be healthy, but with the exact same set up as before the rebuild, you will not notice much. A 50-100 increase on a 306 would require a top end kit and a few simple bolt ons.
 
It depends on how much compression you have lost - typically parallel with the mileage on the engine.

A broken-in engine will make more power than a brand new one.

A 306 is simply a .030 overbore cylinder wall with matching pistons. You maintain the same stroke, 3.0".

It just freshens up the cylinder walls to a 'new finish' and just makes the engine more reliable.

It isn't a 'power mod' at all.

Like me, people do it when they want longevity and are on a budget.

Good Luck!
 
I will say this, if you skip the 306 and spending that money but have the block honed out and use the same pistons thats worth a little. I have two bottem ends, a bone stock one and a .007 honed one. With file fit rings and new bearings in the honed one (other than that its stock) they made...

Stocker: 265/308 to the tires.

Honed: 272/316 to the tires.

The honed bottem end got better gas mileage also, and at the track saw a solid 1 mph better. It is loose which is why its slightly better, but it sounds like a diesel pickup, which might scare people.

BTW I ran my best track pass on the weaker bottem end, but the street tire pass (notice the mph increase) was on the honed one.
 
306

This is just my .02....i recently built a 306 and put it in my 89gt. i was considering a 331 but didnt have the cash. i took an ~86 block with 100k on it, crank, rods, and cam to the machine shop. the honed, bored, new cam bearings, decked, freeze plugs, turned the crank, shaved the rods, balanced, and new pistons. It was around $1400 and they put the bottom end together. i notice a difference in the performance over my 302, but i also added cold air, 70mm tb, egr spacer. i wasnt doing it for the performance, just to freshen up the block. one of the machinist at the shop said it was good to do since everything isnt "perfect" from the factory. i'm glad i did it, but wish i couldve afforded a 331.

good luck!
 
so what 1/4 mile times are you guy running with the 306?

The same as my 160k 302 bottomend...:)

I ran 8.27 at 87.31mph with not tune, no burnout on drag radials, all accessories (p/s and a/c, etc), 3400lb race weight.

I gained 1.3mph by getting my 302 rebuilt to a 306, adding longtubes, and ported intake. So...
 
The same as my 160k 302 bottomend...:)

I ran 8.27 at 87.31mph with not tune, no burnout on drag radials, all accessories (p/s and a/c, etc), 3400lb race weight.

I gained 1.3mph by getting my 302 rebuilt to a 306, adding longtubes, and ported intake. So...

You ran an 8.27 with a stock 5.0 at only 87 mph? Please tell me you mean 18.27...