Adding 100+ HP to this combo

[groberts101]

LOL.. 4.56 gears for a non-OD daily driver?.. nothin' quite like the shiny smell of a polished turd! Whoa!!.. are those stock heads? Dayyuummm!!

[F-BIRD'88]

This low cost streetcar will eat yours from a stoplight if done right. 4.56 gears are a big part of that. It will be very fun to drive too.

The current engine power VS weight is a bit low. at 98 MPH.. You (OP) need to get it up to about 104 105 MPH. (increase overall engine power and reduce car weight too.)

[user-17438]

LOL.. 4.56 gears for a non-OD daily driver?.. nothin' quite like the shiny smell of a polished turd! Whoa!!.. are those stock heads? Dayyuummm!!

My Hauler had 4.56 gears TH400 and a .020" over 454. made for power everywhere.

[statsystems]

4.56 is about the best all around street gear. Been using them on street cars since 1980.

[BBO Omega]

That must be for an engine with no low end torque. I have run 4.56, 4.11, and 3.73 gears in my Omega. The 3.73 work the best for me [11.32NA and 10.40 with 150hp N20 hit] with a 2900rpm converter.

[statsystems]

That must be for an engine with no low end torque. I have run 4.56, 4.11, and 3.73 gears in my Omega. The 3.73 work the best for me [11.32NA and 10.40 with 150hp N20 hit] with a 2900rpm converter.

How big is the engine?

[BBO Omega]

468ci Oldsmobile. Car weighs 4005lbs with me in it and a full tank of fuel.

[statsystems]

I'm 100 inches less. And probably .750 less stroke.

[F-BIRD'88]

If you want to see the effect of say a shorter duration/earlier intake valve closing
using the current cam you can try this for test purpose to see the effect.
Reset the valves to have a bit of running lash like a solid lifter cam has instead of a preload adjustment. Set the lash say at .010" just like a mechanical cam. Then try .015"....
Lock out the distributor mechanical advance curve first, then try this.
This will effectively shorten the running valve duration , as if the cam had a shorter duration.
If 60ft to 100ft acceleration improves thru testing (with traction) you are on the right track.
Do not assume that the cam is installed as stated. It may be out of wack.
If the current hyd cam responds to this duration/lash adjustment test it may need further advancing too. You can find the sweet spot. if the valves get just too noisey you got carried away with the lash play. If you want to keep it like this install solid lifters on it.

The comp lil solid dirt cam I suggested has shorter duration yet all the lift and is a lot more snotty in these motors. (torqey) Its not bad at all on 350's with ported 305 heads.


Do not assume the timing tab/balancer mark is accurate . I bet it is 4deg off.
If you are looking to make this car do what is expected this stuff ( cam installed position. timing mark trueTDC, has to be verified.
On these cars the factory fuel line and tank pick up tube can be very restrictive.
You want 3/8" line and no kinks. A Carter P4570 electric fuel pump is a big help on these cars.

Check the in tank pick up tube and sock. Flair the end of the tube.
if HEI distributor, be sure the engine is GROUNDED to the firewall.

4.56's and traction bars. Ditch that intake manifold. Its not that it is bad. Its just that everything else is BETTER.

[groberts101]

You guys sound like 80's prostreeters who never discovered an overdrive transmission. I had 4.30's behind a fairly well built 460 in an old fairmont and on the highway at 75 it always felt like it wanted another gear to settle down into. Horrible gas mileage and hard to hear over the 4,000 rpm exhaust note too but to each their own.

For this guy.. a 700r4 and 3.73 will match a th350/4.56 in 1st gear torque multiplication factor and fall a little short in 2nd. 700r4 and 4.11 will squash that old school combo in 1st and nearly match it in 2nd. If you're relying on 3rd then the race is probably already lost anyways.

Plus.. just how peaky will those junk heads be and how fast will they fall over the cliff compared to a much fatter power curve gained from far better cylinder heads?

Lifes too damned short to even fool with trying to make the junk this guy threw together work like todays more modernized parts combos. And he can use less gear to do it and will live longer too.

[DrillDawg]

lcl 98, lsa 104, ecl 108, overlap 50 degrees, done in my head so i hope it's right, along with a better head would give him 100+ hp.

[travis]

I’m sure 4.56’s would be a lot of fun at 80mph keeping up with traffic

Doesn’t matter anyway...this thing is junk. Turns out his “425hp street/strip” eBay special is nothing more than a cheaply built stock replacement cast dished pistoned 2 bolt 357 with pistons .048” in the hole, 58cc chambers, barely over 9-1 compression, and a big cam. Judging by the bearings and main caps, it clearly wasn’t happy being zinged up to 7k rpms with the stock crank and rods.

The guy just left here with his stuff...not a very happy camper I might add.

[groberts101]

I’m sure 4.56’s would be a lot of fun at 80mph keeping up with traffic

Doesn’t matter anyway...this thing is junk. Turns out his “425hp street/strip” eBay special is nothing more than a cheaply built stock replacement cast dished pistoned 2 bolt 357 with pistons .048” in the hole, 58cc chambers, barely over 9-1 compression, and a big cam. Judging by the bearings and main caps, it clearly wasn’t happy being zinged up to 7k rpms with the stock crank and rods.

The guy just left here with his stuff...not a very happy camper I might add.

Whew!.. that was a close one! Lol

[RevTheory]

Whew!.. that was a close one! Lol

No shit! What a time bomb.

[F-BIRD'88]

Here the speed limit for 4 lane highways is 100 KPH/ (62 Mph)
If you drive 80 MPH here you will get a huge fine and could even get your car crushed.
The work around for the 4.56 gears is to run a tall P275-70-15 rear tire for when HIghway driving. This allows reasonable cruising at legal hiway speeds

Then run a short M/T P235-60-15 26x8.5x15 ET street tire for drag racing.
The combo works. One friend here had 4.88's in his 80Camaro.
Took them out for 3.42's and the car SLOWED down just like I warned him it would.
(and took all the fun out of the car. (just like I also told him it would)
He put the 88's back in. This one had mild ported camel backs. It ran very strong 12's
was full weight too. Was very reasonable on gas when driving at steady hiway speeds.
If you jaz the gas a lot pass cars etc etc you are going to use a LOT of fuel.
He was surprised on how got it actually was on fuel when driven steady at reasonable speeds.

i did it on a 350 in my 3rd gen firebird with 4.10's and full ported 4416 305 heads 1.94x1.60 valves. But that car is lighter than 3800 weight.

The only thing you are right about is investing in the 601 heads is probabily not worth it
and 2.02 1.60 195cc port aluminum heads will make a lot more power.
i was able to do those heads for very low cost.