455 YC vs. 389 for Driveability and Fun
 

I've got the 455 currently. It needs some love and money to run right. Is this where I should put my efforts?

If I'm puttin' together a motor for a 66 GTO...not numbers matching. And I'm looking for a driver, weekend cruiser. Is one of these motors going to lend itself to being more easily built, maintained and driven?

The ol' Jan and Dean song keeps runnin' through my head....."3 dueces and 4 speed, and a 389".

Part of me feels I'm not being very true to the GTO legacy with the 455. On the other hand, I want a healthy runnin' car.

Could always put a 4" stroke 3" main stroker crank in the 389 and bore it .030" over and make it a 421.

Add the 4" stroker crank & bore it .060" over and it'll be a 428...

Then you get to tell folks it's been "bored & stroked".

Or put an even longer stroke crank in that 389.

389 + .030" over & 4.21" stroke = 442 cid
389 + .030" over & 4.25" stroke = 446 cid

Just add appx. 6 cid for a .060" over bore.

And there are even longer stroke 3" main cranks available.

The possibilities are endless these days.

:cool:

Bret P.

It's not numbers matching and a 455 is going to be more fun with the added cubes then a 389. When you pop the hood you won't see a difference anyway.

I'd say build a 455, pick a cam that works with your torque converter and rear end gear ratio and if you want to have the 3 deuces look then do that as well.. no one will be able to tell the difference between a 389 and a 455 by just looking at the engine anyway.

There's no Replacement for Displacement.................. and fun ;)

I vote for the 455 as well or the stroker. I regret not going bigger with my motor, but at the time, cash was tight and I just had to do the 389 rebuild with stock crank and rods.

I stroked my original 389 out to 447 Cu In and added a Tri-Power replacing the original Carter 4 bbl and added 67 HO exhaust manifolds retaining a near stock look. I love the fact that I have all the extra power and a 66 GTO with it's original "389".

Jim

Jan and Dean did not sing that song. It was sung by a bunch of session musicians in Nashville. They named themselves "Ronnie and the Daytonas" after they recorded the song. They released several more songs, but none matched "GTO" which went all the way to number 4 on the Billboard Chart. By the way, the name of the song was simply "GTO", not "Little GTO".

For the same amount of money, the 455 will make more power everywhere in the RPM range. A 455 at 9:1 will make as much power as a 389 at 10:1, and be more docile with correctly chosen parts.

Did the beach boys ever do a GTO song? Or did they only do "409"?

409 only.
I vote the 455. This way you can use 2.79 or 3.08 gears, still be fast and cruise all day without running hot down the freeway.

Beach Boys did a bunch of car songs that were used as album fillers, that were pretty silly and pretty bad. But in addition to "409" some of the better know ones are "Shut Down" and Fun,Fun,Fun ,and "Little Deuce Coupe". Shut Down was about a 63 Fuelie Corvette and a 413 Super Stock Dodge. Fu,Fun,Fun was about a T-Bird. I guess "I Get Around" could be considered a car song since they say "we always take my car cause its never been beat". Little Deuce Coupe was about a Deuce Coupe that "got rubber in all four gears". People get the Beach Boys and Jan and Dean confused alot because they are all from California and they sound alike and sing the same kind of songs. Brian Wilson wrote several hits for Jan and Dean.

this damn forum answers all life's questions..... the important ones anyway. ;O)

We try.I though I was pretty up on GTO's until I discovered this forum and found out even though I have a GTO, I didn't know anything. There are so many people with so much more knowledge here, it blows my mind. And these people are willing to share that knowledge. BUT, if you want to talk 60's music, I think I can hold my own. ..

Done a few of them. ;)

4.210 & 4.250
nice packages.

Jan & Dean did have a song called "My Mighty GTO". "There's no match cause non can catch my GTO"


Don

455 engined GTO must have a posi-rear & TH400. There, with that said;

Since you have a 4-speed, you will need to focus on Clutch-linkage: I'd go with a HYD throw-out bearing. Z-bars are the main reason I got away from stick-455-cars.

Since you have a 4-speed, you will need to focus on a stout stick transmission, the best Muncie not being strong enough is the 2nd reason I got away from stick-455-cars.

Your 455-4-speed GTO results may differ, yet those are the 2 rough spots AFTER activating WOT.

389 sounds like more fun huh.

455 we'll be more driveable. The torque is down low in rpm's. The 'Tigers' did 'GTO'-'going huntin for a Mustang or a dual quad 409'.

455 have my vote. "Nothing can out run a mean ol' Goat".

After talking back and forth with Dave from SD performance, i decided to build a 400 over a 455 for my 5 speed GTO. I was told by SD that I can make 500-525 hp and around 500 ft lbs, idle nice at 750 RPM, run power accessories and pull to 6,000 in a snap. The basic combo we talked over was a 10.5:1 400, their 290cfm heads and their stump puller hydro roller. That's plenty of power for a street car. It will probably be a little better on gas and I might just be able to keep my 5 speed together if I hook it!

You are working with the right guy..which heads the KRE's?.

Yes, the SD ported 290cfm KRE's.

Why stop at 4.25? Is a 4.5 stroke on a 4.120 bore really too much for a 389? 480 cid lower revving torque monster or is the bore/stroke/rod ratio really that bad?

Geez, that is going to be a SWEET "400"

Ah, just one more ting: What does SD say about 9.3:1 so you can press WOT on 87-to-89 Octane?

I could ask them about that. I'm not sure what a 10.5:1 poncho would need for fuel requirements with a modern chamber, cool temps, and that stump puller. Its on a 112 l/s so it should technically be a little more forgiving and the good modern chambers don't usually require as much timing if i'm not mistaken, like maybe 32 degrees is all so that may play a factor too? I wonder if i could get away with some 89 or 90? Thats a good question to ask them regardless.

Agreed. I guess another part of my thinking was that an honest 500 ft/lbs of tq is completely unmanageable on street tires at WOT, will allow for donuts in a parking lot at any moment, and pull like a train everywhere in the power band. Dave from SD told me my TQ curve would be very flat and broad with the combo too. I don't see a downside to going with the 400 for a stick car really?

With a 4 spd ...389-412 ci for these good reasons above.

Happy 66 w/ YC455
 

Installing a bigger engine than "normal" is exactly the legacy of the GTO. In 64-66 it was the 389 into the mid-sized GTO. That has morphed into built 70's 455s into any GTO.

My '66 originally came with tri-power and the two-speed auto trans, which was long gone by the time I got the car in 1983. At that time it had a tired old stock 400ci-350HP engine from a '68 GTO and a TH350. I put a YC code 1971 455 block under the 400 heads in about 1985 and ran that for many years until I got tired of the continual fight against detonation (i.e. search for high-octane gas). Two years ago I put in a set of 6X-8 heads with about 9.5:1 and have been very happy with the combo for street/cruise/driver duty. It has a vintage E-brock P4B, a new E-brock AVS 800 cfm carb, stock replacement HEI, and a Comp Mag 280 cam. I know this is not the typical build discussed on this forum, but I have had good luck with these parts and I was able to put the combo together cheap with some parts I already had. Still using the TH350 mentioned above, but now with a 2500 stall converter.

Never had this combo to the strip or on a dyno, but I can vouch for the traction-limited behavior, once I got the tune right. I am running the original 3:55 limited slip rear end, stock suspension, with BFG T/A Radials 245/60-14s on the rear. You can smoke the tires anywhere in first gear, half way through second, and bark em good going into third. In first gear, the tires cut loose at about halfway into the primaries, before you even get to the secondaries. This is obviously not optimal for the strip, but the car is a blast to drive and cruise, it idles and starts with no problems. At least I will not waste the tranny this way, until I can get a stronger one in there and start optimizing traction. Took me a while to get it to run cool down here in Texas, but that can be solved, too, lots on this forum about that.

As previously mentioned in this thread, you can run tri-power if you want, and the 455 looks the same from the outside as the 389, so it can look as stock as you want it to. What's not to love? I think you would have to spend quite a bit more money to get the same performance out of a 389, including aluminum heads, roller cam, etc.

Dave at SD performance will give you good advice and get you a great combo to meet your needs. Don't get confused with the many opinnions, go with "Super Dave".

One of the disadvantages of a 455 is the massive torque. You pull up to a light along side of a 69 Camaro with a stout 350 and an out trans. You rev it up letting him know you want some action, you got a 455 and street tires and you smoke the tires so bad your going no where and you watch the Chevy leave you in the dust. Been there done that. If you run a stout 455 on the street you better have some big soft tires or all that torque will get you is tire smoke. I vote for the 400 for a street machine as it will have a better chance of hooking the tires up on the street. personally I hate looking at Chevy tail lights. I prefer looking at the headlights in the rear view mirror.

back to the OP
 

I agree, if one wants to start from scratch, many of the builders on this forum are going to be able to please.

Notice that the thread diverged into a discussion about 4-sp 400s build by SD. The OP was about rebuilding an existing 455 in a 1966 versus going back to a 389. I was merely relaying my experience with the very same decision on a budget. :focus:

No question, 455. Put that tri-power on it and let r rip!

I'm running 85 cc chambers on a 462 with KRE heads and can run on 87 octane...Last friday I ran on a mix of 60%87 octane and 40% 91 octane .I'm at about 10.25 :1.

One of the best combo's I've seen belongs to a friend and fellow board member, Ducks Goat. He has one of the best running 455's in his 65 GTO that I've ever ran across. Street driven, pump gas, hyd flat tappet cam, KRE heads, RPM intake with and out of the box 830 Holley auto, trans and 3.55 gears. Runs solid quarter mile times of 11.66. Even though I've had a 455 once years ago and went back to a 400 in my GTO you can't deny the 455 set up properly will make the better street engine as long as you can get it to hook.

I'm a big believer in more cubes is better...but in this case I think this 400 build will be great.Anybody that has ever dealt with Dave at SD knows that this will be quite an engine....Nick is he building the complete engine?This should be a smooth nice running street engine when done....but it will still do what is described above:DWhat was Daves estimate on power?450hp/500ft/lbs

500-525hp and 500 ft lbs

oh and ill be building it myself. I already have some of the parts, the rest i intend to buy from him. Ill get the machine work done locally and me and an old buddy will do the assembly/startup.

BTW sorry for hijacking the heck out of this thread....


:focus:

TH400 = auto. Do not pass go. Nor collect $100. You're back at Post #15.

Oops I thought you were the original poster...:D

HIS, forgot to put the comma in between the Holley and auto trans. It was a long day.

455 > 389
 

You stated you already have a 455. If it were me, I'd build that engine and don't look back. You can build a relatively mild 455 that will work fine with pump gas with easy to find inexpensive 6x heads and still have a torque monster. That big stroke will put a smile on your face every time you drive it.

The other guys are right that you'll need sticky tires to get all that torque to hook up and then once it does your stock drivetrain is not gonna last... so be prepared for parts to grenade if you bolt on slicks. might as well start saving for the good stuff now