Best Big Block and Transmission Combination

**Slidewinder** · March 21st, 2006, 05:39 PM

This is my first posting as a new member and future owner so let me start by saying hello to all of you lucky Unique Cobra owners!!! My name is Al Slide and I live in Dacula, GA and I'm planning to be Unique Cobra owner within the next 12 months (hopefully that coincides with my wife's plans).

Now that I've decided on an Unique Cobra with a big block Southern Automotive engine, I'm stuggling with trying to decide on the best engine and transmission combination. I'm stuck between a "Super FE" and a 427 (maybe even a sideoiler) with either a toploader or Tremac and either 3:31 or 3:54 gears. I don't plan on much freeway driving but, I would like to end up with a combination that will be very streetable, reliable and be the best combination to help the car retain its value.

Any input you can provide to help with the decision making process is appreciated.

Thanks.

Al

**scott** · March 21st, 2006, 06:40 PM

pay attention to gear ratios and engine reqiurements. my motor likes to run at over 3000 rpm due to the cam, i cant use 5th gear in my tremec unless i'm going close to 100mph

**RJacobsen** · March 21st, 2006, 08:10 PM

Scott- What rear end ratio are you running?

**pgermond** · March 21st, 2006, 08:55 PM

Al,

Welcome!!!

3:31's and a toploader was my choice. I have an SA 406, and at 70 mph it's spinning around 3,000 rpm. I do some freeway, but not a lot, and the combination works perfect for me.

Good luck and good choice

**eliminator** · March 22nd, 2006, 05:50 AM

This question is about money...engine wise.
If I had the money a 427 would be my choice and a side-oiler. The resale value is better and you can truthfully say, "yes, it's a real 427 engine" no excuses.
For the money, value wise the 390 bored, not actaully a 406 would be a good investment. What ever the choice have a good heart to heart conversation with Bill about what you want and what you dont want. The same with any engine builder. The clutch and flywheel are very important. The 427 never had a 11" clutch so why put one in it now!!! Mcleods 12"
(original was 11 1/2") pressure plate and disc is a good choice. Get a 27-28# billet steel flywheel or a good billet aluminum one, again money, money.

Now for the transmission, a 4 speed toploader with a close ratio transmission is the only way to go. For the 427 engine , big input shaft , big output shaft.
With the other FE choice you could use the smaller input and output on a toploader. Sorry 5 spped guys, I hate the Tremac in a big block car. Resale is not as good also.

Rear gear, 427, a 3:31 will work well with the torque it puts out. I have about 505 ft lbs of torque and I like it. Now my only regret is driving my car around with a 3:54 gear and seeing if I like it better, don't know. With the super 403 cu in, or other FE engine I would go with the 3:54 gear because it dosn't put out the torque of the big 427.

So I have the 427 side oiler/toploader combo witha 3:31 gear with an Auburn unit and love it. That my opinion.

One other thing, Do it the way you want it the first time, no compromise, or you will regret it.

**Eric Miller** · March 22nd, 2006, 06:09 AM

AL,
Before you do anything give Dan a call @ Dutton Performance in Alabama you will impressed with the price and quality of there work.I have used both S.A. & Dan .There is no comparison!! I would go with a 427 with a Large shaft Toploader if I did it over.It is alot like what Eliminator said.

Hope this helps give me a call if you like,
Eric
615-427-2800

Dutton Performance
256-820-0706
www.duttonperformance.com
stephendutton@duttonperformance.com

**excelguru** · March 22nd, 2006, 07:01 AM

I chose a 427 s/o stroked to 462 with dual quads, a close-ratio toploader, and the 3:31 rear gear. It's a surprisingly streetable combination. My personal opinion is that the larger shaft on the toploader isn't really necessary on a car of this weight. You'll lose traction or blow a U-joint before you hurt that shaft. Especially if you're running the BF Granite, I mean Goodrich tires. If it were a Galaxie 500 on the other hand, well...

I would opt for the MSD billet distributor, which I didn't do. Wish I had. I replacing the McCleod (sp?) clutch with what I feel is a better unit manufactured by RAM. Been pretty happy with it.

The engine makes ludicrous torque and the acceleration borders on terrifying. In the 3+ years I've owned it, I may have planted my right foot completely to the floor about 6 or 7 times. Every time I do, I'm reminded of why I don't do that. At highway speeds, you will never have to downshift. Just squeeze the load pedal and hang on. You should let off around 140 to avoid excessive jail time.

That's what I've been told by others, anyway. I never exceed 70, myself.

**eliminator** · March 22nd, 2006, 07:06 AM

Yes, the call to Dutton would be a good investment. Always good to look at all the options.

**Slidewinder** · March 22nd, 2006, 04:11 PM

Thanks for all the advice guys. This is exactly the type of input I was looking for and I understand the part about getting it right (the way you want it) the first time. It's a big investment to end up only being 95% satisfied.....the way I am, the other 5% will bug me the rest of the time I own the car!

The adivce on other specific drive train components was also very valuable information. Just when I think I have most things figured out, I find out there's a whole lot more I need to consider but, now's the time to figure it out and not after I get the car!

Keep the advice coming........I'm a "dry sponge" at moment!!

Again thanks for taking the time to respond.

Al

**davebetts** · March 24th, 2006, 03:02 PM

My choice was a Southern Automotive 427 Side Oiler (stroked to 484 cubes) Two 4 barrels. Tremec 5 speed. Jaguar with 3.31 gears. Tons of torque. Tremendous sound. Completely streetable. Can be very, very scarey! Like the extra low 1st gear (when cold) and rarley use the 5th, but when I'm on the Interstate it sure quiets everything down.
I'd do the same if I could build another.
Good Luck and try to get a ride. I was going to do a small block until I experieced the thunder!

**Aggressor** · March 24th, 2006, 04:36 PM

Close ratio toploader, 3:31 rear, and as much "streetable" FE as your wallet will allow.

- Geary

**JeepSnake** · March 24th, 2006, 06:05 PM

Lots of good feedback - I've enjoyed just sitting on the sidelines reading the discussion. (I'm sort of out of this one, seeing as I'm in the smallblock camp!)

I will comment and say that I've been pleased with the 5 speeds in both our cars, again - both with smallblocks. I like the lower first, especially since I've got to creep down a 1/2 mile long gravel driveway to the road! But, I also like the ability - even though it's rarely used - to slip it into overdrive and run at a relaxed rev level on the interstate.

Now, having said that, I'm going to pose a question to the big block guys just for my knowledge, and for the sake of discussion. In most all of the auto/hot rod magazines, the "restomod" trend now is to build big-blocks with monster torque, then utilize an overdrive trans (either manual or auto) that will make use of that low end torque. What is the difference here? Is it just a matter of them building highway cruisers, while this group leans more toward track & road-course type driving? What are the thoughts on this?

**Aggressor** · March 24th, 2006, 06:45 PM

Zach;
Something for your consideration.
Wide Ratio (2.78 bottom gear) toploader with a 2.88 ring gear gives an effective bottom ratio of just over 8:00 to 1.
Close ratio (2.32) toploader with a 3.31 ring gear yields 7.68 to one. While cruising in your 2500 pound Unique an Fe will loaf along unburdened with either 3.31 or 2.88 top ratio.
The wide ratio combination provides more offline grunt with the added benefit of 13% less rpm while cruising.
In resonse to you question, It seems the trend is following similar logic. Monster big cube torque pushing tall overdrive gears while still having the ability to downshift 5 or 6 times to utilize a stump pulling combination on the bottom gear.
Trying to have it all maybe? New tech vs. vintage tech?
Or perhaps just a new high dollar trendy thing.
-Geary

**Tony Radford** · March 25th, 2006, 07:47 AM

Al, I never would have thought there would be so many Cobras in Dacula. I've got a Unique car and a Parham motor. I know of two SPFs in town, but I think I'm the only Unique. I've been driving my car for four years and I've never looked back.

**pgermond** · March 25th, 2006, 04:36 PM

Is it just a matter of them building highway cruisers, while this group leans more toward track & road-course type driving? What are the thoughts on this?

I guess it is simply a matter of personal choice and location. Earlier I said I don't do a lot of freeway/Interstate cruising/driving - mainly due to the fact of where I am located. I'll hop on the freeway for twenty minutes to get to the foothills, and then I'm off on those beautiful two lane roads. In addition, the freeways here are, for the most part, gridlocked from sun-up to sundown and there seems to be an ever increasing number of these idiots that drive like the road is a video game on a computer screen.

Another reason is the fact that I get a bit cramped after just sitting and steering for more than an hour (I'm 6'3" and shrinking) - throw in a bad back and, ......... need I say more?

Not to get to far off topic, here is what I'm talking about as far as some of the two lane roads that I have access to -http://www.pashnit.com/motoroads.htm

3:31's and a wide ratio top loader suit me just fine

(always wanted to use this little guy!)

my $0.02

**will butterworth** · March 27th, 2006, 07:23 AM

Awesome--we have done talked at our house---how can we get our cars to california?No interstates for me. Except mayby one, I-40 across the appalachians in tn. and nc.Will-alabama

**pgermond** · March 27th, 2006, 08:22 AM

Hi Will. Trailers....?

**Slither** · April 5th, 2006, 11:45 PM

Al,

I third the suggestion to check out Dutton Performance. You won't be sorry... Dan is very knowledgeable and can only help with information gathering. I was there on the day that they dyno'd Eric Miller's engine... very impressive

! In fact, the performance data for his engine is in a posting somewhere on this site. Do a search to find it.

Also, Dan had a nice 428 that had been dyno'd, and was ready to go into a Cobra. Though it is probably gone, you might get a good buy if it is still available. It was a nice looking engine

. He had it set up for lots of optional stuff like a choice of valve covers, a turkey pan, a clutch, and a scatter shield. I saw it when I went to drop off the parts to my engine, and I posted photos of it. You should be able to find them, as well.

Good luck!

**Buzz** · April 6th, 2006, 09:33 AM

Originally posted:
"With the other FE choice you could use the smaller input and output on a toploader. Sorry 5 spped guys, I hate the Tremac in a big block car. Resale is not as good also.

Rear gear, 427, a 3:31 will work well with the torque it puts out. I have about 505 ft lbs of torque and I like it. Now my only regret is driving my car around with a 3:54 gear and seeing if I like it better, don't know. With the super 403 cu in, or other FE engine I would go with the 3:54 gear because it dosn't put out the torque of the big 427."

Don't underestimate the SA "Super FE" - true it begins life as a 390 but it ends up as a stout 450+ cu. in. with over 500hp and 530 ft/lbs. of torque.

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