Inliners International Forums General Discussion Engines TOO Hot 250 to a T56 six speed

Hi guys, new member here. I spent quite a bit of time looking through the tech posts and archives but haven't found the answer to my question.

I'm building an Art Deco style roadster from scratch


I'm a metalshaper and will be making the complete body from aluminum. Scratch built chassis etc.

In keeping with the period, I wanted an inline engine. I've recently purchased a highly modified Chevy 250 (now 277).

I have two questions for you inline masters.

First: The motor was built by an engine builder in near DC who built a lot of 250s for the Nascar Dirt Track series. His engines dynoed at 325 with a 2bbl. This engine started as a 68 truck and had the bottom end done/balanced, etc. 307 flat top pistons. The head had more work than normal, V* valves, heavy springs, ported/polished etc. Clifford truck headers and aluminum 4bbl intake with Holly 500cfm. New electronic distributor.

Now for the bad news. 11:1 cfm and 600 lift cam. This car is supposed to look like a late 30's Bugatti, Delage, etc. It NEEDED an inline engine. The car will weight about 2000lbs finished. Weight distribution is 50/50. Corvette C4 suspension front and rear with a 3.07 posi rear. I'm concerned that the engine not be streetable and am looking for things that I can do to de-tune it.

It's been suggested that with a 600 lift cam that due to valve overlap, I won't really see full compression until RPMs get over 3000, probably not going to happen that often but I don't want to have to rev her to 2500 and feather the clutch to get going....

Someone else told me the TRW flat top pistons could be fly cut a good bit and rebalanced to lower the compression. Changing the cam is, of course, a snap...suggestions?

The motor is new. The man who had it built is now a retired GM mechanic. His son had a Nova with a 192 and he was a friend of the machine shop owner who offered to build him the six. They installed the engine and it sounded great, lumpy and you could hear every cylinder fire at idle. The kid said, "But it's not a V8..." The motor was prepared for storage and parked until recently when someone bought the car less motor. A friend picked up the motor and will bring it to me next month.

Ok, so for the motor, I'd appreciate your comments and thoughts. I built a stock 235 10 years ago but thats the limit of my 6 experience.

Next: I picked up a T56 6speed manual from a 96 Camero. The trans has a 1 1/8" 26 spline nose shaft.

I also got with the tranny a flywheel from a 5 speed. I understand the flywheel will bolt to the 250 crank. My question is this. The 6 speed has a 'pull' clutch that is relatively expensive and may/may not work with the 5 speed flywheel. I'm thinking it may be simpler to change the bellhousing and just go with a standard clutch

Does anyone know what I would need to do this?

Thanks
_________________
Kerry Pinkerton
http://wheelingmachines.com

Oh, one more thing, I'd LOVE to ultimately go with 3 side draft carbs. Suggestions for sources and options will be greatly appreciated.

Hello, from Alaska. Nice looking concept (gotta love a photochop ).

I am by no means a 250 or even an inline 6 guru. But in other engine types (both inline and V) I have found that for the driving you describe, forged pistons aren't what you want. If you could get a set of hypereutectics, with the appropriate compression height, and have your machinist fit them to the bore appropriately you will be happier with the performance overall. I would definitely change out a full race cam for something more streetable for the driving you describe.

I can't help you for what bellhousing to use for the T56. Be careful with the late model flywheel, it is probably for an external balance SBC (the later model ones were, had a bolt pattern change at the crank circa 1986 too).

For a clutch, I have a Hays 95-201 set in my Model A. It is a full metallic button type disc, with a 2750Lb pressure plate. It is amazingly easy to push the pedal down (you can push it to the floor with your hand). Dad drove it recently, he couldn't say enough about how light the pedal was, he has a bum left knee. It modulates well too, it's not the grabby nasty bear trap I had come to expect from other brands. I know that set doesn't match you trans (it fits a '92 Mustang W/ a T-5) but they have an equivalent for either the pull type, or the more traditional push type. I found they were cheaper than some other brands too.

For side drafts, I have been looking at putting together a set of SU's, however for the racier look you might try the carbs off a Harley 1200 (use 3 of them). You will be slightly larger per carb than they were set for originally, but people have recommended them to me as they are usually cheap, since the Harley drivers take them off to 'upgrade'.

I posted a similar question (on the carbs anyway) on this forum under:

Inliners International Bulletin Board » Engines » SU's?

It was on page 2 last I saw (couldn't get the actual address to show up, or I would have linked to it).

Thanks for your comments. I usually drive like the proverbial little old lady. I'll no doubt get on it a few times but basically I'm building a fair weather crusier. No top or side windows.

First of all, I LOVE your design and yes, only an inline engine would look good in it.

Secondly, you are correct in assuming that 11:1 CR is going to be too much on the street. I have first hand experience with this as I put a 300 Ford race motor in a '33 Willys coupe. It had Chevy 350 forged pistons with the domes milled at an angle to match the 300 chambers, probably about 11.5:1 CR. I blew two head gaskets trying to run pump gas. Took out the pistons and milled additional off the top and also installed a long duration, high overlap cam. It probably has about 10.5:1 static CR now. Still too high. I have to put a gallon of race gas (110 RON) in the tank with every fillup of 94 Sunoco premium. Goes like stink but given the choice I would rather prefer about 9.2:1 to be able to run pump gas. See if there is enough stock in your pistons to turn some stock off the top - a relatively simple machining procedure.

Thirdly, regarding side draft carbs, check out the sidedraft intake I built for my '30s era champ car project in the 'Ford' section of this BB. Perhaps something like that with 3 SUs would look good, no?

Good luck with your project and keep us updadte.

Oh my gosh! I love the engine!



That is exactly what I had planned to do, a faux dual overhead cam valve cover and also a front cover that looks like a big chain or gear drive up to the cams. I may try to hide the power steering and AC (if I do one) inside the front cover.

Well done. Any more photos?

There is one other possibility I forgot to mention. Water injection. There are several systems out there currently that could be made to work, it is usually recommended against as if you let it run out of water, it will detonate. Alot of the industry currently considers that technology 'dead' as they consider it unnecessary, and one more thing to go wrong. They are correct, as far as it goes. Just a thought. It will still be cammed too high for a pleasant drive, but then the car you are building should be light enough that a warmed over engine of the size you describe should make it haul. The one that's in it would make it a holy terror, if you could get used to driving it.

More photos? Yes. Did you see the crossflow head with side draft SU carbs and stainless exhaust? That is the one I was refering to. Click on "Champ Car replica circa 1930s" in the Ford section.

Read your whole series on the Fordsix site. That's going to be sweet! A friend from Indiana built a streetable sprint car a few years back. VERY authentic appearance. Flathead V8, single passenger, Quickchange rear, the works.

I really like the manifold. That's what I'm thinking about for the Chevy. My Buddy picked it up Sunday and is supposed to be sending me photos. I should get the motor late next month.

How are you going to build the body. I'm one of the founders of MetalMeet.com Lots of good info on shaping sheetmetal over there.

Water Injection now that would be something that was period correct and might work....hummmm

It might be period corerct, but I would check out the current offerings, I have heard (haven't tried it, yet) that alot of the cheaper new stuff uses crappy pumps (unreliable). All the newer stuff I have seen uses higher pressures than the earlier stuff. I have seen one of the Edelbrock setups from the '70s. It used a windshield washer pump. Not sure how reliable that would be for more constant use. The newer stuff uses the higher pressure to inject a finer mist of water.

I'm not saying it won't work (of course it does), just be carefull as it will likely be that you have to fab your own, as that engine isn't supported with that kind of stuff.

I know it works because I work as a maintenance inspector for an airline that is still running water injected radial aircraft engines. It makes a noticeable difference, either inside, or outside the aircraft.

The short easy answer for the engine is to set up your carbs to run E85. This stuff is good to 12.5:1 and is cheaper than premium. Now compression worries are a thing of the past. don't bother with the water injection. Go to www.raceonE85.com for details. But if you really really got to have water injection, I'd go with snow performance. Their water/methanol kits are professional and work. My brother has one on his blown 55 chevy.

They make adaptor kits to put the 6 speed behind a small block chevy, that's all you need to put it behind your 250.

Wilwood makes an inexpensive universal pull-type slave cylinder. I use it on my mustang with no problems. If you can build a car from scratch, you can probably build a simple bracket for it on your bellhousing.

Centerforce would be the light clutch you are looking for, and should handle that horsepower level.

And last, if you put a 300hp engine in a 2000lb car, your old lady driving days are over!

On second thought, you should just sell me that engine and get a stock one. Then you wouldn't have worry about all that unneeded extra horsepower

Kerry, I'm going to use wood bucks to shape sheet steel components. For the tail section I will start with two teardrop shaped rear fenders from a '46 Ford pickup and "clamshell" them together. The three inch chopped "Whippet" grille will be replaced with an unchopped one. I used to belong to Metalshapers but haven't had much time lately to surf the excellent metal shaping websites. I pretty much do most of that stuff in-house. Built an E-wheel, planishing hammer, presses, etc along the way.

You might want to rethink using the T56. It is a double over-drive trans with a forth gear of 1.0:1, fifth gear 0.74:1 and sixth gear of 0.5:1 and with the Dana 44 with 3.07:1 a final drive ratio of 1.5:1. Even with a #2000 car, that 250 is going to have trouble pulling that. The Camaro probably had 3.50 gears.
The T56 has electric speedo and electric reverse lock-out. Even if you had all the correct parts for the Dual-Mass flywheel, it only bolts to a crank with one-piece rear seal.
A T5 is a cheaper and easier choice, but still has a .70 over-drive.
A Richmond Six-spd would give you the extra gear, but again a .76 over-drive.
I think with any of those you would end up with a rear gear change.
Richmond also has a couple of 5-spd boxes and one, called a 4+1, has an under-drive fifth gear of 1.1:1
You shouldn't have to change rear gears.
Uses speedo cable.
Uses standard bellhousing and clutch.

Today, I discovered that rebuilding the T56 is going to cost more than I want to invest. The ONLY local guy who has the tools to tear down and rebuild the 6 speed wants 400 bucks to just to the R&R. Any required parts are extra....so much for the deal of the century...

It will go on Ebay as a parts tranny.

I found locally a T5 from a 88 Camero that is complete except for the throwout bearing. I got it for 400 bucks with a warranty that is good until I get the roadster running (or until the junkyard I bought it from goes out of business...).

Kerry have you gotten the pictures of your engine yet?.........jb

No, I'm going to call Gator and beat him up though..

bump

Thanks Tim. I understand now.