The Stovebolt Site Forums The Shop Area The HiPo Shop Need advice on engine and trans swap for TF

Hi all,

Finally have a question that I couldn't get an answer to from the forum archives. I have a 1956 Chevy 3100, all stock. It is time to give the old 235 and SM420 a rest and drop in a V8 and newer 4 speed. I want reliability, good power, a little rumpy idle, and a smooth shifting trans with ratios spaced better than the SM420. I would like to keep the existing clutch pedal if possible. It would be very cool to adapt the floor starter to work with a V8. Haven't seen that done yet but adapting the linkage to close a relay seems do-able.

What transmissions do you recommend that allow use of the existing clutch pedal and have the shifter close to stock position? What adapter would be needed for the speedometer? Don't need an overdrive as I already swapped to a 3.38 differential and have tall tires. The pickup gets used almost exclusively for cruising with an occasional trip to the Home Depot. No towing or heavy loads, no racing.

Thanks!

I am in the middle of putting a V-8 & 5 speed in my 56. I think the S-10 5 speed is the way to go even if you don't need o-drive.

what George says - plus to keep your floor start you just need to rig a push button on the floor under the floor pedal - and you won't find an "adapter" for the speedo, you'll need to figure out the different drive gear you need in the trans and find that if you can

Bill

Do you know whether the shift lever from a T5 will interfere with a stock seat? Will the factory clutch linkage work?

Looks like 60 mph with a 0.72 OD is about 1700 rpm. Pretty low but still useable on flat roads.

Would a T10 fit the bill? There are several on the local Craigslist, including one with a fresh sbc.

any small block will work with the stock clutch pedal setup, the 55-59's came with 265's/283's using the same clutch arrangement .... and yes, a T10 could be used

Bill

The T10 can take a little abuse and if it's a Super T10 then quite alot. The T5 is fine for a low horse power/low torque engine but are very puny transmissions that aren't suitable for a big engine big tire combo. They came with the shifter in different positions and several OD ratios. The world class T5 used in the Mustangs is better but still about equall to a regular T10.

Hi all,

So, I got some major sticker shock today. Stopped by Jim Green's Performance on my way home to get an estimate for a mild small block and a manual trans. He is a very reputable speed shop guy and does great work. However, the 9 to 12K estimate almost knocked me over! This is not a stroker motor, just a .030 over 325 HP 350 and a new T5 plus R&R of my old motor and SM420. What do you guys think? I see rebuilt 350's every day for 2K and T5's for around $500. This should be an easy, quick swap right? What am I missing?

Thanks again for your help and advice.

you're missing doing it yourself, and learning what it costs to approach owning an old vehicle as a "collector" who wants something "cool" buying it "off the shelf" .... you can find good runners and used transmissions every day, find a setup you feel is decent and install it yourself instead of paying a specialty shop $100 an hour for the work plus their parts markup - settle for what'll make a good driveable rig and skip the spendy cool stuff, a '56 will wow anyone no matter how it sounds

Bill

Good advice Bill. I can do the mechanical work but need to find the time. We are busy fixing up a foreclosure house we bought last spring so that takes up all of our evenings and weekends. Good news is that we have garage space now. Seems like a fine project for the rainy winter ahead.

One thing I am finding is the broad range of definitions for "fresh" or "crate" motors on Craigslist. To me, a crate motor is a new, virgin engine that has never been rebuilt. Doesn't seem to mean the same to other folks as they are advertising .060 over crate motors. Oh well...

Have a look at Summit Racing on line, for a guide on prices. GM Performance 350 / 290 HP long block - $ 2,100.00 / 5 speed manual trans $ 1,600 to $ 2,300. Free shipping ! Add the bits & pieces - should be able to go all new for less than 5k. I think that if you buy thru a GM dealer they even warranty for a year.

The term crate motor means that it was originally bought as a crate motor. People continue to use that term no matter how many vehicles it has been in or how many times it has been rebuilt, so as you say it can be misleading.

If you're looking for a crate motor, talk to your local GM dealer, you should be able to get a crate motor with all new parts and 300 HP for around the $2000 range. I wouldn't get a crate motor from anywhere else. You just have to take it back for them to set the timing and then you have a warranty on your brand new engine.

Hi again,

Spent a couple of weeks looking for donor cars to find a fresh sbc plus manual trans. After checking out a lot of cars that weren't quite as advertised, I decided to go for a rebuild from a local shop that has a great reputation and a warranty. Price is $2500 for a rebuilt 350 including Edelbrock intake and carb, HEI, starter, one-wire alternator, water pump, aluminum valve covers, oil pan. Pretty much a complete package with 320 HP, 370 Lb-ft torque.

I use the pickup for general cruising; not planning to go drag racing but it is possible we might tow a small vintage trailer once the kids are out of the house. Rear diff is 3.38 and is new. My requirements are that it be reliable, bulletproof, decent power and torque, a lopey idle for car shows. Gas mileage is secondary as it isn't driven much but would be nice to get 16-17 on the highway. Haven't decided on 4 speed or overdrive yet; that is next.

He gives options to customize the engine to my requirements. So, a lot of questions that I hope to get your input on.

How important is a 4 bolt main? I believe he quoted a 4 bolt main bearing block.

One piece rear seal or two piece? Not sure what his standard offering is.

Vortec, 2.02, 1.94 heads? His standard is 1.94.

Max overbore 0.030, 0.040, 0.060? My thought was 0.030 but don't yet know what he is offering.

He recommended an Edelbrock Air Gap intake. Is this a good choice for decent power and torque over the full rpm range?

He uses Comp and Crane cams. Any specific cam suggestions?

Headers or stock manifolds? Every set of headers I have had eventually leaked so I was leaning toward stock manifolds. He uses Hedman Elite headers that "don't leak" and are worth up to 20 Hp.

My stock radiator was recently gone through and keeps the 235 cool. Will it be adequate with a V8? Will I need a fan shroud?

Any other questions you would ask before signing on the dotted line?

I can help with a couple points - with a 3.38 rear, an overdrive would be useless .... if you're not going to be racing why worry about max hp? any stock 350 will pull a trailer fine and cruise nicely, and for that price you better be getting as good a warranty as for a crate motor from a dealer .... for exhaust, the stock rams horn style work well and fit perfect with no leak worries .... the rad will be fine but because the SB is shorter than the 235 you will definitely need a shroud [350 in 56 panel]

Bill

For that price I would get a crate motor, but to each their own. What would sway me is the 3-year warranty from GM on their crate motors, and I have seen awesome prices on their motors. I'm doubting that the guy building the engine would give you much warranty past the start up of the motor.

Thoughts on a few of your questions:

The Edelbrock air gap is a really good intake. It flows quite well, and helps to keep the engine cooler and limit heat into the carburetor.

The eDelbrock carb, however, I would scrap in favour of a 570 Holley Street Avenger. You'll be much happier with a street avenger.

Go with manifolds. Exhaust HP gain claims are always much higher than what you'll actually see on a dyno (and especially way more than what you'll feel when you jam on the gas), and headers only make a difference if you're racing (high rpm all the time). Stock manifolds flow plenty well for street applications.

I changed my 235 in my '62 Bel Air out for a 0.030" over 350, and the stock rad has no problem keeping the SBC cool. I'm not sure if the radiator is sized differently on your truck, but it should be fine.

Is the 320 HP he quotes on a dyno test? A lot of engine builders can say that the engine will be a certain horsepower, but that better be quoted with a given cam, lifters, rockers, intake, etc. , and you better have a dyno sheet to show that. Otherwise, you don't know what you're getting is actually 320HP or 290, and you won't know when you put it in your truck, as it will be a big improvement over the 235 so any hp level will seem like 320, if that makes sense.

Check out these crate engines. This shop has a pretty good reputation around here.

http://www.sehrpower.com/chevysr.htm

Jegs has a deal on the 250 HP 350 NEW crate motor (GM Performance Products) with the 3 year warranty for 1499 and FREE shipping to your door..

Plenty of power for your truck and trailer usage with an Edelbrock performer and a modest carb.
IF you want more power in the future stick a cam & headers on it...

my 2 cents

I agree with that.

Thanks all for your replies. Looks like a crate motor is the unanimous recommendation. Will take a closer look at Summit and Jegs tonight.

My radiator plus a fan shroud should take care of cooling.

Will be looking for a T-10 or Muncie transmission next. I am thinking that a wide ratio would be better for my usage - easier towing with a lower 1st gear. Any other thoughts?

Hi again,

Been reading up on crate motors and am leaning towards the L31 truck motor. All new parts from GM, has the good Vortec heads and roller cam and 9.4:1 compression for about 500 more than the 260 HP long block. It comes with a 3 year warranty instead of the 6 month warranty offered by the rebuilder guy I mentioned earlier. It is rated at 255 HP, 330 Lb-ft tq net, whereas the 260 and 290 HP crate motors were gross ratings. Any of these engines will be a huge change from the 123 HP from my 235!

Called the engine builder back to see if he would be willing to start with a new L31 short or long block instead of finding an old block and boring it out. His answer was interesting - made some disparaging remarks about Mexican blocks and not knowing what you get with a crate motor. Reading between the lines, he probably decided it isn't worth his time just to bolt on heads, intake and a carb.

I have installed 6 new crate engines in various vehicles. I used Jegs and everyone has been satisfied. One was a 290HP and the others were 260HP. To be honest I didn't see much difference.
If you look at the specs the only difference is a higher lift cam. I have built and owned performance vehicles and in my opinion the more exotic you get the more problems you can expect. I converted my 56 from a 6 to a V8 over ten years ago.
Along with front disc brakes, power steering, and a 3 speed OD trans it is a great driver. I made up a list of the parts needed for the 6 to V8 conversion. I can provide it to you if it would help.
Fred

Fred, your list would be really helpful. It will undoubtedly save a couple of trips to my FLAPS.

Definitely going with a crate motor, either the 260Hp or the L31. Thanks to everyone's input. What are your thoughts on finding a good used T-10 or M-20? My concern is that many of these were original to muscle cars and might have been thrashed pretty hard but it is hard to swallow the cost of a new trans.

Also, the HD clutch in my '56 has less than 1000 miles (235 and SM420). Could/should I reuse it with the new engine and trans? Don't want to go cheap if it causes problems down the road but there's a lot of life left in the existing clutch.

Send me an e-mail @ [email protected] and I can send the attachment as it is an excell spreadsheet. Any of those 4 speeds would work great but a good one is going to be pricy. Your 6 cylinder likely has a 10" clutch. You will need a V-8 flywheel which is available for either a 10" or 11" clutch. I have used both with the V-8's and I prefer the 11". You will also need a
V-8 bellhousing. None of the other 235 parts can be used on the V-8.
Fred

Hi all,

Bought an L31 long block today. Also got a ZZ4 cam, Edelbrock Air Gap intake, coated headers. Got a line on a rebuilt T-10 so that is next on the list.