The Stovebolt Site Forums The Shop Area Engine Shop 235 to small block conversion

I have a '49 4400 that I'd like to put a small block v8 in. After reviewing previous posts, I would like clarification on a couple of mating issues with my 4-speed.
Does the Manual V8 Bellhousing bolt up directly to the SM-420?
Does the I6 bellhousing bolt up to the back of the V-8?
Which Clutch would be a better choice for low end power application?

Thanks in advance, Marc

Scott Ward has actually done this, so hopefully he'll come in and add some details. I can get you started.

The 235 bellhousing will NOT bolt to your V-8. The V-8 bellhousing will bolt to the SM420. The V-8 bellhousing will NOT bolt to the '49 crossmember, though if you can swap to a '54 crossmember the V-8 bellhousing will bolt to that.

I'd use the V-8 flywheel because you can be sure the ring gear is going to work with your V-8 starter.

So the crossmember from my 55 1st parts truck should work to mount to?

Marc

I had also seen a comment on a previous post that there was some difference with the 400 small block.

Can anyone explain how that might affect my decision? I have access to a good running 400 from a K10. Are they that big of an oddball?
I like the power it has in the K10.

Marc

The biggest difference between a 400 sbc and other sbcs is the fact that the 400 is externally balanced. That means that you have to use the 400's flexplate/flywheel and harmonic balancer. Other than that they are externaly identical.

Internally, the only difference (other than bore and stroke) is the presence of steam holes in the cylinder heads. The reason 400s got a bad rep for overheating is that the early hotrodders (well, early in the sense of bein the first ones to try 400s) would slap their double-hump heads on and run the heck outta the motors...and yes, they would overheat. They didn't realize that they needed the steam holes drilled in the heads. Now if you get performance heads, specify that they're for a 400 and you get "holes in your head."

I run a couple of 400 motors. One in my 80 El Camino and one in my 85 Monte SS. They're great motors. I have another one sittin in pieces in the garage, just waitin for the next project.

So no, I wouldn't let the little differences steer you away from on at all. I think you'll really enjoy the torque you'll get from it. I remember when I first put the 406 (.030 overbore) in my 85 Monte Carlo. It turned it into what I felt an "SS" should have been all along. Now it's bein redone (incarnation II of the 406) to run on the salt flats.

hth,

It should provided the parts truck is also a 4000 series. I would expect it to work if the parts truck is a 6000 series also. If the parts truck is smaller you'll want to measure carefully first.

I haven't done this, I'm sharing what I expect based on what others have told me. So measure first!

You asked about bellhousings, so I assume you plan to use a manual transmission. The 400 small block is externally balanced as Ray mentioned, and finding the right flywheel for it might be a challenge. I think they are available aftermarket somewhere, but I don't know where.

It should provided the parts truck is also a 4000 series. I would expect it to work if the parts truck is a 6000 series also. If the parts truck is smaller you'll want to measure carefully first.

I haven't done this, I'm sharing what I expect based on what others have told me. So measure first!

With which Measurement should I be most concerned? Width between frame rails, width of the crossmember, Position on the frame?

The Donor Truck is a 3800 Series. I have a book from the GM Restoration Package for 1955 that has frame dimensions shown for all the models offered that year. One book for 1st series and another for the 2nd series. If I understand what to look for I can post the dimensions here.

You previously specified '54 for the crossmember. I should ask is that '54 and newer or what? As I said I have a book for 2nd series dimensions as well so I might be able to verify them.

Thanks Again,

Uh?!?!? Bear with me on that last post. I'm still getting used to this boards features. I tried to "reply with quote." Looks kinda garbled.

Putting the V-8 in is the easiest part of this operation. It's all of the other modifications you have to make that takes a lot of time. To have a V-8 in an AD you need to modify the steering if not change it all together. You need to come up with an engine crossmember to support and mount the engine to, which a lot of companies now produce. I had to "clearance" the firewall to make room for the distributor and modify the brake pedal and rod to clear the left side exhaust not to mention I had to convert mine to 12 volts too. You need a GOOD radiator not one that's half plugged from 40+ years of junk.

Now, to bolt the V-8 into your truck, I would suggest removing the whole front clip, there will be alot of modifications to do and this makes it a whole lot easier. I used a mid-70's bellhousing with the starter area notched to fit the block mounted starter. The mounts will need to be adapted but I mounted it into the original bell's location so I wouldn't have to rework the drive shaft. I installed a mid-70's V-8 also, so I used it's original exhaust manifolds only needing to slightly notch the right one to fit. I made my own cross member, but I would suggest buying one, saves time and money in the long run. The clutch was from an 80's 1 ton that had the same spline count as the original 48 had.

There's a lot of work to be done over and beyond installing the V-8, and if you are still up for it, keep asking questions. It's been a long time since I finished mine so I may need a nudge to remember some of the details. I still use the truck often, so I can go to it for reference still.
Good luck which ever way you go,
Scott

And thanks for the plug OldSub!

Thanks Scott: Can you post pics and more info on the steering mods and brake changes? I didn't think of that. He'll will also need a new brake master cylinder so that was going to be boosted anyway.

Cutting sheetmetal is no big deal. I have to replace the toeboard and floor panels at some point also so the cab will be braced for any cutting that needs done. I have over 20 yrs experience with aircraft metal banging and aluminum is much less forgiving.

The radiator looks to have been redone relatively recently. The '49 presently has a later model 235. So its also already 12V. Is there enough capacity in the Six's radiator to cool a V8? If it does I will flush and pressure check it as a matter of good maintenance practice. Or is there an aftermarket radiator to fit in that space? I need that little heater workin good in the winter up here in Minnie.

But that steering might be the bigger issue in the planning stages.

What I did, and the reason I did it this way was because of the parts I had on hand already was, I removed all of the factory steering components from the steering wheel down to the pitman arm. I then installed a 76 Monte column (because I had one) to some brackets I fabbed up. Then I mounted a 75 Chevy 4X4 steering box ahead of the front axle like it would be on a 75 truck. I built a steering shaft out of misc. parts so that I had a pivot joint at each end and a collapsable shaft in between. Just modified (bent) the P/S lines to fit under the inner fenderliner and attached them to the pump. Then I took the original steering link, cut it in half, welded an adjuster sleeve to the arm and threaded a 75 steering arm into the other end of the sleeve. Before welding, Center the steering box, making sure you have the steering wheel level, and make sure the wheels are straight ahead. I used this adjustment sleeve to fine tune the steering wheel alignment to the wheels' position.
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Good luck,
Scott

Thanks for all the help and info. I'm sure I'll have more questions as I go.