Flathead vs. 302
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Freshman User
Joined: Apr 2012
Posts: 29
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From: Lincoln, NE
Flathead vs. 302
Hey guys! I've noticed some posts about changing out the original flatheads for a 302/351. I wanted to know about what kind of driveablility issues anyone has experienced with the flatheads, and reasons for deciding to upgrade. I'm starting a project, and thought keeping the flathead would be kind of neat, but have never actually tried to keep one running during regular driving. Any input would be greatly appreciated. Thanks!!
Senior User
Joined: Mar 2004
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Keep the flathead. Retro is cool.
I can't stand seeing everything (epecially Fords) with a small block chevy in it. The 302 is keeping it in the family but I think you lose some character with a newer engine. I think most people just have a horsepower inferiority complex that makes them do engine swaps. My neighbor has a nice '39 Chevy that he bought with a 305. He had to put a 350 in it just because he couldn't bear to live with a 'boat anchor' or 'truck engine.' I told him to just tell people it was a 283 or 327 and then it would be cool.
Sometimes the driveline is a concern. I have a ****** PU that still has the flathead six. I thought of putting a newer V8 or V6 in it but the driveline isn't up to it. Thus it was either a whole new 4x4 driveline or put a bigger engine in and not be able to hammer on it anyway. Of course if you have stock size tires on your '47 the hp from a 302 won't be a problem to the driveline because you won't put it to the ground anyway.
I can't stand seeing everything (epecially Fords) with a small block chevy in it. The 302 is keeping it in the family but I think you lose some character with a newer engine. I think most people just have a horsepower inferiority complex that makes them do engine swaps. My neighbor has a nice '39 Chevy that he bought with a 305. He had to put a 350 in it just because he couldn't bear to live with a 'boat anchor' or 'truck engine.' I told him to just tell people it was a 283 or 327 and then it would be cool.
Sometimes the driveline is a concern. I have a ****** PU that still has the flathead six. I thought of putting a newer V8 or V6 in it but the driveline isn't up to it. Thus it was either a whole new 4x4 driveline or put a bigger engine in and not be able to hammer on it anyway. Of course if you have stock size tires on your '47 the hp from a 302 won't be a problem to the driveline because you won't put it to the ground anyway.
Fleet Mechanic
Joined: Sep 2010
Posts: 1,586
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From: South Carolina
I plan on running my flathead 6 until it spills it's guts all over the road. No, I don't plan on hauling much, nor cruising at anything resembling "speed", I want to drive it the way it is (or was). I have other vehicles for trips and hauling. This one is a project that I just couldn't refuse. Since everything that came with it from the factory was mostly there, I had to put it back together that way. I have no welding skills, so driveline changes were out and mostly, I didn't have the money to hot rod the thing. By the time I would have fooled around with all of the changes I needed to make, I could (and should) have just bought a new one and had done with it. This one has character the way it is. Besides, how many flathead 6's have you seen lately?
Moderator
Joined: Nov 2001
Posts: 2,643
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From: Orange County, CA
For me the decision was made because I want to drive my '46 as much as possible. I do a yearly road trip, usually for a week at a time, visiting several states in the western/southwestern US. For me, a later model engine is simply a matter of being able to get parts anywhere on the road and being able to easily keep up w traffic anywhere I go. Is the flathead a reliable engine? Of course it is, if it wasn't Ford wouldn't have used them for 20+ years. But for modern traffic, higher speeds, yes, its a bit limited.
Senior User
Joined: Jan 2010
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From: Emerald Coast of Florida
I have several schools of thought on this. If you have a reasonably complete truck than go with what is in it. If reliability and driveability are an issue than modern is the way to go. In my case, my 40 was owned by my father who bought it from someone who installed 74 Nova running gear and powertrain in it. So in an effort to remove the chevy fromit, I am installing a 351W w/C4. The front end of the frame was cut so I am removing it and adding an IFS. If I had a stock or reasonably stock 40 I might not go the route. It's up to you. It's your truck.
Red
Red
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From: placer county usa?
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From: Wild Wonderful WV
I built my '41 rebuilding the Flathead bored the 221 to 239, MSD electronic ignition, C-4 tranny with ford 8" rearend and open drive shaft. I am currently swapping out the Flatty and installing a 5.0 HO Roller because I'm building the truck as more of a daily dirver, so higher reliablility etc. The Old Flatty, while toally rebuilt etc didn't produce enough vaccum to shift the C-4 AND manage the Power disc brakes so I installed an electric vacuum pump to manage the brakes....but still....for my plans now, the small block is much more suitable.
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Thread Starter
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Freshman User
Joined: Apr 2012
Posts: 29
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From: Lincoln, NE
Thanks, Steve. These issues are exactly the kind of things I'm trying to find out about. Never having driven a vehicle with a flathead, I wondered about driveability issues, etc. I won't be using it for long trips, so overheating probably won't be problem, but I wondered if low horsepower or lack of acceleration would be a problem. Not that I'm going to race it or anything, but I don't want to be a hazard in quickly moving city traffic.
A question similar to the power brake problem- does anyone know of a kit that mounts a power steering pump to the flathead? That might be an issue, too. Thanks for the input!
A question similar to the power brake problem- does anyone know of a kit that mounts a power steering pump to the flathead? That might be an issue, too. Thanks for the input!
Lead Driver
Joined: Apr 2002
Posts: 8,813
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From: Littleton, New Hampshire
A stock flathead has about 100 HP. Most 4 cylinder cars these days will run circles around it. I would not consider driving it in heavily congested areas. Put the 302 in and you will be a lot happier. If you do keep the flathead you will need a rear end ratio change to drive over 55-60 MPH. 
Senior User
Joined: Dec 2011
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From: Coaldale, AB, Cdn
I've got a truck ('47) and a car ('54 Canadian Meteor) with the original flatheads. They both ran fine with the exception of some heating/vapor locking issues in 90+ weather. I was in a line-up at the Glacier Park gate one day when the temperature was 95. My '47 truck started getting very hot but I just opened the hood and sped it up. The needle sat on the last peg but no coolant was pushed out. Cooled right down when we got moving again. Both vehicles will cruise 55-60 without any problem, and up to 75 if needed but I'd tend to avoid the freeways where 75 is mandatory. I might add that the truck has 3.7 gears in the rearend and the car (I think) is 3.5 but has a Mercomatic trans so they both rev out the same at cruise speeds.
New User
Joined: Apr 2012
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I'm going with a 302, but then I'm planning on driving 6 hours to reenactment events, and don't have a easy way of towing it back if it messes up. It had a replacement flathead in it, so it wasn't quite orginial to begin with. I'm also planning on being able to tow a 20' enclosed trailer, so 100hp was a bit questionable. Still not planning to drive faster than 55-65mph.
Elder User
Joined: Oct 2011
Posts: 777
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From: Neosho, MO
I'm going with a 302/C4 in my rebuild. Maybe one day I will get the flathead rebuilt and put back into the truck. I'm leaving the motor mounts/ transmission mounts in so I can re-install them later. (other than the clutch area, which I'm still in the thought process of how to modify for power brakes)
Logistics Pro
Joined: Mar 2012
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From: placer county usa?
ya know i have a 46' dump with the flat it's way under powered for today hiway driving but the engine is cool and went to local parts store for cap rotor and points ect well they hadem in stock
i'll kept the flatty
roy
i'll kept the flatty
roy
