Boring a flathead
- Thread starter Ol' Ron
- Start date
Pete
BANNED
How about if you are older than Rumbleseat?? I'm older than salt and you know what the Spartans did with salt.
.250 is a practical first bore for a flathead.
It leaves room for one cleanup...The rest of the engine is usually shot
after that.
I pity all the people that build street flatheads these days..They will never experience the back slapping acceleration and the screech of air going down 4 48's at full throttle...They will never experience the rump rump idle of a 280 degree cam as you idle down the street at 30 mph.
They will never experience the sound of the engine turning 6000 as you bang the next gear...
I always wonder if there are any TRUE enthusiasts left out there like we were in the 50's when almost everyone drove their hot rods to work every day and had at least one stoplight race a day.
We drove to the drags every weekend and raced. No trailers or tow bars.
I guess I am preaching to an audience of one though.
Last edited:
craneygartz
Junior Member
Ol' Ron
Well-known member
Pete, My first flathead was 3 3/8 X 3 3/4. bought the pistons from Von Eslers Speed shop in Chicago. Had the block bored in Ft Athinson Wi in 1950 by the Ford garage in town. When thwy saw the size of the pistons they refused to bore the block unless I paid in advance. 5 bucks a hole. I bought a used cam and lifters at the same time, don't remember which one. That was a while back. Two duces and milled stock heads. I'd like to build another.
Walt Dupont--Me.
Well-known member
I built a 3-3/8x4-1/8 =296 when I was 17 that was 57yr's ago. 3 duces, almquest cam. In a 39 coupe. Use to drag race in Sanford Me. Walt
Pete
BANNED
I wish you had been around out here..I would have let you try out my 32 coupe....(Everyone else did)
If I took everything off it that would come, it weighed 2300 lb.
Turned 120 in 11.34.....That would have put a smile on your face.
That was a 315 ci, 4 carbs, H&C mag and 404 cam on 145 av gas.
Drove it to work every day.
Hey Pete, been there, a flat head block was meant to be bored as far as you could, .187, no need to bore to anything else if you were going to street rod it, run mine 3/8 with a merc crank, 4:55 gears, 400 jr cam, solid lifters, adjustables were junk even back then, 2 afb jugs, noting could out run me for the first 100 yards, not even the olds rocket 88's, i could buy flatheads at the wrecking yard for $15 apiece, i still have one engine ready to build with all the pieces stored in my garage, maybe my grand son will like it, my sons all use the chevy v/8's, where did i go wrong?
PeterC
Well-known member
experience the back slapping acceleration and the screech of air going down 4 48's at full throttle...They will never experience the rump rump idle of a 280 degree cam as you idle down the street at 30 mph. They will never experience the sound of the engine turning 6000 as you bang the next gear... I always wonder if there are any TRUE enthusiasts left out there like we were in the 50's when almost everyone drove their hot rods to work every day and had at least one stoplight race a day. We drove to the drags every weekend and raced. No trailers or tow bars. I guess I am preaching to an audience of one though.[/QUOTE said:
Last edited:
Here's a Lincoln V12 that's been bored to 3-1/16, not much room left. This engine is being installed with a 4 barrel carb set up. Seems the '42 blocks are the only ones cored large enough to do this. This ought to add some "gitty-up" to my '48 club coupe.
Attachments
Pete
BANNED
Not too often..I was well aware of the weakness of 25 tooth gears although they did last longer than the other sets because of less torque multiplication..At the drags I started in second so there was only one easy shift...I road raced with the 25's also and used 1st gear in the slow corners...Early racing antique sports cars developed my skill at double clutching crash box transmissions. (a la 1st gear in a 39 box)
As far as BS, I don't deal in BS...If I post it in public, you damn well better believe I have documentation to back it up.
Oh, one other thing, the timing slips I have were read off the Crocker clocks, the same ones they used at Bonneville in those days.
They used to bring them up for the 4th of July 2 day race every year.
Oh, and YES, 6000 rpm shift point....They would pull to 6200.
With nitro, 6500.
Pete
BANNED
First off, the old saying "no substitute for cubic inches" really applies big time on flatheads...Compression makes them go and it is not possible to get it on small engines...On a 315 which is about minimum inches, it is possible to get 11 to 1 without much work..12 to 1 on all out efforts.
My last engine was 323 ci..The next one is going to be 345 ci...
By the way I do not believe in re-building a stock block into a multi port one by extensive welding. (flatfire) While I have done that and I applaud the efforts of people that do it, I just happen to like the standard basic configuration.
Any more we can't get gas good enough to run these engines on the street unless we use av gas. That's not too bad an option for ocassional use.
After that the ports were done with a flow bench at hand...I leave the finish that comes from a carbide burr on the intakes...NO polishing..I found almost the exact same results as JWL..After a certain valve lift taking the valve clear out did not help any...The exhausts are where a big help can be had by taking the time to go as big as possible all the way through...After botching a few you learn how far to go..I use homemade center port baffles..I use reversion dams at the ex. port exits..2 inch pipe
W type headers dumping into a baffled 4 inch outlet.
I use a .200 deep relief. 1.75 in. valves, 1.685 ex. valves. Titanium valves nowdays...Plain stainless in the old days.
I have used several cams over the years. All performed very well..
The 6355 made the most all out horsepower but was a slug on the street..
Too much overlap...That was the cam I was using when I turned 158 at Bonneville(alcohol)....In the 323 I used a #4 Offy grind...Similar to the 404A..I use intermediate support bearings on the cam..If I have a steel core I use it but not essential.
In the new 345 I will probably use the 505A...Jazzy Nelson had very good success with it...I drill the lifters to get them down to 33 grams.
In the old days I used Isky double valve springs shimmed to 90 on the seat..Nowdays I use Chev valve springs made by Renton Coil Spring Co. because they absolutely NEVER fail.
In the old days, I used Forgedtrue pistons..Nowdays I use Ross.
In the old days I used welded cranks because that was all that was available to poor people....Now I use billet cranks but I am still poor...
In the old days, I took a NEW set of rods, shot peened and reconditioned them before balancing...Nowdays I use H beam rods.
On all the street engines I used an Edelbrock 4 pot manifold with 4 bored out Stromberg 48's....I always used a H&C mag...I always used an aluminum flywheel and clutch cover...If there was room in the chassis I would use a front damper.
On 3 of my engines after 1965 I ran Hilborn's.(not on the street except for a quick run to the triple X)....For drag racing I think when I tried floatless 48's they made as much or more hp than the Hilborn's..I never did the dyno comparison... I ran the 48's at Bonneville..
I found the rod bearings lasted much better when I jacked the oil pressure up to 90 lb.
The new 345 is going to have a dry sump system.
All of these engines would turn 7000...When drag or street racing I usually shifted at 6000 to 6200..
In the old days I would not have given the time of day to anyone wanting this info but for the last 20 years I have been passing it out freely..So far no one has come back to me to say they have tried any of it other than the cams...Myself, JWL and you Ron all seem to be freely passing out what we know..It's free and I enjoy it....I made a good living in pro circle racing in the old days but it's all for fun now......
As you say Ron, KEEP EM' RUNNING.
Ol' Ron
Well-known member
I must say that's an impressive engine. As you know I built my own flow bench before I wrote my book, just for kicks, but it never gave CFM just Percentages.
Later I had the opportunity to use a professional unit. In an effort to gain impressive flow numbers I tried every possible modification to the ports to gain more flow. Big engines need more flow than a small one and 10-12:1 CR impedes flow.
I and many others have looked for the Holy Grail of Flathead power and I believe your the only one that's found it. Thanks for the summery of your engine, wish I could have seen it run.
Take care.]
Ol' Ron
Later I had the opportunity to use a professional unit. In an effort to gain impressive flow numbers I tried every possible modification to the ports to gain more flow. Big engines need more flow than a small one and 10-12:1 CR impedes flow.
I and many others have looked for the Holy Grail of Flathead power and I believe your the only one that's found it. Thanks for the summery of your engine, wish I could have seen it run.
Take care.]
Ol' Ron
Straightpipes
Well-known member
Pete
BANNED
I wish you could have driven it.....You can if you want, drive the 345 when it gets done.