Let's build a drag race 8BA engine
 

So, I am in the planning stages of wanting to build a drag race only engine for 1/8th mi. I have an 8ba block, 1115 Edelbrock heads, a good set of stock rods, 3.75 crank, and a 3x2 intake. I am fully open to any and all ideas as far as cam, displacement, compression, different rods, etc. What are your thoughts on a 255 higher rpm vs a 296 engine?

I know racing flatheads is not a cheap endeavor, but money is not unlimited here. I want to go have fun by building a reliable motor and turn some decent times. I used to race a front engine dragster with the VDRA in Colorado that had a flathead with a powerglide trans. I have since relocated to NC and am starting a new project.

Let's have a discussion and see what ideas are out there.

Re: Let's build a drag race 8BA engine
 

Search the posts here on the Barn by @roseville carl regarding his blown FED with an automatic.

Re: Let's build a drag race 8BA engine
 

HopRod welcome to the Barn.
Since I have dabbled a bunch in a number of fast straight line flathead powered rails heres my thoughts.
To achieve some type of decent MPH and ET your going to need RPM and horsepower. Unless the rail is extremely light less than 1000 pounds which realistically is not possible being only multi carb your extremely limited on what you can achieve.
Being in North Carolina most tracks you will run on I think will be 1/8 mile. So first off your going to need a rear gear thats well north of 411. My choice of power adder to the flathead would be a 471 GMC blower with a decent size Holley dual feed four barrel carb on top. Running a blower drive ration around 12 percent under. You could use a decent stroker crankshaft but most are offshore quality or stay with the 3-3/4 Ford crankshaft which I have found o be extremely strong for most blower combinations. However the rods I would use would be aluminum and the pistons forged light weight possibly from Ross the bore at least 3- 5/16. This would give you a 258 cube combination with the blower the crankshaft HP will be over 300 easily. Now if this is something that sounds good for you I can help you with every part needed for the blower combination. I have plenty of 471 blowers and the intakes for the Flathead in stock and can easily assemble the required drive assembly complete. Theres lots more I could write but for now lets see where this goes. I would suggest one more thing pay attention to information you get. Your looking for ideas and input from the very few individuals here on the barn who actually have the experience needed to give you guidance
Ronnieroadster

Re: Let's build a drag race 8BA engine
 

HopRod where in NC. I’m in Charlotte & may be able to help.
Thanks
Cheers
Tony

Re: Let's build a drag race 8BA engine
 

How much do you want to wrench and how much do you want to spend...
If you want to have fun and not open up that engine on regular basis i would stay away from aluminum rods...H-beam steel rods goes a long way if you´re not going to compete all in. Aluminum rods are lovely and fairly priced but they are sensitive to nicks, stretch and have fatigue issues which will have to be checked regular...just saying.
All in competition you are easily spending north of 12k in a blink...just a billet crank is 3k..rollercam setup another 3k...rods and custom pistons...
If you could get Ronnie or someone seriously competing to help you what they have outgrown will be a perfect start for you and probably a bit friendlier to your wallet...just my 2c.

Re: Let's build a drag race 8BA engine
 

Re: Let's build a drag race 8BA engine
 

Ronnie Roadster is a well known flat head builder and racer. He and his son own flat head records at Bonneville. listen to what he says, he knows what he is talking about.

Re: Let's build a drag race 8BA engine
 

Second this. It's unreal what he is doing and it is amazing the parts that he has lying around "in stock"?

Re: Let's build a drag race 8BA engine
 

Ronnieroadster has a good budget build suggested.
One place you do not want to skimp on though is the cam and valve train.
A 425 with lightened stock lifters is probably the best flat lifter cam you can use. Most of the top doggies in the past used it. A radius lifter cam will go faster but is extremely expensive. Roller cams will not perform as well in a flathead Ford drag race engine as flat or radius lifters.
Aluminum rods are good but have a shorter fatigue life than forged steel H beam rods.
Before you buy pistons, you need to decide what fuel you are going to run and stick to it, especially with a blower. The compression ratio will be different with a blower or naturally aspirated. Alcohol is cheapest at about 2 bucks a gallon. Race gas 10 bucks or more. AV gas about 6. Street gas about 4 right now. On a budget, don't even think about nitro.
A front mounted ignition or mag will be more trouble free than an 8ba type.(no extra gear set to go through)
Use 45 degree sweptback "zoomie" type headers like the top fuel cars. They give some downforce and forward push.

Re: Let's build a drag race 8BA engine
 

We use a scat 4in crank and rods with ross forged pistons ,a 471 with hilborn injection on straight methanol ,A VERY reliable setup, run 13 psi boost ,home made heads,
last meet ran 9.4 @ 140 mph in the 1/4 mile.
Lawrie

Re: Let's build a drag race 8BA engine
 

Wow, great feedback so far. I should have added in my original post that it will need to be naturally aspirated and is going in a Gasser. I am building this to race with the Southeast gasser association in the H/Gas class. I had bought a roller car, a 58 Morris Minor that was set up for a SBF, so I am converting it to flathead powered.
I do have a 4-71 ready to go, but that is against the rules. This new engine will need to run on race gas and I will have a cooling system for the car. It will be backed by a Muncie 4 speed trans and I have a set of 514 gears for it which should get me in the ballpark. I have heard people have had good and bad results with SCAT or Eagle cranks for reasons of balancing issues or just failures. I love to hear from the experienced crowd who have actually done it, not just catalog parts assemblers.
In my dragster, I ran 3 stromberg 97s that I converted over to use with methanol and even ran 20% nitro one time in it. I never to got to realize its full potential since I was learning as I went and didn't quite have my combination sorted out.
Hoping to be better at setting up the full package from the start this time. I think I would like to stay away from Aluminum rods at this point, so would you suggest race prepping the factory rods or go with a set of H beams?

Re: Let's build a drag race 8BA engine
 

I live in the Raleigh area and would love some of you advice/expertise. I actually bought a L100 from you a while back. :)

Re: Let's build a drag race 8BA engine
 

I was wondering why you need a cooling system. Are you going to run it on the street or just drag strips? I knew an old guy from Sulpher La. that ran a flathead in a 40 coupe with no cooling system. The block was filled with cement, he was never beat that I know of, very fast in the 1/4 mile and that was in 59. He never told his secret about how to make the flathead run. Al

Re: Let's build a drag race 8BA engine
 

If you do not want to weld and re-machine the heads for flat top pistons, you can run av-gas. (100LL)
It is MUCH cheaper and will work with 10 to1 compression and your Edelbrock heads very well.
What crank you use will depend on how big you want the engine and the amount of money allotted for it. For a NA gas engine you could get away with a welded stroker just fine and that means you could get up to 352 ci or anything less.

3 carbs will get you going but 4 would be better. Use 48's if you can find them. Use the new 250's if you can afford them and Hilborn injectors would be best.

Go with new forged H beam rods. They can be lightened quite a bit. Even the best prepared stock rods have a very limited life in a race engine.

BY THE WAY, LOSE THE COPPER BRAKE LINES. Most racing associations will not allow them anyway.

Re: Let's build a drag race 8BA engine
 

We ran our old engine in the dragster first up for about 4 seasons, used an 8ba block, stock rods and crank, bored to 3/5/16 with ross forged pistons,hilborn injection, potvin eliminator cam, would run around 115 mph in the 1/4 , 5800 rpm at the finish line, never missed a beat.
That engine is now sitting on the bench next to the coffee table.
Lawrie

Re: Let's build a drag race 8BA engine
 

Your biggest issue is: The intake ports and manifold. It's the limiting factor in getting air into the engine. The bigger the engine the bigger the problem. That's the reason the blower really wakes up the flathead. Us rodders have been looking for the "Holley Grail" here, but so far it eluded us. Good luck, have fun

On a side note. Ibuilt a 258 Hydro engine, similar to our Danbury engines, only abigger valve was used and dual carbs. Boat ran in the hi 50s low 60 MPH. Engine turned 5500 Plus.
Owner was concerned with the family jewels,in/out box was between his kegs.
I b build a 284 /L-100 cam and Mike Davidsons Heads. Pulled 175 @4800 and never saw 60 MPH again.. I blam the prop, but i could be wrong.
Gramps

Re: Let's build a drag race 8BA engine
 

HopRod you may want to check with Quain on H/gas rules if you haven’t already. H/gas in SEGA has a stock head rule.
Look forward to talking in the future.

Re: Let's build a drag race 8BA engine
 

Lawrie, which SCAT crank did you use, did you have a billet one made or is the series 9000 cast steel?

Re: Let's build a drag race 8BA engine
 

Who can do a welded stroker in this area? Not sure what the cost would be, but seems very labor intensive. Cost maybe between a Moldex and an Eagle crank?

I am convinced to use H beam rods, so need to do some research on those.

I don't have copper brake lines, they are Ni-Copp, a Nickle/copper/iron alloy that is fuly DOT approved.
Thanks for info Pete

Re: Let's build a drag race 8BA engine
 

I read through the H/gas rules, seems like a tuff class for a flathead. If I'm reading it correctly they include OHV I6 and 4 cyl (about anything 67 or earlier including VW). A Chevy OHV 6 can put out some power! When we were racing our B/altered (mid 60s) there was a flathead altered (D if I remember correctly) that ran local. I6 OHV were allowed in the same class and it was very hard for a flathead to run with them. We also (later) ran a 2300cc 4cyl overhead cam engine. It would run 9000 rpm easy and I think around 230 hp. Again, not easy with a NA flathead. Tuff to compete with more modern engine designs.

Re: Let's build a drag race 8BA engine
 

I don't know who is doing welded cranks now but I used to get them from Hank the Crank. Whatever crank you choose, when you balance it, you want to make the bob weight as light as possible.

Better make sure the racing association rules are ok with that brake line material. You are not racing with the DOT.

Here is a pic of what can be done with Cat H beam rods to lighten them.

Re: Let's build a drag race 8BA engine
 

Does this mean if you go flat top you can get a higher C/R?

Re: Let's build a drag race 8BA engine
 

Yes.

Re: Let's build a drag race 8BA engine
 

Pete, Can you please elaborate as to why, running flattops, allows higher compression ratios? My 255 running flattops sure is a rattly thing.

Re: Let's build a drag race 8BA engine
 

Hoprod, we just use the standard 9000 series scatt one, so far about 10 seasons and no drama ,touch wood. only thing I would change is we used the scatt H beam rods with the 2.00 journals, I would rather have used the 2.139 journals.still it all works fine.
Lawrie

Re: Let's build a drag race 8BA engine
 

2.00" allows for the use of the Buick bearings, right?

Re: Let's build a drag race 8BA engine
 

I think JSEERY has provided the realistic advice you should be aware of before deciding what to build. If you want to be seriously competitive in the 11 lb. class there is no niche for our Flathead V8 engines.


If I was motivated to compete for wins in that class I would use the Pontiac OHC from 1967. If I just wanted to show up and have fun, and didn't care about being beaten by about half the track, I would use my Flathead.


If you are stuck on the Flathead determine the minimum weight you can build the car to and will fit an engine configuration. For example the 239 cube Flathead must weigh around 2650 lbs. That combination will easily outperform a 296 cube at 3275 lbs. when both engines are built to the maximum performance level. Forget about strokers.

Re: Let's build a drag race 8BA engine
 

It is simple math. A flat circle has less area than a spherical (raised) circle.
To do this you need to either fill a dome head and machine flat or make new heads with no dome.
Another advantage of flat top pistons is the flame front will travel faster over the
shorter flat surface rather than a domed surface.
This is nothing new, The NASCAR guys were doing it in the 50's.

Re: Let's build a drag race 8BA engine
 

How much higher can a comparable combination be with flat tops over domes? 1/2 point or more?

Re: Let's build a drag race 8BA engine
 

If you want to be seriously competitive in the 11 lb. class there is no niche for our Flathead V8 engines.
I have been told I would get some weight breaks and come and have fun.

If I just wanted to show up and have fun, and didn't care about being beaten by about half the track, I would use my Flathead.
The class is still growing and there are various levels of performance in the class. I am not chasing prize money or trophies, I just want to run my car with others that enjoy vintage motorsport. I will end up mostly competing against myself to see how fast I can make it go.


If you are stuck on the Flathead determine the minimum weight you can build the car to and will fit an engine configuration. For example the 239 cube Flathead must weigh around 2650 lbs. That combination will easily outperform a 296 cube at 3275 lbs. when both engines are built to the maximum performance level. Forget about strokers.[/QUOTE]
Why forget about strokers???

Re: Let's build a drag race 8BA engine
 

It depends on the size of the engine. Simple math will tell.

Re: Let's build a drag race 8BA engine
 

Thanks to all those who responded, I really appreciate the feedback.
What should be done with the main bearing caps? do they need to be replaced with aftermarket steel caps or would a center main cap support be sufficient for an under 5800 rpm engine? Would that also be dependent on the weight of the rotating assembly; i.e., bore & stroke?

Re: Let's build a drag race 8BA engine
 

Anything is better than stock.

1- Straps with screws. Good
2- Simple center strap girdle. Better
3- 2 steel caps. (front and center) Rear with strap and screw. Better yet.
4- Full pan girdle with integral caps. Best.

There are some variations of these also.

Re: Let's build a drag race 8BA engine
 

Here's a "link" (https://www.fordbarn.com/forum/showt...le#post1878599) to some reading about a build we did some years ago!

I still have the "pattern" here with me. The final installation was done without the necessity of align-boring OR even align-honing the mains!

It tied the center of the block together and worked really well! The stock car in the picture ran every weekend for some years and ran upwards of 5000 RPM. Never one single issue, it was built for a very good friend of mine!

Thanks, Gary in N.Y.

P.S. One more item I would certainly look into would be to get the block "extrude-honed", never tried it but I believe it MAY be very useful for chasing HP numbers?? Here's a shot (again) of the "pattern" for the girdle.

Re: Let's build a drag race 8BA engine
 

GOSFAST, so do you make those for other people? It looks like the outer bolts are splayed towards the outside of the block. Very neat design!

Re: Let's build a drag race 8BA engine
 

Hi "Hop" (do you have a first name maybe), I don't plan making any more of those girdles, if you take the time I'm sure you can either do one OR get a "good" machine shop to fabricate it for you! The couple I did back then were both "hand-made", before we had use of the CNC. Might be a bit easier to do one on the mill now but I can't help at this time!

Here's the issue with "3-lb straps" (kidding of course with the weight) that straddle the main cap, they don't help with supporting one of the weakest areas (in my opinion) of the block, namely the section where the main bolts/studs reside, down below the main cap register? We're talking only the center main, this is where the most "crank-flexing" occurs!

Thanks, Gary in N.Y.

P.S. I would also consider using a 52% bobweight (instead of the more conventional 50%) for a build that would more than likely be run constantly in a higher RPM band? This is just my own opinion here!

Re: Let's build a drag race 8BA engine
 

I never use a 4-bolt main on a flathead...either toolsteel 2-bolt main cap with ARP bolts or a wide main cap bolted to the panrail.
Anything drilled into the center mainweb is a startingpoint for a crack and a failure.
And if you´re building a performance motor you want to make sure main bore is perfectly straight...friction and flexing crankshafts is not doing you any good.
The only thing that is certain about bobweight calculation is that there is no consensus among engine builders regarding the benefits of over- or underbalancing a crankshaft...you ask 10 and you get a dozen different answers...

Re: Let's build a drag race 8BA engine
 

That is not just your opinion. Also mine and several builders of 410 sprint car engines. I use 55 though.

Re: Let's build a drag race 8BA engine
 

"GOSFAST" uses 52% and you use 55% and agree with him? Looks like "flatheadmurre" is right again.

Re: Let's build a drag race 8BA engine
 

I have been doing it since the first time I ran a balancer in 1954. I have never heard of anyone doing destructive testing to find the ideal percentage.
We use 70% for some single cylinder engines.