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.