Let's build a drag race 8BA engine
- Thread starter HopRod
- Start date
tubman
Well-known member
As I said, it looks like "flatheadmurre" is right again.
Pete
BANNED
We have an old Stewart Warner. Have to lift the crank by hand or hoist over to the drill stand. Good upper body exercise.
Pete
BANNED
He may be right but his math is off a couple.......giggle
GOSFAST
Well-known member
Not exactly, on 98% of our builds we use the conventional 50% bobweight formula, the others (all track-only) get anywhere from 52% thru 56%. We have dynoed literally "thousands" of motors (over a 40 year span) and refer back to the dyno sheets for the best results, including the bobweight numbers!
Thanks, Gary in N.Y.
P.S. Being a Flathead is definitely not going to be running at 7000/8000 RPM on the build were talking here I would use the 52% number! I would definitely also do something (like our girdle) to help keep it all together, at least on that "weak" center main area of the block (see the photo below)! I would also add, if Ford didn't "hang" the 2 large center counterweights on each side of the center main on the later units they would never have been able to keep that main brg from disintegrating. The Chevy race cranks have this same setup! Without those counterweights on 4.750" stroke Chev the mains will never survive, been there, tried it!
Attachments
Pete
BANNED
"Being a Flathead is definitely not going to be running at 7000/8000 RPM".
This part of your statement is totally wrong. An all out vintage circle track engine will have the hp peak in the 6500 to 7000 range and will be run 10 to 12 % over that at lift point on the track. That equates to somewhere over 7000 twice a lap. (assuming you are not in traffic)
I know he's busy getting ready to head out west to Bonneville, but I'd really like Ronnie Roadster to jump in on the bearing cap support part of the this discussion.
I don't want to misquote him, but I think I recall him saying he only uses a strap support on that he designed on the center cap only on all but the Ardun full race motors.
I be interested to see Gary's 4 bolt set up, but I'm struggling to see how it doesn't compromise the pan rail/center web.
I don't want to misquote him, but I think I recall him saying he only uses a strap support on that he designed on the center cap only on all but the Ardun full race motors.
I be interested to see Gary's 4 bolt set up, but I'm struggling to see how it doesn't compromise the pan rail/center web.
Ronnieroadster
Well-known member
Hi Tim OK heres one of my simple secret improvements to add strength to our beloved flathead blocks.
Let me explain what I have learned running our flatheads full out not only for records at Bonneville but also for our many dyno pulls. Theres absolutely no need for the massive girdles I have seen many use however if thats what you want to use go for it but it is waste of money,time and weight.
On all of my record setting flathead blocks to add support to the center main bearing cap I simply place a flat steel support the width of the cap and one inch in height on top of the steel center bearing cap this support is bolted to the cap with 5/16 hardware which is only used to locate this support.
The steel support is long so it touches the inside surface of the oil pan. Now heres where the support is made to the center of the block. On the outside of the oil pan theres a steel plate that touches the outside of the pan wall and also has a flat surface sitting on top of the oil pan covering three oil pan bolt holes. This L shaped plate is held in place by the three oil pan bolts on each side of the oil pan.
Now for the additional strength I add a 7/16 cross bolt that now goes threw the steel outer plate and the oil pan side wall and finally threads into the side of the inner steel center main bearing cap support. This assembly adds a huge amount of central support to the block. Think how much effort it will take to move such a structure.
I can tell you we have tested out our design not something I wanted to do but going for records has had its ups and downs. Here goes on the backup run for the record at the 2 1/2 mile marker we experienced a huge internal failure due to oiling issues the two rear connecting rods which were steel Cunningham rods broke after the bearings seized on the rod journal.
The now broken rods number 4 and 8 began chain sawing the inside of the block the steel cam was broken into many pieces between the center and rear cam bearings. With the cam broken the lifters now joined the cam parts hitting the spinning crankshaft slamming into everything possible.
With that much internal carnage the center main bearing area of the block remained completely intact. The crankshaft survived with a slight run-out in the center when I checked it between centers. I will add on more detail all of the internals in this and all my engines are USA products no off shore stuff EVER.
Oh I forgot to add even with this complete disaster on the return run the car coasted across the line over 170 MPH we bumped the record by 20 MPH at that point we now had two records. Now years latter we have set four more records with our flathead engines each one using this simple center main support design.
Ronnieroadster
Let me explain what I have learned running our flatheads full out not only for records at Bonneville but also for our many dyno pulls. Theres absolutely no need for the massive girdles I have seen many use however if thats what you want to use go for it but it is waste of money,time and weight.
On all of my record setting flathead blocks to add support to the center main bearing cap I simply place a flat steel support the width of the cap and one inch in height on top of the steel center bearing cap this support is bolted to the cap with 5/16 hardware which is only used to locate this support.
The steel support is long so it touches the inside surface of the oil pan. Now heres where the support is made to the center of the block. On the outside of the oil pan theres a steel plate that touches the outside of the pan wall and also has a flat surface sitting on top of the oil pan covering three oil pan bolt holes. This L shaped plate is held in place by the three oil pan bolts on each side of the oil pan.
Now for the additional strength I add a 7/16 cross bolt that now goes threw the steel outer plate and the oil pan side wall and finally threads into the side of the inner steel center main bearing cap support. This assembly adds a huge amount of central support to the block. Think how much effort it will take to move such a structure.
I can tell you we have tested out our design not something I wanted to do but going for records has had its ups and downs. Here goes on the backup run for the record at the 2 1/2 mile marker we experienced a huge internal failure due to oiling issues the two rear connecting rods which were steel Cunningham rods broke after the bearings seized on the rod journal.
The now broken rods number 4 and 8 began chain sawing the inside of the block the steel cam was broken into many pieces between the center and rear cam bearings. With the cam broken the lifters now joined the cam parts hitting the spinning crankshaft slamming into everything possible.
With that much internal carnage the center main bearing area of the block remained completely intact. The crankshaft survived with a slight run-out in the center when I checked it between centers. I will add on more detail all of the internals in this and all my engines are USA products no off shore stuff EVER.
Oh I forgot to add even with this complete disaster on the return run the car coasted across the line over 170 MPH we bumped the record by 20 MPH at that point we now had two records. Now years latter we have set four more records with our flathead engines each one using this simple center main support design.
Ronnieroadster
Ronnie, so if I understand your design correctly, does tightening the oil pan bolts, via the L shaped bracket, increase preload on the main cap?
Ronnieroadster
Well-known member
The oil pan bolts only hold the L shaped support tightly to the oil pan rail surface. Once the bolts are tightened I now drill the cross bolt hole now going threw the L bracket and into the side of the oil pan and finally into the side of the steel support. I use a center drill for this operation. The idea is to get a centered hole location into the side of the main bearing cap support so every time things come apart and go back together the support locates exactly as the first time. Once i have that centered location I now remove the steel support thats on the main bearing cap and finish drilling the needed tap size hole for the 7/16 bolt using the drill press. To keep things accurate every time I do not use an oil pan gasket. I seal the pan to the block using a good quality silicone sealer.
Ronnieroadster
Yoyodyne
Well-known member
Very clever setup, I wouldn't have thought of going through the pan with fasteners.
Do you modify the main cap for a seat for the bar, or just have it bear on the spotface areas for the main bolts? Where are the 5/16 bolts located and how are they used?
I'll never do this to a flathead, but I might be able to apply it elsewhere.
Thanks for the description!
Do you modify the main cap for a seat for the bar, or just have it bear on the spotface areas for the main bolts? Where are the 5/16 bolts located and how are they used?
I'll never do this to a flathead, but I might be able to apply it elsewhere.
Thanks for the description!
This is not to sound like a fan boy, but more so as someone who admires mechanical ingenuity and the ability to problem solve. We are fortunate to have a bunch of these guys on this forum who are willing to share their knowledge and experience freely.
Going to Ron's shop and seeing some of his tricks and modifications he does to these engines is truly inspiring.
Standing next to his race car as it starts up and feeling the exhaust literally punch you in the chest is impressive to say the least. Then you hear the sound of the motor...
I feel very fortunate to have gotten to know Ron and his family. When he gives me advice, I listen.
Going to Ron's shop and seeing some of his tricks and modifications he does to these engines is truly inspiring.
Standing next to his race car as it starts up and feeling the exhaust literally punch you in the chest is impressive to say the least. Then you hear the sound of the motor...
I feel very fortunate to have gotten to know Ron and his family. When he gives me advice, I listen.
Last edited:
Pete
BANNED
Well, I feel the same way. Ron, JWL, I and others have shared much info by email over the years. I have learned many things from them and I hope I have been of help also. I hope to meet them in person some day.
Vintage racing has been very good to me over the years. Much more so than the pro racing that gave me most of what I know.
One of the most important things I tell vintage RACING engine builders is, follow what the TOP current day pros in ANY racing venue are doing to their engines. Then if it looks like that procedure may help a vintage engine, modify it so as to apply and try it.
frnkeore
Well-known member
Is there a cubic limitation in H/Gas? Or a cubic inch to weight rule?
As a basic thing with a N/A, FH, you need as much compress, as you can possibly get.
Make sure you know the compressed thickness of you head gasket, then order your pistons to get .038 +/- .002., piston to head clearance.
The stock deck height is 10.437 +/- .005. To order pistons, you'll have to know that and the depth of the dome in the head, to get things right. The dome varies, in different heads, as you know.
You can use the Ol' Ron method to measure the dome clearance, by wading some tin foil and turning the engine over.
It takes a lot of actual measuring to get max compression out of these engines.
As a basic thing with a N/A, FH, you need as much compress, as you can possibly get.
Make sure you know the compressed thickness of you head gasket, then order your pistons to get .038 +/- .002., piston to head clearance.
The stock deck height is 10.437 +/- .005. To order pistons, you'll have to know that and the depth of the dome in the head, to get things right. The dome varies, in different heads, as you know.
You can use the Ol' Ron method to measure the dome clearance, by wading some tin foil and turning the engine over.
It takes a lot of actual measuring to get max compression out of these engines.
frnkeore
Well-known member
Added:
I don't know how after market piston manufacturer's measure CH (I'm to cheap to order a set) but, Ford measures to the corner of the dome, above the top ring, not to the top of the dome. That corner, also has to be more than .036 from the head surface so, make sure you know what that measurement is. Std CH is 1.530, as I remember.
I don't know how after market piston manufacturer's measure CH (I'm to cheap to order a set) but, Ford measures to the corner of the dome, above the top ring, not to the top of the dome. That corner, also has to be more than .036 from the head surface so, make sure you know what that measurement is. Std CH is 1.530, as I remember.