Well the maiden trip to the track did not turn out well. So, I am looking into options. The current combo is a 440 based 500" with a 4.15 stroke.
I am afraid that it is going into the junk pile. So what I would like to know is a 4.15 or a 4.25 stroke better for a drag engine? I have TF 270 heads, a super Victor and 1050 ultra dominator. The cam is a comp cams solid roller @.050 Int 280* Ehx 284* lift is .672 and .642 with 1.6 roller rockers. The converter is an 8" that flashes to 5500. The rear is a Dana 60 with 4.30 gears. The rear tires are 14 x 32. The car is a 70 Road Runner that is as light as I could make it. With me it weighs 2850.
So What would you recommend for stroke?

Thanks,
Digger73 (Mike)

What is the problem with current engine? If the crank isn't broken then why not use it?

At this point I am not sure what is wrong. The engine died after the first burn out and will not turn over. I haven't gotten very far on the tear down. I just got the engine out and the heads off. The cylinder walls that I can see have vertical marks. The heads look good and the piston tops are still clean. The engine would turn over very slow with the starter but no dice with a breaker bar. So I am expecting the worst case of massive bearing failure.

Digger72 (Mike)

Why are you suspecting bearing failure when you see vertical scoring of the cylinder walls???

Just a hunch. I am thinking that there may have been an oil issue due to the vacuum pump? Like I said I am thinking worst case right now.

Digger73 (Mike)

I've been happy with the 4.15 stroke, I ran it for years with the comp 650 mechanical FT cam to 7000 rpm even 7200 for awhile. And this was with polished, shotpined stock rods.
I do like the lightweight 4.25 crank out there now but it's been a long time since I've looked at rod/stroke ratios.

Pick a pin height your happy to use
Work back to the lightest bobwieght you can with a chev journal rod on either stroke

Aside from the intake, does it have to be a rb block?
In a 400 block a 537 gram Diamond 1.32 piston, one of their custom 130g pins and a 712g k1 6.535 2.1 rod on a 4.25 crank will get you a target bobwieght of around 1870 grams - it would take some exotic components to get a rb down to that, at that stroke

Not enough performance change to go to the 4.25 stroke, unless you can't salvage the 4.15 combo.

I’d get it apart, see what you have to work with....... and go from there.

Keep digging on the autopsy to determine what actually killed the motor? Instinct is oil pressure/bearings problem. Put the crankshaft 'stroke' concerns on the back burner. Your motor configuration sounds fine, get together with Cab (He'll see this and should contact You thru IM) over there in Bend, OR and make a durable motor. This 'racing' stuff is painful some days. Remind Yourself: It's only money.

Thanks for all the kind words and suggestions.
As I stated before I am asking only in anticipation for the worst.
I am a realist in the fact that this is not good no matter what or why.
I am sort of stuck in the RB mode as everything I own is RB based.
I will keep the post mortum going this next weekend. This thing called work keeps getting in the way of my racing.

Digger73 (Mike)

With your combination you're pushing your luck with a stock block. Be it B or RB. With vertical lines I would say something that shouldn't be there is floating around. If you don't have a good oil pan with baffles and good windage tray. That contains the oil around the pickup. I would predict spun bearing.

I have a main girdle and windage tray. the oil pan is a milodon 7 quart with baffles. As for the the pick up, it is a swinging single line external pick up. When warm I had 70 - 80 psi. The vertical lines are not deep just that I can see them. That was my thought also that I have a bearing that has failed. The oil came out as clean as when I poured it into the engine. I even filtered it as it was drained out. Nothing in the filter either.

Digger73 (Mike)

I had the same oil pan and windage tray. With .003 clearance on rods and mains. As I was turning onto return road oil pressure dropped to 10 lbs. The next pass spun two bearings, windowed both sides of the block. I did high tech testing with same pan and windage tray. Strapped oil pan with 7 quarts of water on front of my quad on concrete. Launched it, dang that water was cold! What water didn't come out on launch. Came out when I braked. I fabbed two baffles with BMW style rubber flaps. And welded in covers on both ends of windage tray. Then did the same test, hardly lost any water. It is worth the time and trouble to trap that oil where you need it. Oil drain back is fine too. Have you taken the motor apart yet?

Thanks for the tips.
I have done as much as I could for the oil drain back. I used epoxy to fill in the low places next to the cam. Then I painted the inside of the block. As for the dis assembly, I only got as far as pulling the top end apart then ran out of time. I work 12 hour days so time for the car is limited to the weekends. I will be back out in the shop in a couple of days.

Digger73 (Mike)

What’s our performance goal? Et/mph.

440Source 543 with girdle and ARP 2000 bolts...

Will easily put your car in the 9's on pump gas..

I would like to have the car run low 10's maybe high 9's with the MPH to support the ET.

Digger73 (Mike)

I have a girdle and the ARP 2000 bolts with the combo I have now.
It is running Sunoco purple fuel.

Digger73 (Mike)

I'm betting insufficient ring gap and/or insufficient piston clearance. I'd fix it and run with the 4.15 crank. S/F....Ken M