Hello,
I have a 239 original flathead (F-5). Can you advise me on the 1st thing to do, to increase the power. I don't have $2 grand to sink into it. I'm looking for the most increase with the least money. One friend said a general overhaul. Another said change the heads. Do headers make much of a difference?
Thanks for your expertise.
Brad
Kentucky

 

dual exaust worked for me
you might want to relive the block as well

 

If you rebuild it, put the Merc crank in it with a decent cam. I had a 239 with a Merc crank & 3/16" overbore, (286 ci). Ran very strong.

 

Dual carbs and electronic distributor would bring up the performance. Also depending what trans and gear ratio you are running a 5 speed with 3.50 gears in the rearend might help.


Rod 51F1

 

Thanks guys for the replys, and PLEASE keep 'em coming!

The reason I need the power is that I changed the original 6.66 rear end to a 4.11 posi trac. I was trying to get past 35 mph!, and the 4.11's worked, but I lost the power. The trans is still the original 4 speed.
Thanks again.
Brad

 

The best thing is a supercharger and a small four bbl carb with duel exausts. It sounds expencive but you can find kits for under 2 grand and it will be cheaper in the longrun than putting a merc long arm in there plus you can run up to 4 or 5 psi without going into the motor. Any more boost than that and you might want to put forged pistons and some valve springs in it. The bottom end should be good considering most of the stress it endures is from rpm and not compression. High compression heads lower air flow and limits cam lift. But a blower with good ignition and exhaust would work good for pulling with a stock heads and cam, considering its an f-5 I assume thats what you want to do with it. If your really on a budget dual exhausts, a small four bbl carb, and electronic ignition will help out alot. If you can swing it a good higher lift cam would be good too.

 

IF you elect to rebuild it. Have it balanced professionally. That is the single best thing you can do to the naked engine so it is not fighting itself. Thereafter, porting and relieving and some power adders like heads and such for bolt-ons as your budjet dictates.

 

For better breathing, headers and dual exhaust will give you good value for your buck. Sounds good too.

 

Brad, back in the day when most rodders were on a budget, there were three things that they did to their flatties that returned the most bang for the buck. In order they are 1. Dual exhaust 2. Dual carbs and 3.mild cam. You can do all of these things yourself for under $500 if you are handy and don't have to have everything new. Or if you are like me, I have about $500 in the exhaust system alone due to the stainless Magna Flows that I couldn't live without. My flatty is lightly bored and displaces 250 cubes and with the above mods it is estimated that I am running about 130 HP (stock was 95HP). Steve

 

Steve:

What do you recommend for the cam?

 

I was wondering where the cheapest place to buy a rebuild kit at? I have a 226 flat 6 which I have ready to start rebuilding. The two place recommended so far are egge and kanter. Both place are around $1100.00 for the kit. Is there anywhere else that might be a little less? Not to take over the thread, but I have a 95 hp engine as well for a F-6.

 

SteV8e, I aquired an Isky solid cam from a friend of mine that replaced it with a 400Jr. Now he jokingly said he wants it back. He's got a '51 flatty that is displacing about 276 cubes and the thing will not idle very well but it gets off the line like nobody's business. The cam I have in my 59AB motor is a 77B. It's considered a mild street cam with good low speed and mid range power. I've had it in the motor since I rebuilt it 4 years ago and am very happy with it. Steve

 

Ksmith did you get the new pics I sent you?