I have a '69 460 block and heads and I have an opportunity to buy a set of new Speed-Pro L2443NF-60 forged pistons for $250. I think they are flat tops with the domes removed. I now have L2404F-60's in it. I have someone ready to buy my pistons for $250. Will the L2443's fit in my '69? If so, do you all think that I should make the swap. I know this would raise my compression substantially. The truck will be trailered and will rarely see the street except an occasional run to the strip or drive-on beach for show and tell. I will mainly use it for mud bog racing and swamping. Current engine rundown....

1969 460 .060” over
C9VE 75.8cc heads 2.08 intake 1.65 exhaust
Crank ground, spooned and balanced
9.4:1 TRW L2404F-60 forged pistons
Stock rods, shot-peened
Hi-Vol. rear sump oil pump
7 qt. rear sump oil pan
Comp Cams Xtreme 4X4 FF X4 270H-11 270/278 226/234 554/574
Crane Energizer 1.7 roller rockers
Hardened valve seats
3-Angle valve grind
Port, polish, gasket matched
Edelbrock Performer RPM Intake Manifold 7166
Edelbrock 1411 750 CFM, electric choke
L&L headers into glass packs
C6, RV HD converter
Dana 60 front axle, Trac-Lok L/S, 5.13 gears,
14 Bolt rear axle, Detroit Locker, 5.13 gears
44 Ground Hawgs

I think the compression for the L2404F's is close to being correct, if not, please let me know what it is and what the compression would be if the L2443's were in. Hope I provided enough info. I have got to move on this as someone else is ready to buy the L2443's but I have first dibs. Thanks.

 

I just bought a set of 2443s at +.030 from Jegs and paid $367.92. 10.55:1 c/r with 92cc heads, with dome. If the set you're buying has the dome, it'll have to be removed to come in at about 11.0:1 with your 75cc heads, so factor that into the cost. And new rings, assuming your cylinders are in good enough shape to take a rehoning. SpeedPro moly rings for those pistons cost me $163. And you'd need to balance the set to the lightest piston/pin/rings. With that cam at 11.0:1, an aggressive timing curve and the iron heads, you could be looking at 100 octane gas.

 

Thanks for the reply George. The domes have already been removed and they have been "weighted" as described by the seller. They were purchased for a '73 and I don't know if there are deck height or rod length differences that would make these pistons not work in my '69. They were never installed. There are no valve relief’s, domes, dishes or anything but a flat top on the pistons. The set comes with new moly rings and pins. My engine was just rebuilt and was honed for moly rings. The mechanic that built the engine said that there is a difference in the way he hones for moly rings. Why there is a difference in honing for different rings is beyond me as I'm not a seasoned gearhead, just inclined enough to do installations of all the components. I would basically just be removing my 2404's and installing the 2443's. 1) Would this work for me? 2) Will installing the new set of pistons screw up the balancing that was done on the initial rebuild? I'm helping this guy out because he needs some $$$ and I thought it sounded like a good deal. I am selling my set of pistons just to offset on the cost of the 2443's. Concerning the octane, 3) will that 104+ octane booster that you find in common auto parts stores cut the mustard as far as raising the octane to and acceptable level? There is an executive airport about a mile from my house that someone told me would sell me airplane gas. 4) Would this gas do to raise octane. 5) Are there any repercussions to running this type of fuel? 6) How are you going to achieve the 100+ octane for your engine? Thanks for filling in the blanks. Have a safe and happy Fourth of July!!! (Questions numbered for your convenience!)

 

I'd want to see the receipt for the pistons and talk to who they were purchased from to validate the C/R. That's the only thing that would give a comfort level. I've talked to guys who bought 'resized' CJ rods on ebay that were bent. You've got some dough in the rest of the engine and that's at risk if they aren't as represented.

Your machinist can measure the pistons from the top ring land, talk to a distributor who can give exact dimensions and determine what c/r they are, but he won't go through that hassle for nothing.

There's only 0.022 difference in your deck height (lower) than the '73. Still, that's part of the c/r formula and will increase c/r over his '73 block.

Were the rings file fitted to his block? If so, you'll need to check the end gaps in your block. And I'd sure check the balance if you have to file fit them.

You'll also have to have your machinest rehang the new pistons on your rods.

I've never used the octane booster, so can't answer that.

The government gets upset when you run untaxed aircraft fuel on public streets, but that's your business.

I'm not going to be at 11.0:1 c/r and will run 91 octane with a soft advance curve. I run a Mallory 9000 with mechanical advance.

If it were my money in the engine and I couldn't positively identify the pistons as to c/r without a doubt, wanted higher c/r, and could sell the 2404s for $250, I'd buy new 2443s and have the domes cut. You're already going to spend $50 to rehang the rods and is saving $120 worth the hassle, continual doubt and possible grenading of your setup? Helping a friend is one thing, but don't hurt yourself in the process.

 

Thanks, that is just good sound advice. I do want to bump up my compression so I will probably make the change by ordering new and selling my old pistons. Originally I had planned on running the truck on the street about 50% but I reconsidered and bought a F250 with a 300-6 to drive back and forth to work and to pull the trailer. Now drive time on the street will be <5%. I think the rest of the engine components are capable of handling the 11:1 compression and I will probably have to run Sunoco GT-100, or a mixture with 94 pump gas, at the minimum. If anyone foresees any potential problems that I my run across, please let me know.