[GTO James]

Hi. Sorry about that last post. Just became a member of this forum,great place for information. In my teens my older friend bought a 70 GTO, I knew I had to get one. After trade school and getting my first job, bought my 70 GTO in 73. It had a YS code motor and auto. trans. I read in magazines about the RA IV's and wanted one. While driving by a small wrecker which I had driven by every day for months, I spotted something orange colored in his lot. I stopped in and found a 69 GTO with 400RA IV,4spd,3;90posi. The trunk area had been flattened by a city bus while parked on a street. I bought it and stuck the drivetrain into my car. I drove it for a couple of months,when it developed a piston knock. I tore it down and found a broken piston skirt,it had 46,000 miles on it. I heard later that these motors had this problem because of excess tolerances. I bored it .30 over,put Speed Pro forged pistons,Isky anti pump up lifters,Crane factory replacement 041 cam in it along with clevite 77 bearing,cam and crank. Speed Pro rings,new oil pump etc. Drove the car for one summer then parked it because of gas prices and started a family. This was 1981. I kept putting light oil in the cylinders and turning the motor over every year. Now my kids have their license and they want to drive it,well me too. I dragged it out last year and pulled out the drive train and pulled everything apart,but left pistons in block. I plan to install a MSD 6AL unit to protect it from the kids over reving it. I've heard the rods are the weak link in these motors. If it's used for street and kept under 5200 rpm's, do I have to worry about it. I want to put ARP rods bolts in it and a double roller timing chain. The only things that aren't factory are an 800 Holley double pumper and JR headers. What do you think of the Arma steel crank No.9794054? The intake is the factory aluminum. Do you think I'm over carburated?

[GTO James]

Hi. Sorry about that last post. Just became a member of this forum,great place for information. In my teens my older friend bought a 70 GTO, I knew I had to get one. After trade school and getting my first job, bought my 70 GTO in 73. It had a YS code motor and auto. trans. I read in magazines about the RA IV's and wanted one. While driving by a small wrecker which I had driven by every day for months, I spotted something orange colored in his lot. I stopped in and found a 69 GTO with 400RA IV,4spd,3;90posi. The trunk area had been flattened by a city bus while parked on a street. I bought it and stuck the drivetrain into my car. I drove it for a couple of months,when it developed a piston knock. I tore it down and found a broken piston skirt,it had 46,000 miles on it. I heard later that these motors had this problem because of excess tolerances. I bored it .30 over,put Speed Pro forged pistons,Isky anti pump up lifters,Crane factory replacement 041 cam in it along with clevite 77 bearing,cam and crank. Speed Pro rings,new oil pump etc. Drove the car for one summer then parked it because of gas prices and started a family. This was 1981. I kept putting light oil in the cylinders and turning the motor over every year. Now my kids have their license and they want to drive it,well me too. I dragged it out last year and pulled out the drive train and pulled everything apart,but left pistons in block. I plan to install a MSD 6AL unit to protect it from the kids over reving it. I've heard the rods are the weak link in these motors. If it's used for street and kept under 5200 rpm's, do I have to worry about it. I want to put ARP rods bolts in it and a double roller timing chain. The only things that aren't factory are an 800 Holley double pumper and JR headers. What do you think of the Arma steel crank No.9794054? The intake is the factory aluminum. Do you think I'm over carburated?

[Jack Ferris]

Over carburated? No. Cast rods and teenage drivers? YIKES!! Really a cast rod is ok for street use. I take my 400 to 5800 and have for many years even with GM rod bolts. ARP's are a good idea as well as polishing the sides. If you put in new rod bolts you will need to re-size the big end of the rod. If you grind the side beams you should re-balance the rotating assembly. Jim Butler once told me an Arma Steel crank will hold hard chrome better than a nodular unit but the strength factor is the same. Good luck and maybe you should install a rev limiter!!!

[GTO James]

Hi. Thanks for the info. I would prefer not to pull the piston assembly out because wouldn't I have to be concerned about the rings being already seated, or would I have to install new rings. I didn't thing that changing rod bolts and retorqueing would change any tolerances. As far as rev limiting, the MSD 6AL has limiting chips,so I thougit it would be a good idea. I love your interests, I have 4 daughters,and its mostly their husbands and boyfriends that want to drive the car.

[Half-Inch Stud]

GTO James,

You have a tidy project. I suggest you remove the pistons and leave the rings on the pistons for reuse. Number the pistons to the cylinder for proper re-assembly, and the rings will be all the same for your troubles.

You are corect about the cast rods. Some cast rods do well while other cast rods let go. I think the cast rods usually let go when a kid is behind the wheel. The rods know... Meanwhile, have the rods removed. And put some forgings in there. I truely like your thinking on the REV-LIMITER. But a kid may keep their foot in it, and may also up the limiter some day. Besides, dead cylinders at the Rev-Limit produces it's own set of Crank & Rod bolt stresses.

Last time I checked, you may want to spin the motor to 6200 RPM on 1-2 upshifts...

H.I. Stud