Cad 4.5 4.9 piston specs 3400 replacement?

[Calvin]

Does anyone have the specs for pistons around the bore diameter of the 3400s, such as the Cad 4.5/4.9?

I am looking for pin heights and dish volumes and pin types and diameters.

Thanks
Kurt

[SappySE107]

You can probably google them for silvolite or speed pro.

[Calvin]

I suppose I could spill the beans and let on that I am looking for a piston that will go farther up in the bore with a 3.4 block and a 2.8 stroke. It seems that if I use the DOHC 5 cc dish piston and mill the heads, I might be able to squeeze out 8.2:1 compression. I am looking for 9.5-10.5, hence the piston interest.

Before anyone jumps my shit about no one doing this swap,and not being worth it since you might as well keep the stroke for torque, let me just point out that the limit for Rally America GR2 cars is 3,080 CCs and this would bring me down to a perfect 185 cubic inches. This is still 1.5 years off but I am starting way in advance, just like how I did a year of research before I tossed the 3400 in my GP, which paid off big.

[Calvin]

BTW it appears that the 87-89 Cad 4.5 Piston would fit the bill perfectly with a wrist pin diameter adjustment, perhaps an offset bushing in the connecting rod or 20 thousandths milled off the top for a 10.5-10.7:1 compression ratio.

Kurt

[Guest]

what about getting custom made rods to the length you need so you can use regular 60 degree pistons?

[Calvin]

what about getting custom made rods to the length you need so you can use regular 60 degree pistons?

Ahh, very possible, and wouldn't hurt the rod/stroke ratio too much.
After briefly considering this option, or even custom pistons, I figured for a motor that is going to be built exclusively for abuse should be made of off the shelf, easily replaceable cheap parts.

This is a car that will very likely see wrecks with trees, rocks and embankments. I am shooting for a NA motor that tries to snap the input shaft with torque between 2750 and 5000 RPM, so I don't need anything exotic to set the world on fire.

I am so low-buck on stuff that I will do it when I can get away with it. For example, I had a Chevy Celeb 2.5 that I drove back and forth daily between Midland, MI and Detroit, MI. It lost a piston when the EGR failed. I took another piston/rod assembly out of a used engine, honed the cylinder, and stuck it in. It got me 26000 more miles of hard working service before I wrecked the car and junked it (With less blowby, no less!)

The point is, I would totally go to the pickapart and pull 8 used 4.5 pistons if they measured up in-spec and get them or a set of freebee 660 rods machined to accomodate one another and have $50 invested versus having a $1200 set of rods invested for essentially the same performance. That way when I blow the motor by putting a hole in the oil pan on a rock or loosing the coolant, I can say meh, build another motor for the next event instead of choking down writing another $1K+ check and waiting out some fun events while waiting on the 6-8 week leadtime of new custom parts.

This is not to mention that sometimes I just like to say "Look, I built something out of nothing!!!"

Kurt

[pontiacjeff]

The point is, I would totally go to the pickapart and pull 8 used 4.5 pistons if they measured up in-spec and get them

This is not to mention that sometimes I just like to say "Look, I built something out of nothing!!!"

Kurt

(Audible groan............)

[El_Diablo]

are you running a manual? i would suggest increasing the stroke for a more rev happy engine myself but i like to have plenty of range so i can knock it down a gear while sliding around a corner and still be able to power out of the turn with the left over rpm range (really slows you down if you have to upshift while coming out of a corner so the longer your able to hold that while coming out is gonna help you a lot)

[RacerX11]

i would suggest increasing the stroke for a more rev happy engine

Huh?

[El_Diablo]

wow... i was out of it... heh sometimes i put the wrong words in the wrong order

[Calvin]

(Audible groan............)

Dude, didn't you build an N car? LOL JK