500, 472, 425, 368 Discussion, Anyone ever build a Caddy Big Block? in Cadillac Engine Discussion; Howdy Everyone
As the subject say's, anyone ever build a Cadillac Big Block? I have access to a 425 CI ...
As the subject say's, anyone ever build a Cadillac Big Block? I have access to a 425 CI Cadillac motor cheap, but prefer the 472 or 500. I have just bought an El Camino, and need to drop something in it. I think that the 425 would be OK, but would prefer to have the 500 CI.
The 425 runs great, and as I said it is cheap. I could just drop it in, but thought about building it up just a bit. Any thoughts or suggestions would be great.
Sorry for this late reply, but I haven't been at this site for a week. I'm building a 425 right now that Desk-top Dyno figures will push about 450HP and 490ft,lbs. of torque. What would you like to know about the build up?If you still need to know just post back here....
Thanks for the response! I just bought a 1976 El Camino, and a friend has a 425 with a TH400 he will let me have for $150.00. I wanted a 472 or a 500, but for $150.00 I can't pass on it. I still have a line on a 500, but the 425 is already here. Do you know of an aftermarket bolt on intakes?
What do you plan to do with yours? I would like to build a street/strip car, with more of a lean towards the strip. The 425 is out of a "77" Coupe and I had a chance to hear it run out of the car. My friend has it in his garage and was going to use it in one of his projects til I got the El Camino. I hope to squeeze some more HP out of the 425 if possible since it only had about 180 stock from what I've read.
there is a lot that can be done with the 425. If you're willing to spend the bucks get all the machine shop stuff done first. Mine is bored to 4.120 which makes it a 433 now. It's internally balanced so the crank work may cost a few bucks more haveing to add mallory metal is a bit expensive. I did the porting myself and hoping for the best. The exhaust ports are well shaped to start with but the intakes need some opening up at the pushrod wall. You can't really go with larger valves on the425, not because of the combustion chamber but because of the cylinder wall being too close to the valve and defeating the flow that the large valve would have given. The comb. chambers are 96 cc and widening them around the valves gives better flow but will increase the cc's to about 120, so a domed piston is in order if you want to bring up the compression. I'm running 11:1 static compression and Ross Pistons made me a set with domes the size of the Empire State Building.Intake manifolds: Edelbrock makes a Performer that they say is for the 472/500, but it works on the 425 also.If you want to go futher into the RPM range, then MTS has an adapter plate that lets you use intakes for a 460 Ford, so you could use single plane or tunnel rams.I'm using MTS's #15 cam from CompCams. It's peak is at about 5500RPM but I believe they will grind a cam special if your needs call for something wilder. Desktop Dyno shows a lot more HP if you run a solid lifter or a roller. I also had to change the stock rocker arm setup to a shaft mounted design. Any higher than I believe 6000RPM and you would have to use the roller rocker shaft setup which gets real pricey...Headers you have to whip up yourself unless the motor is staying in the Caddy. For that they sell block huggers. They won't fit in my swap so I have to go with big block Chevy headers and cut off the flanges and weld Caddy flanges in there place....Re-curve the distributor, It's supposedly the Caddy motors major flaw. I got a re-curve kit from Petronix. The original Q-Jet should work fine with some tweeking. Hanyes has a Rochester manual that shows the tricks to hot-rodding that sucker...One last word, these things put out lots of torque, so have a tranny and rear-end that will handle it...Be glad to give you any other info I can