I have a few questions about caddy motors. I have had a few paragraphs written then computer shit the bed or the hamb did not allow it to post for some reason.... It took to long to finish
I know the 1970 500 had the highest power. I know the best heads were 950, 250, 902.... The 902s were used in 67-73 which had all different power outputs. I have the 1971 heads but I have heard the 70s were the best heads. I believe due to runner size.....TRUE???? Also what made the compression ratio drop from 70 to 71. The heads seem to be the same. Piston quench??? Piston shape???
So if I have the 71 heads (and 71 motor) can I just use the pistons that have the better cr(off of 70 caddy)? Would that be a viable swap? Has anyone done this???
If my memory serves me right it was the 71 edelrado that had the highest horsepower stock at 360 horsepower.No matter what engine you have there torque monsters
Most of the power ratings drop was due more to a change from gross to net hp, but there was a drop from 10.5:1 CR to 8:1 or less in the early 70's. I didn't think there was much difference in heads, the CR drop is all dished pistons. These benefit from a better intake, the stock one is below horrible, but it does get the carb down low between the heads for hood clearance. MTS is a great source for info, advice, and parts, Edelbrock makes an intake that'll get you going. The 68 472 in my '36 is roughly 400 hp, huge torque, stock intake, exhaust, mild cam and headwork. It's all in at 4500 rpm, but it gets scary WAY before that! Brian
I run a 472 cu. in. bored and stroked to 518 Edlebrock intake and carb 750 cfm with Sanderson headers. I can tell you it has torque for days and it's the most powerfull engine I've ever had even more than the big block 70 Chevelle I once owned. Rags
According to Big Inch Cadillac by Doc Fromander page 26 The earler heads on 68/73 500's had 76 CC combustion chambers and better and straighter exhaust runners while the 74/76 (which I have one of ) has a much larger 126 cc combustion chamber and less efficient exhaust runners. There is also some design change in the pistons that require pistons that match the heads or you end up with 12.5 to 13.5 compresson if you put the early heads on a 74/76 block with the stock pistons or you end up with a 7.5 compression ratio if you put the big chamber heads on an early block with the early pistons. I ended up with the 500 I have because I plan to put it in my 71 GMC along with the turbo 400 that is behind it in front of a set of 3.54 gears. Hopefully it will have the poop to pull my sailboat over the pass and maybe pull a car trailer once in a while.
what exactly makes the 70 heads different than all others???? I have read 68-69 and 71-73 heads are the same but the 70s have something different or is it just the CR. I think its just the CR. I know the sh*t about the smog rails....compression.... I guess the real question is can the 71 heads make the same power as 70s
Overdrive, Shmoverdrive, you hardly need a transmission. Long-legged rear gears, let the torque do the work. Brian
With 3:54 gears she's gonna be real thirsty. You could use 2:78s and still destroy tires. The 472 and 500s are ideal in a pickup with tall gears. I'm not sure of the 500 but I know the late 60s 472 in stock form was 375 hp and 525 ft. lbs. of torque and that's with the stock intake. By adding the Edelbrock performer alone boosts the hp. to 383 and torque to 540!! All that power is in by 3000 rpms. You want to keep the rpms down and just let the engine kinda lope along. With alittle head work and mild cam they just get stronger.
I have a 472 in a 27 touring car used the edlebrock intake and carb put the larger comp cam that is in the speedway catalog ( don't remember the specs) has pertronix dist. and headers it has a turbo 400 trans with shift kit and a ford 9inch with 3.23 gear these guys are right it is a torque monster and will get away from you in a hurry and forget trying to take off from a dead stop on a damp road
I did forget to mention that you're going to want a Dana 60 under it if you're going to play with it much. Guys I know using a mild built 472 in a pulling truck were exploding every 12 bolt they had in it and the Ford 9 wasn't even close to holding the Caddy. The Dana was the ONLY one that could hold up.
Caddies from the factory came with 2:73,2:93 in limos,and 3:15 in the hearse and ambulances. I once mated a 200R4 to a 472. I needed to redrill the flex plate to the bolt pattern of the 200,which put the bolt holes on the ridge of the flex plate. I machined 3 "d" shaped spacers that fill the void and had the converter bolts tightening up aganst a flat surface Also the horsepower rateing for the engines can be very missleading as in 71 or 72 they change from horsepower at the flywheel to horsepower at the rear wheels. Also the 74 472's were bastard engines,if you get one of them throw away the pistons and the heads,everything else is ok and you can use parts from all the other year 472's
Good thread, I will have to check the numbers on mine. I don't remember what year it came out of. I have a bop TH400 and a bell housing for a four speed gathered up.
I put a 500 in my '63 International C1300. This is my daily driver. I have 36" tires with 4.10 gears and a TH400. With all the tools that I carry the truck is probably close to 7000lbs. I get between 9-11 mpgs. I have to run premium fuel and it gets expensive. I just rebuilt a fresh 500 with 30 over pistons but everything else stock. It will has roller rockers, hi performance oil pump, Flow-Kooler water pump, Edlebrock intake and 750 carb, Pertronix ignition, Chevy big block radiator. My plan is to paint it this week and install in 2 weeks. I chose to keep a stock cam to keep the torque curve low. We'll see if my thought process works. Also, keep in mind the style of flex plate that is used. Stay away from the open hole style and use a solid style. The open ones are prone to cracking as I have found. The power is very pleasing with the 500 over the stock 6. Perfomance can be shocking at times in this old truck. A few pics; Just thought I would share my experience. BloodyKnuckles
I would replace your pistons with 10.25.1 which would be for a 1970 500...do a good valve job and you will have more HP and torque than you can use. Another interesting fact is the 500 only weighs 35lbs more than SBC. 1970 eldo made 400hp and 650 ft lb of torque and got 15mpg with normal driving habits....a 3.54 gear will be no problem but don't shortcut on tranny or it will get hurt. good luck
Looks good. I like the Olds 455 in my pickup too. These old trucks really respond well to big block torque. I also have a 3.54 Dana 60 posi in the rear
One of my friends put a 500 in his '82 Chevy C10 pickup, and the stock 3.08 gears were plenty good enough for it to haul a car on a trailer about as fast as you'd care to go.
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