Cummins or Cadillac?
- Thread starter Woofwagon
- Start date
Woofwagon
Adventurer
Update on the Cadillac. I finally took the cylinder heads, water pump, distributor and front cover off. I do need to put my wheel puller on the crank to take off the crank snout flange. I see no strange wear marks in the cylinder bores and the cross hatch looks to be in good shape. I'm going to spin the engine over in the stand and check the main bearings. If they're good, I may not even bother replacing them. If I do a balance, I'll have to put in new bearings and that will require a resize as the crank will no doubt be polished.
I'm noodling over putting Chevy 454 valves as they are slightly larger and I can get them for cheaper than Caddy 500 valves. I plan on ordering all new valve springs, seals and keepers of course as the stock valve springs can't handle the pressures generated by slightly hotter than stock camshaft grinds. The book "Big Inch Cadillac" has been a great help. I'm looking at about 550 foot pounds of torque at 2800rpm even with this lower compression. I'm in no huge hurry to rebuild this engine so it's going to be done right the first time. I found an RV type pattern camshaft that will generate lots of low end torque and I have a GM3 torque converter lined up for the TH400 if I don't already have that converter in the trans already. With this much grunt, I may also replace the 3.73s in the diffs with a higher ratio to keep from over revving the engine at high way speeds.
I'm noodling over putting Chevy 454 valves as they are slightly larger and I can get them for cheaper than Caddy 500 valves. I plan on ordering all new valve springs, seals and keepers of course as the stock valve springs can't handle the pressures generated by slightly hotter than stock camshaft grinds. The book "Big Inch Cadillac" has been a great help. I'm looking at about 550 foot pounds of torque at 2800rpm even with this lower compression. I'm in no huge hurry to rebuild this engine so it's going to be done right the first time. I found an RV type pattern camshaft that will generate lots of low end torque and I have a GM3 torque converter lined up for the TH400 if I don't already have that converter in the trans already. With this much grunt, I may also replace the 3.73s in the diffs with a higher ratio to keep from over revving the engine at high way speeds.
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justcuz
Explorer
What size tires will you be running? I would calculate the effective gear ratio with the tires before swapping gears.
I run 285/75x16's (32.5") on my 1993 and 2000. Both have 3.73 gears. I can run down the freeway on level ground and let you know what my RPMs are if your tire size will be similar. I'll just leave it out of overdrive and run it up to 65, 70 and 75 and let you know the RPMs.
I run 285/75x16's (32.5") on my 1993 and 2000. Both have 3.73 gears. I can run down the freeway on level ground and let you know what my RPMs are if your tire size will be similar. I'll just leave it out of overdrive and run it up to 65, 70 and 75 and let you know the RPMs.
Woofwagon
Adventurer
Scored a set of NOS Cadillac heads for the engine last night. They were purchased from the Cadillac dealer in Tacoma back in '75 and never used. They have fresh valves, springs and all seals. I'm going to email MTS and ask them if those fresh springs can handle a RV cam grind. I am putting in rocker shafts instead of the hybrid rocker arm valve train there now.
Woofwagon
Adventurer
The BBC is 150 pounds heavier than the Cadillac 500 doesn't have a high nickel content block and was never rated at 550 foot pounds of torque stock. Aside from cam and valve train, these engines are dirt cheap and can be had for about 200 bucks from any junk yard with little to no wear on them. Due to the strength of the materials in the block, these 472/500 Cadillacs were routinely known to go 300K miles with no major work aside from usual maintenance. They're an excellent torque monster engine for a truck. I had thought about the 454, but all the engineered in benefits plus the low cost for parts on the Cadillac changed my mind.
chilliwak
Expedition Leader
Good to hear.....:wings:
The tall deck industrial version, they're a high nickel block but otherwise identical except for the .400" taller deck. GM did that to allow for a taller piston to decrees wear. The BBC just has such better heads and part availability, as well as not having to deal with the BOPC pattern. Looks like your into your caddy engine, just though I'd put it out there, hadn't seen it mentioned.
Woofwagon
Adventurer
For the RPM range the Cadillac can't be beat for my application. The BOPC issue is easily solved with a $60 adapter plate from Jegs. Sorry I should have punctuated my previous post better, I meant to say that the Cadillac engine has a high nickel content block. Also the castings were more precise and there was little to no casting shift to throw off cylinder bores and bearing locations. Caddy parts are actually very easy to come by. Even the HEI cap, lifters and other parts are all Chevy parts.
chilliwak
Expedition Leader
I like the whole idea of a Caddy big block.. It would probably be an awesome propane motor...:smiley_drive: