Cadillac Owners Forum banner

1 - 10 of 10 Posts

·
Registered
Cadillac
Joined
·
5 Posts
Discussion Starter #1
I have a rat rod that currently has a 425 in it. It isn't going anywhere fast. I wish to take it drag racing. It weighs in at 2550 with a turbo 400 and 3:88 9". I am looking to go 12 seconds or better. Someone told me of a hot rod magazine build where they took a 76 500 and put 472 heads on and the chevette they stuffed it in ran 11:0. Does anyone know the details of this or what I should be doing. I have the 500 engine that is a runner as well.
Thanks for any help.
Scott.
 

·
Registered
Joined
·
15 Posts
If you find an earlier 500 ('73 '74?) with the higher compression heads, around 10.5:1 compression, and pistons, you're good to go, but you're going to need new headers since they don't match up. Also if you have the older block with points, you can convert to HEI really easily, it's worth it. Or you can find any year 500 or 472, with a compression of 8.5:1. But if you want more compression, you can put in new pistons and heads in it. It all depends how much torque you want and how much money you want to spend. the trans and mount points should be the same. Make sure you use the oil pump, alternator, ac., and other brackets from the 425 (the 500's brackets are wider and may not fit in your rat rod). let me know if you have any more q's. good luck.
 

·
Registered
Cadillac
Joined
·
5 Posts
Discussion Starter #3
OK, so I have my choice of two 72 eldo's with 500's. Both run. I do not know if they are high compressions at this point. My understanding is that 70 was the only high compression motor though. Is it true that if you take the low compression engine and bolt on the 472 heads it raises the compression to 12:1? Or would you be better off just swapping to high compression pistons and leaving the 500 heads on? I think I need about 425 hp and 500 ft pounds. My budget is about 2000 dollars. Somewhere I also read that the 425 heads on a 71- 76 500 would bring it to 10:1 and the approximate hp levels. Is this true?
Thanks
Scott.
 

·
Registered
Cadillac
Joined
·
5 Posts
Discussion Starter #5
I found the article through a library system last night. It is called "Bad Seed".
In a nut shell they cobbed the thing together and went racing a dozen times.
 

·
Registered
Cadillac
Joined
·
4 Posts
I have the late block-early head combo in a 53 Stude bracket car. Seems to work fine. I use 110 race gas and limit the rpms to 4500 with the stock bottom end. It runs 11.80s at 3300lbs being easy on it. When you start buying aftermarket parts for the caddys the price of fun goes up real fast.
 

·
Registered
Cadillac
Joined
·
5 Posts
Discussion Starter #7 (Edited)
What gears do you run in the Studebaker?
Do you know if the 425 heads truely make a 10:1 ratio and if they flow well enough?

Thanks again for your help.
 

·
Registered
1970 Eldorado Fleetwood
Joined
·
112 Posts

·
Registered
Cadillac
Joined
·
5 Posts
Discussion Starter #9
Does anyone know what the compression does with 425 heads on the 500?
The articles are awesome you hooked me up with.
Thanks.
Scott.
 

·
Registered
Cadillac
Joined
·
4 Posts
I am running 3:50 gears in my Stude with 30 inch tall hoosiers. I have well over 150 passes on the stock 1976 pistons. How much longer who knows. I am runnig a homemade port injected EFI. It is controlled by an electronic kit called Mega squirt. I tune it with a laptop so I can keep it plenty rich. That could account for some of the piston life. It also has 2.19-1.84 BBC valves with pocket ported heads. I cross the line at about 5000 rpm so I may try some 3:25 gears. I started with 3:89 to 3:70 to 3:50. Lots of extra. If I decide to go aftermarket bottom end I'll try them again. It really feels like it wants to rev. I have an nhra stock class Camaro that seems to eat money so not much left for the Stude. I know nothing about the 425s.
 
1 - 10 of 10 Posts
Top