Which way? Change diff ratio to 3:55 or change engine to 383?
09-25-2014, 02:21 PM
#21
Safety Car
Bluedawg and a few others have made very good points. You really need to know what you want out of this engine ie. A 1/4 mi screamer, a fun cruiser a litlle of both. Each engine will have some different components like cam, intake and heads. When they talk about matching your components it is for where you want the power to come in at your tq and hp curve). My last engine was built more with 1/4's in mind so the cam, single plane intake, headers, mufflers, carb and heads were purchase with that intent where the power band was from 4500 - 7500 rpm. This engine just screamed, sent many a C5Z and C6Z to speed shops as they would fall behind that old C3 convertible once we hit the highway. Given that I would go on some cruises as well I didn't want it so high strung that it just wasn't any fun on the street. So there was a bit of a compromise in picking the cam. The GM ZZ383 I swapped in met my needs in that I am no longer taking the '72 to the track, I wanted a fun cruiser. The 450 hits max @ 4500 which is fine for what my needs for this engine are. With swapping in the 3.36 rear it still gets sideways fast. The car feels fast at lower rpm around the street but the other engine would walk all over the new one at the track.
Spend a lot of time identifying what how you are going to spend most of your time in the car. This will help determine what components you should build into your engine. You need to plan from carb to tail pipe in looking at matching components with your desired results keeping budget in mind.
Spend a lot of time identifying what how you are going to spend most of your time in the car. This will help determine what components you should build into your engine. You need to plan from carb to tail pipe in looking at matching components with your desired results keeping budget in mind.
DO MA NEU!
09-25-2014, 09:35 PM
#22
Drifting
How much time to you get to spend in overdrive with your current configuration? Changing the rear gear is also going to influence how much time you get to spend in OD.
I have a mild small block with an XE268H cam/2400 converter/2004R and 3.55 gears. This set up has enough power to be fun and still be a dependable street car. There are some rolling hills in my area and as a result, 4th gear is a touch too much when locked up around 60 mph.
The trans was out of an 87 Monte Carlo SS which had a small block and 3.73 gears stock. If I had it to do over again I would go with 3.73 gears.
http://tri-5.chevyrides.com/rpm.php gear calculator.
I have a mild small block with an XE268H cam/2400 converter/2004R and 3.55 gears. This set up has enough power to be fun and still be a dependable street car. There are some rolling hills in my area and as a result, 4th gear is a touch too much when locked up around 60 mph.
The trans was out of an 87 Monte Carlo SS which had a small block and 3.73 gears stock. If I had it to do over again I would go with 3.73 gears.
http://tri-5.chevyrides.com/rpm.php gear calculator.
09-26-2014, 01:07 AM
#23
Melting Slicks
Thread Starter
Thanks guys, it sounds like the best approach will be diff first and possibly 3.73 geargiven the topography here else use of lockup o/d is too limited but maybe 3.55??
Engine will eventually be a configuration along gdh lines. Max at 4500 rpm sounds like me so I will be looking at what cam compression etc will get me there. As I already spent money on a Performer EPS manifold I want to keep this as well as the Hedman shorty headers for budget purposes. If I can reuse the flex plate and balancer as well would be good as they are also new:-) Thinking some sort of roller cam as they are better for low end torque? No oiling issues at least. I spotted an outfit on e bay that do a rebuilt diff with supposedly good used ring and pinion that will ship here, anyone know if this outfit is any good to deal with? Goes under the name graygracy, doesn't need a core which is important when you are shipping half way round the planet!
Engine will eventually be a configuration along gdh lines. Max at 4500 rpm sounds like me so I will be looking at what cam compression etc will get me there. As I already spent money on a Performer EPS manifold I want to keep this as well as the Hedman shorty headers for budget purposes. If I can reuse the flex plate and balancer as well would be good as they are also new:-) Thinking some sort of roller cam as they are better for low end torque? No oiling issues at least. I spotted an outfit on e bay that do a rebuilt diff with supposedly good used ring and pinion that will ship here, anyone know if this outfit is any good to deal with? Goes under the name graygracy, doesn't need a core which is important when you are shipping half way round the planet!
09-26-2014, 03:19 PM
#24
Melting Slicks
Thread Starter
A 3.55 diff has come up for sale here, I cant look at it as its at the other end of the country but thinking of risking the purchase. Where there any differences in input or output shafts or other things I should ask about before buying? My vette is a 70.
09-26-2014, 05:51 PM
#25
Bluedawg and a few others have made very good points. You really need to know what you want out of this engine ie. A 1/4 mi screamer, a fun cruiser a litlle of both. Each engine will have some different components like cam, intake and heads. When they talk about matching your components it is for where you want the power to come in at your tq and hp curve). My last engine was built more with 1/4's in mind so the cam, single plane intake, headers, mufflers, carb and heads were purchase with that intent where the power band was from 4500 - 7500 rpm. This engine just screamed, sent many a C5Z and C6Z to speed shops as they would fall behind that old C3 convertible once we hit the highway. Given that I would go on some cruises as well I didn't want it so high strung that it just wasn't any fun on the street. So there was a bit of a compromise in picking the cam. The GM ZZ383 I swapped in met my needs in that I am no longer taking the '72 to the track, I wanted a fun cruiser. The 450 hits max @ 4500 which is fine for what my needs for this engine are. With swapping in the 3.36 rear it still gets sideways fast. The car feels fast at lower rpm around the street but the other engine would walk all over the new one at the track.
Spend a lot of time identifying what how you are going to spend most of your time in the car. This will help determine what components you should build into your engine. You need to plan from carb to tail pipe in looking at matching components with your desired results keeping budget in mind.
Spend a lot of time identifying what how you are going to spend most of your time in the car. This will help determine what components you should build into your engine. You need to plan from carb to tail pipe in looking at matching components with your desired results keeping budget in mind.
09-26-2014, 08:57 PM
#26
Drifting
The 3.55 (somewhat) local could be attractive at the right price and in the right condition. I would ask for the code on the bottom of the unit. You could use that to decode the year and confirm the gear ratio.
I bought a used unit from a guy who used to own a Vette shop and he described it as a "pig in a poke" at the price he sold it at. I had to replace the following on the unit.
Side yokes / clips / side seals / gasket / fluid
I was able to use the side yokes out of my 74 on the 78 differential. I sprayed about 3 cans of brake fluid in it to clean it up inside and it has turned out to be a good unit.
Id say to get pictures and discuss the history of the unit and try to get the part number before you go cross country.
I am happy with 3.55 and a 2004R. As soon as I hit a highway or open road 60mph + I just bump it to OD.
Cheers.
I bought a used unit from a guy who used to own a Vette shop and he described it as a "pig in a poke" at the price he sold it at. I had to replace the following on the unit.
Side yokes / clips / side seals / gasket / fluid
I was able to use the side yokes out of my 74 on the 78 differential. I sprayed about 3 cans of brake fluid in it to clean it up inside and it has turned out to be a good unit.
Id say to get pictures and discuss the history of the unit and try to get the part number before you go cross country.
I am happy with 3.55 and a 2004R. As soon as I hit a highway or open road 60mph + I just bump it to OD.
Cheers.
