My 1970 350/300 has finally had it. I'm looking for opinions on economical performance upgrades,rebuild vs crate.
Jegs has a 383 405/440 for $3,000.
http://www.jegs.com/p/Blueprint+Engines/761056/10002/-1
Is this a good option over rebuilding my motor?
Will my stock exhaust manifolds work on this engine?
Will I need to do any other upgrades if I go this route?

 

It does have Vortec heads and you will need a new flywheel/flexplate because it is a 1 piece rear main seal. That is a heck of a deal on that engine. 3K for that is a bargain. It does look like the exhaust will bolt on to that motor. I'll let the Vortec head experts answer that. It is externally balanced so when you get a flywheel/flexplate make sure you get one that is externally balanced. Your current one is internally balanced.

 

You can always get a GMPP 290 engine. It will cost a lot less and everything should bolt right up to it. It will most likely be the same performance level as the engine in your car now. For 2K youd have a new engine and you cansave and re-build your old engine later.

 

Hi S,
If you can determine that your present engine is the one that left the factory in your car make sure you keep it if you decide on a new motor.
Chances are, someday when the car moves to a new owner, it'll be worth more if the original motor comes along with it.
Regards,
Alan

 

Does it make a difference of the company selling the engine? I have found that GM performance engines are a bit more expensive but it sounds better to have one come from GM. I've been pricing the 383's from Pace performance and am just wandering if it makes a difference? Thanks.

 

If it is numbers matching you definitely want to keep the old engine. If not I wouldn't mess with rebuilding it. The crate motors are a nice option and that is a really good price. The exhaust manifolds will fit the Vortec exhaust port but you want to go to headers with the increased power output. Are you running a manual transmission? If not that engine might be a bit peaky for an auto with a stock t/c and if it is an auto then you might want to freshen it up now as well, and add a high stall t/c to work with the new motor. I had a 350-300 with an a/t and it was a pretty limp ride. You will **** your pants with all that power in a squirly old car. Make sure your brakes and suspension are up to the new challenge.

 

Yes the numbers match and it also has the original 4sd and 308 rear.
The body was customized in 1975,and has not been touched sense. It has Appliance deep dish slotted wheels, 50 series tires front and back, fenders radius to match the tires, L-88 hood,and a panelized two tone, multi color metal flake blue/purple flip-flop paint.
The car looks like it came off the cover of a late 1970's hot rod mag.
I never put money into the motor because it just ran good but now that I have to I want to give the car sum guts.

 

With the 3.08 gears and a 4 speed I would keep the build fairly mild. Shoot for low and midrange torque and power. You have 64 cc heads and a hi nickel block and it is a numbers matching 1970. I would build it with a 383 rotating assembly for torque keep the compression around 9.5 to 1 and put my money in a hydraulic retro roller. Here is a 355 combo with 186 heads and a mild flat tappet cam putting out 383 HP. http://www.ryanscarpage.50megs.com/combos11.html
Your stock manifolds and intake will limit your power but you should be able to pull around 350 HP and maybe 400 ft lbs of torque out of a 383 with a hydraulic roller and it will look bone stock, numbers matching and work with your gearing. If you want to use you stock exhaust manifolds a split duration cam is a better option, 2 1/2" exhaust will help, wider lsa will help keep the torque band wider. Here is a cam. I know it is a marine cam but good numbers for the combination above.
http://www.compperformancegroupstore...Category_Code= Headers and a better intake would help a lot. A 3.70 gear would open your build options up big time. See if someone will desktop dyno this combo for you. The power numbers are a guess.