Author Topic: 307 ENGINE UPGRADE  (Read 1738 times)

Offline Dan.Stannard

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307 ENGINE UPGRADE
« on: October 30, 2014, 06:50:04 AM »
HELLO H/O FANS !
I HAVE A 1984 H/O AND HAVE A PRETTY GOOD OIL LEAK PRESENT FROM THE REAR MAIN SEAL. I AM LOOKING AT PULLING THE ENGINE AND FIXING IT, HERES MY THOUGHTS THOUGH. SINCE IT IS A 185HP FROM THE FACTORY IM THINKING ABOUT JUST FRESHENING IT UP WHILE I HAVE IT OUT.
I WAS WONDERING IF THERE IS A CRATE MOTOR OUT THERE THAT MIGHT BOLT IN WITH NO ISSUES (INTAKE-CARB-EMISSIONS-ETC.) DONT KNOW ALLOT ABOUT THE 35O/35O CHEVY CRATE MOTOR BUT IVE BEEN TOLD ITS NOT A DIRECT FIT. AGAIN I DONT WANT TO GET INTO A BUNCH OF SWAPING OVER STUFF.
THANK YOU FOR YOUR IDEAS.

DAN
DAN 84 H/O #1767

Offline Rob.Taylor

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Re: 307 ENGINE UPGRADE
« Reply #1 on: November 02, 2014, 01:04:01 PM »
If that is the only leak is the rear main seal and the engine has no problems. I would just pull the transmission. That would be easier at least that's what I would do. They do have some crate engines out there. If you do change to say a 350 I think your intake would work on it. If I'm wrong someone correct me.
Life is all about timing

Offline Mark.Novak

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Re: 307 ENGINE UPGRADE
« Reply #2 on: November 03, 2014, 01:49:25 PM »
Here is a site I found with a 270 hp  Olds  307.  Price seems to be reasonable.  Mark     

 http://www.precisionengine.com/rebuilt-engines/oldsmobile-crate-engines/index.html

Offline Dan.Stannard

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Re: 307 ENGINE UPGRADE
« Reply #3 on: November 06, 2014, 06:16:15 AM »
YES I FOUND THAT, THANK YOU. THEY STILL MAKE THE 307 BUT IT IS NOW $28OO BECAUSE THEY HAVE TO BALANCE THE CRANK AND DID SOME MORE HEAD WORK TO GET IT TO PUT OF THE HORSE POWER THEY STATED. STILL NOT TO BAD THOUGH.
DAN 84 H/O #1767

Offline luke.krooswyk

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Re: 307 ENGINE UPGRADE
« Reply #4 on: November 12, 2014, 09:48:54 AM »
If that is the only leak is the rear main seal and the engine has no problems. I would just pull the transmission. That would be easier at least that's what I would do. They do have some crate engines out there. If you do change to say a 350 I think your intake would work on it. If I'm wrong someone correct me.

How does pulling the trans make the rear main seal replacement easier?  Now you have to support the back of the engine, and still pull the oil pan and #5 main cap.  This isn't a late Chevy or LS engine with external one piece main seal.

Don't buy a crate engine for it.  I don't have the time to list the dozens of reasons this is a terrible idea...  a mass rebuilder like that is one reason why I ended up doing my engine myself the second time with a local shop that was extremely competent in Olds engines.  No offense, but if you aren't familiar enough with the differences between Chevy crate engines and Olds engines, you won't be in a position to troubleshoot the complications of the CCC and emissions system when it comes to dropping in a performance engine.  When you add headers, the oxygen sensor runs cold and potentially throws a code.  Increased cam duration leads to a drop in vacuum, and you fight potential idle issues. 

As already suggested, your best bet would be to swap in an Olds 350 if performance is your goal, keep the original 307 on the stand, keep the cam mild in the 350, and all your stock CCC system should work.  Paint is all satin black, nobody will know the difference.  Work with a competent Olds builder (BTR performance is one shop I like) to get to where you need to be.
« Last Edit: November 12, 2014, 09:50:46 AM by luke.krooswyk »

Offline Dan.Stannard

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Re: 307 ENGINE UPGRADE
« Reply #5 on: November 21, 2014, 06:36:19 AM »
THANK YOU FOR YOUR INPUT. TO BE HONEST I KNOW VERY LITTLE ABOUT ENGINES AND THATS WHY I ASKED FOR THE HELP. I DONT CAR ABOUT PERFORMANCE, I LOVE THE WAY THE CAR DRIVES NOW. I JUST THOUGHT IF IM GOING THROUGH ALL THIS WORK I MIGHT AS WELL BUMP UP THE PERFROMANCE.
I THINK I WILL JUST STICK WITH FIXING THE OIL LEAKS AND LEAVE IT AT THAT. IF ANYTHING HAVE THE ORIGNAL MOTOR REBUILT.
DOES A OLDSMOBILE 350 JUST BOLT IN WITH ALL THE EMISSIONS?
DAN 84 H/O #1767

Offline luke.krooswyk

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Re: 307 ENGINE UPGRADE
« Reply #6 on: December 08, 2014, 09:21:42 PM »
With a mild cam and modest compression (<9:1) a 350 long block will work with all the 307 emissions equipment.