Olds Smog 307 to '71 Rocket 350 Engine Swap

Bewber wrote:

FWIW, I also REALLY support Nick's suggestion about leaving that dizzy in THAT motor and buying the new one for your friend to use in his project.

Don't like my long-winded "Help me" threads?

Don't mind them at all dude, but an ounce of prevention ALWAYS beats a pound of cure.

Plus, I've been there/done that too many times.

I hear ya, and I'll ask about keeping it.

-Mike

Dropping in a new one isn't 350 Rocket science, but it's real easy to get it one tooth off and have everything be ALMOST great.

Called him and he does want to keep the distributor. It's something they ordered from Jegs so he wants to keep it.

Oh well.

I looked on Ebay and they can be had for around $50 new, or my guess is $10-15 at the salvage yard.

Have not called the local parts stores yet. I'm thinking anything from 1975-79 should work...if I'm right that GM went to HEI in '75.....think that's right....

-Mike

Mike if possible get all the numbers off the dizzy coming out of the engine for future reference and so you can order the same dizzy from JEGs.Its probably just a standard distributor but better to
get that part number now than later.

My suggestion for the 750,. if you look at the cfm ratings for rochesters,. they are all upwards of 750 cfm,. the olds motor will breath pretty good,.especially if you put a decent set of headers on it,. failing that at least weld/epoxy up the exhaust port divider,.and plug the heat riser passages,.(you do live in warm old texass)
the speed shops prefer to sell undersized carbs,. but a 350 olds will handle 750 fine,.just needs to jetted right,.as far as the "too" big argument,. perhaps folks might take a peek back a few years ago when dual quads and 6 paks were popular,. total cfm on those packages was always large.
JMHO./
its your motor,. do as you will.
re-curve a stock dizzy, and it should be dead easy to re-re before you swap motors.
Nick

Thanks again for all the tips and pointers. Looking forward to getting the engine home to my garage.

-Mike

Went and took another look at the engine at lunch. It has an Edelbrock 1406 on it now, but I could not see any numbers on the distributor.

Took some pics, but it was really BRIGHT and hot out there, so there is a lot of glare.

The engine is pretty leaky, it for sure will need new gaskets at least. Check out the oil on the top of the water pump housing?

Lots of cleaning to do!!

Oil on the water pump could be where somebody spilt oil while putting it in the tube,.
tighten up the intake bolts add a bead of silicone over the gasket,. then paint it,. it'll disappear,....er,. the bead of silicone that is,.

typical olds non existant oil leak,.

You sure are brave Nick!

I plan to drive this car and don't want it dripping all over my driveway.

Tarps are like $5.99 at Harbor freight, buy a couple and you'll never get the driveway dirty.

Cadet57 wrote:

Tarps are like $5.99 at Harbor freight, buy a couple and you'll never get the driveway dirty.

I do not like my cars to leak... It's not a freakin Harley, it should not leak.

81X11 wrote:

Cadet57 wrote:

Tarps are like $5.99 at Harbor freight, buy a couple and you'll never get the driveway dirty.

I do not like my cars to leak... It's not a freakin Harley, it should not leak.

details...

Olds are just rather oily engines. The valve covers are hard to keep from leaking because they sit at such a severe angle.

You can use any Oldsmobile HEI distributor out of any engine from '73-mid 1980. Just make sure it has a vacuum advance can on the side. California cars went over to computer controls for 1980, 49-state got them in '81, and Canadian cars NEVER got them. On the other hand most Canadian Olds got Chevy 305's except for the B-body sedans and wagons.

What kind of intake does it have? Edelbrock, nee Weber, nee Carter AFB are square bore whilst Q-jets are spread bore, so there may or may not be an adapter involved based on whether the intake is factory or aftermarket.

On the carb size, that's why I am not crazy about Edel-webers...you have to pick a CFM and hope you got it somewhat correct. I would suggest a 650 electric choke. Yes Quadrajets are 750, but many tests have shown that 350-cid engines and the like never need all that.

Believe it or not, that computer-controlled Qjet on the dead 307 is a mechanically restricted 800-cfm casting...they all were. Somebody tried to tell me I was full of it until I provided pics of the carb to back up my assertion. I think it's limited to about 525cfm total, and the 307 doesn't come near using all of that. In fact the secondary rods in a 307 carb don't even taper(get richer) past about 50 degrees of air door opening.

Thanks for all the info. It's all good to know.

The intake is an Edelbrock Performer 350 and it comes with the engine.

Sure wish I didn't have to wait another week to get it home and start cleaning on it. He promised he was going to pull it next week sometime.

-Mike

Olds motors: If there's no oil under 'em, there's no oil in 'em. Quoted from Cars 2

Mike

200OZ wrote:

Olds motors: If there's no oil under 'em, there's no oil in 'em. Quoted from Cars 2

Mike

I guess I need to go see that!

Well here is the latest update on the Cutlass project.

This is the last year the Olds has to pass emissions tests, and the inspection is out tomorrow. I fired the Cutlass up last night at 9pm...after sitting since the end of June, all it took was three pumps on the gas, and the 307 came right to life. It sounded fine too, amazing it's shot. On the gauge cold it has 60psi oil pressure.

After sitting under the carport for a month it was dusty, so I drove to the car wash and sprayed the dust off. The car wash is about 2 miles away. Car ran fine, a/c blowing ice cubes and engine seemed fine, but when I got to the wash the oil pressure was below 30.

I sprayed the car off and wiped it down....it's SUCH a good looking old car, I just love it and can't wait to get it really "alive" again.

After the car wash, I drove to my mechanic buddie's house that's going to get it inspected for me. The plan is to inspect it cold, before it loses pressure and starts knocking. ANYWAY his house is about 5 miles from the car wash. Driving over I watched the oil pressure gauge slowly drop closer and closer to the red mark. Came to a stop a about a block from his house and the gauge dropped to nothing....doh. I pulled up in front of his house and opened the door to hear the lower-end tapping away. Oh well...

It should be inspected tomorrow, and once the new sticker is on the window, it's time to start pulling it apart.

-Mike

Oh, and after much discussion here, on the Cutlass forum, and with some of my old techs, here is the engine swap plan..

I get the 71 Olds 350 this coming Friday. It comes home and gets put on the engine stand, gets cleaned, gets all new gaskets, a new front seal, gets a new timing chain, water pump, and a general once-over. We're also going to put in new valve stem seals, as it puffed just a bit of smoke when I started it in the 72 Cutlass last week after it sat for almost a month. And yes I am going to "bling" it a little with a fresh coat of gold paint and some chrome valve covers.

The engine has an Edelbrock Performer intake on it, and it's the EGR model with all the ports for the emissions controls. After going back and forth about this A LOT, I've decided to keep the car original and keep the computer.

Here is the method to my madness. To get rid of the computer, I'd have to get a new carb, new disributor, modify the transmission for the electronic lockup, modify the a/c system, modify the cruise control, and remove all that wiring without damaging the stuff I want to re-use.

If I keep it original, all I have to do is find some 1980-85 307 iron exhaust manifolds which have the larger ports and the 02 sensor ports. That's it. Everything else will bolt up as-is. ALL the vacuum lines have just been replaced, and the car has no check engine light on now. In other words, the hardest part of the swap will be remembering where all the vaccum lines go.

So that's where I am now. I'm rounding up new gaskets and such, and have to go get some new exhaust manifolds.

Will post pics as the project progresses.

-Mike

poor 350 engine,.

You rememeber the movies with the little girl who looks solemn and says, "You're going to be sorrrrryyyyy"...?

Take from those of us who have been on both sides of the ECM issue with the same engine...don't do it. That ECM is archaic at best, and it's programmed to run a smogger 307, nothing else.

You can't tune the computer, you can't calibrate a CCC Qjet to ever run rich enough.....just don't go there.

Seal it, paint it, throw a good mechanical 4bbl and distributor on it and enjoy driving it while you work out the other little challenges.

PS, if you wish for your smile to be even WIDER each time you drive it, select an appropriate cam and lifter set and drop it in since you are that far into it. Don't use the parts-store special timing chain, most of them are made 4 degrees retarded.

Cloyes makes an excellent roller timing chain for Olds.

TylerW wrote:

You rememeber the movies with the little girl who looks solemn and says, "You're going to be sorrrrryyyyy"...?

Take from those of us who have been on both sides of the ECM issue with the same engine...don't do it. That ECM is archaic at best, and it's programmed to run a smogger 307, nothing else.

You can't tune the computer, you can't calibrate a CCC Qjet to ever run rich enough.....just don't go there.

Seal it, paint it, throw a good mechanical 4bbl and distributor on it and enjoy driving it while you work out the other little challenges.

PS, if you wish for your smile to be even WIDER each time you drive it, select an appropriate cam and lifter set and drop it in since you are that far into it. Don't use the parts-store special timing chain, most of them are made 4 degrees retarded.

Cloyes makes an excellent roller timing chain for Olds.

great advice,. but we're not on a cutlass forum,. so we don't know what we're talkinabout,.



Nick

Hey now! I appreciate all the advice here!

What got me thinking about keeping the car stock was A LOT of early 80's Hurst/Olds and 85-87 442 owners have done the mod to the Olds 350 and I was told it's the easiest swap in the world. On cars up to 85 there are no mods needed at all. On 86-88 cars, you have to swap the stock small stainless steel headers for 80-85 307 iron manifolds, but that's all.

They said the computer and carb flat can't tell there are an additional 43 cubes, and the cars run great. They said going from a 307 to the early 350 will feel like I've added 100 cubic inches under the hood when I'm done, the difference is supposed to be shocking.

Also said by keeping it stock the cars still get really good mpg...20's on the highway, and most that got rid of the computer and went aftermarket struggle to hit the high teens.

They did advise that I could remove the smog pump and AIR system hoses, and that will clean up the engine bay a lot, and has no effect on the ECM or the running of the car.

I have a long way to go before I do the actual swap. I don't even get the engine home until the weekend, and all I'm planning to do when I get it home is clean it up really well for now. The swap is not going to happen until Sept when it cools down a bit here (supposed to be 107 today...ouch!)

We'll see, but I do appreciate all the advice here!

-Mike

Yes, we know you do, phantom is just being funny...

There's nothing lost by trying your idea, maybe it will run as you like.

The thing is, it's really difficult to get an older, carbureted car to get good mileage and also make good power. Somewhere there has to be a tradeoff, and anyone telling me they are getting into the twenties with a 350 Olds either has it leaned out so much it's leaving 40hp on the table, or they are driving with an egg under their foot.

The ECM will run a 350. But, it's going to be lean with a poor timing curve, and you ARE going to be down on power. The factory ECM has fuel and timing tables loaded into it at the factory, and those are for a 307. The fuel curve and timing curve are designed for a strangled 307 cubic inch engine that GM was trying to wring every MPG out of and keep it clean emission-wise, which was a nightmare on those cars.

Not being mean, but it won't be "shocking". It'll feel a lot healthier, but dropping a 455 in is what is shocking.

I think I understand the mental hurdle you are facing, and that probably is modifying a nice car. For one, you can put everything back stock easily. Just keep anything you remove, and don't hack wires.

Secondly, if you ever sell, you're going to find that you increased the cars value by removing the 307 and replacing it with a 350. Honestly, nobody gives a rats Bee u Tee for a 307 unless it's a low-mileage 442 or H/O. You'll also increase it's value by having it off the computer.
Trust me on that...I've had enough G-bodies that I am intimately familiar with "oh, it's just a 307, thought it might be a 350 or 403"..and "oh crap..I'm gonna rip that computer crap off first thing, they never run right with that junk on there".

These are just my opinions. The ECM/no ECM debate has raged on and on. The 10% that still use them think they are the answer. The other 90% think they are a nightmare.

Good luck, I enjoy sharing anything I can.

TylerW wrote:

Yes, we know you do, phantom is just being funny

Finally somebody understands,.

I get the engine tomorrow after work. Will be cleaning it up this weekend. Pics to follow of course.

Fingers are crossed it's a good motor. It sounded really good in the 71 Cutlass and the compression is good, we tested it. I've only seen it run about 5-mins though.

The 307 in my Cutlass still runs good for 5-mins. Ha!

Thanks for all the advice folks.

-Mike

wow 77 replies and he doesn't even have it yet!!!

Sprocket wrote:

wow 77 replies and he doesn't even have it yet!!!

I believe in planning ahead!

Anyway I'm supposed to pick it up tomorrow after work. Have the engine stand ready to go. Looking forward to cleaning it up this weekend. Dad offered me his pressure washer. Woo-Hoo!



-Mike

Hi all! Went and paid for my engine over lunch today. Some good, some better, some bad....some new questions....well not too bad.

The bad is only that the engine is still in the '71 Cutlass at the shop. Neill's not had a chance to pull it yet, but since it's 1000 degrees I was not planning on doing much on my car until next month, so it's ok. It should be out next week.

The GOOD is it's paid for and as soon as it's yanked I can pick it up.

The BETTER is I was able to get some new info from the actual owner of the car. The engine was rebuilt about 6 years ago and the car is only a toy, so it does not have a lot of miles on the rebuild. He says it's always run fine since the rebuild, does not smoke ever, and the timing chain and oil pump were done, so I don't have to buy those. Good deal! He said when the engine was built it had some oil leaks and it went back twice to have those fixed, but it ran fine after that, it just was never as fast as he'd hoped so he's wanting a bigger engine.

He says the reason he's yanking was to put a big-block Chevy in the car, but Neill, my friend that owns the shop, convinced him to go with a 403 Olds, to make the swap easy. He was asking $750 for the engine on Craigs List but Neill got me a much better deal, which I'm happy about.

Now the new question, he said when they rebuilt it they put a "mild" aftermarket cam in it for a little more power. It runs smooth, not lopey, but I read if the engine is hopped up much at all it will not be happy working with the 307's computer controls.....so it looks like I may be back to the orignal plan.

We'll see. It's paid for, it's rebuilt, I don't have to clean it in the 100-degree heat this weekend. It's ALL good!

-Mike

Dont do anything to that engine Mike.First thing is hook up a vacuum gauge preferably now
before he yanks the engine.Let it warm up and write down the readings at idle and every 500
rpm.Now do the same with your 307 at the same rpms and compare.If they are fairly close then
you are good to go.Take it up to 4000 rpm as you wont take it higher than that anyway.
Jim G

Flasheroo wrote:

Take it up to 4000 rpm as you wont take it higher than that anyway.
Jim G

what,.. is he driving a Bus? a 350 olds will buzz 6000 all day long with decent valve springs,.

phantom 309 wrote:

Flasheroo wrote:

Take it up to 4000 rpm as you wont take it higher than that anyway.
Jim G

what,.. is he driving a Bus? a 350 olds will buzz 6000 all day long with decent valve springs,.

Jim's right, it'll never see more than 4000rpm. I baby my cars.

Texas Mike, if you end up coming to WFNY for the Watkins Glen Tour next year you're going to the back of the pack with Doug and the TBI cars.

New York Mike

For the CCC controls, I was sent an interesting page from someone that done the 307 to 350 conversion but kept the ECM.

http://www.robertpowersmotorsports.com/CCC.html

Lots of good info there.....round and round I go!

Sadly the Cutlass the guy had was stolen. That had to hurt. BUT check out his 94 Caprice wagon, also on this page using the links at the top. Love those chrome Silverado wheels on these!

-Mike

The 350 engine is out of the '71 Cutlass. The harmonic balancer has a hairline crack at the crank keyway, Neill found this when we took the components off the front of the engine.



I'm hoping the 307 balancer will fit from my old engine. I'm planning to use all the 307 parts off the front of the engine anyway.

-Mike

Wanna laugh? So most of you know I bought this car last summer, from the Texas hill country, in a county that did not have exhaust emissions testing. The car had just been inspected when I bought it, and I ran on that inspection all this past year since I knew it would not pass the smog test we have in the larger Texas cities.

The car never ran right when I bought it. It ran so rich your eyes would water, would diesel, and smoked black when first started, stalled, it was a mess. Last spring I found out someone had pulled the check engine bulb and there were a lot of issues under the hood.

Well if you remember I had the carb rebuilt twice, replaced the intake gasket and then the intake itself, ALL the vaccum lines were done, and a few sensors, which got the CE light out, and on the way home from the shop, after the car being IN the shop for months, is when the engine lost oil pressure and started knocking. If it was any other car I would have shot it right then.

Well the inspection was up in July. Today I took the car for inspection cold....and it passed emeission!! Hahahahahaha! It runs great now. It's still gutless, but it's smooth, quiet, runs clean, and drives great.....until it warms up and the oil pressure goes away and it starts knocking!

The inspection place is a mile from my house. Car was not knocking yet when I get there, they put sniffer up the tail pipe, and it passed easy as can be. Amazing. Motor is shot but passes smog.

I've got a nice new inspection sticker on the windshield....time to yank the engine!

-Mike

I think I mentioned this before, but one of the Cadillac guys (with the 307) had the exact same symptoms as you. Hot knock. It wasn't a bad bearing, just a bad oil pump. He replaced the oil pump and the engine is fine with good pressure at idle and when hot. No knock.

jayoldschool wrote:

I think I mentioned this before, but one of the Cadillac guys (with the 307) had the exact same symptoms as you. Hot knock. It wasn't a bad bearing, just a bad oil pump. He replaced the oil pump and the engine is fine with good pressure at idle and when hot. No knock.

I most likely could put a new pump in the 307 and use the car for another year. I've thought about trying that, but just hate to sink any more money into that 307, especially on a guess. It's totally gutless and I've had nothing but issues with it since I bought this car. To get the pan off I'd have to remove the exhaust (these use a crossover pipe under the pan) and jack the engine up off it's mounts. If I'm doing all that I think I'd rather put a 350 in it. Beside's I already bought the 350.

I did read that link you sent. Thanks for posting it.

-Mike

Ok the weather cooled down to 94 degrees today....figured it was time I went and picked up the '71 350.

Backing into the driveway with the new toy on the motorcycle trailer...with my father wondering what new POS I've drug home now...ha!


It's home.




Tags from the rebuilder on the freeze plugs, both on the block and heads..from 2004


Not too bad. Not spotless but no sludge either.


#7 heads with hardened valve seats. They breathe well and are unleaded fuel friendly...good deal!


Getting ready to take off the trailer


On the stand in my garage




Got to find some valve covers and tape it all off so I can clean it up really well, and then start gathering the rest of the parts for the swap.

Engine in the garage and safe, took the motorcycle trailer off and put the boat on.....it's hot and I need a break. Heading out for some R&R! Have a great weekend all!



-Mike

About time Mike

When we going to see the Krylon rebuild pics.

Mike

Krylon?

This is a TEXAS MIKE rebuild, man.

Stingroo wrote:

Krylon?

This is a TEXAS MIKE rebuild, man.

Fine. Duplicolor.

With whats in your garage the greenies would all have heart attacks!
Jim

Still debating about painting it black....correct for my '88 Cutlass....or Olds Gold....correct for a 71 Rocket 350.

I love a project! We'll make it pretty again!

-Mike

Flasheroo wrote:

With whats in your garage the greenies would all have heart attacks!
Jim

Let em!!

Nice grass.






I kid, I kid.

Boy look at that Roadie sag