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Found one for sale locally that I'm interested in as a candidate for a rebuild and swap-in. Looking to replace the 307 in my '89 RWD Caddy. I'm trying to learn as much as I can about this engine, I have to imagine it's THIS VERSION as I'm sure it's the most common? I'm sure this is the um-teenth post about 307-->350 swaps on here, but is this a good candidate for someone who's never attempted a swap before? I'd love it if this swap would give my Caddy a significant power boost.
The 1970 350 came in a low compression (9.0:1) 2bbl and a high compression (10.25:1) 4bbl configuration. Since you said you will be rebuilding the engine, it doesn't really matter which one it is, other than if you want a 4bbl and the one for sale is a 2bbl, then you would need to locate an intake manifold and a carburetor.
In regards to the rebuild, be aware that the common cast aluminum replacement pistons end up with a lot lower compression than they advertise due to too-short compression height. Do some homework and ask questions about the rebuild here to ensure your engine ends up the way you want it and you're not disappointed with the end results.
As said, figure out which version it is. While it is a power upgrade, it has basically the same lame cam as you 307, just a flat tappet version. A cam with more duration on the high compression version is a good idea. The 9 to 1 version would work with your stock CCC set up, are you keeping it? Change all the gaskets, except the head gaskets, unless you want lower compression. Also replace the timing set as well. Also get cast iron manifolds or headers, those tubular exhaust manifold's are a major choke point.
As said, figure out which version it is. While it is a power upgrade, it has basically the same lame cam as you 307, just a flat tappet version. A cam with more duration on the high compression version is a good idea. The 9 to 1 version would work with your stock CCC set up, are you keeping it? Change all the gaskets, except the head gaskets, unless you want lower compression. Also replace the timing set as well. Also get cast iron manifolds or headers, those tubular exhaust manifold's are a major choke point.
I just recently learned the difference between SAE gross and SAE net power measurements so it seems the two 350 engine candidates I found are going to be only a small 20 point boost (worst case scenario) from what my 307's output is. However I think it's still worth it as the 350s I hear have more potential than any 307.
I'm interested in keeping the CCC setup mainly because it ensures things like my electronic climate, cruise control, lock-up TCC, and other features will still work. People tell me that the CCC setup will mostly give me smoother performance across a broad spectrum of conditions. I can't say I know how true all of that is, but it sounds nice and would result in less swapping. Hahaha.
I'm really just looking for my 4,200lb Cadillac to have better get-up-and-go performance and not necessarily turn it into a tire squealing monster. I think I'd be pretty happy with some kind of performance in the 200hp/315lb-ft range for such a heavy car. What do you guys think?
By the way, one engine and trans couple I found has a casting number on the block of 395558 2 and there's a number 6 on the head. The seller thinks it's from a '71 Cutlass. The intake also looks like it's made for a 4-barrel carb. Does that mean that the engine is a 68-70?
Last edited by rustbukt307; Sep 14, 2018 at 07:11 AM.
The #6 heads are from 1970. I would add Felpro head gaskets if it is a 4 barrel engine to lower the compression along with a custom cam or suitable grind for the ccc. Of course maybe a bore scope or pulling a head is a good idea. I would also do a compression test and oil pressure check as well, if possible.
395558 2 blocks were used from 1968 to 1976. There's mis-information out there on the net that they are 68-70 blocks.
The 6 heads were used on all 1970 350 engines.
The way to tell for certain the year of the engine is to look at the VIN pad on the block. The second number is the year of manufacture.
Here are some photos from the ad. Judging by the taped-up area on top of the intake it looks like it's the 4bbl version? Either way the engine looks like a clean survivor that just hasn't been run in 10 years.
Last edited by rustbukt307; Sep 15, 2018 at 10:39 AM.
Looks like a good candidate. It should be closer to 9.6 to 1 with the usual 68 to 70 head cc, 6cc dish pistons .025" below deck and the factory .017" thick head gaskets. Use .040" Felpro head gaskets will put you around 9 to 1. You could get the generic 204/214 cam, which has either a 112 or 114 LSA. It worked like **** with 9.6 to 1 for me. You need a minimum 112 LSA to work with the CCC and probably more duration but around 215 duration max. You also can't have too much cylinder pressure, the factory swirl port timing curve is very aggressive, the stock tiny 350 cam won't work in my opinion. You will need manifolds, any 74 and up catalytic converter manifolds will bolt to your current exhaust. The early manifolds will also work but have a different flange and angle than later manifolds on the passenger side.
Last edited by olds 307 and 403; Sep 15, 2018 at 08:09 PM.
Looks like a good candidate. It should be closer to 9.6 to 1 with the usual 68 to 70 head cc, 6cc dish pistons .025" below deck and the factory .017" thick head gaskets. Use .040" Felpro head gaskets will put you around 9 to 1. You could get the generic 204/214 cam, which has either a 112 or 114 LSA. It worked like **** with 9.6 to 1 for me. You need a minimum 112 LSA to work with the CCC and probably more duration but around 215 duration max. You also can't have too much cylinder pressure, the factory swirl port timing curve is very aggressive, the stock tiny 350 cam won't work in my opinion. You will need manifolds, any 74 and up catalytic converter manifolds will bolt to your current exhaust. The early manifolds will also work but have a different flange and angle than later manifolds on the passenger side.
Thanks, that's really helpful advice. I've never rebuilt or swapped an engine before, but I'm confident that I'm more than capable of doing it. This info will be great to reference if and when I get into it. The seller is away on vacation and won't be back until October, so this gives me some time to plan things out. He's offering $400 with the engine and trans together. I don't intend to use the trans but the seller doesn't want to separate the two. I suppose I could sell that THM-350 and make some of my money back.
Last edited by rustbukt307; Sep 19, 2018 at 10:59 AM.
So, how well will the CCC system attach or hookup to the new 350 engine? Will the E4MC carb connect to the 350's intake? What about all the hookups for vacuum and emissions systems? Do these 350s use EGR? If not can I bypass that system without upsetting the CCC? Id hate to be looking at a blaring Check Engine light after the swap.
Your best bet is eliminating the CCC. The carb will bolt on but either a Performer, A4 or 70's EGR manifold will be needed. The biggest issue is the super aggressive timing curve the CCC has programmed in, a 9.6 to 1 motor won't like it.
Your best bet is eliminating the CCC. The carb will bolt on but either a Performer, A4 or 70's EGR manifold will be needed. The biggest issue is the super aggressive timing curve the CCC has programmed in, a 9.6 to 1 motor won't like it.
What sort of issues will I run into with the less than favorable timing curve? Is there any way to adjust that?
Are you sure that engine was stored inside? The spark plug has rusted so much, the hex is gone from it. To me this says it has been outside. Be sure to inspect the block for freeze cracking. Also don't plan on using the exhaust manifolds from the 307. They will fit and bolt up but will be very restrictive.
Are you sure that engine was stored inside? The spark plug has rusted so much, the hex is gone from it. To me this says it has been outside. Be sure to inspect the block for freeze cracking. Also don't plan on using the exhaust manifolds from the 307. They will fit and bolt up but will be very restrictive.
I don't know for sure, it never really came up in conversation. I just assumed since it's been inactive for 10 years that it's been indoors. I thought it would a lot worse if it spent a decade out in the elements in coastal NY.
What sort of issues will I run into with the less than favorable timing curve? Is there any way to adjust that?
Get the factory service manual and the special tool to adjust the part throttle mixture. An ultra lean mixture with aggressive timing will ping. Your car should have a knock sensor, make sure it torqued to whatever the torque spec is. Without it, the speed sensor needs grounded for the cruise to work and the torque converter controlled either by toggle switch or by a lock up controller.
Hi everyone! It's been a while but I'm back on the 350 swap idea since now I've got a new place with a driveway and a garage in which to do this not to mention some money saved. 👍
That old 350 came and went, so I've found a couple new ones that have caught my eye. Here's what I've found.
('68 engine - $1k) "Here you have a 35k miles oldsmobile rocket 350cu in v8. Pulled this motor out to replace it with an LS. Motor ran perfect when pulled all parts included except trans. Headers, starter, rad, shroud, air cleaner, carb ect. Motor just didn’t make enough bald eagles for our taste so instead of ruining a piece of history we are letting it live on! Make me an offer on this historical gem!"
I also found a '69 with the 9 to 1 and 2bbl for about half the price that doesn't look as good as the '68, but prolly a good candidate for a rebuild.
('69 engine - $450) "I am selling a 350 olds out of a 1969 cutlass. It’s a 2bbl engine with # 5 heads. The odometer says the car has 80k on it weather it’s true or not I don’t know. Engine will fire and run but the water pump bearing is shot so I haven’t had it running long. Had 50 lbs of oil pressure when running. It is complete minus the alternator."
Will the discussions we've had prior with the early-70's engines apply to these late-60's ones too? Bear in mind I want to keep my 4bbl Q-jet as well as the CCC setup so i can have my cruise and lock-up O/D.
Last edited by rustbukt307; Apr 17, 2019 at 11:42 AM.
Will the discussions we've had prior with the early-70's engines apply to these late-60's ones too? Bear in mind I want to keep my 4bbl Q-jet as well as the CCC setup so i can have my cruise and lock-up O/D.
The cruise is independent of the ECU, so that will work whether you keep CCC or not. The lockup converter can be operated with any number of aftermarket kits. Unless you must keep the CCC for emissions reasons, I'd lose it.
The cruise is independent of the ECU, so that will work whether you keep CCC or not. The lockup converter can be operated with any number of aftermarket kits. Unless you must keep the CCC for emissions reasons, I'd lose it.
I'll have to check my FSM I guess.
It seems the seller of the '68 engine sold it, so I guess that leaves me with the '69 option. I could take a trip out there this weekend, it's actually pretty close to my house. I suppose the intake would have to go since this is definitely a 2bbl low compression version. It's prolly not a good idea to reuse the 307's intake since I'm more than positive it will kill the performance. is there much of a difference between the '72 version and the '69 version?
That 69 350 would work well do a compression test on it if still in car, it may surprise you. You need to do the timing chain and gears anyways, the nylon coated cam gear tend to fall apart and end up in the oil pump pick up. Put in a mild cam like I suggested, will help if you have to run the CCC for a bit. You could run your current carb and intake and distributor till you find one. The swirl port intake will kill top end but I would still add richer secondary rods. If you need to overhaul the motor, then pick up all the parts you need, intake, carb and vacuum advance distributor. Any 66 to 72 iron intake would work and be non EGR. Good luck.
That 69 350 would work well do a compression test on it if still in car, it may surprise you. You need to do the timing chain and gears anyways, the nylon coated cam gear tend to fall apart and end up in the oil pump pick up. Put in a mild cam like I suggested, will help if you have to run the CCC for a bit. You could run your current carb and intake and distributor till you find one. The swirl port intake will kill top end but I would still add richer secondary rods. If you need to overhaul the motor, then pick up all the parts you need, intake, carb and vacuum advance distributor. Any 66 to 72 iron intake would work and be non EGR. Good luck.
Thanks man, I really appreciate the advice. I'm gonna run out there tomorrow and check it out, unfortunately a potential buyer never followed up and the seller already pulled the engine. What should I look for when checking this engine out?
Well'p, I bought the '69 350 engine on Sunday, and will be picking it up a week later. Need to clear out some space in the garage for it. I also picked up a stand and crane to get it home and in a position to be torn down. For the price we agreed on, he's keeping the intake, carb, and accessories up front, The engine has a bad water pump so I'm just going to toss that and buy a new one. What's the best intake I can get and will work with my CCC carb and system? I know another 307 intake would, but I've heard they can be restrictive. If that's true then I'm wondering if there's another choice.
The A4 intake used on the 1981-84 307s is a good, inexpensive choice. It flows about the same as the iron 1969 intake and is aluminum. Do not use the 85-90 A5 intake.
The water pump MUST match the accessory brackets and pulleys, so if you are using the 307 brackets get the 307 pump.
The A4 intake used on the 1981-84 307s is a good, inexpensive choice. It flows about the same as the iron 1969 intake and is aluminum. Do not use the 85-90 A5 intake.
The water pump MUST match the accessory brackets and pulleys, so if you are using the 307 brackets get the 307 pump.
Thank you very much Joe. Very helpful info as I conceptualize how this build will go. I'm very grateful to everyone's contributions as I'm going into this for the first time but am very excited to build this thing.
Any tips which metering rods I should use in the E4MC Q-Jet carb I plan to use for the new engine? I know they need to be richer, but how do I ID the ones I'd need?
Make sure the secondaries are opening all the way. Also the air flap can be adjusted to open more, Cliff Ruggles has the specs, I want to say around 1.4". There is a pic in the book to show the measuring point. The factory 307 HO had much richer secondary rods, supposedly EL, not on the list. Some have found DA 440 tip secondary rods on the Vin 9 carb which Cliff Ruggles sells.
Make sure the secondaries are opening all the way. Also the air flap can be adjusted to open more, Cliff Ruggles has the specs, I want to say around 1.4". There is a pic in the book to show the measuring point. The factory 307 HO had much richer secondary rods, supposedly EL, not on the list. Some have found DA 440 tip secondary rods on the Vin 9 carb which Cliff Ruggles sells.
Thanks for the tip. Where or how do I find this Cliff Ruggles?
I'm also having some difficulty tracking down an A4 intake from an '81-'84 307 engine. Any tips on how to find one?
Last edited by rustbukt307; Apr 24, 2019 at 08:20 AM.
Hey everyone. Picked up my '69 Olds 350 yesterday for $300. So far so good, just did a little wipe down and that gold paint is still there under all that grease. The seller kept the intake, carb, and accessories which I won't be using. I'm looking to go with an A4 from '81-'84 intake or the Edelbrock 3711 which has mounts for the hot air choke's stove pipe and the EGR. My first teardown and rebuild, I'm pretty thrilled to get started.
Another issue if running stock exhaust, which sucks is passenger manifold has a 2 bolt flange and different angle. Also the 307's tubular manifolds are restrictive junk. Otherwise, carry on.
Another issue if running stock exhaust, which sucks is passenger manifold has a 2 bolt flange and different angle. Also the 307's tubular manifolds are restrictive junk. Otherwise, carry on.
I agree, I'd rather not use what's on the 307. I'd like to buy new 350 headers and use the Caddy's stock exhaust. I've already got a Flowmaster catalytic converter on the car so that should give it more flow than it would have otherwise. I'd also like to figure out how to do a set of duals on the car but that's another story.
I agree, I'd rather not use what's on the 307. I'd like to buy new 350 headers and use the Caddy's stock exhaust. I've already got a Flowmaster catalytic converter on the car so that should give it more flow than it would have otherwise. I'd also like to figure out how to do a set of duals on the car but that's another story.
You can go with the Thornton shorties down the road, they bolt on wherever your 350 manifolds attach. Ram Air Restorations makes nice 2.5" downpipes for manifolds. As said get a dual hump crossmember or a good pipe bender can route it all under the passenger side hump. My 88 Cutlass is ran like that, all 2.5".
You can go with the Thornton shorties down the road, they bolt on wherever your 350 manifolds attach. Ram Air Restorations makes nice 2.5" downpipes for manifolds. As said get a dual hump crossmember or a good pipe bender can route it all under the passenger side hump. My 88 Cutlass is ran like that, all 2.5".
Are you talking true duals or like a cat-back system? I was thinking of just splitting the exhaust after the cat otherwise I'd prolly have to add another cat to the other side.
Are you also running those Thornton shorties on your 88? I've heard there could be fitment issues with the larger B-body cars with some headers but if they fit your Cutlass I would imagine they'd fit in the larger B like my Caddy.
Last edited by rustbukt307; Apr 30, 2019 at 07:35 AM.
Are you talking true duals or like a cat-back system? I was thinking of just splitting the exhaust after the cat otherwise I'd prolly have to add another cat to the other side.
Are you also running those Thornton shorties on your 88? I've heard there could be fitment issues with the larger B-body cars with some headers but if they fit your Cutlass I would imagine they'd fit in the larger B like my Caddy.
I am running the Sanderson shorties, the Thornton headers didn't exist back then. Very compact as well, 1 5/8" primary and a 3" collector. Eliminate that worthless crossover and go true dual. People have gained a second in the 1/4 mile over the factory 80's 442 exhaust with just manifolds and true duals. From the Y pipe back is decent, the front is so restrictive.
