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Hello everyone I got a Cadillac from the 80s and want to do a swap with a olds 307 and or 350 since it will bolt it nicely to my transmission. Was curious if I could build one. Can’t seem to find the blocks for sale anywhere but eBay. Wanted to build one from the ground up yet not sure where to look. Wanted to ask here before I hit the junkyard and do a complete rebuild on one. I believe I’m looking for a GM 22530856 short block( that’s what I found for 307) havnt been able to find a part number for 350. If y’all could point me in the right directions that would be nice. Also would be interested in buying one if your in California
What is your goal? Just to drive it around or do you want something that you could build a little bit for more power? Pound for pound, the bigger displacement 350 is golden. The 307, while a good engine, was built mainly for reduced emissions and slightly better fuel mileage. It had to give up some torque and power for that.
They're essentially the same engine block besides the bore 84-back, but in 85, the non-442 307s went to roller cams for even better fuel/emissions manners. Easiest way to tell if it's a roller 307 without taking it apart is if it has an A5 intake and 7A (peanut port) heads on it. They are poor performers overall. You'd be better off with a non-roller 307 (A4 intake, 5A heads) for any real chance of upping performance.
A late 60s/early 70s 4-bbl version of the 350 is considered the best, but if you're not building for max power, any year 350 will do. Gas mileage should not be a consideration if you're driving an 80s Cadillac! But if you do want to be considerate of gas mileage, the 307 should be slightly better fuel mileage. Again, sacrificing some power to do that. All the Olds engine accessories should bolt up to either one. Be advised, the 307 and 350 use similar shape valve covers, but the 307 uses 5-bolt covers vs. all 10. So if you're buying those cool 350/455 chrome covers for your 307 with 10 holes...you're going to have to work something out there.
Keep scouring the boards and if you belong to Facebook or other places on the web that car guys hang out, keep asking. Someone is likely to come up with something for you.
What are the emissions laws? Is exempt from an earlier engine swap? What exhaust can you run? If it is factory Olds 307 powered, an Olds 403 is the best, direct swap. I know California is very sticky about older engine swaps into newer body vehicles. The 10 bolt valve covers go on 5 bolt heads, the extra holes just need a dab of RTV to fill the holes.
Last edited by olds 307 and 403; October 18th, 2022 at 06:04 AM.
I found this 69 old 350 that thought my work for a rebuild for my Cadillac. Would this fit on my THM 325-4L GM Turbo Hydromatic I know the 350 on the Buicks and Oldsmobile is in the same era came with front wheel drive stock 82-85. Wonder how’d I’d access the over drive since it’s electronically controlled lock up torque converter. I’ve heard that the transmission can run it but I would nuke the tranny if I floored it.
As for the emissions here in Los Angeles I usually give the smog guy a donation to pass me. I wasn’t gonna bring up I swapped it to anyone. I could always add a smog pump I assume to the 350?
I believe that trans is very similar to the 2004R rwd trans. Transgo does offer a shift kit. https://transgo.com/products/325/
I would also look into servo and boost valve interchange with the 2004R. You can get an aftermarket controller for the lockup. Are you using the stock carb and distributor? I assume you are keeping the 350 mild? What compression and cam are you planning?
I was hoping for some advice from you guys I’m kind of a newbie when it comes to this but I know enough of the process of how to rebuild it. I know a little of about the stamping on the heads and that being said if I recall the 7a was the better option I’ve found some with the 3a so I was hoping this 69 would work for me with a kit. If you can recommend some options for me when I finally find one. My real objective is to have a fairly faster car then my 85 mph ht4100 engine. Also a more reliable block since it’s an aluminum cast.
You will need the Tornado frame and motor mounts for an Olds V8 from a Tornado or Riveria FWD. I would get the machine shop to check over the motor. The Mahle and DSS forged pistons will give low to mid 9 to 1 compression with that 69 motor, both available in multiple oversizes. I would say a Qjet tuned to the motor with the stock intake and a used or Chinese Ebay HEI for an Olds V8. What octane fuel are you planning on using? I assume you want a smooth idle?
Yes I’d like a smooth idle and just anything with some more HP with reliability. Right now I use regular but before I had my engine timed slightly higher for performance I used supreme 91 but when gas prices got higher I retarded the timing back to fsm specifications. If I recall the frame was essentially the same since they all had the same e Body and I believe I can just use the motor mounts from the tornado or rivieras . From my experience the control arms and suspension is the same except for the springs because the weight difference. Will Any of these pre 1985 Olds 307/350 will be ok for my fwd? Or should I only stick to finding tornados and rivieras engines from the same time frame. Sorry if that’s a dumb question
Last edited by Zunzulo; December 28th, 2022 at 10:01 AM.
That 69 350 will work better than the later 350 or 307, if you can get around emissions. Something mild like the 204/214 generic cam should work for what you want.
From Olds 307;
You will need the Tornado frame and motor mounts for an Olds V8 from a Tornado or Riveria FWD.
Originally Posted by Zunzulo
If I recall the frame was essentially the same since they all had the same e Body and I believe I can just use the motor mounts from the tornado or rivieras .
I think what Olds 307 was saying you need the Frame engine mounts (not the frame) and the engine mounts from a Toronado.
Last edited by Dynoking; December 30th, 2022 at 02:01 AM.
Reason: Grammar
Exactly, what I meant. Olds uses different mounts than a Cadillac V8. A good example is the F body 403 mounts. They are a unique solid mount that allow and Olds V8 to be bolted were a Chebby V8 is. They also allow an Olds V8 to be installed in GMC and Chev trucks. I would be shocked if the 4100 used the same engine and probably different frame mounts.
I need these frame brackets and cv axel support brackets..and manifolds..anyone got a
Originally Posted by olds 307 and 403
You will need the Tornado frame and motor mounts for an Olds V8 from a Tornado or Riveria FWD. I would get the machine shop to check over the motor. The Mahle and DSS forged pistons will give low to mid 9 to 1 compression with that 69 motor, both available in multiple oversizes. I would say a Qjet tuned to the motor with the stock intake and a used or Chinese Ebay HEI for an Olds V8. What octane fuel are you planning on using? I assume you want a smooth idle?
I cannot find the frame brackets I need to do my motor swap.. I got new style oil pa
My motor came outta a 85 Riviera.oil pan is a newer style not as deep but it worked... I need manifolds brackets axel with support I guess . Can anyone help me out or possibly have or know who has these parts?
Yes, you can, especially for what you want. Those heads are crack prone and it is the weaker windowed main web block. You can go a few different ways for pistons, from 7 to 9+ to 1, without excessive head milling. You can also go with smaller chamber, better flowing 64 to 72 330 and 350 heads as well. Just drill out the head bolts and one dowel.
Ok awesome I’ll probably pick it up this week since the price with the transmission is a no brainer. It also has all the accessories parts so that will help a lot with the build. I’ll pick up a master rebuild kit and take it all apart and check the block for damage. Thanks for all the help and if you have more suggestions for the build I’d appreciate it. Anything will be better then my 85 horse power current engine
Let us know what you find. CC the heads and measuring how far the pistons are below deck will give the actual compression ratio. Also take a close look at the pistons and take a picture of the dish, factory are 14cc.
Was curious since I’m in California if I could rig a smog pump and manifold from an 80s head on to this 77 for smog regulations.I have the cat converter still and havnt straight piped the car. I’ve heard of others doing that with a 80s block and 80s heads for smog rules. I can pay a couple smog guys here a fee to just pass me and not look but was wondering if you could amuse my question.
Last edited by Zunzulo; February 10th, 2023 at 08:39 PM.
Are there plugs just above the exhaust ports? If not, either those heads need them drilled or you could get a set of later 5A 307 heads and use them. Of course they have a smaller intake port and a smaller 1.75" valve vs your current 1.875". Both have the rotten siamesed center exhaust port and small 1.5" valves. Their bonus is the 10cc smaller chamber if you reuse the current pistons. You could add 1.875"/1.56" early 350 valves and get the machine shop to use a bowl hog under the valves. I used 5A heads stock on a truck, idle to 4500 rpm was decent with a 204/214 cam, shorty headers and a TBI in a truck.
Was curious since I’m in California if I could rig a smog pump and manifold from an 80s head on to this 77 for smog regulations.I have the cat converter still and havnt straight piped the car. I’ve heard of others doing that with a 80s block and 80s heads for smog rules. I can pay a couple smog guys here a fee to just pass me and not look but was wondering if you could amuse my question.
Assuming you are trying to maintain the optics of a 1980 motor, yes all the parts transfer. You will need a set of Olds heads that have been machined for the A.I.R. tubes. That means either crappy 1980s heads or a set of 1966-67 heads (the 66-67 Oldsmobiles with Calif emissions also used A.I.R.).
None, all he needs a compatible catalytic converter, which I assume he has in California, if he has an air pump. Not used to seeing that stuff till 83 on Olds up here. My 81 and 82 307 in Delta 88's actually had factory plugs in the air ports.
So I found a 1978 cutlass with the olds 350 engine and transmission set. My caddy is FWD yet this cutlass is a RWD can I use a smaller flywheel to connect to my transmission.350 should mate right up to the THM325 4 speed transmission found in all 82-85 Eldorados. Can anyone send me a lead on where I can find motor mounts from an 82 or later U Shaped one piece bracket. I think this engine is the best I can find here in Los Angeles
Yes, the 350 is a bolt-in. Unfortunately nothing from your 4100 will work on the Olds motor. You will need not only the front motor mount bracket, but the correct Toronado exhaust manifolds, the correct Toronado starter, the correct Toronado flexplate for the TH325, and the correct Toronado accessory brackets and pulleys. Sourcing all those parts separately will probably cost more than buying a 1982-85 Toro parts car. None of those parts are available new (with the exception of the flexplate and starter), so you'll be searching for used.
Ok I also found some donor 85 rivieras and tornados for about 2k. So I’m trying to haggle the best price right now. You’re right a donor car would be the best bet. I’ll update when I figure out which engines they have under the hood. Hopefully they have 350s with the fuel injection inline
October 17th, 2022, 10:56 PM
