Hi,


I am looking at taking out my trusty 307 and slipping in a 350 or 403. I understand that all the small block engines have the same mounts and everything should just bolt on. Want I wanted to ask here was -


1) How to deal with the Computer Controlled Carb?
2) Jasper or who to supply the replacement engine?
3) Any known issues connecting up to the existing transmission?


I want it to look stock and be smooth like the 307 BUT have more power for accelerating and going up hills when loaded. Something the 307 really can't achieve.


Also, is the 350 or 403 smoother and any issues with over heating? I've heard about the cooling issues with the 403 in general terms but as I'm only driving on road trips and for general use I trust that won't be a worry?


I'd appreciate any advice.


Thank you.

 

A 403 is tougher to cool. Make sure you have a big rad, good shroud, 7 blade fan with a heavy duty clutch. A mild 350 will work with stock 307 parts in good shape. You can use your CCC carb if you stay mild on compression and cam.

 

I'd surf craigs list for a 403, find some 350 heads (for a boost in compression) & a non-cc q jet carb & distributor. Get that all rebuilt.

 

In my years as a full time tech, I had a LOT of bad experiences with mass produced engines, especially those on the low end, price-wise.

 

Hi Gents, Thanks for your comments. I hadn't thought about upping the size of the rad...


I do want a stock cam I think if only to keep it running smoothly.


How will 350 heads on a 403 help? Would the higher compression lead to more heat too?




I hope to leave it at a GM dealer in a smaller town and just let them get on with it....


I hope they will know what their doing! A GM dealer I went to a few years back didn't even know where the oil cap was....


Cheers.

 

There is a difference between a mild cam and a stock one.

Most overheating issues are due to the Siammesed cylinders

Where are you located?

 

Hi Captjim,


Currently in London but will be returning to the U.S. in the next month or so.


My plan is to get a replacement engine and then have work down at the end of a road trip..... The dealer will be able to take their time and have the wagon for months if necessary.


I don't know much about cams but thought a stock cam would make for smoother running like I already have with the 307.


I don't want a hot rod or a thumping big engine which has a lumpy idle if you know what I mean...


Cheers

 

I agree.

 

Do not use an ultra-low compression commercially rebuilt engine.
You may end up with the same power you have now, but half the gas mileage.

If you want to upgrade, get a decent-running motor used, rebuild one yourself, or have one rebuilt.

I would also be very wary of having a dealer do any work on it. Nobody there knows how to work on these cars anymore, and this is a recipe for disaster.

Finally, do not just drop in an engine. Plan the entire package.
The fact that you hadn't considered that you would absolutely need a larger radiator concerns me. You need to think this through before just paying someone else to make your mistakes for you.

- Eric

 

on the streets TQ is king. bigger the CI the better. go with 403. since it a easy swap a 455 would be better. 403 have veary low compression so is easy to over cam and be a dog. for example a buddy of mine had a 403 with a mild camshaft with 205 @ 50 camshaft , it ran good had good power went to the track a few times . he wanted to go faster so he just went to a bigger camshaft 224@ 50 . it lost a lot of low end power was not a easy to drive poor throttle responce. went to the track and ran slower. to fix the problem he would have to raise the compression ratio or put the smaller cam back in.
A good rule of thumb 8 to 1 compression use a camshaft with 210@ 50 max for a 403 small block and 216@ 50 max on a big block works best for a high gear automatic car. uping compression to 9.5 add 10 degrees of duration for a street bound car . if fastest ET is the only thing you want put a 390 or better gear for a small block and 342 or better gear for a 455 regardless of what street cam you put into it will make the best ETs. the first mod i advise is do a gear change first and build around the gear you chose. a 273 or 251 gear car will be slower with any cam much bigger than stock anyway.

 

A stock compression 403 with a mild cam will blow away a stock 307. Even with the awful single exhaust, the difference will be big. There are still good core motors, I have had good luck. You might find a good one still that just needs gaskets and a timing chain. I would do a Vin 9 307 or smog 455 cam at minimum. Also look at a gear swap, run at least 3.42 gears with OD.

 

I am a fan of the 403 engine. I built one and put it in a g-body just to see how they would run. I used a mix of parts I had. Car ran 12.96 @104.95mgh. The stock one angle small valves #5 heads wouldn't flow anymore. Engine never went passed 180 degrees, very streetable. I did put a J&S halo girdle in it just in case. Lol I beat on it pretty good. I hope to dig it out one of these days. Look for a 403. Ken

 

If your just wanting to get the car running nice and don't care about hi performance the Jasper engines are fine. The 350 or the 403 would be fine as a replacement engine.

 

I just went to Jaspers site, their engines are not el-cheapo, they should be fine. Here is what I came up with for a 403,
CARBURETED (8TH VIN-CHAR "K") GASOLINE ENGINE
V8,FLAT TAPPET,W/O A.I.R.

For applications over one ton, please do not include an installation kit.
We do not offer kits for these specific applications.
Price: 3427.00Core Charge: 240.00Review JASPER's Core PolicySkid Charge: 50.00

$3700 without shipping. For a little bit more, you can have a custom engine with better performance, IMO.

 

Remember, that engine will have deep dish pistons, with about a 7-7.5:1 compression ratio, severely limiting power and cam choices.

As Jim (and Clint Eastwood) says, "for a few dollars more..."

- Eric

 

Yes, the pistons will probably be sitting down .050 with a thick gasket. And, you have the cost of the new cam and lifters (unless they will install your cam) and I'm sure it will void the warranty. Will it probably run OK? Yeah. Are you leaving a fair amount of performance on the table? Yeah.

 

Thanks for all the advice.


Performance...well anything must be better than a 307? I want it smooth and quiet...


My Dad had a Holden 253 V8 in 1971 and that went like butter in a fry pan...


That's what I want a 350 or 403 to do.


I note a quote below is without A/C. My wagon does have A/C.


Whats the difference between a smog engine (I assume for California supplied cars back in 1977/78/79?) and a non smog engine? Should I be taking this into account? My 1988 has a cat but I'm in an area were there is no smog testing.


I'm just trying to think ahead in case I move...


Thanks.

 

"Smog motor" is a generic term for every engine made after 1970 (compression decrease) or after 1972 (EGR), or after about 1973 (catalytic converters), depending on your perspective.

It refers to the whole class of large displacement, low performance, low MPG motors made from the early '70s through at least the eighties (at least in my book).

- Eric

 

Hi Eric,


O.k. thanks.


Sounds like I should avoid them like the plague.


I guess a modern motor (from a 1996 Buick Roadmaster wagon) or a twin turbo charged (or super charged 455 from say 1969/1970 might be fun...


All the choices...

 

It will be, but if you are spending that much money, don't you want to maximize your investment? KB makes pistons that work well with the 4A heads, ending with 9.5 to 1 +/- Find a 403 core, have it rebuilt with a mild but upgraded cam and you will be happy, IMHO.

 

Don't settle for mediocre. A well built and thought out 350 or 403 even with a mild towing cam will idle like stock but pack a punch when you need it to. I had a nice little 350 with a very mild cam it idled like stock but ran very strong at the strip and on the street. NOW I know your goals aren't to go fast or racing but I think with some simple upgrades your engine will perform better and be just as efficient as stock. I would talk to reputable olds engine builder and I'm sure you will get the best of both worlds.

 

While I have no experience with their products, Jasper DOES offer performance engine builds. Go to their website and click on the Performance Engines button at the bottom. They also advertise this option in various car magazines. Again, no endorsement, just offering an option if you want to go with Jasper.

I'm sure these are not LESS expensive than their stock builds...

 

That would be a fair assumption, IMO.