Per title.

For an Electra sporting vin Y 307 and TH200-4R, rear gears unchecked yet. Nothing happening before winter.

In a hunt to preserve the museum register status. Only motors available for that particular car during its span ( 77-84 at me) are allowed, so no big blocks. No aluminium heads. Aluminium intake easy enough to hide ( performer ( btw when did it came out?)) or then the stock iron intake. With these laws, i could also fit an Buick there, which would be kind of nice to have Buick in Buick, but then id had to figure out all the auxiliary systems etc etc, far too much work, plus i know the basics of Oldsmobile engines already.

The goal is to keep it quiet, well mannered, and work at low rpms, like an fine car should. And i just want to get rid of that 307. Otherwise fine car is ruined with a motor which barely gets out of its own way. Its power everything, so pretty heavy. Then to the options.

Unchanging options for both would be exhaust manifolds, HEI ignition, and either stock iron or maybe regular performer. EGR is already disabled, and museum registered with it, so thats out of equation.

I have an build 362 at my cutlass, line honed, 2864gr out of rotating mass, decked, .040" quench. Just about perfected. From that motor, id need to swap the cam, of course, and heads to drop compression. Ive had #8 heads, which would drop me right around to 9:1 after valve job.

Other option would be a stock 403 ( i wont be building engine with expenses i used to 362 for that), with maybe the done 7A heads i have on my 362 now, but not sure how playable idea that is, with narrow seats and porting, for low rpm application. Narrow seats atleast aint too good for longevity id think, porters advice was to check them yearly with kilometers i make.

Would a roller cam show benefits at low operating rpms? When building a smooth running engine.

Which makes more sense? Moneywise, 362 of course, since with that option id be only out of money what it makes to rebuild #8 heads, and few gaskets. Torque? Am i losing that much, if any, with 41- or more cubes, depending of overbore, with stockish bottom 403, versus spot-on ( tolerance-wise) 362 bottom?

Ive been pondering this at my head, and like to hear others options. Head says 362, but open to hear discussion. Other than keep the 307

 

I think my vote would be a stock 403 with a 3.23 or so rear gear. Have a set of stock early 350 heads done if you were willing to use enough octane to support 9 to 1 compression with a stock cam

 

Good to hear from you Jouni. Back in the day they thought the 307 was adequate in the big cars, even Cadillacs! Gutless I know and the CCC system is a complicated system... I've not heard of anyone putting a earlier Hei and carb on a 307 but I'm sure it has been done.

 

DX build, one of Mark's cranks, 430-ish cu in.

 

Now, THAT would be an option

 

Its Carter AFB600 and HEI, usual back-then Finnish fix. Fix with what you got.

Its okay, lets say in city, but trying to pass at highway from 75mph, or keeping up with traffic, its awfully slow, finding myself flooring it all the time. And even then, with luck, barely holding with others.

And i like to drive with normal traffic.

 

The 403 has ~10% more displacement, so there's more opportunity for torque there. The main problem is getting a good compression ratio, heads that flow enough, and a good cam. You can go longer duration on the cam in a 403 and get the same manners, as compared to the 350. The only major change to the heads if using early small block heads, is the holes need to be opened up for the 1/2" bolts. Although maybe the #8's already have those? I forget when those where cast.
If you're keeping it in the 300-400-ish ft-lbs range and the bearings and rings are good in the 403, then can just drop some heads on it and go.
I think a roller cam give more power potential with a smoother idle. The roller lobe is able to get more valve open time without adding a whole bunch of overlap. But, you have to buy roller lifters, which is a challenge right now and always expensive.

 

403, 7a, 9:1, A4 or Performer, Exh Manifolds, dual exhaust if possible.
202 / 212 @ .050 / .520 lift Hyd Roller (Engle used to grind them for Mondello (have one in red car, DD for 12 years now)
200-4R, 3.23 - 3.73
See if there is a large diameter front sway bar that will fit car

Cookin with gas, baby! (I love spending people’s money!)

…

 

I vote 403. Even in low compression factory form it makes a buttload of torque, which is what you need to get a pig iron vehicle moving, and it will run on low octane gas without complaining.

 

Use an upgraded radiator for a 403, the one from the 76 should fit right in, it will run 20 degrees hotter than a comparable 350. The 5 blade 307 fan is marginal on a 403, go with the 6 or 7 blade fan. Budget upgrades to the 2004R, bigger boost valves, servo and deep pan with a 700R4 or 4L60E filter at minimum. I have broken 4 of them. If you push 400+ ft/lbs, that budget grows to $1000 US for parts alone. Add a good remote cooler to start. I towed a probably 2000 pound boat in OD without it failing but the extra clutch and steel in the OD for such a heavy car is a good idea. You have a good 362, the #8 heads are good once the lip under exhaust valve is removed. Go with a roller cam like Mark sent me, a 218/218 .525/.525 on a 112. If 350 hp and 400 ft/lbs is enough. You want gain any noticeable power with an A4 over that iron #17 intake other than weight savings, same with the Performer. I owned a 81 Delta 88 4 door for 10 years, it went to 420,000 km through many Winter's, a very good car. That Buick is a much better choice than a G body. Better built, handles better and way less rust issues. If your Wife is happy with it, a very smart move👍.

 

Thanks for comments.

So, its seems like its fresh 403 then. Since the car has originally been E4MC-carbed, im intriqued to install TBI EFI, likely Holley Sniper, since its by far the most used here, and even locally sold ( along the Atomic EFI). Not too interested to start solving the mystery of spliced wires, replace HEI, get EGR and AIR back working correctly, etc.

That would be good project while replacing the fuel tank, to install Aeromotive in-tank system with it, cant remember the fancy name for it. Phaeton or something. It was a really cool car to drive this weekend, just past 800km's, but lazy as hell. Top-speed at highway.. 150km/h.. And even a slight incline, and it barely goes 130km/h gas pedal through the fire-wall.

 

I had an 89 Olds wagon. The first thing I did was swap the rear end with 3.90 gears. With the overdrive and the tall tires, this made a huge difference but was still good on the interstate.

Later came the 403.

 

I have a 350 olds in my 77 Pontiac Bonneville. It's near stock with a 73 short block , 7A heads. 260h comp cams and performer Intake. With a 3.42 gear it's plenty peppy on the street more than enough get up and go ., Not gonna win any races and it has a hard time spinning the 10 inch wide drag radials lol. But honestly for what I use the car for it's plenty. Just a nice cruiser that may become a tow rig for my drag car since I boxed the frame and did a bunch of frame work. Just my 2 cents.

 

And thats just exactly what im looking for, thanks for insight.

After driving more the Buick with Vin Y 307, id say its adequate at traffic up to 55mph, so in city and suburbs it does just fine. But it really falls on its face at highways and higer speed-limit 2-number roads, and thats where i spend far over 50% of time i drive it. I like to drive it, not just cruise around city.

 

It has way too tall of gearing in OD. Do a gear swap, your 3.23 gears are even too low but a hell of a lot better than the factory 2.56 in my 88 Cutlass with a factory 2004R came or your probably 2.73 gears. My 70S has 2.78 gears, under 1400 rpm at 60 mph with the 2004R. It is getting 3.42 gears and posi next, pretty much ideal with 2004R. Your 60 mph is just over 1300 rpm! Even 80 mph is under 1800 rpm if you have the 2.73 gears. My 81 Delta 88 4 door was Ok in town, it actually best on the highway with the 307Y/TH250C and 2.41 gears. It was about the same rpm as your car will be in overdrive with the 3.23 gears.

 

Ill change the gears to 3.23+truetrac alongside when i install the 350. I believe its perfect combination for my use, from city to driving down the highway 90mph.

I actually got my engine out by now and in pieces, no surprises. Through the washing machine and back together. This time i got the whole swap done in just one winter, only expensive thing will be headwork, and if i go sniper now. If money shows so, ill slap it together with carb for first summer..

 

I believe when you consider your limitations the stock 403 makes the most sense.

A GMC motorhomes 403 was rated 200 HP @ 3600 RPM and 330 lb ft @ 2400 RPM
VS a vin code Y 307 which was rated 140 HP @ 3600 RPM and 240 lb ft @ 1600 RPM

If you can emulate the motorhomes exhaust I don't think you would have to touch the stock 403 in order to easily navigate daily driving while keeping up with traffic. Honestly a healthy bone stock 403 should feel like you injected 100 shot of NOS to a code Y 307 in comparison. Without a gear swap.