Pontiac 301 to 400 conversion question

[Bonnewagon]

I too get confused and I've been playing with these motors a long time. I seem to remember very little from the front of the 301 fits the 350/400/455 family. The deck is 1" shorter so alignment is different. The fuel pump, water pump, carb, distributor, oil pump, thermostat and cover, valve covers, oil pan, motor mounts, alternator, power steering pump, and exhaust manifolds with some fudging, all fit. The alternator and power steering pump are the same but the mounts are different, and swapping a PS pump mounting brackets is a pain. Best to just find the bigger motor ALT, PS, WP, crank pulley belt set up w/brackets. You need the A/G body engine mount brackets to use the big motors in our cars. A cool set up is to use the 301 baffled oil pan, and if you are lucky, an old 400 windage tray. The oil filter on a 301 screws to the block, the adapter is needed for the big motors. Some fit verticly, some at an angle. The Z-bar block ball stud for a clutch is located in the same spot. AC brackets are different too. What year motor? '70 and older heads are high compression.

 

[buzz77]

I too get confused and I've been playing with these motors a long time. I seem to remember very little from the front of the 301 fits the 350/400/455 family. The deck is 1" shorter so alignment is different. The fuel pump, water pump, carb, distributor, oil pump, thermostat and cover, valve covers, oil pan, motor mounts, alternator, power steering pump, and exhaust manifolds with some fudging, all fit. The alternator and power steering pump are the same but the mounts are different, and swapping a PS pump mounting brackets is a pain. Best to just find the bigger motor ALT, PS, WP, crank pulley belt set up w/brackets. You need the A/G body engine mount brackets to use the big motors in our cars. A cool set up is to use the 301 baffled oil pan, and if you are lucky, an old 400 windage tray. The oil filter on a 301 screws to the block, the adapter is needed for the big motors. Some fit verticly, some at an angle. The Z-bar block ball stud for a clutch is located in the same spot. AC brackets are different too. What year motor? '70 and older heads are high compression.

Thanks. Its a 1969 block and heads. I have already sourced the crank and waterpump pulleys all the alternator and PS brackets and PS pump unit. Good to know that I can use the oil pan. My block already has the windage tray so thats cool.

Are you saying the 301 stock alternator is different than the 1968-70 alternators and will not align or that I just need the 69-70 brackets?

Now im confused with the oil filter housing. what adaptor is this and where can I find it?

thanks guys

 

[Bonnewagon]

You do know the windage tray is made of unobtainium, right? That sucker is RARE! The ALT is the same, just the brackets are different. In fact you can get one of the high amp 301 units to work as long as you have the right big motor brackets. Be careful with the water pump/timing cover. They changed the bolt pattern late '68 or early '69. I was on vacation 2 states away and the pump quit. I forgot I used the older timing cover on a '69 400 motor and I needed several anxious days to locate a replacement. The 301 oil filter screws to the block, the big motors used an adapter, which one depended on the application. Even the Ram Air exhaust manifolds required a special adapter for clearance. Epay has them and even the aftermarket offers them, so no biggie finding one. Just figure which would fit best, angled or straight. The angled-in one looks like this and is the most common it seems, depending on chassis-

 

[buzz77]

What the heck is unobtanium? its metal or do you mean unobtainable?. My engine is basically a short block with 62 heads. I have found a mid 1969-70 11 bolt timing cover with the correct timing marks and the mid69 alternator brackets (they had a slightly different bend compared to the 67 to early 69 brackets.)

The other thing is whether my block has 2 screws for mounts or something? Something I saw on Butler about the first 400 blocks didn't have all the bolt holes drilled out and I may need some adaptor they sell.

The oil filter worries me with the angled or straight. it seems the oil filter already on the 301 is so close to the firewall, not much wiggle room. I wonder what angle is better for such a tight space

 

[Bonnewagon]

Unobtainium-
"An imaginary unavailable material used humorously to solve otherwise impossible problems; an item of unaffordable price." Sorry, old hot rodder's joke. And either filter mount will fit a G-body chassis. The blocks had 3 different sets of mount holes- adapters will work well if needed. Here is a chart from the AMES site.

Here's the heads chart for #62 from http://www.wallaceracing.com/index.html- as you see several exist, best to check part # if in doubt.
1965 326 250HP 62 / 9780562 1.88/1.60 8.6 c.r.
1969 400 330,335,350,366HP 62,48(MT) 2.11/1.77 72cc
1969 400 340HP(GP) 62 2.11/1.77 72 cc
1969 428 370HP (GP) 62 2.11/1.77 72 cc
1969 428 390 HP 62 2.11/1.77 72 cc

 

[buzz77]

Unobtainium-
"An imaginary unavailable material used humorously to solve otherwise impossible problems; an item of unaffordable price." Sorry, old hot rodder's joke. And either filter mount will fit a G-body chassis. The blocks had 3 different sets of mount holes- adapters will work well if needed. Here is a chart from the AMES site.

Here's the heads chart for #62 from http://www.wallaceracing.com/index.html- as you see several exist, best to check part # if in doubt.
1965 326 250HP 62 / 9780562 1.88/1.60 8.6 c.r.
1969 400 330,335,350,366HP 62,48(MT) 2.11/1.77 72cc
1969 400 340HP(GP) 62 2.11/1.77 72 cc
1969 428 370HP (GP) 62 2.11/1.77 72 cc
1969 428 390 HP 62 2.11/1.77 72 cc

Thanks!

So I will definately need the mm6 adaptors. yeah I have the 1969 heads. Can the bolts from the 301starter be used on a 400? Or will i need new hardware for that?

Now how hard is it going to be to line up the exhaust Manifold outlets to the downpipes?

 

[82GPLJ455]

The 301 starter and bolts will work on the 400.the exhaust isnt going to line up.the 400 has a higher and deck hieght and a little wider than the 301.

 

[Bonnewagon]

I "think" the 400 starter bolts are a bit longer but are easy to get. Since the 400 deck height is 1" taller than the 301, obviously the head and exhaust manifold will be located higher. Depending on the current pipe you may be able to persuade it up a little to fit. The other problem is that the 301 used an EFE valve on the driver side manifold and even though the pipe is flared to fit the valve same as a standard exhaust manifold, removing the valve introduces another inch or more of critical space to fill. The 400 used a similar heat riser valve on the passenger side manifold, over the years it usually gets removed and the shaft plugged. Also what chassis was the motor from, and where do the '69 manifolds dump down? In those years the steering box was behind the axle, so the pipes exited differently. You can use the 301 EFE valve if you use the 301 manifold which is flanged for it, and even though it will physically fit, some will consider the 301 too restrictive on a 400. I say lay them side by side and for all intents they look identical. Using an EFE valve helps a lot in really cold weather to warm the motor up quickly.

 

[buzz77]

82GPLJ,
Are you saying the 301 starter is powerful enough to crank the higher compression 400?

Anyhow thanks 82GPLJ and Bonnewagon for all the excellent advice and tips! I greatly appreciate it.

 

[82GPLJ455]

The starter should be fine.gm used pretty much the same starter on everything.

Im using my v6 starter on my 455,just had to change the nose on it to make it mount up.