Mustfire

What changes will I need to make insofar as motor mounts, flex plate, and harmonic balancer will I need to make? This new engine will be mated to the transmission and engine cradle out of a 85 Buick Riviera.

olds 307 and 403

I assume you beefed up the transaxle? Everything should swap over from the 307, including manifolds and oil filter adapter. It has been a while since I have seen a 80's Tornado drivetrain, how much hood clearance is there? You may need to lengthen the exhaust some due to the extra height and width.

Mustfire

The tranaxle is stock. I don't plan on "hitting" it that hard and if I start having problems, I'll address it then. This is not actually in a car.....I have grafted the entire engine cradle and frame (from the firewall forward) to the rear of a S10 pickup! So, I have a rear-engine, rear wheel drive vehicle. The 307 gave out (no oil pressure) so I decided to rebuild a 455 instead of the the 307. With the old engine, it "went" pretty good and handled like a go-cart! I am hoping to double my performance with the essentially stock 455. So, will the 307 flexplate and balancer fit?

joe_padavano

The TH325L4 is based on the 200-4R. Don't expect it to last behind a 455.

The FWD 307 motors used a smaller diameter flexplate than did all other Olds V8s. Use the 307 flexplate on the 455 to allow the starter to engage.

The low-torque 307 starter will likely have a problem turning over a new 455. The starter bolts to the transaxle, not the block, for this application. I don't think the early Toro starters interchange, but I am not sure.

You need the FWD oil filter adapter from the 307.

The 307 exhaust manifolds will not work. You will need manifolds from a 455 for an early Toro application, and I'm not even sure about those, given the differences between the TH325L4 and the TH425 transmissions.

Use the mounts from the 307. These will bolt directly to the 455 and the subframe.

Use the water pump, accessory brackets, and pulleys from the 307 on the 455.

toymobile

I have a set of 403 Toro exhaust manf. if they will work for you.

Sound like a fun truck, I converted a 350 Diesel to gas with head change, mounted in a Luv truck, had a serious traction problem but a blast to drive.

Good luck.

Johnny

Mustfire

Thanks guys! Keep the replies and the help coming! I knew going in that the transaxle would be my "week link". Does anyone know of upgrades that would help with this problem? And toymobile, I will keep the manifolds in mind. What would you take for them? And Joe, would these fit the 455? I'll try to post some pictures later today.

joe_padavano

They will bolt to the 455 exhaust ports, but the 403 is still a small block Olds with the shorter deck height. I SUSPECT they will clear the transaxle and other parts, but I do not know for sure. The manifolds from the 307 with the 7A heads are also SBO, but were configured for the tiny ports on the 307. 403 manifolds don't have that problem.

Mustfire

I have the 5A heads on the 307.

olds 307 and 403

If they are cast iron exhaust manifolds, they should work fine. I know one guy adapted a 2004R shift kit to work. If you can use some of the better hard parts and servo, that will go a long way in that transaxle surviving. I would add a big plate style trans cooler at the very least.

jcdynamic88

5.7 diesel fwd manifolds will work on the 455,a diesel starter and flywheel would solve your starter issues,fwd 307 oil pan will hit(barely) the crankshaft of 455.if you need fwd diesel 5.7 manifolds i have them,might have a starter and flywheel.i put a 75 455 in a 81 riviera(diesel) once and it was a rocket ship but tranny didn't like it much.jc

Mustfire

jcdynamic88

i love the creativity and ambition.

Mustfire

jcdynamic88, you said that the crank will "barely" hit the 307 oil pan. What can be done about this, or is it so "barely" that it is not a concern?

MDchanic

I f-in' love it.

What a hoot!

As with the old beetles, though, don't hit a tree.


As for the SB oil pan, if you need to use one, you'll need to "customize" it with a hammer.

- Eric