How hard to go from BBC to SBC?

[ratty65]

OK so I am in a bind here. We recently purchased a new to us 1968 suburban for my wife. Well within two days of buying it heard a little tick/ knock. The folwoing week took it over my mechanic and he said it sounded more like just the valves needing a little adjustment. Needless to say the tick went away but the next day it was back again and took it back over there. He took the thing apart and found a bent pushrod. Told him to take his time and now that he has the whole thing apart there is wear on the cam bearing and has not taken the bottom end apart yet as I told him to stop. MY question is I can get my hands on a nice SBC with all accessories pretty much to drop in but am curious what is involved in swapping over? The SBC will have headers on it so i guess im wondering if it will just be the mounts that will be different. The original engine in the suburban seems to be an 1970-1971 396 according to the stamping on the heads and block. I simply dont have the money right now to do a full rebuild on the BBC. .

[Clrussell]

What trans is in the burb now? I'm doing the exact reverse of what your wanting to do. I'm going from small block to big block. So far it's pretty much bolt in other than the crossmember fitment ( a previous owner had moved it it seems). You'll definately need exhaust work, power steering is different if you have that.

Which if you do have p.s. And want to part with the pump/ bracket let me know I need one.

[ratty65]

The trans in there now is a 700r4 I beleive. I know its no longer the TH400. As far as power steering how hard woud it be to mount the current set up on the sbc? or would it be crazy to drive it without p/s?

[Clrussell]

To mount your power steering to your small block you'll just need the accessory brackets. They are different on a big block/ small block I found out.

Your trans should bolt right up, not sure on linkage issues though as mine is a 4 speed.

[ratty65]

Originally Posted by Clrussell

To mount your power steering to your small block you'll just need the accessory brackets. They are different on a big block/ small block I found out.

Your trans should bolt right up, not sure on linkage issues though as mine is a 4 speed.

Thanks for your help. Now the last question would be are the engine mounts the same?

[Clrussell]

Are your engine mounts clam shell or flat? Either way I believe they are the same. Mine bolted right on my 454 and then bolted down in the same spot. (Mine had the flat style)

[imjeff]

Originally Posted by ratty65

OK so I am in a bind here. We recently purchased a new to us 1968 suburban for my wife. Well within two days of buying it heard a little tick/ knock. The folwoing week took it over my mechanic and he said it sounded more like just the valves needing a little adjustment. Needless to say the tick went away but the next day it was back again and took it back over there. He took the thing apart and found a bent pushrod. Told him to take his time and now that he has the whole thing apart there is wear on the cam bearing and has not taken the bottom end apart yet as I told him to stop.

I'm a little suspect about finding "cam bearing wear" and finding a bent pushrod after adjustment. Cam bearings are pressed into the block. I am curious what standard he used for wear. Pushrods often get bent when valves are incorrectly adjusted. I'm not saying your guy did it, but it is a bit curious.

MY question is I can get my hands on a nice SBC with all accessories pretty much to drop in but am curious what is involved in swapping over?

You'll need one with brackets for all your accessories. You're also getting into another unknown motor. Sometimes the enemy you can see is preferable to the one you can't.

The SBC will have headers on it so i guess im wondering if it will just be the mounts that will be different. The original engine in the suburban seems to be an 1970-1971 396 according to the stamping on the heads and block. I simply dont have the money right now to do a full rebuild on the BBC. .

You will need motor mount perches, headers for the application and motor mounts for the application. Will you be doing the swap?

[ratty65]

Originally Posted by imjeff

I'm a little suspect about finding "cam bearing wear" and finding a bent pushrod after adjustment. Cam bearings are pressed into the block. I am curious what standard he used for wear. Pushrods often get bent when valves are incorrectly adjusted. I'm not saying your guy did it, but it is a bit curious.



You'll need one with brackets for all your accessories. You're also getting into another unknown motor. Sometimes the enemy you can see is preferable to the one you can't.



You will need motor mount perches, headers for the application and motor mounts for the application. Will you be doing the swap?

I know what you mean about whether the adjustment he made may have been the cause.However the tick was there before he ever touched the truck so giving him the benefit of the doubt there. As for the wear on the bearings I did come over and did see very little shavings on the cam bearings. Now is it from that or something else ???. I think I may end up sacrificing my 1971 C20 suburban and having the engine swapped into the 1968. IN my 1971 I have a 454 that runs fine so considering that option. I will keep the 396/ 402 and someday when I can afford it have it rebuilt the right way.

[imjeff]

I've seen shavings on cam bearings from installing/removing the cam. When they wear you don't find shavings (they would get smeared around the bearing by rotation). I'm not saying anything bad about your guy, but it wouldn't be the first time a collapsed lifter got adjusted to a bent pushrod. Cam bearings don't cause ticks, they are purely a rotational plain bearing that doesn't usually create issues. Your big block swap would be the easiest if you choose to go that way. Are you doing the swap?

[ratty65]

Originally Posted by imjeff

I've seen shavings on cam bearings from installing/removing the cam. When they wear you don't find shavings (they would get smeared around the bearing by rotation). I'm not saying anything bad about your guy, but it wouldn't be the first time a collapsed lifter got adjusted to a bent pushrod. Cam bearings don't cause ticks, they are purely a rotational plain bearing that doesn't usually create issues. Your big block swap would be the easiest if you choose to go that way. Are you doing the swap?

Unfortunately due to time space and no help available I will not be doing the swap. Under different circumstances I would take my time and do the swap myself unless someone wants to come up and help me do it HAHA!!! I can provide plenty of beer and tequila and some Mexican Arrachera which im sure would be cheaper than paying my mechanic to handle it.!!!!

[imjeff]

I would take you up on it if I were a couple thousand miles closer!

[kwmech]

Could be also that the first valve adj he did not notice the bent rod, then caught it the second time around after it bent some more

[kwmech]

So, what ever happened with this?

[ratty65]

Kept the 396/ 402.....my mechaic that was working on it took it all apart and said the bottome end all loked good and aside from the heads having a little carbon build up it all looked good. SO got a new cam, can bearings valvels, rocker arms, etc and he is giving me a warranty in writing that there was no other damage done and everythign else is ok. Since I had aleady planned on spending a certain amount originally we came to an agreemt to have the work done for said amount since I am a regular custoemr of his and have brought him and continue to bring him business. Also let him take his time with this so he would be in no rush and work on it on slow days. I stopped by today and he said the engine should be back in tomorrow or saturday. Keeping my fingers crossed everything works out.