how to convert pre-CB to common block

[tvanlant]

I've passed the recommended hp level for the pre-common block in my 87 GLHS and I want to switch to common block. I would like to use my rotating assembly, if possible, cam, accessories, and as much else as I can from my current engine.

If you could please list ALL of the things I will need to change.
Thanks, Tyler

[turbovanman²]

Everything external bolts on.

Whats different is the cranks, oil pans and timing related items. CB uses round tooth, you have square tooth so you need to get 2 round tooth pulleys-one for you cam, one for you aux shaft.

[tvanlant]

Can I not use my square timing sprockets off my pre-CB on the common block? Also, if I put a round tooth sprocket on my cam, wont that throw the timing off?

[86Shelby]

Can I not use my square timing sprockets off my pre-CB on the common block? Also, if I put a round tooth sprocket on my cam, wont that throw the timing off?

The square tooth sprocket won't fit on the common block crank. Your cam timing will be off a few degrees. An adjustable cam sprocket or keyways will alow you get it back where you want it.

[tvanlant]

Excellent. So if I get a complete common block short block, all that I will need to change is the sprocket on my cam, correct? All the accessories from my old engine will bolt to it, correct?

[GLHSKEN]

Ues, Accessories bolt on

[tvanlant]

Are you running a CB in your GLHS, ken?

[GLHSKEN]

Mine has been off the road for a bit. I was running an 87 block with tII rods and laid down 291/341 on the dyno. I was not worried about it in the least at that level.

A +40 went bad and toasted that engine. So I built a cb forged engine with a CB 2.2L cast crank. This time the cal did not provide enough fuel and torched a piston... (swapped to a menegon head... what a difference)

[turbovanman²]

Excellent. So if I get a complete common block short block, all that I will need to change is the sprocket on my cam, correct? All the accessories from my old engine will bolt to it, correct?

Yep,



Bummer Ken, you have luck like me,

[Turbodave]

Common block uses a different water pump and pulley. I've never tried to swap one over, but I remember hearing that the non-common block w/p hits the block when bolted onto a common block engine. Can anyone confirm this?

[BadAssPerformance]

Common block uses a different water pump and pulley. I've never tried to swap one over, but I remember hearing that the non-common block w/p hits the block when bolted onto a common block engine. Can anyone confirm this?

I have the '87 water pump on my '89 CB and it fits ok w/o touching the block. Only issue is that the water pump needs to be removed to remove the oil pan or the oil pan needs to be notched to be able to remove the pan with the pump attached.

So, the subject of the thread makes me ask much HP is the non-common block good for?

[cordes]

I have seen many guys state that they get weary of the pre-cb at over 300HP. If it is a TII short block a little more. There have obviously been several guys who have put some good power through them though.

[GLHSKEN]

I have the '87 water pump on my '89 CB and it fits ok w/o touching the block. Only issue is that the water pump needs to be removed to remove the oil pan or the oil pan needs to be notched to be able to remove the pan with the pump attached.

So, the subject of the thread makes me ask much HP is the non-common block good for?

The notching works great... no leaks after I did it.

[Turbodave]

I have the '87 water pump on my '89 CB and it fits ok w/o touching the block. Only issue is that the water pump needs to be removed to remove the oil pan or the oil pan needs to be notched to be able to remove the pan with the pump attached.

So, the subject of the thread makes me ask much HP is the non-common block good for?

I knew I heard of some clearance issue, but that's no big deal if it only comes into play when removing the oil pan. Hopefully that's not something you have to do that often.

[8valves]

So, the subject of the thread makes me ask much HP is the non-common block good for?

Joe O'Connor has dyno'd 370 or in the neighborhood on a pre-common block engine. As far as I know that's been running like that for a long time now. Ken would probably know how long it has been, or at least a guess. I think it's over a couple years.

Aaron Miller

[turbovanman²]

I would believe that if your racing and running max HP all the time, then a CB makes sense. If you keeping the boost reasonable on the street with the occasional strip blast, the non-CB should be just fine,

[GLHSKEN]

Joe O'Connor has dyno'd 370 or in the neighborhood on a pre-common block engine. As far as I know that's been running like that for a long time now. Ken would probably know how long it has been, or at least a guess. I think it's over a couple years.

Aaron Miller

1st time I saw Jope at the track was 2001. still has the same engine. Runs 125mph consistantly

[GLHSKEN]

LOL... You start making over 300whp, you can ONLY run hard for 12-13 seconds at a time seconds at a time... That's a full 1/4 at 105+mph. Not many chances to really stretch the legs.

[8valves]

1st time I saw Jope at the track was 2001. still has the same engine. Runs 125mph consistantly

There ya have it folks, straight from the archives...!!!

Just kidding Ken- you know I'm a respectful young'n.

Aaron Miller

[GLHSKEN]

Lol...