Help help. Just broke motor, what to do!!!???

[JBrady]

The 1uz and 3uz heads should not be interchanged.

The piston shape on a 3uz uses an angled quench surface and the diameter is larger. You want to use 3uz heads on a 3uz.

Both engines are 10.5 compression but 1uz heads on a 3uz will at the very least raise compression and may have piston to head and possibly piston to valve interference.

 

[spf_lexus]

He still can do the block swap, but now he will need aftermarket 1uz VVT pistons with a custom 3uz bore. Not a brick wall per say, but once the pistons are swapped, i'm pretty sure your going to need a rebalance.

 

[spdrcr771]

Hey wait just a minute, this is suppose to be a direct swap. lex says that my vvti heads are the same as the 3uz vvti heads. other wise i would have never bought the motor cause i didnt have the money for custom pistons. its a little late for you guys to be jumping in here w/very bad news. Are yall sure your not getting my vvti heads mixed up w/92-97 1uz heads. Im all ready replacing 3 of the pistons w/new stockers cause of the valve hits on them from where the timing belt broke b4 lex got it. I need to get this issue cleared up ASAP.

 

[Lextreme II]

1uzfe Non VVTi and 1uzfe VVTi is two different engine. I am 100% sure that 1uzfe VVTi is the same as the 3uzfe VVTi engine except few things. Bore is slightly bigger but heads should be the same. I talked to my vendor from a local Lexus dealer about the cams. They are all the same. Therefore, I believe the 1uzfe VVTi head and 3uzfe block should work without any issue. If there is a problem, you can always send back the block and get full refund.

 

[spdrcr771]

Ok thanks Lex, Im crossing my fingers. I havent ordered the pistons yet, or picked up any of the parts I ordered from Lexus yet so im still good. I dont want to have to send this block back, I want it to work. This is where im @ as of this morning, gonna start pulling the motor apart today. I would think that if the heads & cams are the same, vvti1uz & 3uz then the piston design should be the same too. Ill take pics when i get there. I did find pieces of bearing when i took the upper pan off.

 

[Lextreme II]

That is one nice SC.... Love the 2nd gen SC4 and the color too. I have a 95 with 2000 body.

 

[JBrady]

Sorry but that is not correct. It is as I stated. That said it is POSSIBLE that the 3uz pistons will not hit the 1uz heads but the 3uz pistons have an angled/beveled shape which has the corresponding shape in the 3uz heads that create the squish/quench areas. The 1uz has flat/parallel areas. Given the 3uz is larger diameter bore and the pistons have raised areas unlike the 1uz I would be very concerned that this will not work.

 

[spdrcr771]

Well here is the pics. The vvti 400 pistons come up out of the block higher than the 430 ones so that means greater chance of not hitting head & the piston design is almost identical have a look.

98 VVT-i SC400







/ab239/spdrcr771_09/IMAG0148.jpg[/IMG]

 

[spdrcr771]

?? VVT-i LS430

 

[spdrcr771]

This im thinking would be a slightly lesser compresstion set up since the piston doesnt come up as high.

 

[spf_lexus]

Those pics help a lot! The piston "curvature" that is raised above the deck looks identical to the 2UZ pistons I swapped into my 4.7L hybrid. I had piston-to-valve interference and I had to machine the domes flat so that my 1uz heads would fit the 2uz block. If you shave the domes flat, your compression will sit "around" 8.8:1, a little low for N/A. If someone can post a pic of the underside VVT head I can answer this right away.

Clean SC btw!



I have no idea what the VVT heads look like underneath but if its the same as the early 1uz, you will have interference.

 

[spf_lexus]

http://www.v-eight.com/tech_forum/viewtopic.php?f=5&t=30&p=8053


Just found these specs and pictures of an opened 1UZ VVTi. Both motors have very similar piston crown.

I think your swap will work out just fine! Good luck!

 

[spdrcr771]

Those pics help a lot! The piston "curvature" that is raised above the deck looks identical to the 2UZ pistons I swapped into my 4.7L hybrid. I had piston-to-valve interference and I had to machine the domes flat so that my 1uz heads would fit the 2uz block. If you shave the domes flat, your compression will sit "around" 8.8:1, a little low for N/A. If someone can post a pic of the underside VVT head I can answer this right away.

Clean SC btw!



I have no idea what the VVT heads look like underneath but if its the same as the early 1uz, you will have interference.

Thanks for the "clean" comment, it could be better but im always spending my money this way. Performance/mantinance, oh well. Well here are some pics of the heads.

 

[Lextreme II]

Shawn u will pick up one VVTi Monday. So you will know.

 

[spdrcr771]

My Lexus tech buddy came by & brought me some copies of service tech manual's for putting this thing back together, thank god. torque spec's,sequence's, & where to find my stock bearing spec #'s to order parts. He's super anal, & he says it looks like it will work fine, l o l but did say "you wont know untill you put it all back in time & turn the crank. So at this point, im going forward with the build. Thanks for your help lex, I was about to freak out last night & today untill i got the heads off.

 

[JBrady]

Well that is what I get by going by the Lexus factory engine changes official "claims". This was back in 2001 and actually had engineering drawings showing the "changes" made to the 3uz vs the 1uz. I am surprised that the 1uz has the angled and raised quench pads as that is not what I remember from the above stated factory outlines.

From looking at the pictures both pistons designs appear to have a very similar dome design with the 3uz appearing to have a ring roughly the size difference of the pistons machined off the outside edge of the piston. Where the 1uz protrudes out of the block most of the distance of the head gasket thickness. The 3uz does look to be made to work within the casting dimensions of the 1uz heads. I can only guess that the dish portion of the piston has greater volume in the 3 vs the 1 as the larger bore will displace more and if the combustion chamber volume is similar between 1 and 3 heads this would increase compression unless the mentioned dish is larger.

You may want to mock up the engine block and the heads and rotate the assembly using clay to check piston to head and piston to valve clearance. Of course you would need to rotate the cam through its proper range.

Sorry if I caused you to stress out but I really thought my reading of the factory literature made the pictures you posted not possible.

 

[spdrcr771]

Well that is what I get by going by the Lexus factory engine changes official "claims". This was back in 2001 and actually had engineering drawings showing the "changes" made to the 3uz vs the 1uz. I am surprised that the 1uz has the angled and raised quench pads as that is not what I remember from the above stated factory outlines.

From looking at the pictures both pistons designs appear to have a very similar dome design with the 3uz appearing to have a ring roughly the size difference of the pistons machined off the outside edge of the piston. Where the 1uz protrudes out of the block most of the distance of the head gasket thickness. The 3uz does look to be made to work within the casting dimensions of the 1uz heads. I can only guess that the dish portion of the piston has greater volume in the 3 vs the 1 as the larger bore will displace more and if the combustion chamber volume is similar between 1 and 3 heads this would increase compression unless the mentioned dish is larger.

You may want to mock up the engine block and the heads and rotate the assembly using clay to check piston to head and piston to valve clearance. Of course you would need to rotate the cam through its proper range.

Sorry if I caused you to stress out but I really thought my reading of the factory literature made the pictures you posted not possible.

No problem man, you were just trying to help. Im glad you were wrong though. Im wondering if i should mock this up b4 i order parts. Thats alot of f'in work. Just to have to take it back apart. I could do this w/o having to go to torque specs right. just a light bolt together. Those cams are going to suck. that stupid little gear driven cam preload could give me problems, i dont have a bench vice.

 

[spdrcr771]

I fixed that forgo mentioned problem about no bench vise. Made me a 68x32 fold up to the wall work table, w/fold down legs & place to mount the vice. Now i can work with those cams L O L.

 

[spdrcr771]

If everything goes well, ill have the motor put back to gether by friday night. still waiting on a few rod bearings to come in. He do yall know if I have to pull the crank out change out the oil pump? Kinda need to know by friday. I havent really looked at it yet. I have all the pistons out right now. I wasnt going to change the main bearings, but if i gotta pull the crank out then i might.

 

[spdrcr771]

Oh and i got another question. How had is it to change the valve seals? Where can i get a spring compressing tool if my buddy doesnt have one. I dont want a POS eather.