my car is in the shop getting the short block rebuilt... the shop says ACL does not make rod and main bearings for the VQ35... DO the people who have rebuilt their short bocks just use nissan rod and main bearings?

Second question... Should I replace the cams while the engine is out? and can the UTEC control the timing properly?

Third question...my short block is back from the machine shop...they said the stock bore wiseco pistons met all the specs and I do not need to go to an overbore piston....how concerned should I be?...my car only has 13,000 miles on it

thanks for your help,
mark

 

I dont know jack about building motors , but they used stock bore forged pistons on my rebuild . The motor is being redone right now for severe piston slap . I wouldnt suggest any one to use stock bore forged pistons . Some one else maybe able to tell you more

 

1. There are no aftermarket bearings available yet....only factory Nissan.

2. It is best to do cams while the engine is out. To go back in to do them after the engine is in the car is 12-16 hrs of labor. Yes UTEC can control timing.

3. ALWAYS go to an overbore piston with these motors. Any people on the board who have used stock bore pistons have had piston slap issues...even when hot. These motors are very prone to taper in the bores....even in very low mileage motors....like 5000-6000 miles. Suggested minimum is 10-20 thousandths overbore.

 

the engine is not rebuilt yet, and I told them that people have had these problems before and they said it would be fine??????? I am really nervous.. should I take the short block back to the machine shop and have them overbore it or have them build it and get something in writing ( saying that the guarantee no piston slap). How many miles did you have on yours booger? Or does that even matter?

 

2. It is best to do cams while the engine is out. To go back in to do them after the engine is in the car is 12-16 hrs of labor. Yes UTEC can control timing.

do you highly recommend doing the cams??? what are the benefits
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I'd recommend doing cams. You'll get more horsepower with less boost pressure because your motor will be breathing better.

 

A few guys with the JWT's picked up an additional 20-30 rwhp.

 

They said they would use a very low mile block [ block exchange ] They also said it would be fine using stock bore . I got severe piston slap . Dont let them use stock bore pistons

 

do you need to upgrade the valve spring with the JWT? Does the JWT work well with the greddy TT?

 

You can upgrade the springs but they will work fine with the stock springs. I would only upgrade if you were going past 7000 rpm's. The JWT cams should work well with any forced induction kit.

 

thanks for all your help g356gear, failsafe, and booger... I don't understand why the pistons would slap if the stock bore meets the specs. what is the difference b/t .003 clearance in the stock bore and .003 clearce with a .02 overbore?
Could someone explain why you would have piston slap and is it possible to get a good rebuild with stock bore pistons?

 

Like I said earlier...these motors get taper at the top of the bores really quickly. I had a 6000 mile motor and it had taper....and it had all its oil changes and was not abused.
A lot of the slap is dependent upon the type of aluminum that the piston is made of. A forged piston expands differently from a stock cast piston. Therefore the stock pistons can run a looser clearance with no issues....because they expand more with heat. The forged pistons need a much tighter clearance.
Booger is just trying to relay his experience with a very well known 350Z engine builder who also though it would be fine....just like I am sure your machine shop does...but it was not. He and a few others have had problems with forged pistons in the stock bore....regardless of manufacturer type. Take other peoples experiences and save yourself time and money....that's what this forum is for.

 

thanks again g356gear...you rock! How should I tell the shop that I want .02 overbore now that the block is back with the light hone? Just tell them to do it. Who should eat the cost of the stock bore pistons?

 

It's your motor.....and it's your money...it's your decision...not theirs. Did they purchase the stock bore pistons for you or did you purchase them. You may have to keep them and try to sell them on the boards. You should be able to find a new set of overbore pistons in stock from CP racing, forged internals, etc. Either Wiseco, Arias, or CP. Good luck with the project.

 

im getting a .02 overbore..

 

Definitely do the cams while the engine is out. g356gear is right. You will end up spending a lot more money down the line if you do the cams later. They will defintely help make some more power with whichever turbo system you end up going for. F/I Z's respond very well to cams.

 

the bore diameter may be good upon checking the low mile stock block, but remember, you need to hone and get a cross hatch in the cylinder in order for the new rings to seat. even honing will remove material in the bores, thus loose tolerances. best thing, as most have said, is to get the 0.02 overbore and then machine to that spec. if you want to have the best job, get the pistons first, and then have a good machine shop hone each cylinder to each different piston so even small differences in pistons will come out perfect. they can hone to exacting specs, and then the pistons will be numbered to the respective bore.
i have built quite a few forged motors and never heard piston rattle on forged pistons with the guy i use for machining. just tell them what u want. they should be able to do it, if not, then they are a production shop and don't care or they may have given you a set price and want to make more money in the form of less labor.

 

I talked to my shop this morning...he said wiseco sent him a slighty over bore piston from stock ( he said like a .01)and the machine shop matched each piston to a specific cylinder. he is calling the machine shop to double check...I told him I would pay to have the machine shop go to a .02 overbore...that I just want it done right!!!!! I guess we will see what happens... I never imagined this project would be so stressful

 

Because your motor is lower mileage you may be able to get away with a 10 thousandths overbore piston....but it sounds a little fishy that Wiseco would send a "slightly" overbore piston out to a customer. The piston is either stock bore or it's not.

 

That's what I was thinking...I will find out more on Monday, hopefully. Thanks again for everything