More rebuild questions.

[IJ.]

Proper assembly and break in is required.

I ran on the low side of spec in my last build and had 0 bearing issues ie:knock or spun bearings.

 

[Jaguar_5]

No!
You don't need to have the lowest clearance in the spec, but a tightly built 7M, is a happy 7M, you definitely want to be in the spec, off the top of my head, .0015-.0022 i think!

<ninja edit> .0012-.0019

 

[jdub]

I'm with IJ...install bearings on the tight side of spec.

 

[Sl1dewaysSupra]

Alright I will copy those specs and make sure he has the specs tight. Thanks.

 

[Sl1dewaysSupra]

Ok, so I want to match ports. My father knows how to do this so no probs there.(He is an Oldschool V8 guy) Should I just port the exhaust side? If I portmatch the intake side would I notice any gains? Also my uncle was talking about a "Street port", any one know more about this? He just said that there was another place I could port for some added performance. Any ideas?

 

[IJ.]

:runaway: DON'T MATCH PORT THE EXHAUST!:runaway:

 

[Sl1dewaysSupra]

^Go on.......

 

[Sl1dewaysSupra]

Can you explain more IJ?

 

[supramacist]

Ok, so I want to match ports. My father knows how to do this so no probs there.(He is an Oldschool V8 guy) Should I just port the exhaust side? If I portmatch the intake side would I notice any gains? Also my uncle was talking about a "Street port", any one know more about this? He just said that there was another place I could port for some added performance. Any ideas?

I'm inclined to think ...., wich is never safe. You should port the air intake side of the engine. It's really easy it's like a blue spray paint. put the parts where you want them and scribe it, then it's all dremel baby.

 

[mickyg]

Can you explain more IJ?

Do a quick search on "reversion dam" (it's actually an anti reversion dam) and you'll find what he's talking about. It's the manifold's built in feature that allows one exhaust pulse to help pull the next one along. If you port match, it makes for a very inefficient exhaust manifold which will rob power instead of making it!

 

[Sl1dewaysSupra]

Ahhh, glad I asked before I went through w/ it. Would that happen even if I get headers? Is it the same way on the intake side?

 

[mickyg]

To the best of my knowledge, the aftermarket headers are going to be the same diameter tubing. That's just a guess though.

So yes, the "don't port match exhaust side" would apply to headers as well.

As for the intake, I really don't know. From the reports of others, it's not an issue and port matching is OK. I'd wait for further replies from others before I'd make any decisions though.

 

[IJ.]

Micky nailed it!
(sorry been welding all day and just came in)

 

[Sl1dewaysSupra]

Ok, I thought air reversion was when the air trys to travel back to the engine. That is how it is w/ motorcycles at least. I will google it as well .

 

[IJ.]

If you port match a 7m it's been shown on the dyno it makes a measurable difference in the midrange.

Always try and keep the Header larger if possible.

 

[mickyg]

Ok, I thought air reversion was when the air trys to travel back to the engine. That is how it is w/ motorcycles at least. I will google it as well .

I think that's exactly right. The thing that's built into the exhaust port/header junction is an anti reversion device (or dam). It just means there's a ridge where the exhaust ports are smaller than the the header they feed.

 

[Sl1dewaysSupra]

Yeah kinda like a step-up. Anyone know the stock exhaust port size?

 

[Sl1dewaysSupra]

Ok, time to bump! The motor will be rebuilt after I sell my first car.(2-4 wks) Any last words of wisdom before she goes under the knife? I will be using a MHG, decided not to go w/ headers but new exhaust from manni back. Upgrading plugs, wires, starter and clutch. Port and posish intake. Am I missing any thing you guys can think of ( other than what is included in a complete rebuild.)? Can I re-use the OEM head bolts w/ a MHG? (I won't be able to re-torque ARP's imedietly(SP?).) Forgot to add this. What are some break in tips? (Other than don't rev over 4k and stuff the owners manual recomends.) Any type of oil? How long before I can switch to synthetic? Can I run 91 octane gas right off the bat? Stuff like that. Sorry to make such a long post, I just want to make sure my problems are minimal. Thanks much.

 

[supraguru05]

Ok, time to bump! The motor will be rebuilt after I sell my first car.(2-4 wks) Any last words of wisdom before she goes under the knife? I will be using a MHG, decided not to go w/ headers but new exhaust from manni back. Upgrading plugs, wires, starter and clutch. Port and posish intake. Am I missing any thing you guys can think of ( other than what is included in a complete rebuild.)? Can I re-use the OEM head bolts w/ a MHG? (I won't be able to re-torque ARP's imedietly(SP?).) Forgot to add this. What are some break in tips? (Other than don't rev over 4k and stuff the owners manual recomends.) Any type of oil? How long before I can switch to synthetic? Can I run 91 octane gas right off the bat? Stuff like that. Sorry to make such a long post, I just want to make sure my problems are minimal. Thanks much.

dont polish the intake it needs some friction.
dont reuse head bolts use the arps
break it in kinda hard not rpm wise but load wise. be sure to use decent convential oil probably like 10-30 or 20-50 to really keep it thick and keep pressure up. dont switch to synthetic until 500-1000 miles after the break in. change the oil often like after the first 30 minutes and then again at 200 miles. octane on gas doesnt matter

 

[Jaguar_5]

^ Uhm...

20-50 would be way too thick, especially for a new motor. Pressure is resistance to flow, you don't want High pressure, just appropriate pressure.

And you should definitely wait more then 1000 miles to break in!!! I'd wait til at least 3k miles, but I still don't think the engine is 100% broken in by then, don't jump the gun on switching to synthetics.

Don't stay at any RPM for too long.

Heres how I plan to break-in:
[Edit]Single weight 30W mineral oil (non detergent) [/End edit.. had the voice of an IJ in my head Don't use a multi-viscosity, ie 5w30, for break-in]
Start it up, bring to 1500 rpms, pulse the pedal up and down about, probably 1300-1800 rpms, until it warms up (assuming the car runs fine until warmup)
Shut off, change oil, check all fluid levels, make sure theres still no leaks (check on initial crank obviously, and don't forget to pull EFI fuse and crank until you see oil pressure before trying to fire it up)
Then I will essentially drive it normal, not letting it idle real low or ever stay in one spot, give it some pressure (accell and engine braking) but staying below 4k, you don't want to drive it hard, but you do need some pressure (don't drive like a granny) to seat the rings.

Another oil change and check up at 20 miles.

If new hardware, re-torque headbolts / studs after about 5 good heat cycles

Another oil change at 500 miles

Then you're probably good, I'll probably change it again at 2000 though, and then go the 5k miles on it