Chevy Springs Mod + Port/Polish Qs

[theKnifeArtist]

so i heard of the mod putting big block chevy valve springs in place of the stock ones. they are like what 70 bucks i hear? for 24? if so, that seems really cheap, but then again all (most) domestic parts are cheap.
should i go for it? do i really need it? it would elimate valve float, but at what RPM does that really happen? I never really rev it past 6k or even get that high most of the time..mainly cus i'm scared 'cus i don't know if it's safe..so what's you guys' take on this mod?
also,
a guy in my class does port and polishing for cheap and he's a reputable guy. how much does this really do for our engines? is it worth it? it's funny, i bring my head to school to hot tank it and clean it and people are tryin' to sell my machine work and shit in the hallways, haha.

 

[IJ.]

My take on the BBC springs: I'd be concerned that a spring failure means losing the motor as it will drop a valve, at least with duals there's some redundancy.

Point in case>

 

[shaeff]

http://www.mkiiitech.com/forums/viewtopic.php?t=359

-shaeff

 

[jdub]

Port & polish is for a head you plan to feed with a turbo capable of some serious CFM flow. The head is end game...you also have to have the piping and IC capable of handling the flow efficiently. Not to mention the bottom end being able to handle the HP produced. All depends on your plan for the motor

SBC springs or Ferrea's like IJ is using is for making serious HP...you do not want valve float at high rpm. Otherwise, the stock springs are fine for most applications.

So you decided to do a valve job after all...I would
Might as well as long as the head is off.

 

[IJ.]

As a side note ANYTHING you do to improve a motors VE will help no matter what it's output and intended use ie: port job.

With all of the mods done to my motor it makes great power and torque off boost and this helps everyday driveability and getting the whale moving.

Even without the Turbo my motor would be making much more HP and Tq than a stock NA right across the rpm band

 

[jdub]

Very true...a port job will make the head "breathe" better. I tend think in terms of cost vs benefit...if he can get it done right without a lot out-of-pocket, go for it

Just don't gasket match the exhaust side...you want the exhaust ports a little smaller diameter than the manifold.

 

[suprarich]

The spring rate on the BBC inner springs is not that much higher than new stock toyota.

 

[jdub]

The stock springs are 35 lbs seat pressure...the SBC springs are 55 lbs. Take a look at the MKIII Tech page posted above by Shaeff

 

[Mr.PFloyd]

The spring rate on the BBC inner springs is not that much higher than new stock toyota.

question is, how much is new stock toyota in comparison with cost.

 

[need new tires]

for the $60(what i paid) why not put new springs in?
p&p are nice and can yeild some real nice numbers, faster spool and better throttle response.

-shane

 

[IJ.]

Never measured a set of new 7M springs but I'd surprised if they were that light.

 

[suprarich]

The stock springs are 35 lbs seat pressure...the SBC springs are 55 lbs. Take a look at the MKIII Tech page posted above by Shaeff

I have seen the new toyota springs measured out at 43-44lbs?

BTW the chevy springs are BBC not SBC. They are the inner set to a dual spring set up.

 

[jdub]

TRSM, Page EM47, step 13c
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=EM&Page=47

Ya got me on the chevy springs...they are BBC

BTW - got a set of TRD springs on my motor...measured out at 47 lbs iirc.

 

[theKnifeArtist]

and this helps everyday driveability and getting the whale moving.

:rofl:

for the $60(what i paid) why not put new springs in?

that's the BBC springs or the toyota ones...what do you guys mean by toyota ones...does that mean new from the dealer or from the newer supra or what?
and these BBC springs..they're the 2 springs in one deal? and i only use the inner one?

i'm gonna ask that guy what he'd be askin for the P&P, then i'll decide...well i'll post it here and then determine a decision, just like everything with this supra :bigthumb:

 

[suprarich]

^^^ You can only use the inner from the chevy, the outer spring is waaayyy to big to fit in the hole no matter how big a hammer you have.

Jdub - I was just going by some rates from actually measuring new springs. They could be built to a diffrent spec now then when the trsm was written. As with any spring, they are built in batches. One batch may be stiffer than another batch made years latter. Of course...I could be wrong.

 

[IJ.]

My Ferrea's are 80 ft/lb installed

 

[jdub]

Rich - I understand...a higher spring pressure is not going to hurt a thing. Actually desirable IMO. Just pointing out the TRSM spec for using as a comparison vs the BBC springs

IJ - LOL...they better be! At the rpm you can run that motor at, last thing you need is valve float!

 

[theKnifeArtist]

at what rpm does float usually occur?

 

[Adjuster]

Come on guys, for the money, the COMP cams deal can not be beat.

Stock is more money, HKS, TODA or Ferrea are all more money. (And not just a few bucks, but hundreds of dollars.)

The Comp setup has the same resistance to failure as the stock design. (Single spring.)
They have higher installed pressure, can be compressed more before coil bind, and are NEW compared to any old used spring. (Which most people just put back into a used head after doing the valve job, and putting new seals on there...)

Cheap insurance v/s using old springs, and a better option to stock new springs, or the very pricey options out there.

I use them, and have bumped the stock 88T rev limiter and beyond. (IIRC, it was like 7150peak rpm recorded on my Eman when I ran that.)

It was not constant, but it was not a failure problem at that rpm level.

I'm also running 1mm oversize stainless valves, so they weigh more than stock too.

I say do the port n' polish and replace the springs with the comp's. Best deal for the money. (Short of using used 2JZ springs, which are 1.5mm OS stock, and have slightly longer stems, so they are ground down during the valve job to the right height. Problem is your likely out of the hardned end of the tip, so I'd reccomend having your cams modified so the base circle is reduced by the extra height, and leave all the lift and duration you can. That mod should be very cost effective, and result in slightly better cams than stock.)

It's your motor however, so do what you want

 

[bfr1992t]

My '92T springs measured out between 35-37lbs at 65kmiles and in 2001. I switched to Comp Cams 975's around then and haven't had a problem, but then again the odometer is showing just under 71k now.