Tri-angle cut on valves

[rah1482]

My mechanic suggests that I have this done to my valves while having the cylinder head ported and polished. Says the compression will greatly improve. Thats an additional $200 on top of the polish. Is it worth the money ? Anybody have it done before ?

 

[Ian M]

A three angle valve job vs. a standard valve job wont have any effect on compression,the benefit is the flow around the seat of the valve. I haven't seen any specific flow data pertaining to the 4g63,but on V8s and such,a noticeable flow increase is seen with a multi angle valve job.

Although, I think what your mechanic is recommending is having the valves/seats resurfaced rather than just lapping and reinstalling. A lot of folks have luck with just lapping and reinstalling,but having a valve job done,pressure tested,and resurfaced is a good idea especially if you don't know the history of the head.

A multi angle valve job is pretty much standard with a performance valve job,and even standard valve jobs these days. Some of the newer machines actually machine the seats and valves rather than grind,and already incorporate three angles standard.

 

yeah. a three angle is prrtty much standard practice now. but a valve job would only help you, if you have the 200, id say do it.

 

why not do it once and get a 5 angle? and do you have oversized valvel or stock?

Tee

 

i dont know about the whole extra $200...to me that seems a lil bit much...

Tee

 

[CO VR4]

$200 is outrageous. That guy saw you coming a mile away.

Three angle or five angle valve jobs do not change the compression AT ALL. They allow the flow around the valve to be better, and flow may increase as a result, but compression is a function of the piston design, the combustion chamber size, and similar characteristics. If you have valve leakage, it will affect your compression, but only in the practical sense. Just like a bucket of a certain size will hold a specific amount of water, unless it has a big hole in the bottom....

 

yeah bro, let him do what ever he started and get the valve job done later. keep you $200 and take your head to a diffrent shop!

Tee

 

[rah1482]

mechanic doesn't suggest the 5 angle due to tendency to leak. Seats on the head will be machined also to match the tri-angle. Guess that's why it came up to $ 200. Btw, forgot to mention that my engine is a stock RS (rally-spec). Said to be at 240 hp. Pistons, turbo, intercooler, cams and valve springs are different from stock USDM or JDM. So. am assuming that valves are also different (slightly bigger ?).
The head and valve job is in preparation for the HKS cams (264 intake, 272/exhaust)and Crower springs/retainers that I will be installing.

 

[rah1482]

Thanks for your comments. Am enlightened. On another note, been tracking your parts for sale. Seem to have a lot of those 4-bolt LSD's. Most recent was the one with Cusco gears. That was sweet. Wanted to buy that, but shipping to the Phils is a problem. My RS engine came with a close-gear tranny but no differential. So, am still using a 3-bolt. Your Cusco 4-bolt would have made a good match.

 

[CO VR4]

The RS tranny may or may not be compatable with USDM rear ends. Some came with different final drives than those in the US domestic market. If you use a RS tranny with the US rear end, the front wheels and the rear wheels are being driven at different rotations, and you'll burn up either your tranny viscous or your rear end very quickly. I sold three rear ends to one guy here locally in two weeks before he figured out why. :-(

There is info on this board on the tranny IDs that work with US domestic rear ends. If you have one that's compatable, the 4-bolt rear ends are the strongest available.

The CUSCO diff I sold was compatable with the USDM final drive.

 

[rah1482]

Initially, was told that it wouldn't work and I would ruin the tranny. But on further research, was informed that the differential ratios may be different, one is 4:9 and the other 5:1, but they would still work. Man, don't want to ruin the tranny. I hear a terrible sound when I release the gas pedal,after a high rev. Was told it was on account of the performance clutch I installed (clutchnet)not the incompatibility. Am I being misled again ? Could this be the incompatibility, you're talking about ?

 

DO NOT USE THE RS TRANNY WITHOUT THE CORRECT REAR END GEAR RATIOS. search for posts i have made along with a few others. BAD things happen when you run mis-matched final drive's. that said, 3 angle valve jobs are very standard now, when i had my head redone it was all part of the standard deal.

 

[rah1482]

Thanks RTS. Read your post on the tranny/axle thing. scary stuff. Think I'll just put back the original USDM tranny til I get this sorted out.