Engine Assembly Question....

[britz1]

Guys i have got my block back from machinest and are in the process of checking bores and piston clearance....

with my cheap dial bore guage i am reading too much out of round... my machinist says its cos i dont have the torque plate on it.. is this true?

how much dose the block relax when the torque plate is removed?

i am also geting a taper of 0.01mm

also is a digital micrometer nessasary for bores and piston measurment?

Edited November 9, 2012 by britz1

[89CAL]

Torque plate/head will make a little difference, not sure how far out you are but so hard to say for sure if thats why, I dont think it will affect it too much

taper of 0.01, you said you have a cheap dial bore gauge, is it possible that this is the reason?

How much did he have to take out of the bores? or was it just a hone?

If he's had to take a couple of thou out of the bores (to go up piston sizes etc) then i would be a little annoyed if your measurements are spot on anyway

Edited November 9, 2012 by 89CAL

[The Dan]

Torque plates are for Windsors

[JustinP]

Torque plates are for Windsors

haha - so you never use them for RB builds?

My machinist did not use one and I am yet to run it but it has been a small worry in the back of my mind that I should have had them use a torque plate when honing.

Cheers

Justin

[The Dan]

haha - so you never use them for RB builds?

My machinist did not use one and I am yet to run it but it has been a small worry in the back of my mind that I should have had them use a torque plate when honing.

Cheers

Justin

Depends on how competent they are I guess. I use Chilton Engineering. His bores are better than perfect every time I get them back.

We've never used torque plates and never will. They are for engines that have too much flex (like windsors - lol)

I build an RB30 single cam that does mid 8's and a few 1Js that do low to flat 9's and it doesn't seem to bother them at all haha.

Maybe I'm just weird?

[JustinP]

Depends on how competent they are I guess. I use Chilton Engineering. His bores are better than perfect every time I get them back.

We've never used torque plates and never will. They are for engines that have too much flex (like windsors - lol)

I build an RB30 single cam that does mid 8's and a few 1Js that do low to flat 9's and it doesn't seem to bother them at all haha.

Maybe I'm just weird?

Cheer's - that is very reassuring

[r33_racer]

Forget what measurement you are getting with the block relaxed. Torque your head down with head gasket in place and then check the bore size from the bottom end with your dial bore gauge.

That is the only real way to check it, as it is the closest you will get to seeing how much bore distortion there really is when the block is stressed.

If the machinist was any good it should be no more then 0.0002" out of round. Bore taper should be much the same.

Out of round bore will only increase blow by and oil consumption. A round bore with the correct cross hatch is one of the most important things in an RB. It is one of the main contributing factors in the "oil blowing out your catch can" drama that so many people have had the fun of experiencing lol.

[britz1]

Forget what measurement you are getting with the block relaxed. Torque your head down with head gasket in place and then check the bore size from the bottom end with your dial bore gauge.

That is the only real way to check it, as it is the closest you will get to seeing how much bore distortion there really is when the block is stressed.

If the machinist was any good it should be no more then 0.0002" out of round. Bore taper should be much the same.

Thanks bro that is the sort of info i was chasing.... i dont think it is my bore guage as it is consistant and the method i am using to mesure is correct... just no torque plate.... i will stick the head on torque it down n have a mesure..... for reference it was 0.02mm out of round with no plate with the wider side consistantly in ln line with the other cylinders.

[r33_racer]

That is about 8 tenths of a thou which should iron out with the torque plate on to some degree and should with the head on, however......

The next issue is whether or not the machinists torque plate accurately simulates the stresses that the head creates.

[The Dan]

That is about 8 tenths of a thou which should iron out with the torque plate on to some degree and should with the head on, however......

The next issue is whether or not the machinists torque plate accurately simulates the stresses that the head creates.

If the bore is done perfectly parallel and the deck is perfectly perpendicular on both halves, a torque plate isn't going to change anything

[r33_racer]

The torque plate will change the bore dimensions if you bolt it to a block that was honed in a relaxed state....just like the head will when you tension it down and the head fasteners start stressing on the four corners of each bore.

[NYTSKY]

Maybe I'm just weird?

Bat shit crazy!

[The Dan]

Great. Lets do a test. I've got a couple of engines ready to put together. I'll document what I find.

[KiwiRS4T]

I still don't see where you say it has been rebored. Did it just get a hone or has it been rebored for oversized pistons?

[britz1]

I still don't see where you say it has been rebored. Did it just get a hone or has it been rebored for oversized pistons?

sorry dude there 20 thou over so 86.5mm pistons all machined as per CPs Spec there custom dome pistons for higher compression as i am running a rb26 head with some combustion chainber work, i was also planing on doin the old plastesine trick to confirm the pistons dont fowl on the head, even thow my mesurments say there fine.

[Adriano]

I did some engine boring years ago, and just wondering how you coiuld machine a bore out of round? Taper i could see with bad honing practice, but nowadays the honing machines arent exactly rocket science, you arent hand honing with a drill

[NoFigJamHere]

For those people interested in this topic the best way is to Hot Block bore/hone an engine. ie: the block actually has temprature regulated fluid running through it to wotever degrees you require during the entire machining process. And you have to use a torque plate otherwise the fluid cant circulate. Did quite afew RB26/27/28s engines using the equipment PMM (Paul Morris Motorsport) used to have when they did their chev V8 supercar engines in house. And yes it makes a difference 1-2% leakdown compared to 4-6% will always = more power... This technology came here from NASCAR like just about every other power producing secret/tweak/configuration used by the teams here.

[The Dan]

For those people interested in this topic the best way is to Hot Block bore/hone an engine. ie: the block actually has temprature regulated fluid running through it to wotever degrees you require during the entire machining process. And you have to use a torque plate otherwise the fluid cant circulate. Did quite afew RB26/27/28s engines using the equipment PMM (Paul Morris Motorsport) used to have when they did their chev V8 supercar engines in house. And yes it makes a difference 1-2% leakdown compared to 4-6% will always = more power... This technology came here from NASCAR like just about every other power producing secret/tweak/configuration used by the teams here.

PMM race fords don't they? Their engines are based on the Windsor.

Not sure about them doing their machine work in house or when that was or for how long because they were having multiple engine failures and employed the services of Hastings ring experts and tech guys from NZ to help them work out the failures. Chilton used to do their machine work as well so maybe this was all before then?

They also used to use gapless rings which have also been proven to be a wank.

NASCAR are advanced in technology (although some don't see it that way) but what's good for a NASCAR isn't always good for a street car or even a drag car. They are built for purpose and that purpose is unique to that sport. There aren't many secrets after a while and you won't catch F1 teams copying NASCAR and vice versa.

[The Dan]

I would also like someone to explain how your torque plated engine means anything when your engine is actually running under power

Static comp might be better or leakdown might be 1-2% better.....or worse.

Dynamically, none of that matters. Your bore flexes like a barrel when you add cylinder pressure, heat and other factors.

Your torque plate doesn't factor any of that

[NoFigJamHere]

I would also like someone to explain how your torque plated engine means anything when your engine is actually running under power

Static comp might be better or leakdown might be 1-2% better.....or worse.

Dynamically, none of that matters. Your bore flexes like a barrel when you add cylinder pressure, heat and other factors.

Your torque plate doesn't factor any of that

You need to read a bit slower and think a bit longer..... I said you need the torque plate to block the water galleries off so the water can circulate. And can you please tell me how much "flexing" in the shape of a barrel occurs when you add cylinder pressure,heat,moon cycle,wind direction and any other factors? Dont say it depends, lets use 2Bar boost on a engine with 9:1 comp, 9000 rpm, 87mm bore, 77mm stroke,30 deg timing as an example. Just an estimate is ok coz obviously there are other factors.. Im just curious