Race Motor #1

[Holden202T]

Your probably wondering why the subject says number 1 motor ... thats cause i reckon there will be more than one and i have lots of things i want to try so there will be some development motors probably ... so i've gotten all the v6 conversion stuff done on the Torana so i thought i would have a fiddle with the motor that used to be in the Torana (blue 202) and start the prep work for building it to suit drag racing.

Main changes are ARP fasteners where i can get them, mainly want head studs, main studs and rod bolts .... while im at it i plan to machine whatever is needed to get the compression around 12.5-13:1 which will suit methanol/E85 fuel whichever i decide on.

The engine has been rebuilt after the June 2007 floods and in that time has done approx 40,000kms in the Torana before the ecotec went in. During this time i got the delco running on it and it went pretty well.

So i figure with some more bang in the hole and some decent fuel i should be able to get a bit more out of it which should go well in the Gemini. On top of all that the motor that is in the Gemini at the moment is getting minor signs of water in the oil so i thought why not.

So pulled the head off the ex-Torana 202 tonight and started checking things over .......

Things i wanted to sort out are:

* CC head to confirm numbers
* measure piston depth in bore

from this info i can work out how much i need to machine and from where to get the compression ratio where i want it.

Currently i have approx 9.5:1 compression and the head on the motor is my prize head as its the best i have as far as porting etc .... also its been milled ALOT as it was originally on a speedway motor so i am planning to machine the block and / or pistons to get the numbers i want as the more i mill the head the less life is left in it, and its already had some good couple of millimeters machined off it.

so on that note, i wont keep you waiting any longer, heres the pics of my findings.....

on pulling the head off i found that all cylinders seemed to look pretty good EXCEPT for this one, which appears to have major valve seat recession issues which weren't there some 40,000kms ago .... so you can see in this pic, there is a nice angled seat then on the outside of that is a 2-3mm lip ...

P1030516.jpg

its pretty obvious this valve is on its way to water!

P1030517.jpg

so i've been thinking next time i get the chance i want to port my head more mainly just to get a bit more flow around the valve stems cause i can see some areas i know i can improve .... so may aswell do that and while i'm at it i figure i'll probably get hardened seats installed aswell as go up a size as these ones are just stock blue 202 valves....

right, few things, this head has been setup with screw in studs and originally had guide plates and adjustable rockers using a yella terra alloy pivot in place of the original saddle pivots .... these were fine but when i was doing a service on the motor i found half the pivots were broken in the rocker seats so i had to find a fix .... of course yella terra no longer make the rocker pivots and there was really only one option, yella terra roller rockers .... i couldn't justify $400 odd on a set of roller rockers so i started thinking about these VN V6 heads i had pulled apart a while back.... turns out with a suitable pushrod (just happened to be holden v8 stock length) i can run the VN V6 rockers with only requiring the pivot shaft to have a bit cut off the bottom.... so i did that and have thus far not had one issue with it.

P1030518.jpg

as you can see the rockers look very similar to stock 202 rockers, but they are substantially stronger (thicker walls etc) and they are perfect geometry, and have a 1.65:1 ratio compared to the stock 202 1.5:1 ratio.

P1030519.jpg

thats pretty much it for the moment ... plans are to get the head fully stripped and then start porting it .... once thats all sorted and i have some dollars i'll go and see my engine shop about some bigger valves and hardened seats ....

on a side note, all the bores look great so theres minimal that will be needed for the block side of things other than machining!!

[delcowizzid]

least you got too the valve before it dropped the collets off or anything silly.nice and clean in the inlets

[Holden202T]

hahaha i reckon there would have been water coming out the exhaust pipe before i lost the collets!! was still plenty of spring pressure when i removed the retainer etc.

[zrossa]

Howdy,

Interested in your project. What kind of pistons are you going to run. Flat top, Chambered? There is probably a few hp in your combustion chamber if matched to the piston properly. If you are going to rum methanol then you can go for a much higher comp ratio. Is it possable to weld up the cumbution chambers for more compression? Most of the wedge chambers these days seem to have more of a penut shape.

I would be interested in your thoughts.

Douglas

[Holden202T]

well after ccing the head and going through some numbers it is pretty obvious to me that the motor that this head came off is not at all setup for compression .... dished pistons a fair way down in the bores .... SOOOO

plan is to use the bottom end that is in the gemini now as it has ALMOST flat top pistons, they have a 2.2cc bowl in them which if needs be i can machine off the top of them and machine the block a bit to get compression where i want it.

yes i am planning to run either methanol or E85, both of which require very similar compression ratios....

it looks like i might have to machine just a tad off the bottom of my head, if i do that and get the chambers to about 40cc i should be in business ... currently they are at 44cc and with getting the pistons machined flat aswell as decking the block to get the pistsons right near the top i can get about 12.8:1 compression .... even if i leave the dish in the pistons and machine the block down a bit i can get it to about 12.3-12.5:1 so they are all workable solutions.

so i figure i'll use that block, even though its a bit more worn, it actually has better pistons in it (acl race series) and the whole deal has been race balanced ... and then i can keep the motor with the dished pistons for the eaton m90 later on down the track! ... hehehe get it, down the track sorry its been a long week

this weekend should see a bit more progress, i am planning to fully strip the head so then i can take it in to get the seats checked out and ensure its usable .... i'll probably also get the gemini into the shed in the engine removal section and start on pulling the motor out of it so i can get the block and pistsons machined whatever ends up happening.

on a side note i have been thinking about carby or efi and i REALLY want to go the carby atleast for a while cause i have it all on the car running with a carby ... so i'm thinking i might look into running the delco just for spark and controlling fans and stuff like that .... then later on when i decide to go full delco it will be easy ..... to be honest i'd probably do efi straight away if i hadn't have cut a hole in the bonnet for the air filter

let me know your thoughts doug, or anyone else for that matter, im fully open to opinions as this is really just a bit of fun for me to get into racing!!

[VNracer34G]

Is that an insert in that exhaust seat already? Good tip on the rockers thanks, good to see these motors still being used in anger

I'll be freshening my head / replacing exhaust valves thats on my mates VK 3.3 Production Saloon once my V6 is together and changing cam too but as we are only allowed stock cam lift those rockers could give us a bit more valve lift using legal OEM parts

[Holden202T]

nah not inserts in it already, the marks you can see are where they've had new seats cut over time.

on this subject, i took the head in today, looks like the seat is too stuffed to cut a bigger one so i'm gonna have to go exhaust inserts .... not a bad thing cause the head should last alot longer with them, but its more risk of stuffing the head .....

i'm not sure how much truth is in it but my mate doesn't like cutting the heads for hardened seats cause alot of the time you can hit a water jacket and then the head is a great paper weight, so hopefully my head wont have that problem and i'll be right to go again soon .... so shes in the acid wash as we speak, then i'll get my extra porting done later in the week when i get it back, then once the porting is done i'll be getting the exhaust inserts, their race valve seat cuts, which i believe is just the usual 3 angle job aswell blending the seat into the port perfectly etc ....

oh and i need to take 4-5cc out of the chambers so about .020 thou needs to come off the deck of the head i think it works out to be!

should be a good thing

[Holden202T]

got the head back, time to get sore arms and shoulders with the die grinder

[v6bucket]

308 Holden rockers also fit the Holden 6 head if it still has std bolt on rockers & will give you 1.65:1 ratio. If your after more compression the blue 2850(173) head has 47cc chambers (the same size as the XU-1) as opposed to the 56cc chamber as fitted to the 3300(202).With this head & ACL flat top pistons you should get close to 10.5:1 without machining.

[Holden202T]

nah i got adjustable screw in studs for my rockers

the current head chambers are 44cc ... i'm going to machine the head to get it to about 40-41cc and with the block and pistons machined flat and the pistons level with the top of the block i should have about 12.7:1-13:1

depending how much machining has to be done i might need shorter pushrods, thats a small price to pay for what im doing though