Having my Head Shaved

[LeeMcKee]

Hello All,
I am pulling the head off my midget this week to have it resurfaced and ported out. It is a 1500 Triumph that fits my 78 midget.
I have Two questions for you guys.
1) What would be the largest intake valve I can get for this head.
2) Does anyone know a magic number (depth) for shaving this head and getting a fair amount of compression without turning this motor into a grenade.
Thanks All

 

[Matthew E. Herd]

well ... mine's running about 10.5:1 CR, which required something in the vicinity of .150" removed (at least) to get there. However, I'm running a hot cam, etc, and until recently, only used Sunoco Ultra 94 (now it's 93, so I use whatever 93 I find -- still no issues).

As to larger valves, they really don't exist. However, you can get higher ratio rockers (like those available from TS Imported automotive) in 1.55:1 or a complete rocker assembly -- far more expensive -- from VB or Moss. However, I'd suggest not milling the head or changing the rockers unless you do a complete rebuild. Otherwise, you'll be into it again soon.

 

[LeeMcKee]

Thanks Matthew,
I've been in this motor ever since I bought this car. I've put a hotter cam in it, I've gone with the flat head pistons - new rings, etc..., and lightened/balanced the con rods. Baby needs a new clutch so while the engine is out I thought it would be a good time to run the head down to the machine shop. I'm looking at putting a new oil cooler on her and I've got a zenith 1.75 to replace the old 1.25 as well.
I read that Kas Kastener would run 1.62 inch intake valves with brass stem guides and I was wondering if anyone has tried it yet.
As far as the scimming of the head... I HAVE to do something with the head as last time around I did nothing but, regrind the valve seats for a better set of used valves. The head is always on the verge "letting go" because of warping. I don't really want to have the go to race fuel but if I have to I will. I would like to keep the compression under 10:1
can you think of anything else that I could do to help out with horse power?

 

[jlaird]

Just have it leveled, no problems with that should arise.

 

[aeronca65t]

I'm racing the same 1500 engine in my Spridget.
I believe the most you are allowed to remove from the head is 0.125"
I have 0.110" off mine with flat top (9:1) pistons.
I cc'd my head a while ago and the thing has a true 10.25:1 comp ratio.
I'm running Sunoco GT-100 (100 octane unleaded)with 30 degrees of max timing advance (at about 5000 rpm). I can run the 93 octane but with timing backed off to 26 degrees max.
I have stock valves and a "euro" (twin carb) cam.
The weakness with these engines is rod bearings and thrust washers. If you "push" your engine, keep and eye on them, change oil a lot and watch redline in an unbalanced engine (I never go past 5800 rpm).
My rod bearing and thrust washers get replaced every year (about 25 hours of racing or so).

 

[LeeMcKee]

Thanks Nial,
Man! Those are some great pics of you racing. What group are you running with to have all those differnt cars on the track at the same time. I think I saw an '88 honda civic!
About the enigine it is nice to see others race the 1500cc motor. The first bit of advice I normally get from people is to find a sutable MG enigne out of a earlier sprite. Ive always had at least one spitfire so I know the triumphs fairly well.
Thanks again,
/ubbthreads/images/graemlins/driving.gif

 

[tdskip]

Did it hurt?

HA!

 

[LeeMcKee]

[ QUOTE ]
Did it hurt?

HA!

[/ QUOTE ]

Did what hurt? Owning a Triumph? Of course it does! As does owning any British car. When in doubt drive the Honda right?
I've thought about finding some Rover badges to fit my Civic and make it look like one of the Rover Saloons sold back in the early 1990's. That way at least ONE of my British cars will be running on any given day.
Cheers,
/ubbthreads/images/graemlins/england.gif

 

[tdskip]

Sorry - having your head shaved. Head as in skull, noggin, or the thing that keeps the rocks from falling off my shoulders and on to the street.

Sorry - seemed funny at the time. (maybe still a wee little bit funny).

All kidding aside, she sounds like a very nice and fast engine that you are putting together.

Good luck with her and keep us posted!

 

[Morris]

I thought you were talking about the tat, Tom.

 

[LeeMcKee]

That was my next guess. /ubbthreads/images/graemlins/lol.gif

 

[Hap Waldrop]

I've built a couple of "limited prep" 1500 Spitfire motors for SCCA racing. With a flat top piston at zero deck hieght, you need to cut .100" off the head to achieve 11.0 to 1. Now mind you your stock 1500 engine will not be zero deck hieght. It's not uncommon with British quality control being what it was for stock engine deck heights to vary, could be .010", .015" or .020" negative deck for example, so Lee to get it right, you need to CC and do the math and not assume that someone else's engine is the exact same as yours.

 

[LeeMcKee]

Thanks Hap,
I think I'll just get a "deep" resurfacing of the head and not try to push her too much. The pistons are about 3/16 from the top of the deck at the apex of travel.
While I've got your attention what do you suggest about the half moon thrust washer? Is there a fix to the crank problem?

 

[jorg]

How much is the amount of headshave in mm?
Calculating
0,100" x 25,4mm = 2,54mm
0,110" x 25,4mm = 2,79mm
0,120" x 25,4mm = 3,05mm
0,125" x 25,4mm = 3,18mm
0,150" x 25,4mm = 3,81mm
Is this right ?
It seems to be a lot.

Jorg
Germany

 

[leecreek]

Re: Having my Head Shaved *DELETED* *DELETED*

Post deleted by leecreek

 

[jorg]

1" = 2,54cm = 25,4mm
0,100" is a tenth of an inch
right?

Jorg

 

[Matthew E. Herd]

yes, that's correct. 1mm is .0472" so .1" = 2.54mm ... your numbers are correct.

 

[jorg]

I have a 1977 1500 Californian car where I shaved off 1,5mm, took flattop pistons and got a compression ratio of 9,6:1 measured with a syringe. It runs with 95 octane fuel.

Jorg

 

[LeeMcKee]

I'm thinking that 1.5mm will be the depth that I go as well. How does your car run Jorg?
/ubbthreads/images/graemlins/driving.gif

 

[jorg]

It runs fine. The engine is built up wih standard components (valves, camshaft) because of fuel economy. Flywheel and front pulley are lightened, timing is set to 9 - 12° BTDC. It revs up to 5500 with 2 HS4 carbs and standard needles (ABT). Due to the relatively weak valve timing gear I don't want to rev it higher. I also experimented with a single Weber DCOE45 from an MGB with 36 chokes, but this too much for the 1500. Maybe I will try later to set it up with 34 chokes.

Jorg