Fitting new LA X/Indy heads to my 340

MilesnMiles · Post by **MilesnMiles** » Fri Feb 20, 15 10:07 pm

Les, I think so. I'll post up pics when the heads are off.
The pistons are Mahle forged 10.1 but I know my block hasn't been decked. I'm setting it up for TDC and will see where the pistons actually are.

mad machs · Post by **mad machs** » Fri Feb 20, 15 10:52 pm

There are two types of people in this world my friend, those who talk.....& those who fit their cylinder heads

MilesnMiles · Post by **MilesnMiles** » Fri Feb 20, 15 10:54 pm

Hey Mike, they'll soon be fitted don't you worry

You can be joint 'seat of the pants' test jockey!

Mick · Post by **Mick** » Sat Feb 21, 15 12:28 am

While your heads are off you ought to verify your timing marks on your balancer Miles.
The cam will be the cork in the bottle.
Mick

MilesnMiles · Post by **MilesnMiles** » Sat Feb 21, 15 7:04 am

Mick, that's next on the agenda. Get number one on firing stroke and check and mark the damper.

Guy · Post by **Guy** » Sat Feb 21, 15 7:37 am

If the heads off you dont need to have on a firing stroke to verify the damper marking, on my 340 when I checked tdc against the marking on the damper it was five degrees out hence I went to timing tape.

Blue · Post by **Blue** » Sat Feb 21, 15 8:16 am

I find it easier to check with the head on, I can use my adapted spark plug piston stop then.
Don't forget, just bringing the piston to TDC will not accurately find true TDC because the crank can still turn a few degrees after the piston stops rising.
Just to be clear, set a piston stop to hit the piston around 1/4" before TDC, rotate the crank until it hits the stop, mark your degree wheel or damper. Turn the crank backwards until the piston hits the stop again, make another mark. True TDC lies at the halfway point between your 2 marks. Turn the crank to that point and see if the factory mark lines up, if it does job's a good'un, if it doesn't make a new mark. Pour a cold beer and walk away whistling a merry tune.....

Guy · Post by **Guy** » Sat Feb 21, 15 8:29 am

I guess I should have worded that better I used the same way of checking a Blue discribed but nwith the head off and a flat bar with a bolt tapped in the middle as a stop, this was mounted between two of the head bolt holes .

Blue · Post by **Blue** » Sat Feb 21, 15 8:55 am

Yep that works as well!

Mick · Post by **Mick** » Sat Feb 21, 15 9:46 am

That's what i was talking about, i use a plate with a bolt and spin it both ways. I have a converted plug but i find it a bit hit and miss, dont ask me why. When i did the Duster the other day, i just spun it over with the dist cap off and my thumb over no1 plug hole, you definitely feel it on tdc.
Mick

Jon Connolly · Post by **Jon Connolly** » Sat Feb 21, 15 10:13 am

Miles

Well done on the heads

Either heads on or off method works. Heads off is easier to see if your eyes are anything like mine ? but definately mark the 2 positions and go halfway to get tdc

You can then fine tune your setup to work best with existing cam and rotating assembly by choosing the best head gasket thickness

http://www.jegs.com/p/Cometic-Gaskets/C ... 7/10002/-1

Mick · Post by **Mick** » Sat Feb 21, 15 10:17 am

If you run steel shims, that will up the comp slightly.
Mick

MilesnMiles · Post by **MilesnMiles** » Sat Feb 21, 15 11:33 am

Thanks for all the tips, chaps. Reckon with the heads off looks most straightforward, after all they do have to come off!

Dave999 · Post by **Dave999** » Mon Feb 23, 15 4:13 pm

Dave999 wrote:try it as it is

your CR is higher but your flow is higher due to bigger valves better valve job and better port

=you have more to burn but squashed into in a smaller place

It will be harder to ignite because you squshed more of it into the gap at the spark plug, that will delay your spark slightly.

my point was, its going to start and run ok till its warm
you have a decent initial setting to work from, your pistons and cam are still the same. unless you load it up its unlikley to ping. i.e no real danger

Not suggesting you leave it as it is and go out for a good old slog up a hill without tuning it....

that was not the impression i intended to give

Dave

MilesnMiles · Post by **MilesnMiles** » Mon Feb 23, 15 5:41 pm

Gotcha Dave.

Some pics which show the valves and also port comparison. Difficult to see in bad light but the new exhaust ports are bigger than stock J and flow much higher. The inlet ports are also bigger. J heads are just shy of 1" wide, but the new LA X head measure 1 1/8".

More to follow when current man flu respites