Road Race Enduro L28 Engine Build

[josh817]

Curious as to the purpose of this picture?

 

"No coolant between block and head are block. I shouldn't need to do any trimming." can you clarify? That's a good price for a copper HG. Guessing you can do any thickness and bore size?

 

Great looking motor. I don't like that you're making more progress than I am at like ten times the cost! I guess I'm just super slow.

 

And poor. lol

Edited April 5, 2011 by josh817

[z-ya]

Curious as to the purpose of this picture?

 

"No coolant between block and head are block. I shouldn't need to do any trimming." can you clarify? That's a good price for a copper HG. Guessing you can do any thickness and bore size?

 

Great looking motor. I don't like that you're making more progress than I am at like ten times the cost! I guess I'm just super slow.

 

And poor. lol

 

 

Just to show the deck finish.

 

Ummm, the coolant holes on the copper gasket line up with the holes on the block and the head, so there are none being blocked by the head gasket. Yes, you order the thickness and bore size.

 

I don't know about you, but I've spent more on this engine than any other I have ever built. Even though I got the head, crank, rods, and pistons for free. Between, Swain coating, cryo treating, polishing, machining, etc. etc., I've got a lot in this motor.

[z-ya]

Priming the engine with oil (sorry for fuzzy pic):

 

 

Next stop the engine dyno:

 

 

 

Arizona Z forged flywheel:

 

 

[inline6]

Are those carbs modified (tapered bores)... or standard bore? The openings look bigger than original. Also, why did you make an impression of the pistons? That was just to get an idea of the volume of the pop up?

[z-ya]

Are those carbs modified (tapered bores)... or standard bore? The openings look bigger than original. Also, why did you make an impression of the pistons? That was just to get an idea of the volume of the pop up?

 

They are Mikuni 44mm with the chokes removed. So in effect they are 50mm. This is how I received the carbs. This is a mod they did back in the day. Todd at Wolfcreek went through them. According to the guy that will do the final setup on the dyno, properly tuned 44s will perform just as well.

 

To compute the CR you need to know the dome volume. No where in the documentation I had could I find the dome volume. Even Cosworth couldn't tell me what the dome volume was as these pistons were make back in the 70s. So I made a mold and cc'ed the impression. Anyway, I didn't want to make any assumptions about CR. I estimate the final static CR to be 12.5-13:1.

[z-ya]

Here it is on the dyno:

 

 

 

Video on the dyno (sorry for the rotation):

 

 

So far the motor has survived the dyno. And the cryo treated Isky cam survived initial break in. We use RedLine break in additive and Valvoline VR 20w-50 oil for break in. After a good 1/2 hour at 2500RPM we changed the oil with Brad Penn 20w-50. Compression is 250lbs across all cylinders. We had to re-adjusted valve lash three times to get everything to settle in nicely.

 

After a bunch of pulls, we realized that the dyno was not opening up the throttle all the way. It was making 250HP in this state. There is also one plug that we can't seem to get indexed right, so it is up in the head more than we would like (using copper washers). It is not firing as good as the other cylinders because of this. Running 35deg advance right now.

 

More tuning Monday, stay tuned... 8^)

 

Pete

[rjstcroix]

Pete,

 

Awesome work. Bad Dog 2.0 is going to be a savage. Looking forward to the plot.

 

Regards,

 

Ron

[z-ya]

OK, here is the good news, it's making decent power now that the butterflies are opening up all the way:

 

 

 

 

The bad news, a lash pad broke:

 

 

 

 

 

 

 

The good news. There wasn't a lot of damage. The rocker is dinged a bit. Nothing a file won't cure. Not sure why the lash pad just snapped like that. They are MSA 0.170" lash pads. Anyone ever see this before?

[z-ya]

Here is the configuration for the data above:

 

ENGINE: 280Z mon 5-2-11

 

INDUCTION: taper-bored 44 mikuni 36 155f gages 165 175a 67.5ls 35p

Datsun Comp manifold w/44mm isolators

1.375 50mm stacks ITG cleaner in place

wide open stops on all carbs

 

PISTONS: 13-1 Cosworth 87mm

 

RODS: Carrillo 133mm

 

CRANK: Datsun 79mm

 

CAMS: Isky to stock marks .010ih .010eh

Stock ROCKERS timing measured .035"adv (in open more @tdc)

 

FUEL,OIL: SUNOCO STD @2.5 20W50 valvoline w/Red Line break-in

 

EXHAUST: Datsun Comp 3to1 X2 1.375"x24 2.25x36

6" magnaflow 2.25mufflers and 18" tailpipes

5" flex to mk2 dyno exhaust no uego

 

 

IGNITION: MSD 6530 AL-2 programable 35 total

actually measured at 35deg Total

[Noddle]

 

IGNITION: MSD 6530 AL-2 programable 35 total

actually measured at 35deg Total

 

Hi,

 

Would you have a print out of your timing curve ? (RPM / Degree / manifold vacuum )

 

I would love to see how it looks, I assume you done the timing on the dyno

 

or is this one of those 'trade secrets'

 

Nigel

[Lazeum]

First, I love your build & the info being shared There's a lot of stuffs to learn.

 

Regarding the lash pad, I would be concerned. if it has been broken this way, somehow you had side loads where you're not supposed to.

Could it be the spring seat tilted a little?

If not, I would look for something that could have created some rocker rotation back to Z axis: free lash on the lifter, cam profile or rocker pad not flat (can it be even possible?)

 

Regarding AFR, can you please comment? I do my tuning on open road with a wideband & my dyno butt, I'm usually targetting for a baseline AFR of 12.5.

Yours deviates from it, does the dyno show better results with such levels? Could the torque drop at 5500 be caused by rich AFR? same goes for lean AFR at 6500rpm?

I'm curious since you're doing it with much more appropriate tool than me

 

I'm also thinking it might not be tuned completely yet...

Edited May 3, 2011 by Lazeum

[z-ya]

Hi,

 

Would you have a print out of your timing curve ? (RPM / Degree / manifold vacuum )

 

I would love to see how it looks, I assume you done the timing on the dyno

 

or is this one of those 'trade secrets'

 

Nigel

 

Nothing fancy. It is 35 deg above 3000RPM. Basically a flat line. Cranking timing is 15 deg. From 1000 to 3000 it is linear from 20 to 35 deg.

[z-ya]

First, I love your build & the info being shared There's a lot of stuffs to learn.

 

Regarding the lash pad, I would be concerned. if it has been broken this way, somehow you had side loads where you're not supposed to.

Could it be the spring seat tilted a little?

If not, I would look for something that could have created some rocker rotation back to Z axis: free lash on the lifter, cam profile or rocker pad not flat (can it be even possible?)

 

Regarding AFR, can you please comment? I do my tuning on open road with a wideband & my dyno butt, I'm usually targetting for a baseline AFR of 12.5.

Yours deviates from it, does the dyno show better results with such levels? Could the torque drop at 5500 be caused by rich AFR? same goes for lean AFR at 6500rpm?

I'm curious since you're doing it with much more appropriate tool than me

 

I'm also thinking it might not be tuned completely yet...

 

I spoke with Dave Rebello, and two other engine builders and they have never seen this happen before. I'll call Isky next to see what they say.

 

The AFR goal is 13-13.5:1, but with these Mikuni race carburetors, achieving that goal is not possible across the entire RPM range. You have to live with some rock areas to get the AFR ideal on the top end. And since we had the lash pad issue, we couldn't continue to tune. Most likely we are done tuning for this year mainly for cost reasons.

[didier]

Hi, amazing engine, congratulations for your work

just a question : did you put the Z-196 isky cam in your head ?

[Lazeum]

I spoke with Dave Rebello, and two other engine builders and they have never seen this happen before. I'll call Isky next to see what they say.

 

The AFR goal is 13-13.5:1, but with these Mikuni race carburetors, achieving that goal is not possible across the entire RPM range. You have to live with some rock areas to get the AFR ideal on the top end. And since we had the lash pad issue, we couldn't continue to tune. Most likely we are done tuning for this year mainly for cost reasons.

 

I'll be curious to know as well. I haven't seen Paul or Tony reacting to this, I'm quite surprised

 

Regarding the tuning, I understand now, we never have enough money for our little car... Were you also recording EGR during the tuning sessions? I'll be curious to see how they look like (not to provide my non-existent expertise but more to see how it looks like)

[frank280zx]

I had it slip off a lash pad once due to a misfire.

Would the cryo process have anything to do with it?

 

otherwhise my bet would be a misfire and a bad (metal weakness) lashpad...

 

I would not worry to much about it, if you do worry about the qaulity, change all the pads by other ones from a diffrent supplier.

Edited May 5, 2011 by frank280zx

[Tony D]

Got news, the pads all come from the same supplier, regardless who vends them...

 

I like the distributor.

[z-ya]

Tony,

 

Ever seen a lash pad do this before?

 

Dave Rebello said that on early aftermarket lash pads there was a groove machined for oil along each ear. Those would fail like mine. But these don't have a groove.

 

Since I have to run a distributor, I might as well run a good one. I'm triggering the 6AL2 and adjusting the timing curve there using the retard curve. I set the static advance to 40 deg so I could retard it to where it needs to be. We had to drill another hole in the button to get the rotor tab to line up correctly with the cap.

Edited May 5, 2011 by z-ya

[TimZ]

Tony,

 

Ever seen a lash pad do this before?

 

Dave Rebello said that on early aftermarket lash pads there was a groove machined for oil along each ear. Those would fail like mine. But these don't have a groove.

 

Since I have to run a distributor, I might as well run a good one. I'm triggering the 6AL2 and adjusting the timing curve there using the retard curve. I set the static advance to 40 deg so I could retard it to where it needs to be. We had to drill another hole in the button to get the rotor tab to line up correctly with the cap.

 

I have...

 

Probably not what you want to hear, but this happened to me when I dropped a valve seat. The seat held the valve open enough that the pad popped off the retainer and got munged up by the rocker.

This is not to say the you necessarily dropped a valve seat, but perhaps something else allowed the rocker to come off the pad. Valve float maybe?

[josh817]

I was thinking maybe the same thing TimZ, about the valve floating. I chucked a rocker on my motor doing part throttle slowly going through the RPM's up to 7000 RPM. The lash pad was sitting under the cam along with the rocker, but nothing was broken. I'm sure if it was crunched somewhere in there, it would break.

 

Did you find everything in place when you took the valve cover off? Or was it like mine, pieces not where they should be?

 

 

 

 

Also, I'm not a buff on this stuff but I see a groove along the ear of your lash pad, Z-ya. In the second picture. It looks similar to Tim's. And here too, unless he was talking about a different groove:

Then I smoothed any wear on the top of the stock lash pad:

 

Edited May 6, 2011 by josh817