Cylinder and head question

[Axitech]

Getting ready to reassemble my newly rebuilt engine. I've got the case together, cylinders are ready to go on. Here's the issue, in the heads, wherethe cylinder seals to the head surface, there is a groove. the groove is from the heads and cylinder mating and, I believe, compressing the soft aluminum material of the head. The heads were brand new L5 units from ACN and were flawless, so I'm thinking I can go right ahead and reuse them as they are right now, with the groove.

My question though is, what does the groove do to the head capacity? The cylinder now sits further into the head, and this means the piston rises that much closer to the combustion chamber. this would tend to raise compression ratio, right? The groove is not very deep, maybe a .010-.020. I have not measured it. I'll try to get out there tomorrow . It's awful damned cold out there right now.

Thanks,
Bob
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[KROC]

A groove in the head at the cylinder sealing surface is not correct, you should post a picture, it sounds to me like you need the heads machined.

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[jason]

Maybe you are remembering backwards and it's a step.

[mark_85226]

Do you have a picture? If you ordered them for a non-stroker they may have been machined to reduce the chamber volume. This is common for DRD heads since the standard volume is over 60cc.

[Axitech]

Went out and took a pic of each head. Decided to inspect/measure the groove while there. Having issues uploading pics right now, old crap computer. Anyway, the groove isn't so much a groove as it is a slight ridge just inside the cylinder wall. I measured depth of the cylinder seating area in head to top of that ridge and got a maximum of .002.

For some reason I recalled it being worse. Temps are supposed to rise Monday, I'll get back at it then. Thank
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[Axitech]

Ok, got the pics to load. The ridge is less than .002 at it's worst spot.


After three weeks of foot-dragging by the machinist my Ford engine guy said to take it to, I finally pulled the cylinders out of his hands and brought them home.

Here is a quick rundown on the issue. deck heights are .076, .076, .078, and .075. Given these numbers and running them on the engine calculator over at CBPERFORMANCE.COM, and plugging in : 92 bore, 74 stroke, and 60 cc's (advertised) on the heads= from 7.7:1 to 7.8:1 compression ratio.
Cam is a Engle w110 running dual 40 IDF carbs.

Cam recommends running 8-8.5:1 cr.. What would be the downside of running with 7.7:1 cr ? Other than NOT getting maximum power, I can't see a downside. Upside would be far less chance of pinging and detonation. Or, at least that is what I think right now.

What do you all think?
Thanks, Bob
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[spanky324]

I would talk to John at Aircooled.net he knows his stuff!

[esde]

I would kill both issues with one operation. Cut them a little to raise your compression, and clean up the cylinder mating surface.

[modok]

WOW the chambers on those heads ARE huge.
The good news is you could run regular grade gas pretty much all the time.

Running higher octane than needed actually runs worse.

[slalombuggy]

Get your compression up or your engine will run like a dog. The reason you raise static compression with bigger cams is because they bleed off running compression due to the longer overlap (time both valves are open). Run the minimum compression for that cam or find another cam. I see no problems running 8:1 and regular gas. Were the heads loose causing that groove in the heads?

brad

[Boolean]

I would not run that engine with less than 8:1. Preferably 8.5 to 9 with premium fuel.
Low compression kills torque(power) and MPG.
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[Axitech]

Mod ok, yeah, the motor was a fresh build with maybe 2500 miles on it. I was 100 miles from home. On arrival I was going to pull it and re torque everything. Just outside Harrisburg, I looked in the mirror and saw the big cloud of blue smoke from the cracked case.
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[modok]

I hope your new case is better than the old! yikes.
cylinder sunk in .002 is OK, I've seen then sink .004 and still seal fine. They usually do it worst by the outside as that where the exhaust and HEAT is. Might be slightly alarmed at that level of movement in only a low number of miles tho.
I don't believe any re-torque is needed if the cylinders are seated on the case wide and solid and good heads(germany or mexico) are used, but, it might be a good idea if that's not the case.
EEPCo heads and old MOFOCO hold the record for worst, the cylinders sink in massively like the heads were made of bubble gum, and I hope the china heads won't be in the same category. Only one way to find out. Get back on the road!

[Axitech]

Local. Machine shop say s they can fly cut the heads and give me a final setting of 55 cc's . $275.
Seems a tad high to me. Brothers website says $35 or $45 per.
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[the2ndcashboy]

[modok]

Wow, I'm at $60 a head, and that seems to be high enough to eliminate all customers. I don't really like doing them (don't have specialized VW setup, just mill and facing head)

[Axitech]

Yeah, I'm about to box them up and send to Brothers. Waiting for a phone call to let me know they want the work and off they go. Sent John at Aircooled an email asking how much he thinks they would need to mill off to get the 60cc chambers down to 55cc's, and if he thinks those heads have the ability to be milled that far. He's really helpful in that stuff. So, if all goes well, I'll be mobile again in a couple, three , weeks. I hope!
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[esde]

message sent

[Axitech]