bowtienut

iTrader: (1)

The smaller cam will be better all around, especially with your mild gearing.
Just give Lloyd an accurate CR number, so he can consider that and maybe adjust installed position (ground-in advance) if necessary.

Casey96SS

Should of mentioned I will be putting 3.90 gears in.

I stopped at the machine shop today. They said they might be able to save the cam using some undersized ID cam bearings and grinding the cam journals. They are going to check everything out when I drop the short block off at the end of May. I hate to have non standard sized cam bearing journals, but I do not really plan on swapping cams or rebuilding this motor again.

bowtienut

iTrader: (1)

I'd still stay with the smaller cam with 3.90 gears. That's not very steep for an M6.
If they're capable of grinding those cam journals, no harm in going that way. It doesn't affect the block whatsoever.

Casey96SS

I was planning on having the machine shop set up the block for .035" quench. I was originally thinking of having the pistons .009" in the hole and using a .026" head gasket.

I used the VR .026 5898 previously and ended up using coolant somehow. Lloyd checked the heads out and there were no issues with them. He said he also recently had another customer that had a coolant leak with the VR 5898 gaskets. I guess I do not have 100% confidence in the VR .026" gaskets and do not want to have to pull the heads again after this thing goes back together.

Would it make much of a difference zero decking the block and running the Felpro .039" 1074 gaskets for .039" quench? Am I just splitting hairs with the extra .004". Is it possible to run the pistons .004" out of the hole to achieve .035"? Also not sure what the normal tolerance stack up is too with a freshly machined block and bottom end. Should I expect piston depth to be within a few .001" of each other or does it tend to vary more?

Just asking because I would like to have my numbers straight when I drop the bottom end off. It seems like every machine shop I have talked too, the guys start to get a little pissy when you start talking numbers and dims with them.

bowtienut

iTrader: (1)

Stick with .009" in the hole and the .026" gasket.
With Lloyd verifying the head decks good and fresh machined block decks, if you have problems with the .026 gasket then you'll have the same problems with the Felpro 1074. Money says it's not the gasket; it's either bad surface(s) or faulty assembly.
I've used the MG 5716G .026", never an issue. I'm not sure if the VR 5898 is exactly the same.

KW Baraka

iTrader: (7)

I would ordinarily agree with Pat on this. But the issues you site would make me want to have the block checked. It may have to be decked a bit to insure that it's completely level.

KW

Casey96SS

Yes, planning on having the block decked, line honed, and torque plate bored/honed. I doubt the block has any cracks since it was not using coolant before the head swap, but I will probably see what the machine shop says about checking for cracks too.

Do you guys think there would be any added insurance if I use copper spray on the head gaskets when I put it back together? I know it is not required for the .026" gaskets, but just looking for any extra help I get get to make sure the gaskets seal for good this time. Have not head the time to research this yet to find out if it is appropriate for this type of gasket.

bowtienut

iTrader: (1)

No, use copper spray only on metal embossed (ie. shim) gaskets. Using it on a composition gasket surface will do more harm than good.

cardo0

I've never seen a head gasket that has instructions for using copper sealer. LT1's have reputation for blown head gaskets Casey. Plenty of snake oil fixes to.

bowtienut

iTrader: (1)

Huh?
That's like saying internal combustion engines have a reputation for blown head gaskets!

Casey96SS

I measured my head cc this past weekend. Turns out my combustions chambers are 54cc and not 56cc.

This bumps my SCR up to 11.98:1

Cylinder Bore Size: 4.030”
Piston Stroke Length: 3.48”
Head Gasket Bore Diameter: 4.10”
Compressed Head Gasket Thickness: .026”
Piston Deck Clearance: .009” (.035" quench)
Combustion Chamber Volume In CCs: 54cc (verified)
Piston Dome Volume In CCs: -5cc (adds 5cc to combustion chamber volume)
Rod Length: 6.000”
Piston compression height: 1.250”
Piston Stroke: 3.48”

I ran the DCR calculator from Wallace Racing and got the following info:

(My current cam Int Adv Close is 57.7 deg ABDC and local elevation is 600-ft.)

Static compression ratio of 11.98:1.
Effective stroke is 2.85 inches.
Your dynamic compression ratio is 9.87:1 .
Your dynamic cranking pressure is 208.18 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 9.87 :1.
V/P (Volume to Pressure Index) is 182

Do you guys think this will be ok on good 93 octane, running the stock cooling system, and correct plugs? Still planning on using Solomon for the tune with datalogging.

cardo0

No. But u need to measure the piston to deck vol with liquid to be accurate. Same person saying quench is more import than lower C.R. talked u into a lousy thin head gasket. Just because he got away with it dosent mean u will - to many variables. Some one has led u over the edge of the cliff.

Use a thick gasket. U need a bigger cam (larger duration). U can still have the head chambers reworked for a few more cc like unshroud the vlvs and contour the large/thick areas.

bowtienut

iTrader: (1)

Know your limits, cardo0. If you ever built an LT1 that wasn't an embarrassment, you might understand the quench and timing requirements that go along with it. Or maybe you do, and it's just your argumentative attention-begging nature coming out again ..??

Casey, stick with the .026" gaskets. I'll say it again for the slow learners reading this: Keeping the quench tight requires less timing advance for best power and therefore better detonation resistance. Just be sure your entire timing table is correct, and not just the high MAP columns from dyno tuning.

I get 11.94 SCR and 9.44 DCR assuming a 106 ICL. IVC 65 deg ABDC.
IMO, even 9.4 DCR is pushing it a bit too far on pump fuel. I think you'll have to be too careful to enjoy it when it's up to temp in hot weather.
More intake duration is of course a natural recommendation.
Or......if you want to work with what you have, get some offset bushings and degree your present cam to about a 110 ICL to drop the DCR to 9.2, which is practical with a 160 tstat and proper fan programming. A minor compromise in power, but it's your budget, so you decide.

BSmiff

So many options!!!!! But it does seem like running the .026 gasket would be perfect but after having that + decking the block + milling the heads + getting a cam....how close are we getting to the piston with the valve? Im all for having a tight quench and getting a great burn but not at the cost of PTV clearance.

bowtienut

iTrader: (1)

Quench clearance is a minor factor in PTV clearance. Cam/valve timing is the overriding factor. You won't have an issue with any sensible cam you would want for this type of build unless you advance the cam excessively, such as to a 100 deg ICL or less.

Casey96SS

Thanks for all the help so far Pat! I am not sure why I have to make everyone of my projects so complicated!!

Being that my cam is somewhat f'd up to begin with, do you think the easiest solution would be to talk to Lloyd about a custom cam first? Another $300 to $400 dollars is not the end of the world.

I do not really want to have to start putting more money into the heads to have the combustion chambers opened up if is even possible.

Attached is the spec sheet on my current cam. IVC is listed at 57.7 ABDC which I think think actually makes things a little worse than 65 IVC you listed above. Also, is the 4.1 degrees of timing advance typical for a performance cam? I did not know if this would help or hurt the current situation.

bowtienut

iTrader: (1)

You can't use those "advertised" valve events on AI's cam cards. I don't know what tappet lift they get those at, but they sure as heck aren't the traditional .006" tappet lift. If they were, your advertised duration would be only 261 deg -. That would be some nasty intensity on those lobes to get 226 duration at. 050" ! Your advertised duration on that cam is about 276 deg.
I noticed the same bizarre "advertised" numbers on the cam I had from them. They may do it intentionally to try to keep people from copying the cams.

Yes, 4 deg of ground in advance is typical.

Casey96SS

I brought my block to the machine shop last week. Cam bearing bore is bad. Could be fixed but would require $400 to $500 in difficult machine work plus $100 special cam bearings. Does not sound worth it to me, so I am on the hunt for a new block. They may be able to polish my cam journals and check it for straightness and possibly save it, but I am not overly concerned about that.

Since I am no longer using my original block I started looking at forged 383 rotating assemblies. I could not really find anything that seemed to play real nice with my 54cc heads compression wise. Kind of seems like I would be better off with some more CC in the heads for a 383 so I do not think I am going to go that route. This is also kind of a learning experience for me so I do not really want to put $2,000 plus into budget forged bottom end parts and screw something up I did not know about.

So it is back to the stock crank with some fresh 54cc LE2 heads. I want this to be a decent running street motor and I am not really after pushing the boundaries of pump gas and having to mess with cam timing and all that.

What would be a good quench and SCR for a street motor running a 226/234ish 110 LSA cam?

Using typical +5CC Mahle Pistons I come up with the following combinations:

.035" Quench; 11.94 SCR (Would require a 227/235 110 LSA Lunati cam from Lloyd)

.040" Quench; 11.76 SCR (226/234 110 LSA cam?)

.045" Quench; 11.60 SCR (226/234 110 LSA cam?)

Which would be the most 93-octane friendly combination (if any)? Thanks for any input!

Casey96SS

I bought a better graduated cylinder and measured my head cc again just to be sure. Turns out they are actually 52cc which bumps up my compression even more.

I would like to keep the compression in the 11.5 range to be completely safe on pump gas. I cannot seem to find a piston/quench combination that works with my 52cc heads. If I could find a piston in the 8 to 10 cc range, that would probably be ideal. Unfortunately they all seem to jump from 5 or 6 cc up to 16cc.

Anyone have any suggestions? I am assuming custom pistons are fairly expensive?

hrcslam

I think they are all going to react similarly to knock, a tighter quench helps but so does a lower SCR.

At this point I'd talk to Lloyd Elliot and see what he recommends.

I'm running .043" quench at 11.8:1 SCR on a 230/238 110+6 grind. No issues with detonation on 91 octane in Phoenix heat.

If you have a good tune it shouldn't be an issue, especially if fully forged.

Personally, I'd go with the highest SCR with the tightest quench, then put the smallest cam recommended by LE and tune it very well. Hope you know a good LT1 tuner (preferrably dyno) or can do it yourself. I ended up doing mine my self, even after taking it to a dyno tuner.