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 Page 1 of 2 12
Username Post: To quench or not...        (Topic#253835)
octanejunkie 
Contributor
Posts: 595
octanejunkie
Loc: Los Angeles area
Reg: 11-12-09
12-04-10 11:42 PM - Post#2013685    

The motor in my truck, in my sig, is running around 9.2 SCR, 8.2 DCR; average deck height is .027, current head gasket is a felpro marine (thick) gasket

If I put .015 coated shim gaskets on instead I could get close to .042 quench - would this make me more detonation prone?It would raise my CR across the board... 9.8 SCR and 8.6 DCR

'59 Chevy 3100 Stepside
0.030-over 350, mild (214/224 @ .050) 112 LC cam,
vortec heads, air-gap, 600cfm carter, Holley Avenger EFI, 2-1/2" rams horns,
Bowtie Overdrives 700R4 w 2200rpm stall, 3.42 posi rear on top of 31.5" BFGs


 




bobb 
Super Senior Member
Posts: 5328
bobb
Loc: paradise
Reg: 09-05-03
12-05-10 12:34 AM - Post#2013690    
    In response to octanejunkie

iron heads?

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


 
Wheels56 
Senior Member
Posts: 264
Wheels56
Loc: CA
Reg: 02-17-02
12-05-10 07:21 AM - Post#2013754    
    In response to bobb

If the engine runs OK now there really isn't a reason to do this. Yes it will optimize your quench but unless you change the cam to take advantage of the higher compression you won't notice much difference.



 
octanejunkie 
Contributor
Posts: 595
octanejunkie
Loc: Los Angeles area
Reg: 11-12-09
12-05-10 11:07 AM - Post#2013873    
    In response to Wheels56

  • bobb Said:
iron heads?



Yes, iron vortec heads

  • Wheels56 Said:
If the engine runs OK now there really isn't a reason to do this. Yes it will optimize your quench but unless you change the cam to take advantage of the higher compression you won't notice much difference.



I was thinking about a cam change sometime in the future, CC XE268 perhaps...

'59 Chevy 3100 Stepside
0.030-over 350, mild (214/224 @ .050) 112 LC cam,
vortec heads, air-gap, 600cfm carter, Holley Avenger EFI, 2-1/2" rams horns,
Bowtie Overdrives 700R4 w 2200rpm stall, 3.42 posi rear on top of 31.5" BFGs


 
IgnitionMan 
Valued Contributor
Posts: 3412

Reg: 04-15-05
12-05-10 12:33 PM - Post#2013901    
    In response to octanejunkie

LESS prone to detonation. And, yes, you should get that quench down, but not by thin gaskets if possible.

There are a lot of issues that come up in setting quench, like some Solv-O-Lite pistons referred to as "de-stroked". These pistons have the pins set .020 UP from stock compression height, as years ago, some brilliant bozo thought that bad fuels would need less compression ratio, so they moved the pins UP in the pistons, destroying the detonation resistance of the correct quench.

Years ago, I did a small block Ford with these disasters of pistons in it, had a .055 gasket, and the pistons were down in the bores .040. I did nothing more than take the whole engine apart, deck the block .040 for zero deck, and rebuild with .042 head gaskets. No more pinging, no more detonation.

I strongly getting the quench right.



 
octanejunkie 
Contributor
Posts: 595
octanejunkie
Loc: Los Angeles area
Reg: 11-12-09
12-05-10 03:02 PM - Post#2013962    
    In response to IgnitionMan

Well, without my knowledge, my shop installed SpeedPro 423NCP pistons, pin height is .020 higher making the compression height 1.540 vs. 1.560 - so to avoid a .015 gasket, I'd have to change my pistons.

In addition to that, my average deck height is .027, meaning some pistons are .024 and some are .030 in the hole, the deepest one is .032 - either my deck is warped (not likely since it was cleaned up) or the rods are not even, most likely.

If I really want to get this motor right, it looks like I need to rebuild it, but truthfully, it runs OK and I was just considering the thin gasket to gain quench easy and cheap if and when I swap cams

'59 Chevy 3100 Stepside
0.030-over 350, mild (214/224 @ .050) 112 LC cam,
vortec heads, air-gap, 600cfm carter, Holley Avenger EFI, 2-1/2" rams horns,
Bowtie Overdrives 700R4 w 2200rpm stall, 3.42 posi rear on top of 31.5" BFGs


 
bobb 
Super Senior Member
Posts: 5328
bobb
Loc: paradise
Reg: 09-05-03
12-05-10 04:06 PM - Post#2013988    
    In response to octanejunkie

i would go with gaskets. im running corteco ss shim gaskets now and have no problems.

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


 
Rick_L 
Honored Member
Posts: 27446
Rick_L
Loc: Katy, Tx, USA
Reg: 07-06-00
12-05-10 04:09 PM - Post#2013992    
    In response to octanejunkie

In the 60s all Chevys came with .015", .018", or .022" stamped steel head gaskets. They never let me down once, and I don't think they will on a street 350.

We ran them on iron headed race engines all the time. The only time I ever saw anything distressing was on a 650 hp destroked 350. Some evidence that the heads were lifting enough to see a compression leak past the bead. But never an outright failure or a water leak.

To use these gaskets you must use some kind of sealer to prevent water leaks - we always used K&W Copper Coat or Permatex Hi-Tack.

Yes the composition gaskets are a little better and they don't need sealer. That doesn't mean they are "must use".

Thing is, these thin head gaskets can solve your quench situations much cheaper than replacing an otherwise good set of pistons.

Just my opinion.



 
IgnitionMan 
Valued Contributor
Posts: 3412

Reg: 04-15-05
12-05-10 04:14 PM - Post#2013994    
    In response to Rick_L

It's a gamble on the gaskets, but it is the easiest way to correct the quench.

See what I mean by pin heights, all over the place, due to bozo's that refuse to design the pistons right. Sometimes, design engineers cause more problems than they are worth.



Edited by IgnitionMan on 12-05-10 04:15 PM. Reason for edit: No reason given.

 
octanejunkie 
Contributor
Posts: 595
octanejunkie
Loc: Los Angeles area
Reg: 11-12-09
12-05-10 09:26 PM - Post#2014116    
    In response to IgnitionMan

I'd like to set the quench and choose the best cam for my driving style, what I have now is OK, I just don't think it is as good as it can be.

My biggest issue right now is poor fuel economy/mpg, at best, I get just under 14 mpg with mostly highway driving, just under 12 mpg in the city.

'59 Chevy 3100 Stepside
0.030-over 350, mild (214/224 @ .050) 112 LC cam,
vortec heads, air-gap, 600cfm carter, Holley Avenger EFI, 2-1/2" rams horns,
Bowtie Overdrives 700R4 w 2200rpm stall, 3.42 posi rear on top of 31.5" BFGs


 
IgnitionMan 
Valued Contributor
Posts: 3412

Reg: 04-15-05
12-06-10 11:52 AM - Post#2014296    
    In response to octanejunkie

Getting the quench right is good for about a half point of C/R with iron heads, as much as 1 full point on aluminum head engines. Case in point, the 10.25:1 C/R of the ZZ3/ZZ4 engines. If their quench distance were as much as yours, these engines wouldn't run well at all, and would detonate worse than they do now before changing the distributor settings around to work correctly.



 
MikeB 
Ultra Senior Member
Posts: 10058
MikeB
Loc: Plano, TX
Reg: 08-28-03
12-06-10 02:11 PM - Post#2014349    
    In response to IgnitionMan

I’d be leery of using steel shims unless block deck and head surfaces are very flat. If you must go that route, I’d use the .022” gasket to be on the safe side.

GM makes a .028” composite gasket that will drop your quench to ~.055", but that's still .010"-.015" from ideal, especially for the resultant 9.7 SCR.



1982 C10 SWB pickup: Unmolested base truck, original paint. Originally had 250 six and 3-on-the-tree
Now has 355 with Vortec heads, RamJet roller cam, LS6 beehive springs, TH350
Retired, but working part-time on 50s-70s cars & trucks.


Edited by MikeB on 12-06-10 02:25 PM. Reason for edit: No reason given.

 
octanejunkie 
Contributor
Posts: 595
octanejunkie
Loc: Los Angeles area
Reg: 11-12-09
12-06-10 03:02 PM - Post#2014364    
    In response to MikeB

Heads and block were milled prior to this build, should be pretty straight...

'59 Chevy 3100 Stepside
0.030-over 350, mild (214/224 @ .050) 112 LC cam,
vortec heads, air-gap, 600cfm carter, Holley Avenger EFI, 2-1/2" rams horns,
Bowtie Overdrives 700R4 w 2200rpm stall, 3.42 posi rear on top of 31.5" BFGs


 
72novaproject 
Senior Member
Posts: 3221
72novaproject
Age: 62
Loc: D/FW Texas
Reg: 02-18-03
12-07-10 07:44 AM - Post#2014631    
    In response to octanejunkie

Back in the late 70’s /early 80’s, we weren’t allowed to use anything at the dealership but the factory steel gaskets even though we could get fel-pro right down the street at the local parts store. Never had a problem with them even on an engine that had been over heated enough to crack a head. We would sneak down to the Ford Dealer and buy their sealer because it was better. Basically just rubber cement for the most part.

Steve

To each problem exists a solution...now think.

The ZD Nova Page


 
rumrumm 
"17th Year" Silver Supporting Member
Posts: 2075
rumrumm
Loc: Macomb, IL
Reg: 10-18-01
12-07-10 08:35 AM - Post#2014665    
    In response to 72novaproject

It is the 8.6 DCR that bothers me. That is simply asking for trouble, IMO. With iron heads, you need to keep your DCR below 8.0 to avoid detonation problems. I think you have to figure out how to avoid this Catch-22 situation you have: too much quench or too high a DCR.

Lynn

"There's no 12-step program for stupid."


383 sbc, Eagle, AFR, SRP, CompCams, Edelbrock, FiTECH. Dyno #'s: 450 hp @ 5700, 468 ft. lbs. torque @ 4300.

http://photo.net/photos/Lynn%20Johanso n


 
ss3964spd 
"6th Year" Gold Supporting Member
Posts: 4620
ss3964spd
Loc: Fairfax, Va
Reg: 12-21-00
12-07-10 11:46 AM - Post#2014735    
    In response to rumrumm

  • rumrumm Said:
It is the 8.6 DCR that bothers me.


Unless he proceeds with the cam change. But isn't the XE268 (224/230 + 110 LSA) pretty big for a 350? Me thinks you'll need to also change your 2200 stalled TC. If you spec the 268 grind on a 112 that will bleed off a little dynamic compression.

Back to the original Q; assuming no other changes I don't think you'll notice any seat of the pants difference by tightening the quench and rasing the comp a 1/2 a point.

Dan

If I recall correctly my memory is excellent. My ability to access it is not.


 
IgnitionMan 
Valued Contributor
Posts: 3412

Reg: 04-15-05
12-07-10 01:14 PM - Post#2014769    
    In response to ss3964spd

I've used stock stamped steel head gaskets for just about 40 years now, for pistons that sat down in the bores correctly, and have had NO problems with them. I also paint them with silver laquer paint just before install, per factory recommendations.

Corvette engines used to have a -.005 to zero deck, and used TWO stamped steel head gaskets per side, worked also....very WELL.



 
scottsdale84 
Forum Newbie
Posts: 79

Age: 33
Loc: Oakland IA
Reg: 11-19-08
12-07-10 01:43 PM - Post#2014779    
    In response to IgnitionMan

isnt that how the ss 409 were from the factory too?



 
IgnitionMan 
Valued Contributor
Posts: 3412

Reg: 04-15-05
12-07-10 05:50 PM - Post#2014911    
    In response to scottsdale84

The 425 horse 409, and Z11 427 engines used to stacked steel head gaskets, everything else, single steel gasket.



Edited by IgnitionMan on 12-07-10 05:52 PM. Reason for edit: No reason given.

 
Rick_L 
Honored Member
Posts: 27446
Rick_L
Loc: Katy, Tx, USA
Reg: 07-06-00
12-07-10 06:35 PM - Post#2014933    
    In response to IgnitionMan

So far only MikeB has badmouthed stamped steel gakseets, I wonder if he's ever used one. Or had one fail under "reasonable" conditions.

And yes, silver rattle can paint is a sealer that works, it's not critical what you use, but you have to use something.



 
fritz1990 
Dedicated Enthusiast
Posts: 6514
fritz1990
Age: 56
Loc: Kansas
Reg: 02-16-03
12-07-10 07:25 PM - Post#2014964    
    In response to Rick_L

My 496 had GM shims in it with 10.5 comp, no problems in 3+ years.

As far as the paint for the shims, I heard that it was mainly for preventing rust of the steel gasket more so than the sealing. I always use Copper Coat on my shims, never a problem here. Would have used them on my 498 too as I have a few sets of the GM shims left. Don't think my AFR heads would have appreciated it though.

Regards, Jeff

1998 K1500 6.5 Coal burner
1965 C10 with 498 BBC AFR Heads
1964 C10 Ran 348W for 6 years, now SBC.

Corvettes owned: '74 '77 '78 L82 Silver Anniversary, 2002 LS1

Don't have a nervous come together!

http://picasaweb.google.com/fritz199090


 
IgnitionMan 
Valued Contributor
Posts: 3412

Reg: 04-15-05
12-07-10 07:35 PM - Post#2014970    
    In response to fritz1990

In the industrial area just behind where I grew up in Santa Fe, Springs, Ca., years ago, there was K&W Copper Coat. We kids used to go ride our bikes in front of the place, and the workers used to throw cans of Copper Coat at us. Too bad we were too young to know what the heck it really was, we had bazillions of cans of it.



 
fritz1990 
Dedicated Enthusiast
Posts: 6514
fritz1990
Age: 56
Loc: Kansas
Reg: 02-16-03
12-07-10 08:28 PM - Post#2014998    
    In response to IgnitionMan

Sounds like the small town I live in. Was a main railroad depot in the 30's-40's. Lot of the 'ol timers said that when they were a kid the coal trains would stop in for shift changes. They would go call the RR guys names, make faces at them and aggravate them until they started throwing chunks of coal at them to get them to leave. They then picked up all the coal and took it home for heat.

Regards, Jeff

1998 K1500 6.5 Coal burner
1965 C10 with 498 BBC AFR Heads
1964 C10 Ran 348W for 6 years, now SBC.

Corvettes owned: '74 '77 '78 L82 Silver Anniversary, 2002 LS1

Don't have a nervous come together!

http://picasaweb.google.com/fritz199090


 
IgnitionMan 
Valued Contributor
Posts: 3412

Reg: 04-15-05
12-07-10 09:04 PM - Post#2015009    
    In response to fritz1990

We didn't taunt them, we just rode all over the place.



 
octanejunkie 
Contributor
Posts: 595
octanejunkie
Loc: Los Angeles area
Reg: 11-12-09
12-07-10 10:36 PM - Post#2015036    
    In response to ss3964spd

If I went with a XE268H-4 on a 114 LC I could bring the DCR down to 8.28...

'59 Chevy 3100 Stepside
0.030-over 350, mild (214/224 @ .050) 112 LC cam,
vortec heads, air-gap, 600cfm carter, Holley Avenger EFI, 2-1/2" rams horns,
Bowtie Overdrives 700R4 w 2200rpm stall, 3.42 posi rear on top of 31.5" BFGs


 
rumrumm 
"17th Year" Silver Supporting Member
Posts: 2075
rumrumm
Loc: Macomb, IL
Reg: 10-18-01
12-08-10 07:17 AM - Post#2015119    
    In response to octanejunkie

A DCR of 8.28 is still too high with iron heads. Try your combination with the Magnum 270 cam. It is of a similar size but the intake valve closes later and will lower your DCR.

Lynn

"There's no 12-step program for stupid."


383 sbc, Eagle, AFR, SRP, CompCams, Edelbrock, FiTECH. Dyno #'s: 450 hp @ 5700, 468 ft. lbs. torque @ 4300.

http://photo.net/photos/Lynn%20Johanso n


 
ss3964spd 
"6th Year" Gold Supporting Member
Posts: 4620
ss3964spd
Loc: Fairfax, Va
Reg: 12-21-00
12-08-10 12:41 PM - Post#2015238    
    In response to rumrumm

He's running a 8.2 DCR now without issues, but agree with the 270.

OJ, if you go with a 114 the engine is apt to feel a little lazy compared to what you have now - though the curves will be wider.

As a side note; Comps' XE grinds are generally regarded as noisy buggers, and the one I had in my 396 certainly was. Took me quite some time to figure out that the noise wasn't coming from the lifters (hydr), or from the rockers - it was coming from the valve seats. Multiple emails to/from Comp finally confirmed it. The XE lobes close the valves very fast, and a little hard, onto the seats - but apparently not hard enough to do any sort of damage.

Dan

If I recall correctly my memory is excellent. My ability to access it is not.


 
C10 Sleeper 
Valued Contributor
Posts: 3426
C10 Sleeper
Loc: Redding Ca
Reg: 03-17-09
12-08-10 07:53 PM - Post#2015417    
    In response to ss3964spd

I had the 292 magnum cam in my last 350. It was a good cam and easy on the valve train. I know there are better cams out there but I really like the magnum cams.

http://photobucket.com/C10Pictures


 
greg_moreira 
Very Senior Member
Posts: 3274
greg_moreira
Reg: 10-06-03
12-08-10 09:52 PM - Post#2015470    
    In response to ss3964spd

  • ss3964spd Said:
He's running a 8.2 DCR now without issues, but agree with the 270.

OJ, if you go with a 114 the engine is apt to feel a little lazy compared to what you have now - though the curves will be wider.

As a side note; Comps' XE grinds are generally regarded as noisy buggers, and the one I had in my 396 certainly was. Took me quite some time to figure out that the noise wasn't coming from the lifters (hydr), or from the rockers - it was coming from the valve seats. Multiple emails to/from Comp finally confirmed it. The XE lobes close the valves very fast, and a little hard, onto the seats - but apparently not hard enough to do any sort of damage.



Im glad somebody actually has this on record from Comp. I try to tell folks this regularly, and some guys look at me like ive got three heads! Even a lot of the noise with solid flat tappets and solid rollers is related to this. The concept is to open the valve as fast as possible, get it to a higher lift as quickly as possible, hold it there at the higher lifts for as long as possible(area under the curve), and close it as quick as possible to trap cylinder pressures.

You usually dont find these sort of seating velocities with many hydraulic cams....but comp dialed them into the aggressive XE cams. Hence....a lot of the noise.

Back to your regularly scheduled programming!

About the topic at hand....Id try it. Neither static or dynamic compression mean anything if there isnt something to compress. AKA... cylinder filling.

Kinda doesnt matter what the "rate" of compression is if there isnt much cylinder filling present and you arent compressing a "full" and adequately dense mixture to begin with.

This is why neither static, or dynamic compression can be exactly pinpointed to a gauranteed number that will work.

A forced induction engine proves this. You need lower compression ratio figures because your mixture volume and density is greater(which ultimately affect cylinder pressure, which is really the only thing were trying to control).

Even in naturally aspirated form, the quality of the mixture can vary, and the effectiveness of the compression ratio can too. thats why we only have guidelines and not gaurantees.

What we do know is you are working fine with the ratio you have now. We also now that better quench is, well, better! heh.

And with the amount of ethanol we have blended in modern fuels nowadays, I wouldnt be shocked if it took the extra half point of compression without issue whatsoever. Worst case scenario is you have to undo the head gasket swap, but at least you will be able to say you tried it and found its limits.



 
rumrumm 
"17th Year" Silver Supporting Member
Posts: 2075
rumrumm
Loc: Macomb, IL
Reg: 10-18-01
12-09-10 07:07 AM - Post#2015556    
    In response to greg_moreira

FWIW, Harold Brookshire designed CompCams XE line of cams. When he designed the Voodoo line of cams later, he designed a ramp that did not let the valves close quite as quickly, and as a result they do not produce the clicking noise the XE cams do. According to Harold, the Voodoo line makes more power than the XE cams do.

Lynn

"There's no 12-step program for stupid."


383 sbc, Eagle, AFR, SRP, CompCams, Edelbrock, FiTECH. Dyno #'s: 450 hp @ 5700, 468 ft. lbs. torque @ 4300.

http://photo.net/photos/Lynn%20Johanso n


 




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