First the Quench/DCR question. If I put a Comp XE274H cam in my 355 and use a .026 composite gasket, I get a .048 Quench and 8.14 DCR. If I use a .015 rubber coated steel shim gasket instead, I get a .037 quench and a 8.36 DCR. BTW the SCR ranges from 10.05 to 10.33 when switching the gaskets.

With a stock height iron block and aluminum heads, which gasket would you choose? I'm torn 50/50 each way. I think the 8.36 DCR would be ok with the tighter quench but should I even worry about it. It sounds like .048 quench would be ok with a 8.14 DCR. I could be off just a little on the deck height but did use a dial caliper to measure it. So I guess my real question is if the quench was as high as .050 - .055 and a DCR of 8.14 would you switch to the .015 shim gasket? What are the pros/cons to the shim gasket?

The cam question is this: I was stuck on using the XE268H cam due to being able to find a lot of proven builds in magazines using it and talking to people that have it and like it. I also was a little scared of the RPM range of the 274 cam for my street driven vette. However, if it go with the 268, I end up with a DCR of 8.32 on a .026 gasket (.048 quench) and 8.54 DCR on a .015 gasket (.037 quench). I'm not thrilled with either of those numbers and the 274 cam brings them back down where I want to be.

So, is the XE274H a good cam for a 355 with a TKO-500 manual tranny and 3.73:1 gears in the back for a street driven vette? I'm not racing this thing but want a good street vette. I've already got the heads and pistons so if I can manipulate the cam to get the build right then that's the route I'm going.

Thanks all!

 

I like to see someone doing their homework while building a motor so there will be no suprises. Yours is a mild buildup and I would recommend the XE274 cam with composite gasket and you will be fine.

 

As you've seen on the thread I started about this, it seems that all the people that know about this stuff, recommend getting quench down first and working everything else off of that.

When I first learned about quench, everyone recommended a quench of .040-.045. Your .048 is not much more than that. However, I seem to recall seeing some head gaskets in the .020-.021 range on Summit's website. You may want to check and see if you can get something like that. That would get your quench down in that range.

It looks like you would be better off with the 274 either way. You don't have the limitation of a torque converter.

Just the .02 from a guy that is also in the middle of the learning curve.

 

I like the idea of the .037 quench but wasn't sure if I'd have any problems with using the .015 steel shim gasket so far as sealing. I'm looking at the fel-pro 1094. Summit doesn't have any non steel shim gaskets in the .020 range. I know I can get the VR .026 composite gasket from Jegs though.

I guess I knew the quench was important but was having second thoughts on the gasket sealing ability and bringing the DCR back up to 8.3:1 after seeing I could get it down to 8.1 using the .026 composite gasket.

I plan to run an aluminum radiator with dual fans and a cold air intake. That along with some other things should let me run the DCR in the 8.3:1 range on 93 octane. I think I've finally worked out my combo, just can't decide on that darn gasket now......

 

With Motorhead.............But not very often! You will be happier with the bigger cam. I think there is a GM Performance Parts gasket for Aluminum heads that is thin.

 

Summit has a GM PP gasket that is .028 and .051 but nothing else when I use their search. Of course, using the search at Jegs I can't find the VR .026 gasket now either....

 

180 degree thermostat??

 

Yep, the plan is to add the 180 degree thermostat along with the radiator to try and keep everything cool.

Anybody got a link to the Victor Reinz 5746 gasket for sale? Google is hiding it from me.

 

Felpro 1094 Rubber coated steel shim gasket. Safe for use with aluminum heads. .015 compessed thickness. Look here $19 each. http://www.flatlanderracing.com/felprochevysbhead.html

 

I'm between that one and the VR 5746. Nothing has been done to the deck of my block and it actually looks like the machine shop could have cleaned the deck a little better so I may take a scotch brite pad to it. I'm wondering if I will have sealing problems with the Felpro 1094 shim gasket? The heads are brand new. I'm also reading mixed thoughts from people where some think the shim gasket (fel pro 1094) could cause brinneling on the aluminum heads; not good.

 

Shinodavette, what other top end parts are you running on your 355, just out of curiosity.

 

Here you go I bought mine at NAPA locally. Part #NGA5746

http://www.napaonline.com/MasterPage...er+Head+Gasket

 

Trick Flow 23 Degree 64cc Aluminum Heads
TRW Speed Pro Power Flat Top Forged Pistons
Sealed Power Performance Piston Rings
Summit True Roller Timing Set
Summit High Volume Oil Pump and Pickup
Comp Cams XE274H Cam and Lifters
Comp Cams valve springs
1.6:1 Full Roller Rockers (haven't picked a brand yet)
BG Speed Demon 650 Carb
Edelbrock Performer RPM Air Gap Intake
Hooker side exhaust with Jet-Hot Sterling finish
with Spiral Turbo Baffels
Probably going to run an L-88 style air cleaner
with L-88 hood and fresh air chamber
Trying to decide between Dewitts and BeCool alum radiators w/dual fans and 180 degree thermostat
MSD Distributor, coil and 6AL box

I think that's the bulk of it. And as of this morning, I think I'm going to go with the VR .026 composite gasket and run the 8.1 DCR and .048 quench and see how it goes.

Should be a fun combo....

 

Thanks for the link!! Now if only the Napa site was working this morning.

I'll try to get it a little later today.

 

most of the napas have them in stock, if not they can get it there. It about 5.00 cheaper on the net then what I paid at the store.

 

Works out about the same once you figure in the $4.95 shipping. But, there's no NAPA close enough to me to want to drive there for the $5. Advance is the major auto parts store around here so napaonline.com is just easier. I got them ordered this morning.

I'm starting to think they don't make these any longer. The Mr. Gasket catalog doesn't have them. The next closest one is the 1193 I think with a .028 compressed thickness. It sounds like a nice gasket but I wanted the .026. Hopefully it will ship from NAPA. Summit and Jegs both list the 1193 but not the 5746. We'll see.

Thanks!!