need some info & opinions

my 74 454 is an original 10,000 mile motor. right now the motor is partically apart, the bottom end is in tact.

I have a set of 68 427 "215" heads that are done w/2.19 & 1.88's installed.

1-is there a difference between closed and open chamber pistons?

2-if so, can you use closed chamber heads with open chamber pistons?

3-and if you can, what are the advantages or disadvantages of using that type of setup?

thanks for any info..............................Tom

 

I have almost the same thing with my LS5 '72 454. Came with a set of 427/435 heads, and stock flat tops...

Check the cc's to be sure but I did the math and the cr came out like 9 to 1...and these heads gave 11:1 w dome pistons for 1967

 

A 74 most likely still has the flat tops with the chamfer around the edge. You can install open or closed chamber heads on them.

If you have a true open chamber piston, you can't use a closed chamber head. 99% of the time you can use an open chamber head with a closed chamber piston, but every once in a while you need to clearance one corner of the dome.

If you have much cam at all..or even if you don't, make sure to ck the piston to valve clearance with the 2.19's. Stock lo-perf pistons don't have a very big valve relief and the 2.19's can get real cozy with respect to *radial* clearance around the edge of the pockets.

JIM

 

The machine shop that did the heads said they were either 99 or 100 cc's, can't remember, but do have it marked down. I am looking to bump up the compression slightly, maybe a point or a point and a half with these heads, so I have been told. thanks for the info..

Jim,
thanks for the reply...
I am replacing the cam with an ISKY 270/280 HYD MEGA
here are the specs....
Intake Timing.........................Exhaust Timing
Duration 270 DEG..................280 DEG
Open 21 Before TDC............Open 74 Before BDC
Close 69 After BDC.............Close 26 After TDC
Cam Lift .310.....................323
Valve Lift .542......................565
Valve Lash .000 Hot..............000 Hot

Overlap 47 DEG
Lobe Center 114 DEG

here are a few pics of the stock flat top pistons in the block



I also checked out a roller setup, but that is a little to much for the budget at this time, and since I already have the cam, and the springs for the cam were already installed when the heads were done, I am staying with this setup, I had purchased the cam kit.

Also talking around, the feeling is that with this block and the low mileage, not to even take the bottom end apart, since you can still see the cross-hatch pattern and that the rings are probably seated just fine. The other school of thought is to fully take it apart and get it checked and then either use the same pistons and new rings, or purchase a new piston setup. And the other thought was not to get the block bored, as it would probably just need to get honed.


So any additional thoughts or opinions are greatly appreciated.

some additional questions....
4-what head gaskets would be the ones to use?

5- it is good to go to the one piece oil pan gasket that are available?

6- would you stay with the stock pistons, or get something different and if so, what would you recommend?

Again thanks for all input, always appreciated.

BTW, I am switching to a 427/390 factory aluminum intake, and either get my Q-Jet rebuild or use the factory replacement NOS Q-Jet for a 70 454 that I purchased a few years ago.
My goal is a 6000 to 6500 prm range and around 450 HP with this setup.

 

Well....it looks like the cylinders are a little wet with oil. Did it burn any or smoke at WOT?

I'd use a thin steel shim head gasket to get as much compression as possible.

Those stock cast pistons are getting close to the edge of their happy lifespan if you regularly spin 6500 RPM with them.

If it was mine, and I wanted to do it right...I'd bore it and install some forged pistons that I never had to worry about. And if I did that, I'd use some with a dome to get compression up and then work over the original 049 open chamber heads. But heck, by then I'd be thinking,,,,I already bought pistons..why not just get a 496" stroker crank/rods/pistons and REALLY have some fun!

Otherwise, if it's not using oil you can take a chance..but understand that often when you add power, marginal ring seal goes away. I'd keep RPM in the low 6000's which is all that cam/intake/carb setup will want anyway...use the closed chamber heads and have some fun. These combos can run very well indeed!


JIM

 

I think that the reason the cylinders look wet with oil is that I squirted oil into the spark plug holes long before I started disassembly, if that makes any sense.
The PO stated that his parents drove the Vette, mainly his Mom on short trips, I don't even think this engine ever saw any WOT's except maybe when his Dad drove it, so I doubt that it even approached anywhere near 6000 r's. No oil comsumption problems ever with the engine from what I was told. And from what I understand, the stock
LS4 wasn't capable of reaching that high of a rpm range in its stock form. From what I understand is that they run out of breath around 4500 r's or slightly higher.
Is there a particular brand head gasket that you use or recommend?
The other items you recommend may be out of my reach, so I have to work with what I have for now. If I do go with forged pistons, which brand is the one to buy?
Also the original heads on the 74 were 781's as the 049's were on the 73. Don't know what the difference is between the two, I would assume emissions!!! I also have another set of 781's that are already done, besides the stock ones, but I fell for the 215's which hopefully will work out just fine for me.

 

If you go with a steel shim head gasket, Mr Gasket is your only choice.
They work just fine.

On forged pistons, your best value in forged pistons will be Icon or Probe.
There are lots of other good ones though.

The 781 & 049 heads are almost identical, and are both very good street heads.

 

I've built these combos several times over the years. The open chamber heads flow better..and have more potential for power..but at these RPM's the closed chambers will do fine. Compession will wake things up a little and help especially if the heads have been ported any.

I didn't do all the math..but is that the 221/232@.050 version on a 114 LSA?

It should be an awful nice driver and pretty smooth with that LSA. Peak HP is going to come in down in the low-mid 5000's or so I'd guess at best.

I'm not sure you're going to see 450 HP with that intake/cam combo. It's pretty mild overall.

JIM

 

thanks for the info on the pistons, will check them out. will also look at the head gaskets from Mr. Gasket.

how about the one piece oil pan gasket they now have for the BB???
has anyone used one yet???

the 215 heads have had everything done to them, ported, polished, harden seats installed, valves cut, etc., etc., the only item that would be needed to be done with these heads would be to have the intake and head ports matched. Will probably end up doing that.
I am thinking maybe I'll be at 9:25 to 9:50 compression ratio with the 215 heads, does that sound about right?

you are correct on that version, it is the 221/232@.050 on a 114 LSA

if I don't achieve the 450 HP mark, no biggie, just want a nice driver as you mentioned with some additional power over stock when needed.


as usual, thanks for the continuing replies, it is a big help.....

Tom

 

The one piece oil pan gaskets are good. The regular ones work well on big blocks too...but the one piece are a little easier. Sometimes have to re torque them once after they've run, but no biggee.

Not sure how many cc's those pistons hold in the valve pockets or that big chamfer...but even if it's only 5cc (doubtful)...and using a 100cc head...and maybe a .020" deck height and a .022" gasket...I'm getting about 9.10 compression. If they are 10cc on the pistons it's down in the 8.75 range. Those things out of the box typically ended up in the high 7's for compression when actually measured.

Detonation will not be an issue!

A motor like this will respond well to a tight LSA cam and I would definitely advance the one you have to the 108-110 I/C range.

Port matching the intake to the head will help a little..but nothing dramatic. If you change rockers sometime..go for 1.8's on the intakes at least.

JIM

 

copy on the above info........
I am thinking about a rocker change, so you are suggesting 1.8's on the intakes and I would assume keeping the exhaust at 1.7's ???
what is the benefit of going to 1.8's on the intake as opposed to the
1.7's ???
and what is the recommendation for rockers?
also from what I understand as far as lifters go, is to stay with a GM lifter, as they are harden steel on the bottom of the lifter.
and of course pushrods, which are good brands, or just go with what Isky recommends?

Tom

 

The exhausts usually don't need as much help..especially since your exhaust lobe is already 10* bigger and a little more lift. It won't hurt to throw 1.8's there also..but not as much usually. The intake side is always tougher to get the most out of.

For brands stay away from any of the imported junk. Pro Form, CAT etc. Stick with any of the Comp, Crane, Crower etc. Your cam could get by with regular rockers..but maybe look at Elgin for some 1.8 long slots for low $$$ help.

Lifters are the same...just get good ones....not no name *white box* stuff. Valvetrains are NOT wear to go cheap...it will bite you every time.

Your heads likelyhave 5/16" pushrods? I would use some good .080" 3/8" ones with the correct guideplates. You don't need exotic here, just decent quality.

I'm assuming you have the correct springs and have read everything you can about flat tappet cam break in procedures right? Don't take the easy way out here either.

JIM

 

450 hp is just a number...on its face it means nothing, unless all you want to do is just be able to say that it makes 450 hp.

The combination you are looking to do will most likely satisfy you in the overall performance of the car, dyno sheet or not!

I've got a stock LS4 car also, and you are correct that it runs out of snot around 4500. The real limiting factor on these motors is not so much the compression, as it is the cam...which you are changing.

Personally I think that your 215s with the 2.19 valve, and just about any cam above .500" lift will make for a real nice running combo.

Once apon a time I had a 396/325 with a stock 215s, roller rockers, and a Crower solid 517/530. Ran very well up to 6K, pulling down 12.45 in a 67 Chevelle (granted there were also 4.10s, 4k stall, and 3" exhaust in the deal)

Ive enjoyed following your posts, and look forward to seeing what you choose to do with this setup.

P.S I remember seeing your 781s for sale, and if they had a bigger valve (and eliminated the exhaust rotators) I would have been at your doorstep ringin the bell!

 

Jim, as always thanks for the advice, it is appreciated. The one item about lifters that was recommended to me was to stay with GM lifters as they are the strongest ones out there.
Yes I do have the correct springs as they were part of the Isky cam kit I purchased, and were install at the correct spring pressure.
Also reading as much as I can on cam break-in procedure, and will probably have questions before that time comes around.......

Dave, sounds like that was one great running Chevelle you had at the time.

From what you, Jim and others have commented on the cam, it seems to be a good choice. I am thinking of not even taking the bottom end apart any further other than changing the cam, and just using the stock pistons with this setup. Will clean up the piston tops and take some measurements just to be sure, and if needed to be completely torn down, will do it. But with only 10,000 miles on the engine, I think that I will be ok. Not going to be a track car, although I would like to get some times in once it is done and broken in with the new cam. Will be lucky to see 3000 miles a year if that, and that is with taking it out every weekend of the year. Just looking forward to enjoying the extra power this setup will produce.
Thanks for checking out the thread, always open to comments and suggestions from everyone.
Yes, those 781's are still for sale, just did a repost for them. You can always make an offer, sounds like you may still be thinking about them.......... Later..........................Tom