[protamine]

Thanks for all the help so far.

My last post I was going to do (69 Camaro - tired CTW 402, M21, 3.42 rear street car)

408
CTW block 0.030
6223 crank / Scat 6.135 rods / Straub 229/241 HR cam / 781 heads with 2.19/1.88 and 5 angle job. - all of this is sitting in my garage (sans cam)
I ordered 2242 NF 0.060 pistons, for the 38cc dome but only a 0.335 dome. They just got delayed 2 months...meaning I could lose all summer

There are other 30-40cc domes available but with a 0.5" dome, in stock currently at Summit - I'm worried about the higher dome in a open chamber head. I'm sure the builder can do valve relief and all that but seems unnecessary with good planning.

Options:

1. wait. its just a month or two, do it right
2. go with the icon 0.5" dome and figure it out
3. go with less compression and a less dome and play it safe

or

4. get a 4.25" bore block and build a 427 as there is a lot more 4.25 / 4.28" bore pistons available. Easy enough, already have the crank and rods.


Basically I dont want to have the whole thing apart and wait 2-3 months for pistons....again.

 

[bracketchev1221]

The compression will be a little high with the icon pistons. You'll be pushing about 10.5-1 compression. I ran the 2287 Speed pro pistons which got me in the same place. It can be done, you just need to be careful. The one benefit is that it is an open chamber piston so it will fit with those heads. The Speed pro pistons are closed chamber and may require clearancing for the dome in an open chamber head. If it was me, I would CC the heads to get a real compression number and work to put the ICON pistons in. They are also a lighter piston compared to the weight of the old Speed Pro pistons.

 

[hydro462]

People usually over due two things when rebuilding a engine,
1) the compression is way too high. 9:1 should be the tops on a street engine..
2)They always use a cam with far too much overlap and duration..

With 9:1 compression, your starter spins like there's no compression, you get to run 87 octane and you get to crank up the timing. With my 454, I run 20 degrees initial with 16 mechanical starting at 1000 and all in by 2400..

 

[shovelrick]

I have forged Autotec/Racetec pistons (complete rotating assembly) from Mike Lewis racing engines aka Wolfplace a member here on TC, give him a call

 

[Ialone]

On my 396/408 I was using AFR 265 heads, (Milled to 102cc) and no matter what piston I would have used (few to choose from) the pistons still needed to be machined and valve reliefs cut. I ended up with a 9.0:1 Comp ratio.

cant tell you which way to go, it's always time and money.

 

[oldguy67]

Thanks for all the help so far.

My last post I was going to do (69 Camaro - tired CTW 402, M21, 3.42 rear street car)

408
CTW block 0.030
6223 crank / Scat 6.135 rods / Straub 229/241 HR cam / 781 heads with 2.19/1.88 and 5 angle job. - all of this is sitting in my garage (sans cam)
I ordered 2242 NF 0.060 pistons, for the 38cc dome but only a 0.335 dome. They just got delayed 2 months...meaning I could lose all summer

There are other 30-40cc domes available but with a 0.5" dome, in stock currently at Summit - I'm worried about the higher dome in a open chamber head. I'm sure the builder can do valve relief and all that but seems unnecessary with good planning.

Options:

1. wait. its just a month or two, do it right
2. go with the icon 0.5" dome and figure it out
3. go with less compression and a less dome and play it safe

or

4. get a 4.25" bore block and build a 427 as there is a lot more 4.25 / 4.28" bore pistons available. Easy enough, already have the crank and rods.


Basically I dont want to have the whole thing apart and wait 2-3 months for pistons....again.

do yourself a favor,for the street drop comp. to no more then 9.5:l or less.

 

[Georgia69]

I dunno, the 496 in my Chevelle and the 355 now in my Impala were both right at 10:1, both start very easily. I do run 93 unleaded, which is available at EVERY gas station here in Georgia - can't speak to availability in other regions.

If you drop compression to 9:1, that cam might be a tad large in a 408ci - JMHO.

 

[protamine]

I dunno, the 496 in my Chevelle and the 355 now in my Impala were both right at 10:1, both start very easily. I do run 93 unleaded, which is available at EVERY gas station here in Georgia - can't speak to availability in other regions.

If you drop compression to 9:1, that cam might be a tad large in a 408ci - JMHO.

My thoughts too. The big cam will bleed off some of that compression. The BP 3 miles from my house has ethanol free 93. I dont want 9:1. If its too bad I can always put aluminum heads on down the line.

 

[68Chevele]

Thanks for all the help so far.

My last post I was going to do (69 Camaro - tired CTW 402, M21, 3.42 rear street car)

408
CTW block 0.030
6223 crank / Scat 6.135 rods / Straub 229/241 HR cam / 781 heads with 2.19/1.88 and 5 angle job. - all of this is sitting in my garage (sans cam)
I ordered 2242 NF 0.060 pistons, for the 38cc dome but only a 0.335 dome. They just got delayed 2 months...meaning I could lose all summer

There are other 30-40cc domes available but with a 0.5" dome, in stock currently at Summit - I'm worried about the higher dome in a open chamber head. I'm sure the builder can do valve relief and all that but seems unnecessary with good planning.

Options:

1. wait. its just a month or two, do it right
2. go with the icon 0.5" dome and figure it out
3. go with less compression and a less dome and play it safe

or

4. get a 4.25" bore block and build a 427 as there is a lot more 4.25 / 4.28" bore pistons available. Easy enough, already have the crank and rods.


Basically I dont want to have the whole thing apart and wait 2-3 months for pistons....again.

All I can say is you're going to love how that 396 pulls with those 781's on it. Put a set on back in 1989 and the 396 pulled like a good 427, was pretty amazed at the difference over the closed chamber heads.

 

[oldguy67]

I dunno, the 496 in my Chevelle and the 355 now in my Impala were both right at 10:1, both start very easily. I do run 93 unleaded, which is available at EVERY gas station here in Georgia - can't speak to availability in other regions.

If you drop compression to 9:1, that cam might be a tad large in a 408ci - JMHO.

Wish we had it in Conn.,91with corn

 

[snow427]

One thing I will say to be aware of if you go to a 427 is the crank may need a lot of work to balance it. I did the same things years ago with a forged 396 crank and TRW pistons and the guy that did the balancing said it took a lot to balance it. With newer lighter pistons it may not be as big an issue but just something to keep in mind if you go that route.