pulled my BB today
Thread Starter
Racer
Joined: Jan 2009
Posts: 261
Likes: 1
From: frederick maryland
pulled my BB today
got my 402 out of the 73 today without any snags
hopin to increase the performance a bit, possibly swappin to closed chamber heads along w a cam swap, detail the engine bay while im there.
pulled one of the heads and found L2383 pistons a bit less than .02 down measured w a straight edge and feeler gauges. buddys bringing a good dial indicator by next week. cant find any definite info on these pistons, does anyone know the dome cc? can these be used on closed chamber heads?
my local machine shop has some closed chamber heads i can test fit, which i will do, but thought id ask first.
also have a pix of the bores which look good to me(cant feel any ridge), and the 6272292 heads. .045 head gasket was installed, i figure the CR was 8-8.3 depending on the actual head volume. ill get these cc'd later as well.
my local machine shop will either freshen my heads, or take them in trade and do a set of closed chambers for me, whichever i prefer
any comments appreciated
hopin to increase the performance a bit, possibly swappin to closed chamber heads along w a cam swap, detail the engine bay while im there.
pulled one of the heads and found L2383 pistons a bit less than .02 down measured w a straight edge and feeler gauges. buddys bringing a good dial indicator by next week. cant find any definite info on these pistons, does anyone know the dome cc? can these be used on closed chamber heads?
my local machine shop has some closed chamber heads i can test fit, which i will do, but thought id ask first.
also have a pix of the bores which look good to me(cant feel any ridge), and the 6272292 heads. .045 head gasket was installed, i figure the CR was 8-8.3 depending on the actual head volume. ill get these cc'd later as well.
my local machine shop will either freshen my heads, or take them in trade and do a set of closed chambers for me, whichever i prefer
any comments appreciated
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Quick search on Summit turned up this link; should help a bit with sorting out the CR options. Dome shape looks about right.
http://www.summitracing.com/parts/sl...3f30/overview/
http://www.summitracing.com/parts/sl...3f30/overview/
Instructor
Joined: Aug 2012
Posts: 164
Likes: 1
From: Lancaster Kentucky
I'm rebuilding a BB right now, I could make some recommendations but I dont really know what you currently have (carb,cam,intake,etc) nor what you are looking for out of it. I can tell you with that low of a CR, you are leaving some horses on the table. Great to see another BB getting wrenched on!
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Those are .030 over TRW forged pistons for a 402. Or you could say a .060 over 396. Should make you around 408" now. They are closed chamber style.
There's a lot of oil getting into the cylinders judging from the look of the heads and piston tops. Look at those dark spots on the cylinders...that's where rings aren't making good contact which is really not good since it's right at top of bore where all the pressure is going to be happening. It would be a good idea to have a machine shop hone them with a TQ plate to make sure they are truly round and will seal up like they should.
I'd definitely use a thinner head gasket to help quench along with some heads to help compression.
JIM
There's a lot of oil getting into the cylinders judging from the look of the heads and piston tops. Look at those dark spots on the cylinders...that's where rings aren't making good contact which is really not good since it's right at top of bore where all the pressure is going to be happening. It would be a good idea to have a machine shop hone them with a TQ plate to make sure they are truly round and will seal up like they should.
I'd definitely use a thinner head gasket to help quench along with some heads to help compression.
JIM
Pro
Joined: Sep 2012
Posts: 600
Likes: 6
From: Key West Florida
i would try and find a 454 block now and build a 427!, just take crank and rods out of the 402 and put them along with new pistons in the 454 and BAM! 427, thats how i built mine in my Monte Carlo, used L-88 pistons with open chamber 781 heads untill i could afford an aluminum set. to me nothing is cooler than saying "yeah its a 427"
Thread Starter
Racer
Joined: Jan 2009
Posts: 261
Likes: 1
From: frederick maryland
thx everyone...valve guides are bad, i know i was gettin some oil in there..took those pix in almost no light w a flash and cheap camera. heres some better ones w natural light. i read up on the honing without torque plate issue after my last post, looked at the pics of other examples, and i believe the 2 vertical shiny areas that may be everyones area of concern were probably caused by my lousy photography skills.
not gonna open the bottom end on this engine, if it comes to that ill simply replace the head gasket and drive it.
plan atm if everything checks out is to install a set of fresh closed chamber heads, get the CR up to 9.5-1 or so, and call C Straub about a roller cam. probably go w a 750DP of some flavor, and a performer rpm. not sure on the manifold yet, id have to give up a bit more air cleaner height to get the rpm in there i believe, and it will probably be too restricive. not sure. i had a performer 2.0, 670SA and a 27/8ths i believe aircleaner on a 2" drop base w the stock hood
there is an area at the top(12 oclock) of the cyl where the cross hatching is nearly gone however
thoughts?
not gonna open the bottom end on this engine, if it comes to that ill simply replace the head gasket and drive it.
plan atm if everything checks out is to install a set of fresh closed chamber heads, get the CR up to 9.5-1 or so, and call C Straub about a roller cam. probably go w a 750DP of some flavor, and a performer rpm. not sure on the manifold yet, id have to give up a bit more air cleaner height to get the rpm in there i believe, and it will probably be too restricive. not sure. i had a performer 2.0, 670SA and a 27/8ths i believe aircleaner on a 2" drop base w the stock hood
there is an area at the top(12 oclock) of the cyl where the cross hatching is nearly gone however
thoughts?
Pro
Joined: Sep 2012
Posts: 600
Likes: 6
From: Key West Florida
when i first built my 427 i had 10:1 compression, iron 781 heads, a voodoo cam, 60203LK, weiand intake, dual plane with open center plenum, edelbrock 800cfm carb, MSD street fire dizzy, and 1 7/8 primary headers in a 4klb monte carlo with a TH350, 3.42 gears and on a 28" tall tire it went high 7's in the 1/8 mile, it was around 375-400hp at the fly wheel and tons of tq! very good combo! cant imagine how it would be in a corvette!
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