Free big block
Thread Starter
Drifting
Joined: Jul 2022
Posts: 1,359
Likes: 822
From: Wisconsin
2024 C3 of the Year Finalist- Modified
2023 C3 of the Year Finalist - Modified
2022 C3 of the Year Finalist - Modified
Burning Brakes
Joined: Nov 2012
Posts: 788
Likes: 100
From: Indianapolis IN
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,040
Likes: 4,395
From: Marlton NJ
3904390 are pretty decent heads.
People call them "390s"
Large oval ports, 98cc closed bathtub chamber size, 2.06/1.72" valves, 66-67 396s & 427s from 325 to 400HP
Benefit from bigger valves, chamber/valve/port backcuts and port matching. Can easily run 11s at the strip.
Pretty much the smallest chamber size of the BBC heads.
Valves are shrouded, more so with bigger valves, flow benefit from chamber back cuts.
Icon & KB calculate their CRs at .a typical 040" quench, depending on how you get there. Block deck, head gasket, etc.
You can always juggle thinner/thicker gaskets to fine tune it.
Last edited by leigh1322; Nov 26, 2023 at 06:58 PM.
Thread Starter
Drifting
Joined: Jul 2022
Posts: 1,359
Likes: 822
From: Wisconsin
2024 C3 of the Year Finalist- Modified
2023 C3 of the Year Finalist - Modified
2022 C3 of the Year Finalist - Modified
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,174
Likes: 9,305
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Please pay attention to what these guys are saying about compression ratios.
For everyone that wants to be an engine builder...Yes you can massage any garbage head to give you good flow numbers if you know what you are doing and have the proper tools to do it. Or you can spend $1000-2000 to have someone else do it and bench test them. Or just buy lighter better ones. I dont have the tools or experience for it or a flow bench, but I am an adult and have a job. So i chose to buy nice aluminum heads.
And just taking off those same restrictive closed chamber heads and dropping on nice aluminum ones changed my opinion of 396 motors. Although it wasnt setup for it. I lost 2 points of compression and caused other issues but i was desperate and had the aluminum heads on the bench. Please listen to these guys about compression ratio. Those old heads are 100 cc chambers and going to 115cc will kill alot of vacuum and give you issues. Plan on compression with heads and pistons at the same time. Edelbrock makes a reasonably priced head. Reasonable on a big block is still twice what a small block would cost, but it will get you a 100cc chamber again
For everyone that wants to be an engine builder...Yes you can massage any garbage head to give you good flow numbers if you know what you are doing and have the proper tools to do it. Or you can spend $1000-2000 to have someone else do it and bench test them. Or just buy lighter better ones. I dont have the tools or experience for it or a flow bench, but I am an adult and have a job. So i chose to buy nice aluminum heads.
And just taking off those same restrictive closed chamber heads and dropping on nice aluminum ones changed my opinion of 396 motors. Although it wasnt setup for it. I lost 2 points of compression and caused other issues but i was desperate and had the aluminum heads on the bench. Please listen to these guys about compression ratio. Those old heads are 100 cc chambers and going to 115cc will kill alot of vacuum and give you issues. Plan on compression with heads and pistons at the same time. Edelbrock makes a reasonably priced head. Reasonable on a big block is still twice what a small block would cost, but it will get you a 100cc chamber again
Burning Brakes
Joined: Nov 2012
Posts: 788
Likes: 100
From: Indianapolis IN
1968 was the first yr for an Olds 455, but it's taller than a BBC and perhaps wider also.
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Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,174
Likes: 9,305
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
If you do it, start a thread with lots of pics. I would love to watch and follow along
Instructor
Joined: Aug 2022
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Yeh I forgot the yr on the (68) Delta 88. I purchased it 30 yrs ago after it was gutted by fire but the engine and tranny were unharmed. Turns out it was a factory tow vehicle so the 400 tranny was heavy duty and the motor had factory forged rods as well as the desirable C coded heads! I spent a small fortune at the time building it and landing it in my 75 Cutlass. The Cultass is worn out but the 455 is still solid as a rock and I really want to put it in the Vette w/the Muncie that's already in the Vette. My main concern is what modifications if any will be needed to mate up motor mounts. Everybody and their brother has put a Chevy in a BOP but I can't find one person who's put a BOP in a Vette
Instructor
Joined: Aug 2022
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Some where on this Forum someone posted a chart w/all the American V8's and their dimensions. As I recall I was confident the motor will fit and maybe even under the stock hood but I'll of course need to revisit that
Instructor
Joined: Aug 2022
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I've been hesitant to mention it on this forum as I'm sure I'd get an endless parade of hard cores reading me the riot act for even considering such blasphemy on a very well preserved matching numbers ac 4 speed Vette. All that said it is a 77 and not worth a fortune. If it was a 125 miles on the odometer pristine museum quality piece I'd sell it quick and buy a Vette to drive. Also I intend to keep the Vette 'till I pass so all I care about is dependable, good looking and unnecessary amounts of torque. As soon as I pay the Vette off (less than a yr) I'm attacking this full speed ahead and will definitely document as well as lean on y'all for help/advice.
Burning Brakes
Joined: Nov 2012
Posts: 788
Likes: 100
From: Indianapolis IN
(and yes.. I'm guilty of installing a solid lifter 396 into a '69 442 4-speed around 1977, but it had a sbc 350 when purchased. Gawd what fun ensued)
Instructor
Joined: Aug 2022
Posts: 209
Likes: 107
I'm guessing the exhaust may be one of the biggest hurdles - if trying to make use of headers. I know where there's a nice 68 442 post coupe that it would fit easily into !!
(and yes.. I'm guilty of installing a solid lifter 396 into a '69 442 4-speed around 1977, but it had a sbc 350 when purchased. Gawd what fun ensued)
(and yes.. I'm guilty of installing a solid lifter 396 into a '69 442 4-speed around 1977, but it had a sbc 350 when purchased. Gawd what fun ensued)
My Cutlass is a 75 Salon. 2 door Luxury Sport model. Plush bucket seats w/ac and electric windows. Original drivetrain was 350 Rocket w/350 THM tranny. I did a near frame off resto and put the 455 in it and even though it was a show winner inside/out and underneath I didn't restore it to look at and it remained my daily driver so subsequently living on the Gulf Coast has done it's damage and the rust and electrical failures make it hard to enjoy. Even the interior panels have begun to crack and disintegrate. As mentioned if I won the lotto I'd spend the probably 40 grand it'd take to bring her back to glory. Of course I'm biased but it really was the coolest mid 70's Cutlass I've ever seen. Putting the 455 in my Vette would really help me feel connected to my Olds that I hate to give up on
Instructor
Joined: Aug 2022
Posts: 209
Likes: 107
I'm guessing the exhaust may be one of the biggest hurdles - if trying to make use of headers. I know where there's a nice 68 442 post coupe that it would fit easily into !!
(and yes.. I'm guilty of installing a solid lifter 396 into a '69 442 4-speed around 1977, but it had a sbc 350 when purchased. Gawd what fun ensued)
(and yes.. I'm guilty of installing a solid lifter 396 into a '69 442 4-speed around 1977, but it had a sbc 350 when purchased. Gawd what fun ensued)