1973 440 Upgrade
#1
Mopar Fan
Thread Starter
1973 440 Upgrade
Hello, I have a 73’ 440 I want to upgrade.
Engine specs :
MSD6AL / Holley Sniper EFI / Edelbrock Torker II intake / Stainless exhaust / Comp Cams camshaft : Hydraulic Flat Tappet, Advertised Duration 284/296, Lift .507/.510
Heads and pistons are stock.
I want upgrade the heads and maybe the pistons. I will go on Edelbrock Performer RPM (75cc) for stay in the RPM range of the other parts.
If I change pistons I will go on KB237, with the new head they will give me something like 10.7 comp.
My Dodge Challenger is not a race car, and I never drive it hardly, I never go above the 5000 RPM.
So, if I just change the heads, I will be at something like 9.5 comp, and I will be close to a 1970 HP 440.
So my question is : 9.5 or 10.7 comp ? What is the quality of both and the default ?
Thank you !
Engine specs :
MSD6AL / Holley Sniper EFI / Edelbrock Torker II intake / Stainless exhaust / Comp Cams camshaft : Hydraulic Flat Tappet, Advertised Duration 284/296, Lift .507/.510
Heads and pistons are stock.
I want upgrade the heads and maybe the pistons. I will go on Edelbrock Performer RPM (75cc) for stay in the RPM range of the other parts.
If I change pistons I will go on KB237, with the new head they will give me something like 10.7 comp.
My Dodge Challenger is not a race car, and I never drive it hardly, I never go above the 5000 RPM.
So, if I just change the heads, I will be at something like 9.5 comp, and I will be close to a 1970 HP 440.
So my question is : 9.5 or 10.7 comp ? What is the quality of both and the default ?
Thank you !
#2
depends on what you want, really. i would go with 9.5 so pump gas works well and won't detonate. but if you have a nice sized wallet 10.5 is definitely gonna wake that thing up and add horses.
#3
Mopar Fan
Thread Starter
Thanks
#4
Mopar Lover
I would not go 10.7, the oem cast pistons will do what you want and increases in compression give small percentages of power increase. My only concern would be piston to valve clearance with the new cam and likely no valve notches on piston top. Now the piston is probably far enough down the hole but I would still check it.
#5
Mopar Fan
Thread Starter
I would not go 10.7, the oem cast pistons will do what you want and increases in compression give small percentages of power increase. My only concern would be piston to valve clearance with the new cam and likely no valve notches on piston top. Now the piston is probably far enough down the hole but I would still check it.
On papers the 1973 pistons are .123 in the hole.
The Performer RPM instructions say that : " These cylinder heads have larger-than-stock
valve sizes and may not work with the valve pockets in stock pistons, especially if a high lift cam is used. The use of aftermarket pistons and/ or custom machining to your pistons may be required."
what minimum clearance do you recommend me ?
Thanks.
Last edited by Apewalski70; 01-19-2020 at 03:42 AM.
#6
Super Moderator
The problems with not buying new pistons is two fold and the first is low compression limiting your cam choice to little more than stock. The second issue with stock 440 pistons is that they are extremely heavy ( 850 grams +-) and there cast limiting rpm to just over 5000 rpm.
I highly recommend new pistons......I've always limited the cr to 9.5 with iron heads, but I do know a few builds that are in the 10:1 cr. on pump gass with ironheads.
if your using stock heads I would stay as close to 9:1 as possible.
I highly recommend new pistons......I've always limited the cr to 9.5 with iron heads, but I do know a few builds that are in the 10:1 cr. on pump gass with ironheads.
if your using stock heads I would stay as close to 9:1 as possible.
Last edited by Iowan; 01-19-2020 at 05:22 AM.
#7
Mopar Fan
Thread Starter
The problems with not buys new pistons is two fold and the first is low compression limiting your cam choice to little more than stock. The second issue with stock 440 pistons is that they are extremely heavy ( 850 grams +-) and there cast limiting rpm to just over 5000 rpm.
I highly recommend new pistons......
I highly recommend new pistons......
Okay thank you. The engine already have a bigger than stock camshaft (Lift .507/.510) maybe the pistons are not stock, I should check all this before buying anything. I will probably go to KB237.
#9
Mopar Fan
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