403 Build
#1
403 Build
Thought I'd post this.
Been at the dyno all weekend. Did a 403 (it was given to me as a basket case) and a 455, both with iron heads, both with RPM intakes.
There have been numerous posts here asking if it's ok to use big block heads on a 403 without a loss of tq etc. Typically Joe P has stated "why not"? "Olds used those heads on a 400 big block so it only makes sense".
Well, as usual he's correct. I'll post the dyno sheet but here are the build specs;
.039 over 403, KB 6cc piston, .020 in the hole
N crank
4 main halo
Stock rods
C heads, 2.07/1.68 with just a clean up but no bowl work
221/228@.050 on a 112, in at 107 Custom Lunati Hyd Roller
5/16 one piece restricted pushrods
HS 1.6 rockers
9.0:1
QF 750 Slayer
Performer RPM intake matched to the heads
Accel HEI 30* Timing
1 3/4 Flowtech headers
Melling HV pump with purple spring
451hp@5600/512tq@3600. Run on 91 octane pump gas.
It pulled and revved great all the way thru. Stopped at 30* only because it made more power than I thought it would and it had stock rods.
Thanks Guys.
Been at the dyno all weekend. Did a 403 (it was given to me as a basket case) and a 455, both with iron heads, both with RPM intakes.
There have been numerous posts here asking if it's ok to use big block heads on a 403 without a loss of tq etc. Typically Joe P has stated "why not"? "Olds used those heads on a 400 big block so it only makes sense".
Well, as usual he's correct. I'll post the dyno sheet but here are the build specs;
.039 over 403, KB 6cc piston, .020 in the hole
N crank
4 main halo
Stock rods
C heads, 2.07/1.68 with just a clean up but no bowl work
221/228@.050 on a 112, in at 107 Custom Lunati Hyd Roller
5/16 one piece restricted pushrods
HS 1.6 rockers
9.0:1
QF 750 Slayer
Performer RPM intake matched to the heads
Accel HEI 30* Timing
1 3/4 Flowtech headers
Melling HV pump with purple spring
451hp@5600/512tq@3600. Run on 91 octane pump gas.
It pulled and revved great all the way thru. Stopped at 30* only because it made more power than I thought it would and it had stock rods.
Thanks Guys.
Last edited by cutlassefi; November 6th, 2016 at 02:23 PM.
#5
http://www.jsmachineoldsmobile.com/403CARNAGE.html
#6
Question and comment
No aftermarket rods? I thought you did not use stock rods on your builds?
Regardless that is a great build. Congrats. Perfect engine for the 77-79 F body cars and the plethora of G body cars. Imagine a 79 HO or an 80 442 with that engine in place of the stock 350 yet everything bolts up as it should.
Regardless that is a great build. Congrats. Perfect engine for the 77-79 F body cars and the plethora of G body cars. Imagine a 79 HO or an 80 442 with that engine in place of the stock 350 yet everything bolts up as it should.
#8
Thanks Trip.
Here's the dyno sheet.
Dave- you're right I don't use stock rods. But this was on a bit of a budget because the guy got screwed to begin with. Plus imo the sb rod is stronger than the bb rod, to a point.
I'll post the 455 dyno sheet over in the big block section.
Here's the dyno sheet.
Dave- you're right I don't use stock rods. But this was on a bit of a budget because the guy got screwed to begin with. Plus imo the sb rod is stronger than the bb rod, to a point.
I'll post the 455 dyno sheet over in the big block section.
Last edited by cutlassefi; November 7th, 2016 at 05:19 AM.
#9
I am willing to bet that 403 made more torque considering the peak was at the start of the graph at 3400 rpm! Very nice, I will be getting you to do a custom cam for my 424ci 403 based motor down the road. Only a 4 main Halo as well, hopefully it holds up with that serious twist.
#10
Thought I'd post this.
Been at the dyno all weekend. Did a 403 (it was given to me as a basket case) and a 455, both with iron heads, both with RPM intakes.
There have been numerous posts here asking if it's ok to use big block heads on a 403 without a loss of tq etc. Typically Joe P has stated "why not"? "Olds used those heads on a 400 big block so it only makes sense".
Well, as usual he's correct. I'll post the dyno sheet but here are the build specs;
.039 over 403, KB 6cc piston, .020 in the hole
N crank
4 main halo
Stock rods
C heads, 2.07/1.68 with just a clean up but no bowl work
221/228@.050 on a 112, in at 107 Custom Lunati Hyd Roller
5/16 one piece restricted pushrods
HS 1.6 rockers
9.0:1
QF 750 Slayer
Performer RPM intake matched to the heads
Accel HEI 30* Timing
1 3/4 Flowtech headers
Melling HV pump with purple spring
451hp@5600/512tq@3600. Run on 91 octane pump gas.
It pulled and revved great all the way thru. Stopped at 30* only because it made more power than I thought it would and it had stock rods.
Thanks Guys.
Been at the dyno all weekend. Did a 403 (it was given to me as a basket case) and a 455, both with iron heads, both with RPM intakes.
There have been numerous posts here asking if it's ok to use big block heads on a 403 without a loss of tq etc. Typically Joe P has stated "why not"? "Olds used those heads on a 400 big block so it only makes sense".
Well, as usual he's correct. I'll post the dyno sheet but here are the build specs;
.039 over 403, KB 6cc piston, .020 in the hole
N crank
4 main halo
Stock rods
C heads, 2.07/1.68 with just a clean up but no bowl work
221/228@.050 on a 112, in at 107 Custom Lunati Hyd Roller
5/16 one piece restricted pushrods
HS 1.6 rockers
9.0:1
QF 750 Slayer
Performer RPM intake matched to the heads
Accel HEI 30* Timing
1 3/4 Flowtech headers
Melling HV pump with purple spring
451hp@5600/512tq@3600. Run on 91 octane pump gas.
It pulled and revved great all the way thru. Stopped at 30* only because it made more power than I thought it would and it had stock rods.
Thanks Guys.
#13
I believe .542. Jets were 76/84 I believe. Didn't change any air bleeds so whatever the carb came with was fine.
By the way, look at the oil pressure. Std pan, restricted pushrods. That's all you need at this level. Although you'd probably pick up a few more hp with a deep pan not filled all the way.
By the way, look at the oil pressure. Std pan, restricted pushrods. That's all you need at this level. Although you'd probably pick up a few more hp with a deep pan not filled all the way.
Last edited by cutlassefi; November 7th, 2016 at 01:49 PM.
#15
Lol! I use 20W-50 high zinc in everything to start with. Sometimes I change it to something lighter, sometimes I don't, depends on the clearances in the engine being dynoed.
This one could go 10W-30 in the winter, 10W-40 in the summer. Probably pick up a few hp in the process.
#17
#21
Favorite heads?
This was obviously quite successful. Of the iron heads, which do you now prefer for the 403, big block heads or 350 small block? Or is it too soon to say.
Thanks
Thanks
Last edited by Oldcoyote; November 10th, 2016 at 02:22 PM. Reason: 350
#22
Thanks Mark, from basket case to beast. I appreciate all the time, work and extra miles you went to make this right knowing I got screwed the first time around. I am glad I was introduced to you and you were able to fit this into your schedule and help me out. Much more HP/TQ than you originally told me and I know it was done right this time. People cannot say enough good things about you on this site and I agree.
Thanks again,
Pete
Thanks again,
Pete
#23
4 Barrels of Laughs
Join Date: Jun 2016
Location: I moved to pittsburgh so I can be near Primantis
Posts: 405
holy crap.
I mean like wow.
I would have never believed it. it did this without the bottom end becoming a semi attached rotating mass of junk?
how much would one of these cost? it would be a nice fit in a 78 regency...be able to bark with the base hemi chargers....
question... .039 over? why such an odd size or a misprint?
I mean like wow.
I would have never believed it. it did this without the bottom end becoming a semi attached rotating mass of junk?
how much would one of these cost? it would be a nice fit in a 78 regency...be able to bark with the base hemi chargers....
question... .039 over? why such an odd size or a misprint?
#24
You can buy this particular motor for a very reasonable price.
https://classicoldsmobile.com/forums...ile-403-a.html
https://classicoldsmobile.com/forums...ile-403-a.html
#25
holy crap.
I mean like wow.
I would have never believed it. it did this without the bottom end becoming a semi attached rotating mass of junk?
how much would one of these cost? it would be a nice fit in a 78 regency...be able to bark with the base hemi chargers....
question... .039 over? why such an odd size or a misprint?
I mean like wow.
I would have never believed it. it did this without the bottom end becoming a semi attached rotating mass of junk?
how much would one of these cost? it would be a nice fit in a 78 regency...be able to bark with the base hemi chargers....
question... .039 over? why such an odd size or a misprint?
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