When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So I find myself in the middle of a build, the engine is a 425 olds. Stock crank, stock rods, new higher compression stock style pistons, comp big ***** thumper hydraulic roller retrofit cam, speedmaster aluminum heads, I have a variety of intakes available but will most likely go rpm airgap. My question is this. Am I going to make enough power to bother the bottom end? Would it be wise to get aftermarket rods and pistons? Will I need to run a halo on the main caps? I'm worried that my dad got the better of himself and was shooting to high for the stock bottom end. Any thoughts or insight would be appreciated.
Last edited by Sonoman; August 2nd, 2019 at 06:26 PM.
Keeping the piston/rods as light as possible is a big part of making the BBO short block together. I think all the 425 cranks are forged, so that helps. If the pistons need replacement, get good quality pistons like CP.
So I find myself in the middle of a build, the engine is a 425 olds. Stock crank, stock rods, new higher compression stock style pistons, comp big ***** thumper hydraulic roller retrofit cam, speedmaster aluminum heads, I have a variety of intakes available but will most likely go rpm airgap. My question is this. Am I going to make enough power to bother the bottom end? Would it be wise to get aftermarket rods and pistons? Will I need to run a halo on the main caps? I'm worried that my dad got the better of himself and was shooting to high for the stock bottom end. Any thoughts or insight would be appreciated.
I'm reading the book listed above currently, definitely looks like I'll have to do some checking and finger crossing
Some 425 blocks have the 45 degree cam angle.
The bore is the same as a 455 , 425 has the shorter stroke and uses a 7 rod.
25 free cu is always nice when on a budget free HP/TQ at a lower RPM
Read the book and take your time planning your build.
Go to RealOldsPower and check out the build section.
Rocket racing also sells parts
Look up Milan's builds on ROP
Using parts you already have can compromise a new build if they are going to prevent you from reaching your goals.
We have a first class machinist on Classic Oldsmobile if you are looking for one.
Good Luck
First thing: Find out what lifter bank angle you have.and lifter diameter.
X2.
Mahle makes a great new piston for the 425. Use the 7.00” H beam rods from Rocket.
I’d use the regular Performer intake, not the RPM AirGap.
No halo needed at this level.
Last edited by cutlassefi; August 3rd, 2019 at 03:36 PM.
Thanks for all the great advice so far, I purchased that book and have been reading it diligently. Hoping to get started soon, first step look at the lifter bank angle lol.
[QUOTE=cutlassefi;1188998]X2.
Mahle makes a great new piston for the 425. Use the 7.00” H beam rods from Rocket.
I’d use the regular Performer intake, not the RPM AirGap.
No halo needed at this level.[/QUOT could you elaborate on the intake comment further? Also I'd like a bit more info on those pistons as well please.
My current selection of intakes include an edelbrock torquer, a holly street dominator, and an offenhouser dual port. However I'm not against purchasing new. From reading the above book the torquer or street dominator seem appealing. And dad always seemed fond of the torquer
My current selection of intakes include an edelbrock torquer, a holly street dominator, and an offenhouser dual port. However I'm not against purchasing new. From reading the above book the torquer or street dominator seem appealing. And dad always seemed fond of the torquer
The Holly street dominator is a very good intake.
Get the bottom end right and the heads and you can fine tune from their.
A good balancer is also a must have.
The Holly street dominator is a very good intake.
Get the bottom end right and the heads and you can fine tune from their.
A good balancer is also a must have.
I have a tci rattler anyone have good luck with those?
I have a tci rattler anyone have good luck with those?
Try posting on ROP they have a wider performance audience.
I know the ATI is very popular.
Your goals will dictate the quality of parts that you will require.
What are your goals?
Take the internet feed back but in the end try and stick to one Oldsmobile specific Vendor and a quality Machinist.
Last edited by Bernhard; August 5th, 2019 at 09:08 AM.
X2.
Mahle makes a great new piston for the 425. Use the 7.00” H beam rods from Rocket.
I’d use the regular Performer intake, not the RPM AirGap.
No halo needed at this level.[/QUOT could you elaborate on the intake comment further? Also I'd like a bit more info on those pistons as well please.
A regular Performer, #2151 would be best. I'd sell all the rest of what you have. I've made 540hp on a 455 with that intake.
The Mahle piston is available in a .030 oversize, 4.155. It has 10cc valve reliefs, a modern ring pack and is forged and coated. I sell them with rings shipped for $679.00.
Hope this helps.
A regular Performer, #2151 would be best. I'd sell all the rest of what you have. I've made 540hp on a 455 with that intake.
The Mahle piston is available in a .030 oversize, 4.155. It has 10cc valve reliefs, a modern ring pack and is forged and coated. I sell them with rings shipped for $679.00.
Hope this helps.
So finally did a little checking I believe I'm in the clear on the lifter angle the diameter I think I'm good aswell. To my understanding the d means it's a late model block and I'm pretty sure it didn't come from a tornado. But I'll pull one of my lifters and check when I can.
August 2nd, 2019, 04:54 PM
