briancrittendonii

How much differance will there be between a 403 and 455. Will it be crazy noticable on the strip? and the biggest question of them all is what are the best performance parts to use for the 455. PLEASE I need names.

AggieOlds

Size does matter, 455. One of the major performance distributors of Olds 455 parts and complete motors, Mondello Performance Products, www.mondellotwister.com.

Oldsguy

Although you would find that Mondello is not that highly rated in some Oldsmobile performance circles. I agree with AggieOlds, more and bigger is better. HOWEVER, you will find a lot of staunch supporters of the 403, many of the "Burt Reynolds" Firebirds cars had the Olds 403 and they are good engines.

badd andy

Consistently Spin A 403 Over 5500 Rpm,and It Will Disintegrate.

Fishydoo

Hi , i'm new to the forum. Just interested what rev's you think a stock 455 crank can handle? Eng is a '72 model.

69deltaconvert

I have seen 403's send the crank and rods through the oil pan if you rap them up to around 8500 was where the I saw went kaput. But people do make engine girdles and lighter rotating assemblies to prevent this. I would say best bang for the buck is a 455 but others will disagree. Fishydoo keep it under 5500 to tell you the truth if its all stock I would keep it below 4500 but thats me.

Redog

I've done a lot a reseach on this, and a 455 is good if you can get HD srpings for the car in question. The 455 adds about 200 lbs to the front end over a SBO.

The 350 can be bulit-up the same as a 455. The 350 will rev a bit higher and quicker than the 455, but the 455 has more torque that a 350. However, the build-up of both motors is about the same. Plus remember this, the best thing about a SBO is the BB heads can put onto a SB engine.

Personally I was a bit bummed to find out that the 350 is a better build for me. I wanted the bragging rights of saying I have a 455 (or a 7.5 liter) motor or even the 403 (6.6 liter) motor, but with putting a 455 in my project, I need about 50 or so more HP to get the same numbers in the 1/4 mile

Kennybill

Oh Boy, here we go. What kind model of Olds and what engine is in it now? I have raced 350's/403's/425's/455's. NO OLDS ENGINE can live at 8500 RPM's. Now I will tell u what I know. I have bracket raced a 403 for 4 years. Engine is pretty mild, stock #5 heads are holding it back. 12:90's@105.85, 60's only 1:80's. Shift @5500, comes through @ 5150. A guy @ realoldspower has 850 runs on a 403 that goes 11:90's, shifts @ 6300 and through the traps @6500. I have seen more 455's spun bearings/rods through the block than the 403. I have never personally seen a 403 hurt yet. In my "main" race car I run a 425, I like them better than the 455. Whatever fits the best use. Put a big oil pan on it whichever engine u use. Ken

Oldsguy

Kenny, those are some beautiful B bodies, especially the '69 98!

Kennybill

Thank You, Both 98's are 4-door 1967 LS'. Green one is a 71 Delta

Oldsguy

DUH! I should have known that.............

Eightupman

I have not heard from anyone in any of these forums that hold Mondello in high regard. Evryone (that I have talked to) says his stuff is overpriced junk. There is another company that I read of in one of these forums that is about to introduce some Olds Hi-perf parts.

texasred

True enough on Mondello...but you need to visit www.realoldspower.com . There's already lots of companies already building Olds Hi-perf parts. You just can't buy them at Jeggs!

C.J.

olds 307 and 403

The olds 455 is not a screamer with its big 3" mains. The 403 can spin just as high as a 455. The 403 has much better bore/stroke ratio, just the windowed mains hurt the extreme rpm ability.