olds 403 clearance specs looking for acurate info

[gmrocket]

keep it on the loose side, if your running the stock light weight scalloped crank, it's like a wet noodle and will tear up the mains if clearance is on the low side...even your grocery getter with a small cam will want to flex that crank.

I would go .0025" minimum on the rods ....

I ran deep into the 11's with that junk crank , factory rods and Pistons...over 2000 runs and it's still together in a street car now.

It was set up very loose

[dave brode]

The clearances that Bill Travato recommends are very wide.

https://www.amazon.com/How-Build-Max-Pe ... 1613250738

http://www.btrperformance.com/

[rocketracer380]

Depends on application for what he's doing he'll be fine stock motor thats never gonna see the hi side of 5000

[gmrocket]

When i do any 403 it gets more clearance.

Those cranks are just grey iron and are extremely flimsy due to the scalloped design. It's barely stable in a 260. The stock measured compression is about 7.8:1. He is upping that to 9 with an energizer cam...it will make a lot of torque which is hard also hard on cranks...more tq=more flex

I have a blown up 403 I kept for a show and tell...engine had edelbrock heads and a mild cam. Engine lasted a month, it exploded and broke the crank in 5 pieces, tore out all 5 main caps, broke the bell housing etc.

[racinnut15xm]

When i do any 403 it gets more clearance.

Those cranks are just grey iron and are extremely flimsy due to the scalloped design. It's barely stable in a 260. The stock measured compression is about 7.8:1. He is upping that to 9 with an energizer cam...it will make a lot of torque which is hard also hard on cranks...more tq=more flex

I have a blown up 403 I kept for a show and tell...engine had edelbrock heads and a mild cam. Engine lasted a month, it exploded and broke the crank in 5 pieces, tore out all 5 main caps, broke the bell housing etc.

My dad tried to run the 403's in a IMCA mod for a couple seasons, they would last a couple nights before doing exactly what you mentioned pulling all the main caps out and destroying the bottom end. He had somehow retro fitted a set of big block heads to the block, think he still has the heads. Motor was killer coming out of the corners but all the chevys would run him down on the straights at the old half mile.

[crazycuda]

This is just going to be a low rpm, auto trans, in a 3800lb car with 2.76 gears. Basically sound good and be good at 0-60 resto.
Customer might see 5k a year on it

[rocketracer380]

Damn I've had good results did a 403 for a customer std clearences comp ended up at 11:1 do to heads being 64 and kb pistons put a set of .080 cometics dropped it to 10.2 which gave me horrible quench installed xe 284 RuNs mint crazy power suprized me been together 3 years and been over 6000 multiple times a new build lasting 1 month must of had a bad crank or something used 350 n crank maybe that's why it holds together no straps studs all stock stuff desk top Dyno puts me at 450 HP for what your doing it should be fine I'm about to embark on a stroker 403 wish me luck

[gmrocket]

Damn I've had good results did a 403 for a customer std clearences comp ended up at 11:1 do to heads being 64 and kb pistons put a set of .080 cometics dropped it to 10.2 which gave me horrible quench installed xe 284 RuNs mint crazy power suprized me been together 3 years and been over 6000 multiple times a new build lasting 1 month must of had a bad crank or something used 350 n crank maybe that's why it holds together no straps studs all stock stuff desk top Dyno puts me at 450 HP for what your doing it should be fine I'm about to embark on a stroker 403 wish me luck

so you used the 350 nodular crank? if thtas what you meant ya, I was talking about the stock 403 crank

crazy power? that's funny

[rocketracer380]

By crazy I meant impressive torque haules a 4000 # car seat of the pants felt like a lo twelve to hi 11'sec car not bad for a basically stock rebuild with cast heads and a cam and headers at least it lasted more than a month

[crazycuda]

You guys have any luck using the 292 ford 2 pc seal vrs the stock rope?

[Cutlassefi]

You guys have any luck using the 292 ford 2 pc seal vs. the stock rope?

Yes works fine, yes Fel-Pro BS4161 I think.
Go with what gmrocket said.
Not sure why anyone would say that the 403 crank "grows" more than any other cast crank. It doesn't, that's simply not true. Maybe they meant flex?
I did a 403 last year, .0023 on the rods and about .0025 on 1-4 mains, a little more on 5, with a 3/8" thick 4 main halo. Had 75psi of oil pressure with 15W-40, still runs great, made 451/512 corrected with an RPM intake, 9.0:1 and C heads. No issues.