Hey guys Im in the process of gathering parts and materials for an olds 350 rebuild. So far I have a performer rpm, Holley 650, cloyes double roller, 1972? 7a heads, lunati voodo can and lifter kit Advertised Duration (Int/Exh): 256/262
Duration @ .050 (Int/Exh): 213/219
Gross Valve Lift (Int/Exh): .485/.499
LSA/ICL: 112/108
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1000-5300
Includes: Cam Kit

And matching valve springs. Ive been reading the forum and I'm thinking of just taking all of these parts and using them to build a 403 instead since from what I understand everything that I've bought will swap into the 403. I just wanted to get some further insight from some of you guys that are more knowledgeable on the subject and what else from my 350 can I use if I were able to score a bare bone 403 block. Last but not least what all cars came stock with the 403 in case I can find one at the local pull a part. Thanks for all of your knowledge and help in advance!!!

 

What year is your 350 block? I'm not an expert on this subject, but the 403s were all later castings which I believe had thinner walls and windowed mains. From the level of build it sounds like you're going for, it probably wouldn't be an issue, but if your 350 is an earlier casting, this might be something in it's favor. The 403 would have been '77 to I believe '80, and it came in a lot of different cars, F-bodies, A-bodies, B-bodies, C-bodies. Your best bet for finding one sitting around would probably be in a Delta 88, LeSabre, 98 or Electra, although depending on where you are there might not be a lot of them just sitting around.

 

That sounds pretty good are you going to upgrade pistons? Machine work? Stock valvetrain or roller tips? Some of these guys are very knowledgeable cutlassefi, 380racer, ahpilot64 I'm sure someone can give you some extra insight.

Do you have a goal for the engine? Street strip, daily driver.

Good luck and post pics.

 

They made a gazillion 403s, they are easy enough to find. However, IMO, they have design flaws that don't make them a good platform for a performance build. As Integration mentioned, the thin (and Siamesed) cylinders are the problem. Tough to hone, ring seal is an issue, pistons are too heavy, overheating issues, and prone to detonation. Just my opinion, some guys love them. For about the same price you can stroke the 350 to 375 or 380 cubic inches, have a stronger block, lighter pistons and rods. I have seen a lot of guys build 403s and be disappointed.

I have the next size up Voodoo in a 10.25 to 1 355 in a 71 Skylark and it is a hoot to drive and very reliable and low maintenance. With the cam you have in a 9.8 to 1 SBO it should be perfect.

 

The block is a 79 so both will be windowed. It will never see the strip or anything like that I just want something that Is better than stock and that knock me back into the seat from time to time lol

 

No real goal for the engine. I just wanna freshen it up and keep another good olds engine on the road. It'll be 100% street driven. I'm planning on going with speed pro forged flat tops with scorpion pedestal mount rollers. Seeing as the cylinders are siamesed I'd only get the machinist dondonthe very minimal to get everything back fresh

 

About how much HP/TQ are you getting with your 355? And what the most compression that you would run on a build like mine. I'm planning on getting the speed pro flats

 

Somewhere around 350HP/400TQ, but I had a LOT of work done to the heads.

With the cam you have, keep it under 10. If you have not bought the pistons yet, go with the 6cc dish. Also, find and early block, it will cost about the same as drilling out the bolt holes on the heads.

 

Dang. Well I already had the heads done. They put bigger valves in them welded in the exhaust divider put the new springs in and ground out the exhaust bump

 

Sounds fine, just get the chamber CC'd so you can choose the best pistons to get the CR where you want it.

 

Ok. Is there a way I can do it myself because I really don't want to add more money to the head job I'm already at $700 lol

 

Yep, all you need is a clear sheet of thin semi-rigid plastic with a hole in it. Use a little bit of grease around the combustion chamber, and position the plastic with the hole somewhere near the edge of the chamber where it's close to the top as the head sits on your bench. Then you precisely meter in some oil. A burette is good if you happen to have one sitting around because it will contain more than enough oil, but you could use a syringe too. Just add oil slowly, avoiding bubbles and keeping track of how much it takes to completely fill the chamber. Alcohol works too instead of oil, and is a little bit easier to clean up. I'm sure there's a better write-up of it somewhere but this gives you an idea.

 

The shop should do it for you for no charge (they should do it as part of the job, really) since you spent a fair amount of money. If not,
http://www.fordmuscle.com/fundamentals/ccing/

 

X2 on what captjim explained.

 

Thanks Capt! That helped a lot. So you don't think it would be a good Idea to go with the 403 on just a very mild street engine?

 

I am just not a fan. It sounds like a great idea, big inches in a small package, but it is not the easiest engine to work with. Some guys love them. I would build a stout 350 to 355-380 inches and be done.

 

Ok cool. That'll probably be easier for me since I already have the block anyway. It was just an idea I came up with from reading the forums lol