So I'm building an olds 403. I'm collecting parts as machine work is getting done. I'm pretty well through the machining process. Had it bored .030 over got mondello high compression pistons. The times coming to pick heads and a cam. As far as the cam goes I'm pretty well set on .250/.256. The heads mainly where it's a toss up I'm debating on edlebrock heads with 77cc chamber, which with my set up will take me to what I believe to be around 10.2:1, or 350 #7 heads or the #7a heads. I've heard the edlebrock vs 350 heads is pretty close but I truly wouldn't know. So if anyone can throw in some input that'd be awesome. So yeah tell me what you think and thanks in advance!
403 performance advice.
- Thread starter Solidhank
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Solidhank said:
Personally, I would buy the Pro Comp aluminum heads. I have worked #5's on my 403 that easily cost $1500 to get them where they are. They are heavier than Edelbrocks or Procomp, likely flow less and require a lower compression ratio. If you go Procomp, have someone qualified check guides and install valves and fresh springs. There are a lot of guys out there using them with good results.
Check out http://www.realoldspower.com you'll find more than you'll every want to know there...
Dr. Dan know's a thing or two on these and has some impressive 403 builds.
I'm building one now with stock pistons and ported #5's and I am currently considering:
Ultradyne H15 231/239 @ .050 517/541 lift on a 110 installed at 105.5
Or a couple Dr Dan is running in his '83 & '84 H/Os:
Comp 236/[email protected] 538/528 lift on a 110 installed at 105
Custom Ultradyne 219/[email protected] 489/499 lift on a 112
With #5-7 64cc heads you need to run stock pistons, running flat top pistons is gonna give you 11.5:1 compression and won't run without pinging with an iron head.
A 77cc head will get you just shy of 10.1:1
Both with a .040 head gasket...
.027 will get you 12:1 and 10.4:1 subsequently...
What are the specifics on the pistons?
Hope you got them from the real Mondello performance shop @ http://www.mondello.com and not from Lynn at mondellotwister.com
Dr. Dan know's a thing or two on these and has some impressive 403 builds.
I'm building one now with stock pistons and ported #5's and I am currently considering:
Ultradyne H15 231/239 @ .050 517/541 lift on a 110 installed at 105.5
Or a couple Dr Dan is running in his '83 & '84 H/Os:
Comp 236/[email protected] 538/528 lift on a 110 installed at 105
Custom Ultradyne 219/[email protected] 489/499 lift on a 112
With #5-7 64cc heads you need to run stock pistons, running flat top pistons is gonna give you 11.5:1 compression and won't run without pinging with an iron head.
A 77cc head will get you just shy of 10.1:1
Both with a .040 head gasket...
.027 will get you 12:1 and 10.4:1 subsequently...
What are the specifics on the pistons?
Hope you got them from the real Mondello performance shop @ http://www.mondello.com and not from Lynn at mondellotwister.com
What the heck is a .250/.256 cam? Also you cannot choose a can before knowing what your CR is amongst other things and your CR is going to be totally different depending on whether you use aluminum heads or early 350 heads.
Best thing to do is buy them from Bernard Mondello, Joe's son, he is not affiliated with Lynn at mondellotwister.com, avoid that vendor, he bought Joes name and soiled it.jociha said:
He specializes in ProComp heads and usually sells them with all the required machine work and ready to run for $1200 which is a deal.
http://www.ebay.com/sch/bernardmondello ... 7675.l2562
This question seems so ridiculous from a cheap person's perspective... Why spend thousands on iffy parts for a fractional gain in performance when the old 350 heads work just fine for hundreds of dollars less and offer better longevity? So what if they are a few pounds heavier - that's what gives them the reliability and longevity they are known for. The choice seems obvious to me...
pencero said:
Well your are partly right, pro comps also known as pro star and a couple other names are iffy, I would never run them but if you have a good quality set of aluminum heads, there are a couple good brands out there, they probably flow better on there worst day out of the box then a quality worked over set of iron heads would do on there best day. In the end it is all about the money, you can spend a lot of money porting iron heads.
jociha said:
What heads are those???
Bulldogs, Rocket Racing and Knowlton heads are probably the only ones that might flow better in a raw form comparison but are pretty much out of the scope for a street build like this.
Procomps and Ebrocks pretty much flow the same as C heads out of the box, the benefit is that they are aluminum and you can run higher compression.
There are guys running 9's on ported C heads...
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