Hello everyone,

I'm about to start a new SBO build and would like your input. I've built a stroked 330 before (352 cui) and I will go the 330 route again. Why? Budget and availability (I have the block, crank, heads and I live in Sweden) and I think it's cool...

The engine (340 cui):

330 #1 block bored to 4.000", zero decked
330 crank, stock stroke, turned to 2.100"
6.200" Chevy rods (Scat Pro Comp)
Forged Chevy pistons, 1.425" pin height
#2 heads, big valves, mildly ported, good valve job
10-10.5:1 compression.
1-3/4" headers.

The car (not yet purchased):

1975 Pontiac Firebird
3.90 rear gears
3000 stall
Will run on 98 octane RON

I want this engine to rev fairly high (6500 rpm) while not loosing everything on the bottom end. While not in the plans right now, there could be nitrous in the future.

What do you think about the heads? I'm thinking 2.000"/1.625" valves and pocket porting. Should I go for bigger valves? More serious porting? They will get a good multi-angle valve job, back cut valves if needed.

What intake do you guys recommend? I'm thinking Performer RPM or Street Dominator.

Cam and carb? Around 220 duration, 0.500" lift, 750 CFM on the carb? LSA? Single or dual pattern?


Thanks for looking!

 

Forgot one thing - oil system!

I like to run my bearing clearances a little loose - mains at 0.0030", rods at 0.0026" with said components. Should I use a high volume pump and bigger pan at 6500 rpm?

 

6500rpms is not a problem for the engine in stock form......except I would have a higher capacity pan as well as the hi volume pump. Other then that, there are no tricks or precautions necessary to spin those RPMs.

2.07/1.71 valves in a small block head with a pocket port are where your gains will be at.

I have never used a Street Dominator on the street, but I have used an RPM and the RPM is a great street intake. So I would say stick with what works, but maybe others have positive experience with a street dom.

For a cam, I would venture you'd be more into the 230* @ .050 territory. Dual patter always work better with the crappy exhaust ports on an Olds.

If nitrous is possibly in the future, go ahead and open up your ring end gaps an extra .005".

 

2.07/1.71 huh? Any downsides to such big valves?
Do you think there's risk of shrouding the intake valve in a 330 chamber? How close to the chamber wall can you get without problems?

I'm looking at the Ferrea 5000 series. Is it worth going for dished heads and undercut stems? Any other recommendations?

Thanks!

 

I'm no cam expert so when I built my 352 I had Bill Trovato spec a cam for me. Since it seems 99% of all Olds engines out there are running dual pattern cams I was a bit surprised when he chose a single pattern. I don't have any dyno numbers or track times yet but I feel this little cam is damn sweet. Pulls hard from down low and just keeps going (even though I'm probably past peak HP I usually shift at 6000, it just wants to keep revving. Come spring I will wound it out to see when it lays down).

Cam is 211/265 0.472 108 installed at 105. Engine has 9.9:1 comp, W31 valves and 1-3/4 headers, 2.5" exhaust.

I guess my question is - Does Olds engines (mildly modified) always work better with dual pattern cams? Even with a 1.71 exhaust valve, 1-3/4 headers and good exhaust?

 

I do a fair amount of single pattern cams for Olds. And I get the same question, "I thought a dual pattern would be better".
Not always the case. Yes the exhaust side of an Olds head isn't great but it also depends on the specific application.
However I don't think you need a 1.71 exhaust valve. 1.68 is way big enough, I'd even opt for a 1.625.
And for a cam I'd do an Erson Viking 100H (222/222@.050). I do a lot of those for small block builds. Great power, good tone and throttle response, especially with 10.0:1 or better.

Jmo

 

I agree, but where can you find a good stainless valve in those sizes with the proper stem length......actually, preferably +.100" on the stem length?

I am working with a valve company as we speak on their Olds lineup of valve offerings.

 

I forgot you have a smaller bore size. You'd probably be a little closer then necessary and shrouding would occur.

 

SI or Milodon. Or you can just buy them from Edelbrock.

 

I'm not a mind reader and very bad at the guessing game. The last time I played the guessing game my answer was "Christina".........then I got slapped.

Got any part numbers?

 

So how close is too close for shrouding? Does increased shrouding negate the gains from a bigger valve?

I've made some measuring and calculating on a bare #2 head (without valves, not exactly super accurate but in the ballpark):

W31 valves:
Intake 0.157" from chamber wall, 0.150" from cylinder wall
Exhaust 0.134" from chamber wall, 0.126" from cylinder wall

2.07/1.71 valves:
Intake 0.118" from chamber wall, 0.110 from cylinder wall
Exhaust 0.091" from chamber wall, 0.083" from cylinder wall

2.07/1.68 valves:
Intake 0.118" from chamber wall, 0.110 from cylinder wall
Exhaust 0.102" from chamber wall, 0.094" from cylinder wall

Picture shows W31 valves in #2 heads

 

Yes, as you increase valve size and get more shrouding you get diminishing returns.
Don, I'll get you part numbers but with all due respect SI and Milodon have websites and summit carries a lot of the Edelbrock valves.

 

But you would agree on the 2.07 intake valve?

 

SI shows their competition series valves on the site, and they show all specs. They only offer the 1.71 exhaust valve. Their street replacement series does not list sizes, but I am assuming the replacement big block valves are 1.625" in size......which are 4.668" tall........which is really too short for a small block head because the only way to get it to work is to really sink the valve in the head.

Milodon does not list any valves for Oldsmobiles on their website. Summit has Milodon valves for Oldsmobiles, which are 1.71......and also 4.668" tall.........as well as Manley valves with the same specs.

I see Edelbrock does have a 1.68, do you have a length on those?

 

SI "Portflow" 1.68 exhaust valve is an SEV2610-45+.100. That and the Edelbrock valve are listed as a 4.820 length. Std length is listed as 4.740. I've used about a half dozen sets of the SI, no issues. As is with a lot of valves these days, they're made in Brazil, not China.

Hope this helps!!

 

That is exactly what I was looking for. Thanks!

 

The stock bore of a 330 is 3.938".

The stock bore of a G-block 400 (which came from the factory with 2.070/1.625 valves) is 3.870".

There's still less shrouding with the 330 than with the G-block 400.

 

What are the pros to running a taller valve except placing it higher (or is that lower?) in the chamber? Any positive effects on valvetrain geometry (running Harland Sharp S5001 rockers)?

 

Great you are working a 330, most interested in what you are doing. I suppose you already know that the crankshaft and rods on
a 330 are forged?
Just realized you are Karl Anders Jonson, I talked? to you on You Tube in regard to you putting headers on your '65 Cutlass 330.

 

Sorry, just noticed the link had gone walkies so here it is again below

http://www.442.com/oldsfaq/ofhed.htm#Heads

Check out this link and as for valve performance specifically look under the Performance Modification heading.Awesome site for info! Cheers

 

Has nothing to do with the relationship of the valve in the chamber. It allows you to use taller springs. But yes it will change your rocker to valve tip relationship, you'll need to check that with the HS rockers but you'll probably be ok.

 

That explains why the G block was such a turd.

 

I was just doing some thinking here, and you also have to take into account that with all BBO heads that had the larger intake 2.07" valve from the factory, they all had 30* seats as opposed to the standard 45* seat. The 30* seat really helps low lift figures (under .400 especially) because of more curtain area at the same valve lift as a 45* seat. I would surmise that at lower valve lifts, the bore shrouding is not so much of a factor until you get into higher lifts.

Also, all BBO heads had 1.625" exhaust valves with a 45* seat except for some Ga heads that had a 1.687" valve with a 30* seat. Those Ga heads with the large exhaust valve were only fitted in heads that had a 2.00" intake valve.

 

The rods on EVERY Olds V8 are forged.

 

Thanks for all the input guys, I really appreciate it!

With bigger valves I need to open up the throats a little. What is a good throat to valve ratio in an Olds head such as mine. I see street specs all over the place ranging from 85% to 90% and more race-inspired heads using even more.

SBO #2 heads have very big throats in stock form (Int 1.752" Ex 1.437"). These are the numbers with an untouched throat:

Stock valves: Int 93% Ex 92%
W31 valves: Int 88% Ex 88%
2.07/1.71 valves: Int 84% Ex 84%

Are all Olds heads like this?

 

Good to know, thanks.Come to think of it it's always the crankshaft that gets specific mention re forged.Now I know why! Always learning on this site, great to hear from people with good knowledge like on this 330 build thread.

 

Everything I have measured on stock heads seems to show that the small block heads from 64-72 were about the same in the throat area. The changes in the heads seemed to be in the roof near the guides (70-72 heads had a shorter roof than older stuff) and the short side radius was also a bit different between 64-69 heads compared to 70-72.

I would have your throat area at 88-90%, but be careful when grinding. It can be easy to get a bit carried away and make it bigger. Also, it is important (and difficult) to keep the throat area concentric with the guide.

I actually turned down a used valve to the size I am aiming for and try to sneak up on it that way. I did it in a valve grinder, but if you don't have access to one, chuck a used valve up in a drill press and grind it with a carbide while it is spinning in the drill chuck.

 

I like this thread. I have my ported #6 heads with W31 valves. I plan on getting the guides checked, a fresh valve job and add a 2.07" intake valve and open up the bowl to take advantage of the bigger valve. Of course they will being going on the 425 small block, hopefully machined and put together next year and running mid 9's for compression.

 

I am interested in your comment that 6500rpm is fine for a stock 330.Factory specs say 315hp at 5200rpm and 360ftlbs torque at 3600rpm(I think).Although my engine (with a warm cam) revs freely and quickly to 6000rpm with no load when driving or racing I have the redline set at 5200rpm.It seems to feel right so 6500 seems a long way away.Do you think they are still able to produce good power from 5200 to 6500rpm?
My car has had the big cap style Delco HEI system installed which I have been told is only good for 5500rpm.I have also read that above 5500 the sump can get sucked dry, maybe that's because the oil flow back down is somewhat restricted so your oil comments are spot on but am I right about the oil return issue?

 

I read my comments and they are a bit misleading. When I said 6500rpms in stock form, I should have said the short block (stock form) can handle 6500rpms. The cam and valve springs are not made to go 6500rpms in stock form. You won't gain anything by going that high unless you have the cam, compression, and valve springs.

About oiling, I had a stock pan and hi-volume oil pump on my 350 that spun to 6500 all the time. Upon inspection of the bearings when I tore it down, one rod bearing showed slight signs of a problem starting. It could have had to do with sucking the pan close to dry I suppose......either way, a hi capacity pan just makes a whole lot of sense if you are going to spin a small block to 6500. Seems like cheap insurance to me.

I don't see why you couldn't go higher then 5500 with the stock HEI. I always have an MSD ignition in my cars so I really don't know the answer, but maybe someone else with more experience can chime in about that.