Goofy

Hey guys, still pondering my 76 /350 rocket rebuild from bottom up. Which heads would go the best with this engine ( valve size/chamber size) Thanks for your help

captjim

If you are going to rebuild the engine, use the #8 heads. Mill them a tad, a little port work with larger intake valves. Use Speed Pro flat tops with those heads for a Cr of low 9.xx to 1, cam in the 215 @ .050 neighborhood, and you have a fun little engine.

71supreme

Hey Goofy, Here's a great article on #8 heads I recently came across. http://www.members.shaw.ca/gregtsmith/Head_Porting.htm

Hope it helps.

80_cutlass

Sweet article.

I am glad to see someone using #8s. I guess the ideas about #5 and #6 heads being the the one and onlys are getting updated.

sb

Warhead

#8 heads have always been good units, having very similar ports and valves to earlier heads. They will work fine in a street application with today's available fuels.
The advantage of earlier heads is primarily due to the smaller combustion chamber.
Nice article, many people have different trains of thought on porting, several things here I personally do not agree with. I, personally, would definitely NOT waste my time polishing the chambers.
Get porting advice from J&S machine, or Mark Smith at M&J Perfomance.
My Opinion
Jim

80_cutlass

Interesting.

I have some in my shed. May have to look at them again.

Any hope for my 3As???

sb

Rickman48

Agree w/ warhead - polishing the chambers doesn't help much, if at all!
I'd also get the exhaust guide to more of a 'teardrop' configuration - reversion right there is a real killer!
Best article I've seen in a long time - applies to any head!

captjim

No.

Kyle's 77 Cutlass

That is wild how much HP you can get out of port and polish, but the thing I don't understand is why you want to raise the cc's. Doesn't that lower the compression ratio and the loss of some power?

MDchanic

71 Supreme, that's a great link.

For those of us who are good mechanically, but have never ported a head, it answers a lot of questions. I've got it saved, along with a bunch of other stuff, for the end of the month, when I intend to go pick up a mystery motor to redo on the cheap.

Good to know those #8 heads have the potential that they seem to have, though I'm waiting to see what's inside the motor before thinking too hard about what internals I might want or need...

- Eric

Kyle's 77 Cutlass

but the thing I don't understand is why you want to raise the cc's. Doesn't that lower the compression ratio and the loss of some power or am I wrong. advantage or dis for doing this

80_cutlass

The 1cc increase in combustion chamber size was a by product of getting rid of the chamber bumps that are suppossed to help with swirl. He got that back with the larger valves.

Generally speaking, you want smaller combustion chamber volume. He achieves this in his build with flat top pistons, therby raising the compression ratio.

The reason people like the #5 and #6 and #7 heads is the smaller combustion chamber, making high compression easy to attain even with less than ideal pistons....stuff I learned from this thread is that #8 are good flowing units.

sb

Kyle's 77 Cutlass

so if a person wants to have at least 10to1 ratio, what does a person needs for heads.flat top piston's or a little dome

cutlassefi

Depends on the displacement.

Kyle's 77 Cutlass

so if i went with 5's this work, or what would do the best for a set of heads

captjim

Read this if you want to,
http://www.oldspower.com/vb/showthread.php?t=36717

There are a lot of variables, but flat tops and older 350 heads will get you 10 to 1 +/-, but you have to measure everything, you may end up at 9.6 or 10.4.

The primary benefit of #8 heads is that with flat top pistons you get a nice streetable low 9.xx to 1 Cr. They also have larger exhaust valves and hardened seats. 73-76 350s are also SMW with decent cranks, but for whatever reason a lot of guys think they are inferior for a performance build.

Kyle's 77 Cutlass

When did they start pitting in hardened seats? I would end up punching the heads out for bigger valves, then they would install hardened seats?

rod

with any head just grinding the casting ridges and flashings will make a noticabe inprovement . if you havent done any porting practice on a set of ford heads first, olds heads are to valuable

Kyle's 77 Cutlass

Done a little back about 12 years ago when I did my chevy 350, just cleaned them up,didn't go crazy on them. Olds heads have 2 sets, #8's and #7A's. well they are 2 complete blocks. The #8 that engine still runs and is in the car I want to restore. The other is a spare car I bought for body parts, they aren't any dame good, some is usable but not all what I needed. came with a engine not know if it runs and 2 trans. Lost on some but gain on others. Found another 77 olds but have to go see this one. This one at lest is only 12 hours away, the other was 30 hours away. Talk about a road trip that was.

captjim

First year was 72, unleaded fuel. There is a debate as to whether hardened seats are needed. The #8 heads already have a larger exhaust valve, it is plenty for what you are doing.

tonycpe

I have been using unleaded in my 1968 350 with # 5 heads for decades. valve seats are fine so far . mostly drag racing the last 5 yrs.

rod

i havent worked on small blocks for quite awhile, but my 64 cutlass had the number one heads with roller shaft still have them but i never heard of any buildups for em.they just collect dust i put 455 in 64 and 67 cutlss best move ever.hope you find somrthing that works out.

Kyle's 77 Cutlass

Nice, I like your page. helps. So what is the highest CR you can go with 94 octane, maybe add some octane boost

Kyle's 77 Cutlass

Never mind my spare motor #395558 2 with #8 heads, now confused

FreeBird

This is also a good article about head porting, thought I'd share this:
http://65corvette.nonethewiser.net/t...al/diyport.pdf

71 Cutlass

Didn't learn a lot of new info from the article, as someone posted earlier, much of the info can be applied to head work in general. My question is, will small block Olds heads for the aftermarket (that are worth the investment) ever be produced? Seems like there was talk of this some years back, yet nothing ever came to fruition. Anyone have any news on that?

cutlassefi

Imo there are good small block heads, big block heads. If your application warrants the extra volume of a big block head then put those or the Edelbrocks on it. If not do a proper valve job, clean up and install bigger valves in a SBO head and you'll have a nice combo. The real question becomes are there any really good big block heads. The answer is not for less than 3K+.

Jmo.

380 Racer

I agree Mark. It all depends on what you are going to do with them. My #7s worked very good and flowed some real good numbers. The problem was that they were ported too far and leaked water. I like my Rocket Racing heads and I think John made sure I got a smaller chambers for my SB. You are also correct Mark........I have about $3000 in the heads and intake.

Kyle's 77 Cutlass

What are rocket racing heads?

cutlassefi

Expensive! Lol! No really, just go to www.rocketracingperformance.com and check them out. But if I may say so, a bit much for your upcoming build.

Kyle's 77 Cutlass

most likley, I aint going to make a living on racing up here.Have to keep swing a hammer. Just want to pull some Rockford's, and have lots of fun with her

380 Racer

I was just letting 71 know that heads for a SB are available. They are just in BB form. And yes they have been used on the street.

71 Cutlass

380,
Thanks for the info. In your opinion, how much better would you say the Rocket Racing heads are than a set of ported #7 heads with big block valves are? I know the question leaves a lot to be desired, but am curious to know whether or not your appreciation for the RR heads is so great you would recommend them without hesitation over a set of re-worked stock heads. If so, I think this is very good news for the Olds small block community, who have had very little to choose from over the years when it comes to good aftermarket performance parts.

380 Racer

My #7s had the heat crossover filled, the exhaust dividers welded up flush. The valves were 2.10 intake and 1.71 exhaust. They flowed 270 on the intake and 208 on the exhaust side. Too much porting turned them into a sprinkler system. Tried to have them fixed 3 times to no avail.

Got the RR heads and sent them off to be ported, put them on and gained .3 right out of the box. Ran them for 4-5 races and pulled them off when the engine got freshened up. The porting I had paid for to who I thought was a good friend, turned out to not a good friend. No porting and a screwed up valve job. So yes I believe they are very good heads. But......be forwarned they're not as pretty as Edelbrocks and a few lbs heavier. Of course I'm not after looks........I prefer performance.

Kyle's 77 Cutlass

Wow those would be some wild heads. Is there an end to build an engine