I have a early 70's 350 that I pulled out of a ck. Its been rebuilt/ cleaned as well as honed, and resurfaced.. Its got a set of 883 heads that are mildly cleaned up and milled as well as dished pistons. The motor has about 1k miles on it after the rebuild.

I'm looking to get a set of new heads and install them over the winter being the car is off the road again until april/may. I want to raise my current compression to around 10.5:1 but no higher than 11:1. I will be changing the current dished pistons to forged flats. Im am unsure of what size combustion chamber to go with.

What do you guys recommend as far sizing goes? Also Id like to keep the victor jr. intake manifold I have now if I can because its also been resurfaced and powder coated aluminum silver.

 

well it all depends on how much cash you wanna spend.. id say go with a 64cc head with a 195cc intake... so many different head company's out there but my 2 cents... AFR and DART are to of the top heads

 

Well I'm asking about sizing to get the compression ratio I want. I am decently knowledgeable about the different company's and how much they cost. Before I decide which company to go with I need to know which size combustion chamber to go with as well as what style head so that I could maybe keep my refinished Vic.jr intake manifold.

Would a 64cc be too small with the stock rods and flat top pistons? What would that bring my comp ratio to?
Remember my original pistons are dished and the compression ratio is 8.5:1 I think don't quote me on it.

My question wasn't about budget or brands. I still have to figure out other things before I go there. Thanks scamaro355 you didn't really answer my question but thank-you again for the reply.

 

ok to get an accurate compression ratio you have to know the following.. well ill just give u a link then its not just a guessing game, you'll know.. http://www.csgnetwork.com/compcalc.html

 

To answer your question as to what size, we have to first consider how high you want to spin it. The VicJr is a high reving intake. I'd look at something in the 180-195CC runner, probably the larger side to go with the intake. I think the intake deserves the larger runner with larger CSA.

If you go to BRODIX website, they have a sizing chart that reflects compression. It's a good tool.

I'm running a special, $950/set for Profiler. 100% american made if you want to look at them.

 

Yea I know that about the vic jr. that is why I took it off my current setup because it bogged down low on hard acceleration. I replaced it with the dual plane performer. It gave me better performance where I needed it. Im just hoping to be able to utilize the vic.jr. with the new heads. It looks like I will most likely be going with a 62-62cc head with a 195cc-200cc intake runner. Im leaning towards a cast head I was talking to a guy in my shop tonight and he recommended the WP sportsman II. I have been thinking about going with RHS as well. I just hope I don't run into clearance issues with the flat tops and a 62CC-64CC combustion chamber without changing allot.

I cant have the motor out until the spring. I was hoping to get the bare heads as well as pistons and assemble the heads with new springs and hardware over the winter. Looks like I'm going to have to wait until the motor is out and measure everything before I buy a set of heads.

 

Sounds like you're taking a solid, methodical approach to this. Nice to see.

 

Yea well there have been way to many times were I have jumped the gun and decided to get something only to find that I had so much more time work and money ahead of me. I don't have the time or money to waste on a simple mistake. Id rather not wait but I can.

Thanks for the help guys.

 

If its got dished pistons, you'll need something alot smaller than 64cc to get over 10:1... the good 305 heads are 53cc and 58cc and that would get you in the range you want. They also are actually pretty good heads with bigger valves.

 

I have a 350 in it not a 305. It was pulled from an early 70's ck that I honed decked and resurfaced. Currently I have dished pistons with the Chevy 882 casting heads which have a 76cc combustion chamber. With the dished pistons I am making around 8.5:1. Now if you read my first post I said along with the heads Im going with a set of forged flat top pistons. The only reason I referenced the dished pistons is because I don't want to run into clearance issues.

The 305 heads I really dont think have the size Im looking for to reach the power goals I am expecting down the road. Without major modification I don't think they would be of any use to me. I could be wrong.

The heads Im leaning toward right now have a 62-62cc combustion chamber, 190-200cc intake runner. 2.02/1.6 with over .500 max lift.

Ive been recommended these heads the world products WRL-011250-1 and have been strongly leaning towards these unless I can find an equivalent or better head for less money.

 

Id suggest the angled plugs...

 

Sorry, my bad... I just skimmed and it came back to bite me

Generally, a 350 with flat top pistons and heads with a 64cc chamber will net almost exactly 10:1... it will vary a little either way depending on deck height and head gasket choice.

Honestly, I wouldn't sweat the actual figure of the compression ratio too much, as long as its within the right range for the cam, it doesn't make a big difference in power output (2-4% per full point once you get to 10:1, typically)

Go for the better head design FIRST, and let the compression ratio come second to that. A more modern head design (lets say AFR, or even GM Vortecs) with only 10:1 compression will still make way more power and better driveability than an ancient head design (lets say some old 'fuelie' heads) with 11:1 compression.

As long as the compression ratio is within the right range for the camshaft you'll be using, don't worry about the actual figure too much - get the better designed head, not the one that will make slightly more compression. A better design will work MUCH better in every way over a little more compression. Angled or straight plugs don't make much difference on a street engine either. Use whichever will be most convenient with your headers.

If it was my 350, I'd go for a set of competition ported AFR 195cc or 210cc heads. Just my 2 cents though.

 

Most manufacturers will make the chamber to size if you ask. There is a charge though, typically about $200.

Remember, if you take a lot off the bottom, you have to take some off the intake side.

 

Thanks for the response air Adam. The afr 210's are a great head but are a little more than I want to spend which is why I am leaning toward WP-011250. I have a few books I have read and have spoken to a few people around my shop recently and it seems to be that compression is the way to make good power on a tighter budget. Like I said I heard great things about the WP heads as far as cost to power. The reason why I do not want to go over 11:1 is because Id still like to run on pump gas. Otherwise I would be looking toward more of a 12-14 figure. The cam wont be chosen until after I have my heads assembled and ready to go. I have a buddy that works for comp cams as a tech and he goes out of his way sometimes to get me the information I am looking for. As well as a slight discount on parts.

 

good luck running pump gas with 11.1 you'll have to pull timing outa it which will cost u power... but to each is own

 

I'd back it down .5 points....

 

I did make it a little unclear. I did say I wanted it close to 10.5:1 but no higher than 11:1. What I meant was <11:1 and >10:1. with my target 10.5:1.

Off the record according to many professional engine builders from what I was told with 93 octane the highest compression ratio you should run is 11.2:1 with the right cam.

In 2 of Dave Vizards books as well as well as popular hot rodding magazine they state this. For you to run 93 octane with an 11.2:1 comp ration your engine should not be running at more that 170º nor should the temp outside ever reach 115º. Headers should be wrapped and hood venting is crucial to release hot air. A cold ram air intake as well as a heat deflecting coating on your intake manifold is optimal. Cool gas and a cooling tank should be used but is not necessary.

I do not want to go through the trouble trying to run pump gas on an 11:1 motor. Id rather it be around 10.5:1 like I said in my previous posts. Which is why I have been asking questions. I want to do this right the first time. I don't want issues with compression/fuel or clearance issues.

Thanks again for the reply's. The more the better. It makes it easier and easier for me to do the right things.



PS. my car is no daily driver. She is no garage queen or race car either. I see max 100-300 miles a month depending on how busy I am and the car is only on the road <5 months out of the year.

 

11:1 is fine on pump gas as long as you have the right cam. I did it when I had my small block, (11.3:1 actually) and never had any problems. Engine was my daily driver for 2 years. And I did it with some ancient cast iron heads too. It just has to be a little more finely tuned.

That said... the power difference between 10:1 and 11:1 in a motor that is otherwise the same (same heads, cam, intake, exhaust, etc) will be so small you'd never notice it. It wouldn't be more than 8-10hp difference I would bet. As long as it lands somewhere between 10:1 and 11:1 I wouldn't worry too much about it, though the higher end of that will require a more precise tune to keep it running well. Theres more room for error if you stay closer to 10:1.

If you want a good aftermarket head thats got a reasonable price, the Dart 200cc Iron Eagles would be an excellent choice for a street 350. I was very close to pulling the trigger on a set of those for my 350 before I decided to go with the big block instead. They are an excellent head.

Brodix also makes a good budget aluminum head in 180cc and 200cc castings called the 'iron killer' heads. Also an excellent head for reasonable money. A set of 200cc iron killers would also be an excellent choice.

 

Thanks looks like I will be staying closer to 10:1 if that is really the case about HP. Also thanks for the recommendations on heads. What is wrong with the WP heads I was looking at? What makes these better aside from the name. I believe the WP heads un-assembled are 380$ and 580$ assembled give or take. Which is pretty much my price range. I was looking at brodix heads when I originally put together my 350 and they were around 2000$ for their cheapest set assembled.

 

The best looking head in that price range I have seen is the Profilers that Injectors Plus sells. I've never used them mind you but the ports look awesome. You won't find another sub 1000$ pair that flow 270cfm either, if you do let me know.

There are some other decent heads in that price range too. I don't know about those sportmans, haven't used them or heard much about them. Surely they aren't crap but if you are investing $1000 into some heads best make sure they are worth it.

 

WRL-011250-1 are the World Sportsman II heads... theres nothing inherently wrong with them, I had a set of those on my 350 at one point too lol. They are a decent head, but they are a pretty old chamber design. They are basically the same chambers GM used in the '60s. While theres nothing wrong with that, the heads that I suggested (Iron Eagles, Iron Killers) are a MUCH newer head with a more modern chamber design. Because of that, they breathe better around the valves, they are less detonation prone, and will make more power because they burn the fuel charge more efficiently. So the Sportsman II's aren't bad, just old technology. The two I suggested above are a more modern design, so they are a better head to an extent.

 

Thanks. I heard the sportsman II heads are continuously changed over time to keep up with the competition. While the heads still resemble popular 60's style heads they have fast-burn chambers and other improvements since when they were introduced in 1987.

Ill have to take a look at the other heads and their design before I lock down on a decision.

 

Great info! Yep, those IKs are nice. as are the Darts. All good products.

 

Well, like I said, they aren't at all a bad head - I used a set myself and I really liked them. Stayed on that small block untill I sold it. The nice thing about the Sportsman II heads is that they've been around long enough that you can get a little bit older set thats been rebuilt or used original in really good shape for almost nothing if you know where to look. I got a completely rebuilt, unused set for only $500 cdn a few years ago.