#61  
Old 09-26-2018, 01:33 AM
Baron Von Zeppelin Baron Von Zeppelin is offline
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Originally Posted by Baron Von Zeppelin View Post
Tom, i forgot what heads you used on that 301T short-deck build.
Which heads were they ?
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Originally Posted by ponyakr View Post
What would be an aprox cost to have somebody make an intake for it, if you had to pay full price ?

Went and found some of those answers via search.
Goal was 425'ish HP - Pump Gas


Quote:
Oct 2012 =
I hired Dave at SD to build me a intake and do a set of heads for the small bore.He chose a E single plane intake to cut down and a set of small valve 15 heads.Plan is for 9.5 CR.He did a 2.05 intake and a CNC 260 @ 600 port job.The crank is a 63 326 unit
Quote:
Hope Dave jumps in but I think he cut the flanges off,bolted a set of heads with a head gasket to the block,bolted the flanges on the heads with a intake gasket and then cut the intake at the proper angle and welded it back on?I already had the 301 water X over.
In May 2014 -
wound up with 475+ HP @ 6000rpm with Hyd Roller Cam


Last edited by Baron Von Zeppelin; 09-26-2018 at 01:52 AM.
  #62  
Old 09-26-2018, 10:21 AM
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Default 4" vs 3.75" crank

So this is a quick model on Performance Trends Engine Analyzer. I used a .030" over 350 with kre small valve heads that flow 260cfm, headers, single plane intake, Holley 750cfm, 10.5:1scr and SD Performance's Old Faithful cam.

One run is with the 3.75" crank and the other is with a 4" crank.....You can guess which is which!
Attached Files
File Type: pdf 360 vs 383.pdf (180.8 KB, 114 views)

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  #63  
Old 09-26-2018, 12:16 PM
hurryinhoosier62 hurryinhoosier62 is offline
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Karl, I’ve seen dozens of these computer models on engine performance proven highly inaccurate by real world results. Don’t put much faith in them.

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Old 09-26-2018, 12:37 PM
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Karl, I’ve seen dozens of these computer models on engine performance proven highly inaccurate by real world results. Don’t put much faith in them.

Well of course a computer simulation would not be exactly the same as "real world" results! Hell, "real world" results aren't the same every time. It will give a general idea and a visual representation to show the general difference between two engine with only the crank stroke being changed.

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Old 09-26-2018, 12:38 PM
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I've posted this info before. But some, or most, probably don't remember it. I bought a '69 Tempest, which had been built for NHRA Stock class racing. The guys who built it later sold it to a Chevy guy. He tried to do some bracket racing with it. But he wound it up too tight & broke a cast rod.

He then had another 350 shortblock rebuilt, & put the #48 heads back on it. He gave me the dyno sheets from the engine build. It made 434hp. He said the car ran mid 12's. Don't know what cam he used. It had an alum intake & Holley carb when I first saw it. But, he gave me the Q-jet that was on it when he bought it. Never made it to the track. Our local track didn't open at all in 2010, so I sold the roller. But, the engine sounded good.

I still have that shortblock, at another guys shop. I may one day take a closer look & see what cam it has. Will also see if the TRW L2339F030 pistons are still usable. For all I know, rust may have ruined it beyond repair. There was a flood at the shop a few years back.

  #66  
Old 09-26-2018, 12:41 PM
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1.25 HP to CI is a good rule of thumb for a good HP street pump gas pontiac engine in my experience.Tom

  #67  
Old 09-26-2018, 04:02 PM
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I had a 70 Lemans once with a stock 350 in it. One day a stud decided to break so I put a set of #62 heads on it along with a stock Q-jet and iron intake. The cam was stock and it was also std bore, block was fly cut from the factory. I had 2 1/2" dual exhaust with dronemasters on it along with a 3.23 ratio gear. I felt like I added 100 HP to the car, it really scooted after those mods. I had to run premium after that but it was worth it.

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  #68  
Old 09-26-2018, 05:25 PM
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"...a 70 Lemans...with a stock 350...block was fly cut from the factory..."

That's interesting. A small valve 350 had chamfers from the factory ?

Were they on both sides, for both intake & exhaust valves ?

Does anybody know exactly which 350 blocks had no chamfers, 1 chamfer, 2 chamfers ?

  #69  
Old 09-26-2018, 06:27 PM
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Pic of 1970 350 that had #11 original heads now has #48 heads

A short block is primarily and air pump nothing magical

All else equal modest changes in pump volume shift around what RPMs the power is made

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Last edited by Formulas; 12-17-2023 at 10:11 AM.
  #70  
Old 09-26-2018, 06:38 PM
Baron Von Zeppelin Baron Von Zeppelin is offline
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Originally Posted by ponyakr View Post
...had been built for NHRA Stock class racing...
350 shortblock rebuilt, & put the #48 heads back on it. He gave me the dyno sheets from the engine build. It made 434hp. He said the car ran mid 12's.
Just wondering if those #48 heads were mostly un-touched since it was per NHRA - or if maybe they had been treated to some massage therapy at some point.

Did you get the heads too ? or get a decent look at them ?
[no concern about rule book - just interested if they were worked or not]

I might would eventually actually do this imaginary 350/0.060 with some DIY-Worked #670's and medium zone hyd. flat tappet cam if my nephew winds up with a 66 GTO. I could donate a 350 and pair of #670's to the cause.

  #71  
Old 09-26-2018, 07:14 PM
hurryinhoosier62 hurryinhoosier62 is offline
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Quote:
Originally Posted by tom s View Post
1.25 HP to CI is a good rule of thumb for a good HP street pump gas pontiac engine in my experience.Tom
Precisely, Tom. A ..030 over 350 yields 359 cubic inches. 359 x 1.25 = 448.75 hp. That would be more than enough power, especially in a light car such as a G body LeMans or Grand Prix to shock the 400/455 guys. Like Tom, I like to think outside the box. Imagine a .060 over 350 with a 3” 4.00 stroke crank, LS based pistons with either KRE or E heads with 72cc chambers. 389 cubic inches x 1.25 =486 hp. That would rival the power produced by many street 455s and 428s

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  #72  
Old 09-26-2018, 11:52 PM
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I seriously considered building a 350 but eventually decided on a 455. My plan was .030 over 350, 4.25 crank, 7k3 heads milled to mid 80s cc, 6.800 bbc rods. 407ci with 9.5 comp. I think it's a great performance upgrade for stock looking matching number builds. I don't think the 350 makes sense for an all out performance build

  #73  
Old 09-27-2018, 12:09 AM
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Originally Posted by ponyakr View Post
"...a 70 Lemans...with a stock 350...block was fly cut from the factory..."

That's interesting. A small valve 350 had chamfers from the factory ?

Were they on both sides, for both intake & exhaust valves ?

Does anybody know exactly which 350 blocks had no chamfers, 1 chamfer, 2 chamfers ?
I can speak to 1969 and 1972. My blocks had both sides chamfered, just like the pictures above.

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  #74  
Old 09-27-2018, 12:26 AM
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Quote:
Originally Posted by ponyakr View Post
"...a 70 Lemans...with a stock 350...block was fly cut from the factory..."

That's interesting. A small valve 350 had chamfers from the factory ?

Were they on both sides, for both intake & exhaust valves ?

Does anybody know exactly which 350 blocks had no chamfers, 1 chamfer, 2 chamfers ?
http://forums.maxperformanceinc.com/...d.php?t=797514

  #75  
Old 09-27-2018, 02:10 AM
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http://forums.maxperformanceinc.com/...17&postcount=8

From the info posted in that thread, it appears that we MIGHT could say that MOST '68-'74 350's had double chamfers. Has anybody here seen a '68-'74 350 block with none or only 1 ?

One guy posted that he knows of 1 block that didn't have any.

So, has anybody else seen one from ANY year that had none or 1 ? If so, do you know what year or at least the casting number.

"... I believe the chamfers were there to unshroud the valves, not for valve deck clearance since Pontiac used a flattop no valve relief piston in the 350 that would have hit the valve before the valve hit the deck. The unshrouding may not have been needed in the later blocks with deep chamber heads and eliminated when the casting changed in 1975-76..."

I'm trying to think about this. Ya'll help me here. When the valves are fully open, the pistons are not at TDC, therefore would logically hit the deck(if any part of the valve would contact the block on the way down) before they could possibly hit the pistons. I assume the valve reliefs are need mostly for larger, longer duration cams, which might have the valves open a bit more at TDC or very near TDC.

I suppose that's why engines with really big, long duration cams need deeper reliefs.

I think the no relief pistons began in '74. All '74 350 heads had small intake & exhaust valves, and the deeper chambers, actually slightly larger than the 6x-4 head chambers used in the last 350's. At least that's what this Wallace info says. The biggest cam used that year was an 066, in the GTO. All others were smaller.

http://wallaceracing.com/head1.htm

But, a guy posted that he had a '74 that had both chamfers.

The 6x-4 heads had 2.11 intake valves. So, did the '75-'77 350's have just 1 chamfer ? I have a '77, but haven't pulled the heads yet.

A Pontiac friend told me that what he did was to bolt the head to be used, to the bare block, then turn it over an look down into the cylinder, to see which valves might hit the block, and exactly where, then grind the chamfers there, if needed.

The pic below is of a block with only 1 chamfer. But, I don't know what year or casting number.
Attached Thumbnails
Click image for larger version

Name:	1 Chamfer .jpg
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ID:	493720  


Last edited by ponyakr; 09-27-2018 at 02:59 AM.
  #76  
Old 09-27-2018, 03:33 AM
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OK, here's some more pics I have listed as 350 blocks.

(1) Only 1 chamfer. Appears to be for the intake valve.

(2) I have this listed as a '70 block. But it don't have all 5 motor mount bolt holes drilled. Does anybody know which '70-'74 blocks didn't have all 5 holes drilled ?

(3) Lookin from the bottom of a cylinder, with a small valve head bolted on.

(4) With a big valve head bolted on. Don't know if the big valves would actually hit the block or not, if dropped. Anybody know ? Anyhow, it's easy to tell why the blocks had double chamfers for big valve heads.

Don't have a pic of a block with no chamfers. Anybody have one ?
Attached Thumbnails
Click image for larger version

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Name:	1970 Firebird pontiac 350 CI.jpg
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ID:	493724  


Last edited by ponyakr; 09-27-2018 at 03:39 AM.
  #77  
Old 09-27-2018, 04:03 AM
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Wow, here is a 500810 block, which would have had 6x-4 heads, with 2.11 intakes & 1.66 exhausts. But the chamfers are on the exhaust valve side of the cylinders. That blows my theory out of the water.

https://www.partrequest.com/auto-par...k-252260646166

And, to complicate matters even further. Here's a 350 said to also be a 500810, which has double chamfers. I realize that chamfers could have been added somewhere along the way.

https://www.partrequest.com/auto-par...0-253442524678

So, from what I've seen, I really can't say FOR SURE, which blocks had how many chamfers. I reckin everybody who plans a 350 build will just have to examine the block he plans to use, to see how many it has, and add or enlarge chamfers as needed.

More chamfer info:

http://psp.aquacomp.net/topic.asp?TOPIC_ID=1035

http://psp.aquacomp.net/topic.asp?TOPIC_ID=9903

http://transamcountry.com/community/...?topic=41573.0

http://www.pontiaczone.com/forum/arc...p?t-21173.html


Last edited by ponyakr; 09-27-2018 at 05:02 AM.
  #78  
Old 09-27-2018, 04:58 AM
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Quote:
Originally Posted by ponyakr View Post
OK, here's some more pics I have listed as 350 blocks.

(1) Only 1 chamfer. Appears to be for the intake valve.

(2) I have this listed as a '70 block. But it don't have all 5 motor mount bolt holes drilled. Does anybody know which '70-'74 blocks didn't have all 5 holes drilled ?

(3) Lookin from the bottom of a cylinder, with a small valve head bolted on.

(4) With a big valve head bolted on. Don't know if the big valves would actually hit the block or not, if dropped. Anybody know ? Anyhow, it's easy to tell why the blocks had double chamfers for big valve heads.

Don't have a pic of a block with no chamfers. Anybody have one ?
In response to #4: When I assembly checked my 72 350 with my #12's, the EXHAUST valve hit the block at approximately .510 lift. I didn't check with small valve heads, but I suspect a 1.66 valve might not hit at all.
Reference thread:
http://forums.maxperformanceinc.com/...d.php?t=770414


So... With that being said, I think small valve heads could support significant lift in a 350, or at least heads with no larger than 2.11/1.66 valves. But definitely check valve to bore clearance on a 350, as well as valve to piston clearance. And I would guess that smaller valves would have less shrouding/better flow?

I have a set of 7H1's and a set of 47's. I might put those on my 69 350 HO block and see how the valves fit with the bore. 7H1's are weird: 1.96/1.77. 47's are 1.96/1.66.

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Last edited by Squidward; 09-27-2018 at 05:06 AM.
  #79  
Old 09-27-2018, 05:06 AM
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Thanks for that info. Great pic !

What was the bore size ?

  #80  
Old 09-27-2018, 05:13 AM
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Thanks for that info. Great pic !

What was the bore size ?
40 over, so 3.915.

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