Author Topic: Pontiac 350 Block ONLY Thread  (Read 8551 times)

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #120 on: February 17, 2019, 01:54:20 PM »
"...small valve #16's. Should do very nicely..."


Yeah, those should work.

But they'll need lots of work. Will require screw-in studs. Most tap the holes for 1/2" threads & use the ARP 290-7201 studs, made for that purpose. These studs have a 7/16" top & a 1/2" bottom. Most who have done this say that the bottom threaded portion is too long, so that a small amount must be cut off, to keep it from bottoming out before tightening up.

Today, they're $84 at Jegs & Summit, with a $99 + order. 

https://www.summitracing.com/parts/arp-290-7201?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-arp&gclid=CjwKCAiAwJTjBRBhEiwA56V7q7XC9nZijOzDRGVZwGVPIJt1NN1VZ7xRnEShzYF7WjgdoK3Nmo4ImxoCyjgQAvD_BwE

https://www.jegs.com/webapp/wcs/stores/servlet/SearchResultsPageCmd?Ntt=arp+290-7201&requestYear=&storeId=10001&catalogId=10002&langId=-1&year=&make=&model=&submodel=&engine=&Nrpp=&No=&persistYmm=false

Some recommend installing 7/16" heli-coil inserts, so that BBC studs can be used. These studs are much cheaper, from many sources. But, the machining cost will be more. So, I assume the cost will be similar. I'm assuming between $200 & $250 total, either way. 

Then you'll need one piece stainless valves. Most recommend Ferrea 5000 series. Most usually opt for bigger valves, at least for the intakes. But, there have been some nice running 350's using smaller valves. Also, if you plan on a cam with near .500 lift or more, you probably need to go with longer valves. This allows for a taller valve springs, which can handle the higher lift cams. Probably need at least a 1.7" installed height spring. I think most Pontiac D-port heads came with only about 1.6" installed height.

https://butlerperformance.com/c-1400522-camshaft-valvetrain-components-valves-ferrea-racing-ferrea-5000-series-hi-performance-valves.html

Will need to know the actual size of the chambers, since most say that the actual size is, many times, more than advertised. So, you might need to have some shaved off, to get to the CR you want.

Many say that if you plan on much hard run time that you go with hardened valve seats, at least on the exhausts, for use with unleaded gas.

Will also need positive valve stem seals & the whole performance valve job, done by someone who knows Pontiac heads & has had experience with these operations I've mentioned.
This is good to know. Hardened seats and screw-in studs are definitely happening. Also the machinist I have in mind is very well-versed with Pontiacs, so no worries there. Only thing left that I'm concerned about is what the cc's will come out to be. I have heard that some 16's come out at 78-80cc, and on the wallaceracing cylinder head chart, these exact heads are listed as 78cc. However, most of the advertised cc's are off anyways, hell even some of the heads that are listed as screw-in studs are actually press-in, so I just have to hope it measures closer to 72. I would not want to have to get the heads milled, because then I will have to deck the block as well. If I had to, I would get it done, just want to avoid it. I understand there are potential clearance issues to watch out for in such a process. I don't want to resort to milling the intake either. Fingers will remain crossed.

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #121 on: February 17, 2019, 07:20:38 PM »
https://www.youtube.com/watch?v=cA8-NQEUnv0&t=1s

Found this while searching 350 builds. 400 horsepower? I'd like to know more!

oldskool

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Re: Pontiac 350 Block ONLY Thread
« Reply #122 on: February 17, 2019, 11:06:02 PM »
"...I would not want to have to get the heads milled, because then I will have to deck the block as well..."

Milling the heads does not mean you have to "deck the block".

"... don't want to resort to milling the intake either. Fingers will remain crossed..."

The correct procedure is to mill the same amount off the intake surface of the head, that is milled off the chamber surface of the head. That way, the intake bolt holes should line up, without milling any off the intake manifold, itself.

The reasons for milling the block decks is to (1) square 'em up with the crank centerline, (2) to reduce the piston top to deck(deck height) distance, or (3) to produce a finish smooth enuff for Cometic head gaskets.



EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #123 on: February 18, 2019, 10:12:02 AM »
"...I would not want to have to get the heads milled, because then I will have to deck the block as well..."

Milling the heads does not mean you have to "deck the block".

"... don't want to resort to milling the intake either. Fingers will remain crossed..."

The correct procedure is to mill the same amount off the intake surface of the head, that is milled off the chamber surface of the head. That way, the intake bolt holes should line up, without milling any off the intake manifold, itself.

The reasons for milling the block decks is to (1) square 'em up with the crank centerline, (2) to reduce the piston top to deck(deck height) distance, or (3) to produce a finish smooth enuff for Cometic head gaskets.
Ah, I get it now. Don't know why I thought you had to deck the block when milling heads, obviously I was on crack.

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #124 on: February 20, 2019, 03:49:39 PM »
Some news on the camshaft front, only 3 companies ever got back to me, and they were Butler, Crane, and Lunati. I already shared the patterns that Butler suggested, however Crane sent me a cam card.



Lunati was a mixed bag from a service standpoint. I filled out a whole spec sheet from their website about my car, the motor, and the trans (was like 5 pages worth), and then initially they emailed me back suggesting I call so they could get more details on my planned combo, however the guy who answered had literally no clue what I was referring to. So all that time filling out their sheet was a waste anyway, and he only asked for 10% of the details I went through the trouble of providing anyway. Then after all that, they link me to a cam they already have a pattern for and which I think was linked here already by oldskool, (just checked, it's the 262/270 HR one). However I feel like I'm finally getting the gist of understanding which cams would be good and which ones are too big for a poncho 350, which was a big part of why I wanted so many recommendations. So it's not a total waste, but was a little frustrating.

I do have good news from my local machine shop though, I was able to get a quote for the heads which came out to $600 for converting the studs, magnaflux and clean, milling (assuming it's even necessary), valve seats, valve job, and I'm assuming painting is covered but I have to call him back tomorrow anyways so I'll check then. Even if I go a little over that, to me that doesn't seem bad at all compared to brand new bare KRE or Edelbrock heads. I would be buying new hardware and a cam for either so I don't mind still having to shell out for that. Hope to have more good news soon. The fire for this bang for buck build is slowly growing!

Re: Pontiac 350 Block ONLY Thread
« Reply #124 on: February 20, 2019, 03:49:39 PM »

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #125 on: March 02, 2019, 09:33:29 PM »

I reckin the main downsides of the small 350 bore are:

(1) With larger valves, chamfers are needed for valve to block clearance, if a decent size cam is to be used.

(2) There are no reasonably priced 350 head gaskets made now. The high price Cometics are the only ones I know of. So, most use the regular 400-455 gaskets. These big bore gaskets reduce compression, when used on a 350.

Coming back to this now as I finish gathering parts... just how much compression will I lose with the regular 400-455 gaskets? It's looking like I'm not gonna be able to pull the motor anytime soon, and paying a shop to do so is out of the question for me. That would blow the whole budget in one swoop. So the cometic gaskets are sadly out of the question.

Btw I cc'd the heads with a kit I bought from Jegs, they came out to 75cc.

oldskool

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Re: Pontiac 350 Block ONLY Thread
« Reply #126 on: March 03, 2019, 10:23:16 AM »
"...just how much compression will I lose with the regular 400-455 gaskets?..."

You can figure it fairly close by using the Wallace CR calculator.

http://www.wallaceracing.com/cr_test2.php

I just compared a Fel Pro 8518PT, which is .045 x 4.3, to a Cometic .036 x 3.95, & got a .33 CR increase. So if you are 9:1 with the Fel Pro gaskets, you'll be 9.33:1 CR with the Cometics. The Fel Pro 1016 gaskets are only .039 thick, but cost a lot more than the 8518PT gaskets.

Some guys increase CR by running the pistons .005 above the deck. It's quite common in some racing classes which require flat top pistons & a specific head.





EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #127 on: April 15, 2019, 12:58:04 PM »
Does anyone know the deck height of an unmodified 350?

oldskool

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Re: Pontiac 350 Block ONLY Thread
« Reply #128 on: April 15, 2019, 02:32:11 PM »
Does anyone know the deck height of an unmodified 350?

From what I've read, most Pontiac engine specs can vary, from what was published. So, the ONLY way to know FOR SURE is to actually measure it.

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #129 on: April 15, 2019, 11:59:57 PM »
Does anyone know the deck height of an unmodified 350?

From what I've read, most Pontiac engine specs can vary, from what was published. So, the ONLY way to know FOR SURE is to actually measure it.
Good ol' Pontiac always keeping us guessing.

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #130 on: April 19, 2019, 10:41:13 AM »
"...just how much compression will I lose with the regular 400-455 gaskets?..."

You can figure it fairly close by using the Wallace CR calculator.

http://www.wallaceracing.com/cr_test2.php

I just compared a Fel Pro 8518PT, which is .045 x 4.3, to a Cometic .036 x 3.95, & got a .33 CR increase. So if you are 9:1 with the Fel Pro gaskets, you'll be 9.33:1 CR with the Cometics. The Fel Pro 1016 gaskets are only .039 thick, but cost a lot more than the 8518PT gaskets.

Some guys increase CR by running the pistons .005 above the deck. It's quite common in some racing classes which require flat top pistons & a specific head.
So here's a crazy idea... how about a custom set of copper headgaskets? I found a few speed shops who can make them to any spec you need, Pontiac 350 bore included. Big downside is the price, was quoted at $250 per set but was also told they'd offer discounts for multiple orders (ie if we started a "group buy"). I don't know much about these things, and when I search online I only find results for "hardcore" racing, as in single digit e.t.'s, boosted, or in excess of 11:1 compression ratios. Saw some complaints about leaking, but then, people say the same things about MLS gaskets as well. Wouldn't surprise me if the recommended install procedures weren't followed correctly. The surface finish requirements are also not as strict as with MLS gaskets. Then again, not a single one of these was a daily driver, which really makes me think: practical, or no? What do you think, TAC?

mz-formula

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Re: Pontiac 350 Block ONLY Thread
« Reply #131 on: April 19, 2019, 11:14:06 AM »
Buttler offers a custom cometic head gasket.
 https://butlerperformance.com/i-24626126-cometic-custom-mls-head-gaskets-choose-bore-type-bore-thickness-set-2-com-head-gasket.html?ref=category:1234803.

I am pretty much sold on the idea of a buttler stroker kit for my 350 at this point.  Gasket wise, in my mind, I am spending x number of thousands on an engine... Why get cheap on the gaskets.  Yes it costs a bit more to have them correctly sized for a 350, but if your going to do the job right, don't cut corners.  Especially in the engine.

oldskool

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Re: Pontiac 350 Block ONLY Thread
« Reply #132 on: April 19, 2019, 02:04:20 PM »
"...how about a custom set of copper headgaskets?..."


Copper head gaskets usually require wire O-rings, with proper grooves machined in. The Cometic gaskets, with the proper smooth surface finish, is probably the best way to go, tho not the cheapest.

"...WHAT SURFACE FINISH IS REQUIRED TO US AN MLS HEAD GASKET?
A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design..."

https://www.cometic.com/faq.html#q31023


When you order Cometic gaskets, you'll have to tell them if your block will have valve clearance chamfers(notches) at the top of the cylinders. Otherwise, they'll come with perfectly round holes, which are not good, if you have cyl chamfers.

http://www.spottsperformance.com/cometic%20head%20gaskets

Lots of places to buy. Jegs & Summit are probably 2 of the cheapest. Probably not many, if any, vendors who stock 350 Pontiac gaskets. They'll likely have to be special ordered, no matter where you buy. But, I could be wrong.

Summit shows that they have some .027 thick gaskets they can ship today. These would be good if you had a .010-.015 deck height. Would give you a .037 to .042 quench distance. Don't know if they're really in stock, nor if they are for the chamfered cylinders or not. Can't see why anybody would stock 350 gaskets without provision for the chamfers, since so many Pontiac 350 blocks had 'em, from the factory. All the other Pontiac head gaskets I've ever bought had provision for the chamfers. Never bought one with perfectly round holes. I used the cheap Fel Pro 8518PT gaskets on most all my 400 & 455 engines. Even tho the bore size is 4.3", the bores of those are not a perfect circle. You can easily see that by putting your cursor on the image on this amazon listing, to get a close-up view.

https://www.amazon.com/Fel-Pro-8518-Cylinder-Head-Gasket/dp/B000C2AF3I

https://www.summitracing.com/search/part-type/head-gaskets/make/pontiac/engine-size/5-7l-350/engine-family/pontiac-v8?N=4294924325&keyword=Cometic%20Head%20Gaskets

https://www.jegs.com/webapp/wcs/stores/servlet/SearchResultsPageCmd?Ntt=cometic+cylinder+head+gasket+pontiac+350&requestYear=&storeId=10001&catalogId=10002&langId=-1&year=&make=&model=&submodel=&engine=&Nrpp=&No=&persistYmm=false

With more cubes, the thin, small bore gaskets would not be as big a deal. Could still get decent CR, depending of course on the head chamber size.

http://www.wallaceracing.com/cr_test2.php

Here's just one example: 3.910 bore, 4.25" stroke, 87cc chambers, 4cc valve reliefs, .039 x 4.3 gaskets, .000 deck height. CR = 9.34. That ain't bad for a pump gas street engine nowadays.

Or, you can run the 4" stroker crank, and 80cc heads & get about 9.44 CR.

Some 350 blocks will safely bore .060 or even a little more. But, some won't even go .060. Shop has to sonic check the cyl walls for thickness. Core shift & corrosion can reduce wall thickness of some cylinders.

« Last Edit: April 19, 2019, 03:19:33 PM by oldskool »

Garry

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Re: Pontiac 350 Block ONLY Thread
« Reply #133 on: April 20, 2019, 02:18:14 AM »
Years back I had an o-ringed 428 and after paying stupid money for copper they ended up hanging on the wall. What a pain. That was back when Butler first came out with those cometics and once I put those on I never had to pull the heads again. It was a 13.5 to 1 motor on spray.

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #134 on: April 20, 2019, 09:41:56 AM »
My beef with the MLS gaskets is I'd have to pull the motor to get the surface finish that's required for proper sealant. Makes them not an option for me right now.

Re: Pontiac 350 Block ONLY Thread
« Reply #134 on: April 20, 2019, 09:41:56 AM »



EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #135 on: April 21, 2019, 10:42:50 AM »
Here's another idea, could be dumb but here it is anyway: would it be fine to use the fel-pro's with the 4" or so bore and o-ring those or fill in the space somehow?

oldskool

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Re: Pontiac 350 Block ONLY Thread
« Reply #136 on: April 21, 2019, 07:28:10 PM »
Here's another idea, could be dumb but here it is anyway: would it be fine to use the fel-pro's with the 4" or so bore and o-ring those or fill in the space somehow?

Bad idea.

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #137 on: May 08, 2019, 02:19:14 PM »
I have a better possible solution to the head gasket problem for others like me who don't want to go through getting their surfaces decked. Fel Pro makes gasket sheets which you can cut & drill as needed or give to a machine shop to match the bore size etc that 350's need. The catch is it's only available in 3/64" which is .0468, kinda on the thick side but I think that'd be less of a disadvantage vs having the incorrect bore. The material is called Pro-Ramic 121, and the manufacturer part # is 2498.

Here is a link to their master catalog, you can find it on page 1274: https://www.fme-cat.com/digipubZ/Fel-Pro-Master-Gasket-Catalog-900-16/mobile/index.html?doc=9182325A26BBDDD1628348722A5085AE&page=1299
« Last Edit: May 08, 2019, 03:53:26 PM by EspriTA350 »

oldskool

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Re: Pontiac 350 Block ONLY Thread
« Reply #138 on: May 09, 2019, 02:49:21 PM »
IMO, even if that would work, it's WAY too much trouble.

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #139 on: May 13, 2019, 02:19:11 PM »
IMO, even if that would work, it's WAY too much trouble.
Why don't you think it would work?

oldskool

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Re: Pontiac 350 Block ONLY Thread
« Reply #140 on: May 13, 2019, 04:16:59 PM »
IMO, even if that would work, it's WAY too much trouble.
Why don't you think it would work?

I reckin I don't understand. Are you saying that there is a blank piece of head gasket material which you can cut all the correct holes in, to make your own head gasket, that will actually seal a Pontiac head to a 350 Pontiac block ?

I never heard of such a thing. If any Pontiac guys have done this, I'm not aware of it.

Even if it would work, can you imagine how much work it would be to cut all the correct holes in 2 gaskets ?

EspriTA350

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Re: Pontiac 350 Block ONLY Thread
« Reply #141 on: May 13, 2019, 05:16:58 PM »

I reckin I don't understand. Are you saying that there is a blank piece of head gasket material which you can cut all the correct holes in, to make your own head gasket, that will actually seal a Pontiac head to a 350 Pontiac block ?

I never heard of such a thing. If any Pontiac guys have done this, I'm not aware of it.

Even if it would work, can you imagine how much work it would be to cut all the correct holes in 2 gaskets ?
It's uncharted waters for me too. It has been done with other makes but I've yet to stumble upon it on any Pontiac forums. I suppose the reason you don't hear of it too much is most other engines have the correct size gaskets or guys just swallow the MLS pill and deck their blocks. Copper sounds to be less than ideal for a daily, and those would have to be custom too which means $$$. MLS and 4" bore fel-pro, well, we've covered those already. The custom fel-pro seems to be the best option for someone in my shoes.

Re: Pontiac 350 Block ONLY Thread
« Reply #141 on: May 13, 2019, 05:16:58 PM »
You can help support TAC!