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I'm replacing the "067" cam in my 67 400 with the "068" factory spec cam. My car is a TH400 auto with A/C, power steering and power disc brakes. Will the "068" cam produce enough manifold vacuum to run all this stuff?
 

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Am also looking for 068 cam, so exactly what cam (brand and #) is that now. A search on Summit doesnt even show a cam for 69 and a thread with a cross reference table to several brands all show more lift than the original 068. thanks
 

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The Melling SPC-7 is probably the cheapest 068 cam. The cheapest price for one is usually on Ebay. But, Summit has a "beat-a-price" deal.

Some Ebay sellers don't charge tax. Summit now does charge me tax. Makes about 10% difference.

https://www.ebay.com/itm/Melling-SPC7-Hydraulic-Camshaft/264440053770?epid=230515130&hash=item3d91db000a:g:m2sAAOSwg0BZzIW5

I get a 10% vet discount at AZ & O'Reilly. It's enuff to pay the tax. Don't know if it'll work on ship-to-home orders or not.

https://www.autozone.com/internal-engine/camshaft/melling-camshaft-spc-7/107135_705947_0

https://www.oreillyauto.com/detail/b/melling-4252/engine-parts---mounts-16774/camshafts-16806/camshaft-12073/bf5c45108abb/melling-camshaft/spc7/4441260

The Summit 2801 is a sort of higher lift version of the 068. It's cheaper but will probably require new springs. But, if you're gonna buy new springs anyhow, the Summit cam will save a few bucks, and provide slightly more power.

https://www.summitracing.com/parts/sum-2801

https://www.ebay.com/itm/Pontiac-V8-stock-valve-springs-400-455-389-350-428-GTO-Firebird/283643140543?epid=672937061&hash=item420a72d9bf:g:LYAAAOSwmrlU0mJ9
 

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Ok, thanks all, am Oregon so sales is only tax we dont have. Yes, am changing heads so will have new springs, etc. Dont know why I couldnt pull up anything on Summit, as I have read previous posts by you guys and you were getting Pontiac cams there. Will call them if all else fails. Appreciate the info, mav
 

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"...Dont know why I couldnt pull up anything on Summit, as I have read previous posts by you guys and you were getting Pontiac cams there..."


https://www.summitracing.com/parts/mel-spc-7

If you know the brand & part number, you can just enter it in the "search" box. "068" is not an actual part number. It's just the last 3 digits of the part number GM used. So 068 has always been used, by Pontiac guys, to ID it. Same with the 744 & 041 cams. The Melling numbers for these cams are SPC-3 & SPC-8.

http://ronspontiacpage.com/reference-pages/stockcamspecs.htm

If you just wanna see what Pontiac cams Summit has listed on their site, you can enter "camshafts", in the "Search" block, then click on "hydraulic flat tappet", then enter the car brand & engine. I always enter Pontiac 455.

https://www.summitracing.com/search/part-type/camshafts/make/pontiac/engine-size/7-5l-455/engine-family/pontiac-v8/cam-style/hydraulic-flat-tappet?N=cam-style:hydraulic-flat-tappet&SortBy=Default&SortOrder=Ascending

You can either scroll down the entire list, or you can click on certain cam specs you like, and different brands, from the left hand column, under the words "Narrow Your Results".

I have noticed that not every Pontiac cam made is on this list. Sometimes, if you know the brand & part number of an unlisted cam, it will pop up & say they can order it for you & many times have it shipped directly from the factory or cam warehouse.

Many brands, other than Summit brand, can be found for cheaper prices than Summit lists. But, as mentioned, sometimes you can get the same or a slightly better price from Summit, thru their Beat-a-Price deal. You can click on those words at the top of their page & see the details.

https://help.summitracing.com/app/answers/detail/a_id/558?

Obviously, to get that deal, you need to find a cheaper price somewhere else. I usually find cheaper shipped prices on SOME stuff, on Amazon & Ebay. But, sometimes AZ, O'reilly, Advance Auto, or Rock Auto will be cheaper. You can usually get a 25% online discount for Advance. You can even buy & pay online, & pick up stuff they already have in stock. Earlier this year, I bought 3 batteries at one time & saved quite a bit this way. Was by far the cheapest price I found for batts.

To get the 25% off code, I usually Google "25% advance auto coupon".

https://www.offers.com/advance-autoparts/?path=zof-566254-gls-100a1a&adposition=1t1&creative=336724612455&device=c&network=g&source=s&gclid=CjwKCAjwxaXtBRBbEiwAPqPxcDmmcvQONPBnHm9qG7y2XaMDpHEQtN8_zI8BwGOIrjTtL2keAfkx8BoC8ggQAvD_BwE&em=6826476

This will not work on all special order items, but WILL work on most stuff they have in stock, that are not already under some special sale price.
 

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Hey thanks, yeah I tried putting in part # and brand and found it , but when I put in camshaft then entered the car (under recent vehicles) it wouldnt show anything. Found the Melling spc7 cam though, also checked amazon, etc. , everybody seems right at $120 on it, (lowest I found). thanks again for info, mav
 

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I may not need any cam, am I the only one who wasnt aware of the Dealer Service Information Bulletin dated Feb. 3 1967? Its in Zazzarine/Roberts GTO restoration guide (pg. 384). What started this is a compression check I did a few days ago and 7 cylinders were 162-173, but #2 was 149 so thought I had a problem. (car is 69 judge Ram Air 3). I looked at the Motors Manual and they show 195 pressure. I called previous owner and he said it never had that much even when it was new. Hard to remember almost 50 yrs. ago but he was pretty sure it was about 170. I wont quote the bulletin unless you dont have the book and are interested. Curious what you guys have for comp. pressure on similar engine. later mav
 

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There is only one way I know of to get an aprox CR on a Pontiac engine.

And to do that, you must have all the necessary info to plug into the calculator.

You need:

(1) Bore size

(2) Crank stroke

(3) Actual measured combustion chamber size(not estimated or from a chart somewhere).

(4) cc volume of the piston valve reliefs

(5) Head gasket bore size

(6) Head gasket crushed thickness

(7) Deck height(distance of piston top from block deck, when at TDC)

Compression Ratio Calculator - Wallace Racing

Then you can reduce the CR slightly, because the head gasket bores are not perfectly round, & there's a small distance from the piston top, to the top piston ring. Don't if either of these items are included in the calculator.

The calculator is only as accurate as the info you enter.

PS: I just reread your post. Looks like you were asking about cyl pressure, NOT compression ratio. But, somebody else may need the info. So, I'll leave it posted.
 

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Yes, I was talking about cylinder pressure, see what you mean about calculating the comp. ratio, not only need heads off, but looks like somebody that knows what they are doing needs to do the measuring. All I know for sure is heads were milled .030 and it pings at 1000 ft. elevation or less. I was worried about #2 cylinder because of lower pressure than the rest, till I happened across that bulletin, now not so much. Had already committed to "new" set of heads, but wont hurt to have an extra set, just in case....anyway thanks for all the info, later mav
 

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Yes, I was talking about cylinder pressure, see what you mean about calculating the comp. ratio, not only need heads off, but looks like somebody that knows what they are doing needs to do the measuring. All I know for sure is heads were milled .030 and it pings at 1000 ft. elevation or less. I was worried about [URL=https://www.gtoforum.com/usertag.php?do=list&action=hash&hash=2]#2 [/URL] cylinder because of lower pressure than the rest, till I happened across that bulletin, now not so much. Had already committed to "new" set of heads, but wont hurt to have an extra set, just in case....anyway thanks for all the info, later mav
Generally the cylinders should all be within 10% of each other. The fact that cylinder #2 is low indicates a potential issue - rings, valve, cam lobe or just a bit of carbon. If the car runs fine and does blow smoke or burn a ton of oil, I wouldn't worry about it unless you are OCD. For what it is worth, my "low compression" motor read ~ 150 psi (when cold) if I remember correctly - whatever it was, it wasn't the 190-210 psi that I read about, so it confirmed (to me) that it was in fact a low compression motor out of a 68' Catalina (which for the record runs quite well given the age and unknown mileage).
 

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My '65 with a 389, close to 11:1 CR, with a cam that bleeds off a lot of CR at idle is at 172-175 in every cylinder. Engine overhauled in 1981,, Compression checked last year. 50k miles. My '67 with lower compression than stock (9.3:1) and an 068 cam has 170-175 in every cylinder. My buddies stock '67 GTO with 067 cam and 670 heads had 205-210 compression in every cylinder. The consensus is with a Pontiac, the max. cyl pressure for pump gas is about 150-170 psi. With current fuels, I've found this to be the case. My small block Chevy I have in a '61 Corvette runs a stroker crank, 64cc heads, and slightly dished pistons. It has a cranking compression of 200 psi in every hole. 383 CID. It runs on 91 octane without pinging....something impossible for a Pontiac.
 
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