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Topic Review (Newest First)
12-29-2011 03:44 PM
72chevyBuild I like the 260H, i had one on my 283 SB with 305 HO heads and a holley intake and that motor ran strong. But i am running camel hump heads and a stock intake, i just want a good cam to run with that.
12-29-2011 02:34 PM
BigEd36 The 260H, with shorter duration, will have better torque and responsiveness at take-off and low speed driving with a stock torque converter and hiway gearing. Comp Cams shows an RPM operating range of 1200-5200 rpm for the 260H and 1500-5500 rpm for the 268H, so the 260H brings on the bottom end at a lower rpm, basically right off of a fast idle speed.
12-28-2011 09:55 PM
72chevyBuild Why? Cause of the duration difference?
12-28-2011 09:53 PM
cobalt327
Quote:
Originally Posted by 72chevyBuild
Since my compression will be close to 10:1 do I need to change my converter?
You are quite a bit short of 10:1. In any event, I'd use the 260H over the 268H.
12-28-2011 06:01 PM
72chevyBuild thanks for the info i feel better with using the 268H cam without changing my converter.
12-28-2011 05:57 PM
BigEd36
Quote:
Originally Posted by 72chevyBuild
Since my compression will be close to 10:1 do I need to change my converter?
With the 268H your dynamic CR will drop slightly to 7.78. Comp Cams literature shows the 270H as "Biggest cam with stock converter but better with 2000+ stall" so both the 260H and 268H are mild enough to work well with a stock converter, but both would show increased performance with a slightly higher than stock converter. On Comp Cams free simulator software, CamQuest.com, the recommended TC for the 260H in a 327 is 1500-2500 rpm. The recommended TC for the 268H in a 327 is 2000-3000 rpm.
12-28-2011 11:02 AM
72chevyBuild Since my compression will be close to 10:1 do I need to change my converter?
12-28-2011 08:34 AM
72chevyBuild No I am not going to do any more bore to it. But the casting numbers on the block are infact a 307 from 1969. But I am still deciding to use the 260H cam or the 268H cam still undecided.
12-27-2011 11:26 PM
BigEd36
Quote:
Originally Posted by 68NovaSS
The do share the same bore, but not the same stroke. The 283 stroke is 3.00", the 307 is 3.25".

I'll give you a start in your search, the 740P piston was manufactured by Ohio Piston & Pin, now out of business, and sold under the brand names Nytel and Ertel. They were once associated with Dynagear, but not sure in what capacity.

Maybe some here from back in the day can shed more light.
According to the Badger Pistons website:

Quote:
History:

July 2008 Badger Pistons, LLC relocated its operation and warehouse to Bedford Park, Illinois.

May 2006 - Badger Pistons, LLC relocated its manufacturing operation and main warehouse from New Albany, Mississippi to Marinette, Wisconsin.

February 2003 - Badger Pistons, LLC was formed with the acquisition of the piston manufacturing plant and the remaining piston inventory of Dynagear Corporation.

1998 - Dynagear Corporation acquired Ertel Manufacturing Company. Shortly thereafter, all piston production was consolidated at the New Albany, Mississippi location.
I have to wonder whether 72chevy's engine is in fact an original 327 or a 307 overbored .125". Can a 307 be safely bored .125"? No matter, if it's using a 740P piston it must be a 327. If it is in fact an original 307 with a .125" overbore I would be very leary of doing any further overbore for this build.

Cobalt327 made a good suggestion to run the compression ratio figures. I ran the compression ratio using 4" bore, 3.25" stroke, 5.7" rod, standard .025" deck height, a .015" thick by 4.1" bore head gasket (Fel Pro #1094), 7cc for piston dish (flat top with 4 valve reliefs), and 64cc heads (the double hump heads). I got a static compression ratio of 9.43. Using the specs for a Comp Cams 260H I got a dynamic CR of 7.99 so your build is well within range for pump gas use.

Ed
12-27-2011 05:30 PM
72chevyBuild the cam i have is like a 204 to 208 duration not a 210 or 212.
12-27-2011 08:12 AM
72chevyBuild Yeah I think my cr would be around 9.5 or 9.75 to 1 but I also have a 260h cam I am thinking about using? What do you think?
12-26-2011 10:42 PM
cobalt327 Makes sense- the 740P is a 327 SBC slug. So your 307 is now a 327.

Nothing wrong w/that cam duration and cylinder head- keep the quench tight, the CR might be a bit low, but w/a short cam that's OK. Might want to run the dynamic CR numbers just to be sure you're in pump gas territory.

Long tube 1-5/8" headers, a dual plane intake and a Q-jet would make a pretty sweet street engine.
12-26-2011 03:59 PM
72chevyBuild Just found out my 307 is bored to a standard size 327. Planning on running camel hump heads and a small mild cam around a 210 or 212 duration. Anyone got some opinions on that? I would like more help on my build
12-21-2011 09:57 PM
72chevyBuild Yeah the 307 has the stroke of a 327 but the bore of a 283. But I'm just wondering what size it is, I am thinking probably .060 over. Thanks for the info
12-21-2011 09:25 PM
68NovaSS The do share the same bore, but not the same stroke. The 283 stroke is 3.00", the 307 is 3.25".

I'll give you a start in your search, the 740P piston was manufactured by Ohio Piston & Pin, now out of business, and sold under the brand names Nytel and Ertel. They were once associated with Dynagear, but not sure in what capacity.

Maybe some here from back in the day can shed more light.
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