although the roller set up will cost you, you'll save money on oil changes over the life of the engine.
Need cam advice
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 801
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From: Middletown Delaware
Need cam advice
73 vette automatic trans with 291 heads installed. cam is shot. Not sure what cam is installed only numbers on the back of cam are 1261 with K1,C5, and D5 stamped between journals. I think its a stock cam. Any suggestions for a cam replacement.
Safety Car
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From: Bridgewater nj
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 801
Likes: 17
From: Middletown Delaware
It was my understanding that to use a roller cam the valve spring pressures need to be higher than stock. I have no idea what my spring pressures are. Did compression test before I tore engine apart and all cylinders were around 185 psi. Not sure what the ratio is. Do not know stall speed. I will have to check rear ratio.
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
Your TH400 has a 2000 stall convertor. 90% sure you have a 3.08 gear. With your increased compession this cam is a good fit. You will need springs, pushrods and cam button. Any cam upgrade will require new springs. http://www.summitracing.com/parts/lu...make/chevrolet
Last edited by 63mako; Sep 30, 2014 at 05:34 PM.
Race Director
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From: Millington Illinois
St. Jude Donor '08-'09
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Le Mans Master
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From: Las Vegas - Just stop perpetuating myths please.
Not sure what cam is installed only numbers on the back of cam are 1261 with K1,C5, and D5 stamped between journals.
That doesnt match up to a GM cam as GM or a square or a diamond cast into the cam near last journal and part number is stamped on other side of that last journal. Your compression press will change with a new cam even though 185psi is a great press for street engine.
With 291 (1967-1969) heads installed have to assume those same stock vlv springs are installed. U should be able to just throw in a L82 cam for the 350 hp rating and not have to change springs - though its always good to test/check the vlv springs. L82 cam is GM part number 3896962 but make sure u install new lifters with it.
Try: http://www.northernautoparts.com/part/cs-cs1095r
or:http://www.autozone.com/autozone/par...er=179422_0_0_
or: http://www.oreillyauto.com/site/c/de...eyword=3896962
The old double hump head and L82 (L46) cam swap is as old as it gets for 350 ponies in a small block Chevy. Both Melling and Sealed Power still make the L82 cam but the sealed power is nearly twice as much. IMHO the L82 may make a little less power/torque than the Howards cam but the long lobe ramps are better matched for the higher compression with iron heads and the wider lobe sep angle make it a better diver. But that Howards cam is still a nice cam no doubt.
Hope this helps and good luck with whatever u choose.
That doesnt match up to a GM cam as GM or a square or a diamond cast into the cam near last journal and part number is stamped on other side of that last journal. Your compression press will change with a new cam even though 185psi is a great press for street engine.
With 291 (1967-1969) heads installed have to assume those same stock vlv springs are installed. U should be able to just throw in a L82 cam for the 350 hp rating and not have to change springs - though its always good to test/check the vlv springs. L82 cam is GM part number 3896962 but make sure u install new lifters with it.
Try: http://www.northernautoparts.com/part/cs-cs1095r
or:http://www.autozone.com/autozone/par...er=179422_0_0_
or: http://www.oreillyauto.com/site/c/de...eyword=3896962
The old double hump head and L82 (L46) cam swap is as old as it gets for 350 ponies in a small block Chevy. Both Melling and Sealed Power still make the L82 cam but the sealed power is nearly twice as much. IMHO the L82 may make a little less power/torque than the Howards cam but the long lobe ramps are better matched for the higher compression with iron heads and the wider lobe sep angle make it a better diver. But that Howards cam is still a nice cam no doubt.
Hope this helps and good luck with whatever u choose.
Race Director
Joined: May 2005
Posts: 10,674
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From: Millington Illinois
St. Jude Donor '08-'09
The 11 to 1 compression L46 shared the same cam with the 9 to 1 compression L82. L46 makes 350 HP. L82 makes 313. This cam is designed for high compression, iron heads and has a real late intake closing point and wide duration, perfect for a 10-11 to 1 compression iron head motor with a manual or lower gear differential. It also has a duration @ .050 of 222.
http://www.superchevy.com/how-to/eng...ng/holley.html
Your compression is under 9.5 to 1. A modern grind with a lower duration will retain better cylinder pressures, will be noticeably stronger at low and midrange RPM, make more power and torque across the entire operating range, make more peak power and is a much better match for your auto, 3.08 gearing. Don't trust 40 year old springs when changing cams, not worth the chance for $60 and a little work. I have used the Z28 springs and retainers set up @ 1.685 (extra .015 shim) with similar ramp rate and lift cams and run them past 6000 RPM regularly with no issues.
https://sdparts.com/details/scoggin-...-center/sd1004
https://sdparts.com/details/scoggin-...s-center/sd364
Pocket port and good 3 angle valve job will help your heads big time.
1.6 rockers would also be a plus. The stockers are not 1.5. Usually vary from 1.35-1.45+
http://www.superchevy.com/how-to/eng...ng/holley.html
Your compression is under 9.5 to 1. A modern grind with a lower duration will retain better cylinder pressures, will be noticeably stronger at low and midrange RPM, make more power and torque across the entire operating range, make more peak power and is a much better match for your auto, 3.08 gearing. Don't trust 40 year old springs when changing cams, not worth the chance for $60 and a little work. I have used the Z28 springs and retainers set up @ 1.685 (extra .015 shim) with similar ramp rate and lift cams and run them past 6000 RPM regularly with no issues.
https://sdparts.com/details/scoggin-...-center/sd1004
https://sdparts.com/details/scoggin-...s-center/sd364
Pocket port and good 3 angle valve job will help your heads big time.
1.6 rockers would also be a plus. The stockers are not 1.5. Usually vary from 1.35-1.45+
Last edited by 63mako; Oct 1, 2014 at 09:40 AM.
Le Mans Master
Joined: Oct 2002
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From: Las Vegas - Just stop perpetuating myths please.
4 degrees advance makes the most low/mid range torque and is the choice of most professional builds/racers like Lingenfelter & Vizard. That would be the intake centerline 4 degrees advanced of course and u need to use a degree wheel with a TDC tool/piston stop to verify this im sure u know.
As for the L82 cam i believe it will be more complimentary to your stock vlv springs with its longer/slow lobe ramps - unless u plan to change vlv springs also as my '74 shop manual says both L48 and L82 shared the same vlv spring (1974). And i think the melling cam was not only cheaper than the sealed power cam but had better specs by the tiniest factor.
Thx for the feedback and please let us know how it runs or a compression test result if u are interested yourself.
As for the L82 cam i believe it will be more complimentary to your stock vlv springs with its longer/slow lobe ramps - unless u plan to change vlv springs also as my '74 shop manual says both L48 and L82 shared the same vlv spring (1974). And i think the melling cam was not only cheaper than the sealed power cam but had better specs by the tiniest factor.
Thx for the feedback and please let us know how it runs or a compression test result if u are interested yourself.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Thx for the feed back Dave and your effort here to share some valuable info. It keeps us straight when we try to help ourselves and others. Glad to read u are happy with your performance combo of mostly stock parts.
That 'bout as good and economical as it gets here.
That 'bout as good and economical as it gets here.