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Which cam profile???

 
Inkfreak
I love my Chevy Chevette!
Posts: 9
Joined: 02/08
Posted: 02/26/08 08:55 PM

I am building a 1986 Astro V8 Conversion and welcome any opinions..I have a 350 cid 1 pc rear seal engine , flat top pistons , Summit 3.75 stroke crank , factory rods , Weiand Air-Strike intake , Holley 650 Dbl pumper , 64cc iron heads w/ 1.94's , True roller timing set , HEI dist.. My choices so far for cam profiles are : Advertised Duration 282/ 292, Lift .465/ .488  , Advertised Duration 292/ 302, Lift .488/ .510  , and  Advertised Duration 268/ 276, Lift .489/ .504  .. All claim to need little or no stall converter  ... Also any ideas as to @HP/TQ figures  .. Also have MSD 6 AL ignition box..All replies  welcomed....Thanks. P.S. This is going to be street driven , and no emmissions/ecm to deal with.. Is this an ext. or int. balanced engine?? 1988 350cid one piece seal..  

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Pontiacman2
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Posts: 891
Joined: 01/08
Posted: 02/27/08 07:52 AM

I would recomend one of these because of the size of the carb. you are using P#CCA-12-213-3 from compcams witch has a .501/.501 lift or a lunati streetmaster P#07102 it has a .507/.507 lift the lunati will most likely work the best with a 2200-6200RPM power band.The 1986&UP one piece rear seal are external balanced but use the same balancer as the internal balanced but the flex plate is different because it has a bob weight on it making it external balanced.For a hp/tq. figure I need to know what it is going to be bored to as well as witch cam you use the part number and if the heads are ported or not and a casting number off the heads.  
Pontiacman2
Pontiacman2

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prostock1
V-6 Camaros rule!
Posts: 27
Joined: 01/08
Posted: 02/27/08 09:05 AM

you state it has a 3.75 stroke crank,most likely it will have to have a 400 balancer.i would check with summit to make sure.  

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Inkfreak
I love my Chevy Chevette!
Posts: 9
Joined: 02/08
Posted: 02/27/08 10:23 AM

The engine is standard bore and the heads are 3947041 69-70 302/350 64cc with no mods other than roller tip 1.6 rockers . The rods are standard 5.7 rods .The pistons are +6 cc flat tops with 2 valve reliefs . I am pretty sure I'll go with the Summit split pattern  292/ 302, Lift .488/ .510  . Does that help with estimates any?? I also have a Holley Street Avenger 770cfm if I need to upsize.. A lot of reading has led me to believe that a split pattern would be better for these old heads.. I've heard that now that you can get better flowing heads affordably now that more single pattern cams are making a comeback..Any news on this?/Thanks  

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Inkfreak
I love my Chevy Chevette!
Posts: 9
Joined: 02/08
Posted: 03/05/08 11:50 AM

Any ideas ?? Anyone?  

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Pontiacman2
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Posted: 03/05/08 01:03 PM

With the .488/.510 cam headers and the rest of the parts you have you should have between 320 and 350 horse power and close to 400TQ but be sure to check the piston to valve clearance because the 1.6 ratio rockers will give you a .521/.544 gross lift witch I think is a little more cam then you'll need on the street and reqiures a 2800-3000 stall converter.I would recomend the .465/.488 s.r.e cam instead because it will most likely perform better with the stock heads giving you more bottom end power.  
Pontiacman2
Pontiacman2

Professional Hi-performance engine builder

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Inkfreak
I love my Chevy Chevette!
Posts: 9
Joined: 02/08
Posted: 03/06/08 07:52 AM

Thanks for the advice...Now that I've all but got this engine together I have had alot of parts almost literally fall into my lap..So now I'm considering a few changes..I've come across a GM #12370846 Roller camshaft and lifters with all accs. needed to install in my block. Also a set of stamped steel 1.5 roller tip rockers ,and a set of 191 centerbolt heads that have had a little port work done . And a GM dual plane high rise intake for the centerbolts.And a set of Keith Black Hypereutectic Flat tops w/ no valve reliefs. Basically everything from a buddy's engine that got scattered across the road on an over-rev..(lucky me) ...So I have my set-up or his newer style top end set-up. Eenie , meenie,miney , you know..Now it's back to the books , I guess..I hear the 191's are crap , but I'm not building a top-fuel dragster , just a weekend toy .. Can I tap into the motor minds again???  

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Pontiacman2
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Posted: 03/06/08 09:46 AM

I would use the flat tops with the valve reliefs junk the 191 swirl port heads they are carp and very low performance I would stick with the s.r.e .465/.488 cam because I have had the g.m. roller cams and they suck.Also would use the weiand intake instead also watch how high you get the compression ratio so you can still run pump gas.  
Pontiacman2
Pontiacman2

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Inkfreak
I love my Chevy Chevette!
Posts: 9
Joined: 02/08
Posted: 03/06/08 05:52 PM

Thanks for the info...191's are gonna get tossed and roller going on the trading post..What's up with the 3973487 heads ?? Are they better than my 041's for my set-up?? I know they are 75cc 1.94's but don't know the runner size...Also I am going with your cam advice and installing the summitracing .488/.465 282/292.  

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Pontiacman2
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Posted: 03/07/08 06:13 AM

The 487 was used on some LT-1 350 and was rated at 330 H.P. was availible with 1.94/1.50 and 2.02/1.60 valves and the 041 are a good H.P. head and was availible with the same valves sizes as the 487. With the flat top pistons and the 64cc heads 041's you should have aprox. 10.5:1C.R. may be a little higer and with the 487 head you should have aprox. 9.5:1C.R.  
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Pontiacman2

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