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Old 08-22-2012, 08:57 AM
jxhinoj
 
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355 Combo

Hello, i'm new to this site and don't really know how to use it and i'm not a mechanic learning from youtube LOL... i just bought a 1968 RS Camaro and i want to change the top end. Need help to see if this will be a good street high performance combo for my 350 and how much horse power and compression will i have. The previous owner didn't know what parts the engine had. I removed the old heads and had 345pn seal power pistons with a EX262 cam. Don't know what kind of rods or crank i have and i don't want to remove the oil pan since the block is in my car, so here are the parts.
  • 1968 350 over 30 2 bolt maine
  • RPM Edelbrock Aluminum cylinder heads 64cc chambers 185CC runners
  • Edelbrock head bolts 8550
  • Howards Cam 221/221 duration lift 470 108lsa
  • Howards lifters anti-pump
  • Comp Cam 1.52 roller tip rockers
  • Edelbrock head gasket .038
  • Edelbrock RPM Air gap
  • 570 Street Avenger
  • Mallory dis. HEI
  • 6L MSD box
  • 1 5/8 headers with 3" flange with flowmasters/dumps
  • PA 700R4 transmission and 2200-2500 Hughes Stall Lock-up
  • 373 POS. 10 bolt

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Old 08-22-2012, 04:08 PM
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about 320 hp with that carb and those heads
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Old 08-23-2012, 05:12 AM
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Should i go with a 650 holly DP or a 750
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Old 08-23-2012, 07:44 AM
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I would use a 750 double pump holley.In this forum you will find most people do not like double pump holleys.The only thing not great about the holley is poor fuel economy.This is mostly due to the driver enjoying the performance.
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Old 08-23-2012, 09:00 AM
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Thanks i will go with the 750 Holly mechanical DP for performance

Holley 0-76750BL - Holley Ultra Double Pumper Carburetors - Overview - SummitRacing.com
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Old 08-23-2012, 09:15 AM
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thats quite an expensive carb price.Look around.Pat{I forget his last name} advertises in the back of hot rod mags,sells complete,custom built H.P. carbs that match your engine for a good price.Ill try and find his add,or you do the same
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Old 08-23-2012, 09:46 AM
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That Howard's cam is only *slightly* more aggressive than the XE262 cam. The 1.52 rockers will help power a little more too. Not sure of the flow numbers on those Edlebrock heads, but the Howards cam is a single profile (221/221) which implies this is targeted for aftermarket heads that have better exhaust flow than factory heads. You may want to find the numbers for your heads and compare them to some factory head flow numbers. The XE line of cams have longer duration on the exhaust to help compensate for poor flowing factory heads. Either way the cams are so similar you should not have to change the torque converter stall speed. That said, I am not sure changing the cam makes any sense because they are so similar, what is the point (unless the old one has wiped a lobe or otherwise worn out).

All said I think your HP will be around 350+ with this setup. You can compare some engine setup and power numbers here: Ryan's Engine Combination and Bible Site.

You can also google topend kits. Edlebrock makes them and many other companies do too. Basically you buy these parts, bolt em on and can expect X horsepower. Kinda nice for comparison sake. Keep in mind, you probably don't want to say, "wow i will take the 600 HP topend kit", because that will have a radical cam and unless you take the proper precautions, you will not have vacuum to operate your power brakes, or have the proper torque converter, and you will not have any torque/power in the low end, so driving stop light to stop light will suck.
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Old 08-23-2012, 09:53 AM
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I will look around for a cheeper price, i just put together my motor last night see picture below. I will replace the old 570 street avenger with the 750. My timing was at 18deg at idle 800 RPM, total timing is 38deg is that normal. I will take it for a spin after work today
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Old 08-23-2012, 10:15 AM
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Is to late i just put the motor together last night lol...., I should have gone with a little bigger cam and check the flow numbers on the heads first. The XE262 had a couple of worn out lobes. I keep thinking i should take the motor back apart and go bigger thanks for the info Silver.
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Old 08-26-2012, 08:53 AM
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355 Combo

If you decide to change cams. Here is a Comp Cams XE274H 12-246-3 1800-6000 490/490 230/236, 110 lsa, 2200+ Stall. With a 750DP carburetor it should produce about 394 hp at 5500 rpms and 419 lbs torque at 4000 rpms. Remember any kind of port work done to your heads adds more power.
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Old 08-27-2012, 05:24 AM
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Thanks cdminter59 if i do decide to change it, I will go with the XE274H that's the cam i was going to put in the first place. [COLOR=#000000]dminter59[/COLOR]
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