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304 combo help |
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sc/1967
AMC Apprentice Joined: Jan/08/2012 Location: Albany, OR Status: Offline Points: 45 |
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Posted: Jun/07/2013 at 3:27am |
Before I start with telling you my comb, I know that building a 360 or 401 will be way better at making power for the money. However I bought This motor off Craigslist about 6 months ago for $275. The motor was a long block. It had no intake, carb, headers, dist, etc, but it turned out to have .030 L2340 forged flat top pistons, was balanced, had a comp 280H cam, the block and heads were notched to fit the 2.02int./1.68exh. valves and the heads have had unshrouding done around the valves as well as some minor port work. I have a Edelbrock R4B intake Holly 600cfm vacuum sec. carb MSD 6AL ignition, MSD dist., MSD plug wires and coil and it will be mated to a 727 in a 67 rogue. when we tore this motor down we found bent push rods caused by piston to valve interference from some one installing that comp 280h cam with no valve reliefs cut in the pistons. After thoroughly inspecting the pistons they surprisingly seem to be in great shape only damage is where the valves were hitting. I am planning to fly cut the pistons for reliefs and reuse them and the rods, install all new bearings, rings, re-hone the block, add a new cam and lifters, and reballance. My question is on camshaft and the whole combo in general. I want a cam that will work with my stock converter in the 727 but will take full advantage of the large valves as well as have a rough sounding idle. The car will be mainly a street car but will see plenty of track time too. I also have questions on cylinder heads. The 304 heads that have been notched and worked over for larger valves had double spring valve springs but we found a couple were broke and Im not sure if the guides are worn or if the valves were bent during contact or not but should be a 58cc head giving me a compression ratio around 10:1 to 10.5:1 but would need to be checked and likely rebuilt. I also have a set of 360 heads that were rebuilt stock in 07 but are a 64cc head and should me a compression ratio around 9.0:1 to 9.5:1. I am on a pretty tight budget and am wondering if I should spend the money on the 304 heads or use the 360 ones? Also I found screw in studs for a 460 ford that are 5/16 on bottom and 3/8 on top that should allow me to use adjustable valvetrain and roller rockers without sending the heads out to be drilled and taped for the larger studs. Has anyone herd of this being done before or see a problem with doing this? If i go with the 360 heads could I put the 304 heads on a 360 at a later date and get them to perform well with the smaller chambers and large 2.02/1.68 valves or are the runners too small for a 360? any and all help will be greatly appreciated thanks.
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nda racer
AMC Addicted Joined: Nov/28/2009 Location: Ohio Status: Offline Points: 2591 |
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Forget a stock convertor unless you're happy running in the high 16s. 2500 stall wasn't enough for a 272 HMV Crane. 3.54s weren't really enough either.
600 carb is way too small for a stock smog 304 with a 272 HMV. |
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wantajav
AMC Addicted Joined: Sep/04/2009 Location: PA Status: Offline Points: 1150 |
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Ahhh bench racing....my favorite pastime
X2 - on the vote against a stock convertor. is there a non-lock up TF convertor out there on the market, even if it is a Mopar one and you have to cut off the starter ring? Can you get a TC from a 6 cyl 904 to reduce weight & get a higher stall? I blame the way tight stock convertors on AMC cars which is why they weren't even faster when they were new.
I'd ditch these (over?) worked big heads that may have valve guide issues in favor of a set of stock 304 heads that have an oversized intake valve only and some clean up work only. This gets you out of the mismatch, you need good air velocity more than total flow to get a good 60ft time, sell the heads you have to a TransAM high revver. Living with Worn valve guides and the engine isn't even together yet is a concern, I've known people who ran a junkyard combo did OK but that's another strike against these particular heads
A little nervous to hear the piston tops got beat up eating a valve but if you are sure then OK
How much can it cost to get the heads redrilled for proper studs that are known to work right? Probably not that much. do you need all that with a 280 cam anyway? (.490 lift) I thought below 0.500 lift you could run stock valvetrain on an AMC engine.
Can you run a small N2O plate on this car? Might be the most cost effective way to really get down the track with this set up.
sounds like a cool Rogue, looking forward to the updates.
Mike
Edited by wantajav - Jun/07/2013 at 8:33am |
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5476 |
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If the valves kissed the piston, they are bent too.
Scorpion and Harland Sharp both make adjustable bridged roler rocker arms for the 5/16" thread. You adjust them by shimming or buying the correct push rod length.
My choice would be the smaler valves, 270HL Isky or 268H Comp - lower the idle speed so it lopes, start with the RFB and 600 Holley but, you may want to up size the carb latter on, higher stall converter.
Tou ARE going to run headers, right?
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A0M797X112187
AMC Nut Joined: Mar/18/2009 Location: Belton, MO Status: Offline Points: 278 |
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My first question to you would be how quick do you want your car to be at the track ? What are your goals as far as ET and MPH ?
From there, it makes it easier to select parts. Even with the smallish factory valves, the factory heads flow well enough and combined with the relatively long stroke ( for the displacement ), a 304 can be made into a decent performer.
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-D Payne AMO 2834 ( Expired ) NAMDRA 3770
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sc/1967
AMC Apprentice Joined: Jan/08/2012 Location: Albany, OR Status: Offline Points: 45 |
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I would like to get the car into the mid to low 13s. I might swap to t5 trans later or use a stall in the 727 to allow for a bigger cam. I also plan to eventually swap the R4B intake to a single plane either a torquer or a rpm air gap with a bigger carb. The car has free flows right now but will be getting headers as well. Thanks for your help.
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