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  #31 (permalink)  
Old 04-21-2006, 11:48 AM
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i've got 12 to 1 right now. i have 240lbs cylinder pressure the heads gaskets used are for stock rebuilds. so there not made for that kind of pressure. i'm going copper and lower the compression to 11.1 to 1.

yes they ran the AF ratio monitor. it also picked up a lot of water in the jar from just one pull. it smoked like mad, i was hoping i was just running rich, guess not. they said my carb setting where right on all the way threw.

you can't tell it has blown head gasket from it idling or driving it. but it does smoke when you rev it. i had a feeling they where blown but hoping it was just running rich.

i'm running sunco blue 110/114= 112 mixed 2 parts 93 1 part race gas for around 100 octane

i just checked my rpm and mph and it looks like i had 10% slippage

here's a little video if it idling.
http://videos.streetfire.net/video/6...DDD1F584EC.htm

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Last edited by 71javelin; 04-21-2006 at 12:08 PM.
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Old 04-21-2006, 12:47 PM
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hey guys, i'm starting to think it's a cracked head. my temps are around 150-160 here in florida. the crack is letting water go into the exhaust port and out the exhaust?
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Old 04-21-2006, 01:26 PM
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LOL! maybe cracked head

NO thinkin' allowed, only tear down inspection and testing!

do a compression test now on all cylinders so you can start a log book for changes- results

thanks for the 240psi info, no I don't like desk top dyno,

video= first time I ever heard exhaust resonance "bounce" a microphone diagram! I think you just invented a new exhaust sound test tool!

Last edited by red65mustang; 04-21-2006 at 01:32 PM.
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Old 04-21-2006, 01:28 PM
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Quote:
Originally Posted by 71javelin
hey guys, i'm starting to think it's a cracked head. my temps are around 150-160 here in florida. the crack is letting water go into the exhaust port and out the exhaust?
If you have been getting 240 pounds cranking pressure consistant from cylinder to cylinder you don't have a crack(or a blown head gasket). The 240 pounds is consistant with 12 to 1 compression.

Try Felpro steel composite gaskets. They should hold unless you get a lean condition. Sometimes you can stack 2 gaskets to lower the compression 1 point.

You may have to magniflux the head to find the crack. Also, the heads could be warped and if so, will not seal. When you remove them, always unbolt in the reverse order you torqued them to prevent warpage.

The video of the engine idiling sounded consistant with a high compression engine and quiet mufflers. There is always a lot of smoke of stuff burning off new (and fresh cleaned) parts. I really liked the cars. They are special.
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Old 04-21-2006, 05:16 PM
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Try retarding the cam 4 degrees before you monkey around with thick head gaskets and lose any quench you might have. 240psi is a bit on the high side for 100 octane, detonation is probably what killed the head gaskets. Use better fuel.


Larry
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Old 04-21-2006, 05:30 PM
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Quote:
Originally Posted by coldknock
Try retarding the cam 4 degrees before you monkey around with thick head gaskets and lose any quench you might have. 240psi is a bit on the high side for 100 octane, detonation is probably what killed the head gaskets. Use better fuel.


Larry
Yep, 110 - 12 minimum for 12-1 with iron heads and 90 deg air temperature.
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Old 04-21-2006, 09:16 PM
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i'm thinking of tearing it down and starting over. i'd really like to check the crank bearing. i've got a quench of .032. my pistons are .015 above deck with a .047 gasket

i wish i could get some better feltpro gaskets. all they make of amc is the stock oem. ROL makes a performance gasket but there only .039

i'm thinking of maybe taking .008 off the top of the pistons and then dish them so i have a 17cc dish. that should get me a quench of .040 and compression around 10.5 to 1 i'm going to call venolia and see if they can be wacked. if not i'll have to get new slugs. then again i might need them anyways after seeing a few of my plugs today. i should have the heads off tomorrow and i can check for piston and wall damage.

PS: i didn't build this motor. a so called pro did that's in my car club. i would of never built it with that much compression. i told him i wanted 10.5 to 1. he told me it was going to be 10.8 to 1 and swore up and down it would run on pump gas. needless to say i'm building my own from now on and i'll never let him work on anything of mine again.

coldknock- thanks for the idea, i'm thinking of going to a little bigger cam that would match my combo better. the gasket i was thinking of is a .055 gasket that would give me a .040 quench and then open up the chamber on the heads to get 4-5cc more to knock it down to 11.1 to 1

i'll let you guys know what i find tomorrow. thanks for all the input

Last edited by 71javelin; 04-21-2006 at 09:29 PM.
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Old 04-21-2006, 10:02 PM
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Quote:
Originally Posted by 71javelin
i'm thinking of tearing it down and starting over. i'd really like to check the crank bearing. i've got a quench of .032. my pistons are .015 above deck with a .047 gasket

i wish i could get some better feltpro gaskets. all they make of amc is the stock oem. ROL makes a performance gasket but there only .039

i'm thinking of maybe taking .008 off the top of the pistons and then dish them so i have a 17cc dish. that should get me a quench of .040 and compression around 10.5 to 1 i'm going to call venolia and see if they can be wacked. if not i'll have to get new slugs. then again i might need them anyways after seeing a few of my plugs today. i should have the heads off tomorrow and i can check for piston and wall damage.

PS: i didn't build this motor. a so called pro did that's in my car club. i would of never built it with that much compression. i told him i wanted 10.5 to 1. he told me it was going to be 10.8 to 1 and swore up and down it would run on pump gas. needless to say i'm building my own from now on and i'll never let him work on anything of mine again.

coldknock- thanks for the idea, i'm thinking of going to a little bigger cam that would match my combo better. the gasket i was thinking of is a .055 gasket that would give me a .040 quench and then open up the chamber on the heads to get 4-5cc more to knock it down to 11.1 to 1

i'll let you guys know what i find tomorrow. thanks for all the input
In a pinch you can bleed off some compression by retarding the cam 4-6 degrees. This puts the valves farthur away from the pistons so there is no problem there. Usually you can cut domes off pistons (that are forged solid) but dished pistons require a different forging.
There are a lot of new parts for AMC V-8s. Check out these edelbrock heads:
http://www.edelbrock.com/automotive_...rmer-rpm.shtml
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Old 04-22-2006, 07:42 AM
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food for thought:
this years F1 rules say V8 only, (any V8 balance is not the best possible),
after millions and million of $$$$ spent to design and build and test the new V8 motors , almost 1/2 broke (motor or tranny due to crank vibration) in the first race.....

your article link does say AMC 400ci practical max 500hp or break the bottem with a 3400lb car, use that as the bench mark max for your "thinkin"

max keith, a member: "alot more gooder ain't always more good" sooooo true!
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Old 04-22-2006, 10:25 AM
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Quote:
Originally Posted by 71javelin
coldknock- thanks for the idea, i'm thinking of going to a little bigger cam that would match my combo better. the gasket i was thinking of is a .055 gasket that would give me a .040 quench and then open up the chamber on the heads to get 4-5cc more to knock it down to 11.1 to 1

i'll let you guys know what i find tomorrow. thanks for all the input
0.015 above deck! How close is your top ring to the deck? That's just begging for a stuck ring in my opinion, but that's just my opinion.

If the top ring is far enough below the crown to be safe I'd just open the quench to 0.040 and stuff a bigger cam in it. There's no need to give up HP.

There's no off the shelf hyd roller, that I know of, for an AMC that's going to do the job with the converter you have. Something around 240-245@ 0.050" and 110 LSA would be great but it will likely be a custom grind.


Larry
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Old 04-22-2006, 12:32 PM
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i started a new thread

i got one head off, it doesn't look good.
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