340 stroker help?

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cudatom

cudatom
Joined
Jan 2, 2007
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Buffalo,NY
I am having issues with my 372 stroker. It is a "toned down" high compression engine that I have to run racing fuel in on the street. I was told it is @ 10.72:1 comp now. I want to make it more streetable, but had @220lbs on comp test so not sure what way to go with it. It's a 30 over 340 w/ domed pistons, 3.58 stroke, has 549 lift cam, 70 cc open heads and 90 head gaskets. I have to back the timing way off to make it run at all on the street and the fuel costs are killing me! Any help would be great. Feel free to PM if you have ideas! Thanks!
 
Cometic make some thick *** gaskets almost to order. REuseable too. Just a thought..but a 90 is already a thick *** gasket! Milling the pistons? or a high bleed cam...
 
TksPishta! One idea better than none! yeah Ive been thinking of just tearing it down but did not want to get into the bottom end. Im still waiting for the builder to send me specs and part numbers so I can make some progress! They not on my top ten list right now!
 
It should be full floating pistons. Take the lower end apart and have the domes milled off. At some point you have to commit to really getting into it.
 
check your initial timing, a lot of times poor idle and cruising performance comes from not having enough initial timing to create the vacuum signal the carb needs to correctly meter the fuel. hook a vacuum gauge up anywhere on your manifold and increase your initial timing till you stop seeing any large increases in vacuum. then adjust your idle from that point. http://www.forabodiesonly.com/mopar/showthread.php?t=56694 good thread to read through right here
 
I agree with everything said. 220 cranking is up there. You would need a very short, very slow advance curve with lots of initial. I would wait for the specs and cannot make a better suggestion until more info is provided. My personal fave thing to do would be to machine a custom dish or something like that into the pistons-provided the pistons lent themselves to that. Other than that I would consider a cam change or at least degreeing it to verify that you do not have an extreme amount of advance in there right now. More info. J.Rob
 
thanks guys. I am supposed to taklk to the guy that built it today. If he cant help I guess its pull it apart and figure it out the hard way. never bought an engine built buy someone else and never again!
 
OK I learned that the pistons were originally supposed to make like 12:1 comp, and the cam is specs: .549/.549, 252/252 duration @ .050, 112 lsa. 308 deg adv duration. It has 70cc iron heads w/ 90" head gaskets. The initial timing was @ 30 deg at 3000 rpm. If I put anymore into it it pings even on race fuel. I think im gonna pull it and tear it down to look further. I was hopeing to change to aluminum heads and differnt cam so I did nt have to tear bottom end apart but not sure at this point. TKS Guys
 
Is it a solid flat tappet cam?
Sometimes when the lash goes too large it makes the cam act like a smaller cam and bring dynamic compression up. If lash is like .022 or above bring it down to like .016 and see if its better.
Or it just has less than optimum burn in the open chamber from sharp chamber edge or incorrect plug choice.
You certain TDC mark is correct? I have a new balancer that is 4 degress out. Put timing to 38 to get 34 etc but that is alot of cranking compression so maybe the cam is too advanced u could try retard it 4 deg or something
 
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