Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
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Finnaly took her for a drive tonight. I didnt go far because I have Open headers right now. I was expecting a fast ride but it feels like the old 305 is still under the hood. I What could it be? It diesels when you turn it off do you think the timing is way off? Another think i Didnt have the Vaccum advance hooked up could that make that much of a difference? I could barley break the tires loose. I have a 6 speed and a 3.08 open rear, but I have the 3.73's and Hd Torsen ready to put in. I wish I could find a chassis Dyno somwhere here in Southern Utah I should be turning about 350 at the wheels
Is this a new engine? If its not going to feel like much until you get some miles on it. Hook everthing up right check that timing "sounds way to quick" and take it easy for awhile. I remeber back when i first swaped my 305 for a 350 I felt real disapointed untile i got it all tuned up and broke in then no comparison 350 all the way.
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If you really want to be original slap in a TURBO DIESEL!
there has to be something seriously wrong with the timing or the fuel system, that thing should crank hard even if it is new
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91 RS W/carbed 350, Vortec heads, performer rpm, Comp cams Xtreme energy 224/230 duration and .477/.480 lift. BFG Drag radials. 3.42 posi,Corvette servoed 700r4, 3000 stallconverter. Edelbrock TES, 3inch cat, flowmaster with single 2.5 inch exit.
Best time yet to come
12's?? :crossthumbs:
Could my clutch be slipping? I hope somthing is wrong because If I wasnt the guy who swapped the motors Then you could never convince me it had more than a 305
Yea its probably still tight then. Set the timing to 10-12 and eleiminte the vac leaks. that should do the trick. What octane fuel do you have in it? some places in uta have 87 as min and some 85 it should run on the 87 in high altitude but bump it up to 91 that should help the diesling if the timeing is set right. gl
Unless it has moved the timing was 12Btdc. It does have some of the cheap gas in it right now just what was left from the 305. I am using a Holley 4160 model wiht the secondary metering plate. Jets are 71 in Primary 73 in the Secondary. Vacumm advance isnt hooked up but it will only bring in 3 degrees at 5 " Hg
Timing curve is
It also has a light spring in the secondaries. My tires are a near bald 215-60-16 inch rim Not very wide or sticky plus the open rearend. It wouldent rip them loose by dropping my foot I had to ride the clutch to get them to rip loose and they never would come loose in second gear.
If the motor is that tight, you have a big problem. I installed a new crate motor in my car (ZZ4) and it was a huge difference from the stock 350.
The vacuum advance has to be hooked up.
More tuning.
Your timing curve contains at least part of the explanation.
All your centrifugal advance should be in by about 2500 to 2800 RPM. You need some lighter springs in the distributor. Get yourself a curve kit.
Like others have said, a new engine built to production tolerances doesn't necessarily produce max power right away. It usually takes a few thousand miles before it reaches its full potential.
Concentrate on getting it to run right, then drive it normally for a while. Don't thrash on a brand new $4000 motor if you want it to be as good as it can be and to last a long time. Avoid things like WOT runs to red line in low gear, as well as the obvious like overheating, low oil level, and flooding with excessive fuel.
Vacuum advance should have no effec ton how hard it pulls at WOT, but may affect its tip-in and general driveability. Most engines with performance cams want about 8-10° of static timing, a smooth advance curve from about 1200 to 2500 RPM with about 20-22° max of centrifugal, then 6-10° of vacuum advance on top of that starting at about 12" of vacuum and all in by about 16" depending on things like gear, car weight, etc. No vacuum advance will make it use too much gas cruisiong, run hot, and generally feel lazy at light throttle.
Dieseling is usually caused by the idle being set too high.
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"So many Mustangs, so little time..." ICON Motorsports
How long should I take it easy? The HEI was set up by salle chevrolet. They sold me the motor so I figured if Anbody knew how to set the advance curve it would be them. Im not even going to drive it agian until my exhaust is on I have a Hooker Here in the box I just need to find a Exhaust shop to make some pipes to connect the headers and the catback.
They set you up with an extremely conservative curve, that's all I will say. The Fast Burn heads supposedly require less total advance than many others, but that curve you posted still looks awful lazy. They may have done that just to keep it out of the detonation zone. Try that first, it's cheap and easy, and you can always put it back. Obviously if it ever pings you've gone too far.
2-3k miles ought to be a good loosening-up period. The way I break in a new motor is to drive it mostly as I normally would, minus the 1320' runs. I don't baby them by any means, but I don't beat on them either. For the first couple of miles (like 5 or 10) I'll typically get on the freeway, and in some gear like 2nd or 3rd, run it from about 2000 to 4000 at half throttle, and then let the engine brake the car back down to 2000; I'll do that for several miles, maybe 8 or 10 times. Then cruise for a few miles. Then do it again, maybe 2500 to 5000 RPM this time with a little more throttle. Then cruise a few more miles. Then change the oil, check all the fluids, make any final adjustments and button everything down. Then drive it normally, not babying it or thrashing it, for a couple thousand miles; then change the oil again, and head to the dyno or whatever... it should be ready.
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"So many Mustangs, so little time..." ICON Motorsports
personally i break them in by driving them hard for first 50 miles but no hard starts from a stop. then easy up until 500. it sounds to me that your carb and timing is way off. an engine like that can't just be thrown together. recomended is 10 degrees initial timing and total of 32. they also recomend 750cfm carb. it's not a lack of being broken in, it's a lack of proper tuning making it slow. just get it tuned in properly. be a good idea to call scroggins dickey tech dept or who ever you bought it from so they can help you tune it with the stuff you have.
350 all the way.
