tuning questions (kinda long)....

[thinman56]

....here's another shot of the adapter.....

 

[addo]

Could you be getting a standing wave in the adaptor? What do SR and Thad reckon? That "shelf" in it flags my eyes.

 

[Funky Cricket]

Could you be getting a standing wave in the adaptor? What do SR and Thad reckon? That "shelf" in it flags my eyes.

same thought, that doesn't look like it flows "nicely" into the log..

also, check your spring rates if you can (though I don't know what they should be: anybody else?), as you said, they could be part of the problem.

 

[Anonymous]

thats it...the c ar is trashed...it junk, unfixable...so sell it to me



very ncie looking car...good luck
chaz

 

[thinman56]

thanks, chaz, but i think it's time you got another 'stang, your advice is starting to get tainted.

suddenly i hate my custom adapter and the guy who made it. i can see how the flow might get funny at high volume flow rates, and that would happen under various loads at the same rpm. guess i better get a clifford adapter, cha-ching....

thanks, folks, keep you posted.

 

[addo]

What about "pinning" some wire in there and reprofiling the inside with Cotronics epoxy or JB-Weld? The wire would stop chunks falling into the motor. It would also allow evaluation of whether this really is the problem. Only thing is - do these epoxies tolerate fuel mixture?

 

[thinman56]

yea, addo, i thought about filling and reshaping, but i'd hate to have a piece break off and do a cylinder. if the clifford adapter fixes the problem i'll eventually fix it permanent, either rout out the adapter and have the head remachined to open it up, or wait for the new FSPP head.

 

[Anonymous]

This is an interesting thread, please keep us up to date-I am very curious as to what it turns out to be. I noticed you keep saying 4000 rpm under all different driving conditions, that has me thinking ignition as fuel demands and delivery differ greatly under different conditions even at the same rpm.
Is this in all gears?? If so i would start looking at the ignition system --Especially the diszzy. There was another thread--about recurving a DS2 that refered to 'hitting the wall" at certain rpm when the recurve was done a certain way --just sounds very similar.

 

[thinman56]

hate to beat this to death. opened up the adapter some more, no change, still spits and pops and loses vacuum at 4,000 rpm. installed the old distributor to see if it was ignition-related, no change. i've had the timing all over the place, hooked up the vacuum advance to ported source, no change.

here's something interesting, well, in a bad way. i put my compression data in the calculator found here, and only got 8.3:1! 53 cc chambers, 0.045" deck, 7 cc pistons, .038" FSPP head gasket. i assume that's the compressed height? i measured the deck height when i had the head off and cc'd the chambers myself. is it possible that 4 grand is all you can get from 8.3 compression? i'm running out of options to check.

 

[gtm1086]

Well I'm running a very close set up to what you are running. Holley carb with an adapter, difference is a big cam. I'm currently up to a Holley#75 main jet which if I remember right is 0.083. I’m also running a 5.0 power valve. Mine seems to loose steam around 5000 rpm. You might want to try to give it a bit more fuel. I agree with some of the earlier posts. The adapter and log head are limiting factors. Although a sure fix is a new aluminum head.

 

[Anonymous]

whats is a safe rpm limit for the 200's anyway? I always wondered

 

[Funky Cricket]

I never had my capri over 4K.. would just drop on it's face, mine I am pretty sure was a combination of the log head, carb that needed rebuilding and the stock valve springs..

if everything else is good (ignition, feul pressure, carb tuning) it just may be the valve train can't keep up...?


as far as safe rpm, 7 main on a 6 cylinder, I didn't think these things HAD a limit we could reach.. the top end seems the be the big problem.

 

[MustangSix]

....0.045" deck,.....

That's quite a far ways to have a 200 piston down in the cylinder. Are you sure of that? Stock deck is between .020 - .025", normally.

One thought was that your fuel may be running away from the front jet because the carb is sideways. The other thing might be that acceleration is causing the fuel to rise in the rear of the bowl, causing the float to cut off your fuel.

Jet extensions to the rear would help the first problem. A reshaped float woud be need to fix the other.

 

[thinman56]

thanks for more responses. jack, i'll check the deck height again in the fall when i take it apart, i did check it with a dial indicator. as far as the fuel supply, it does the exact same thing whether i'm accelerating or creaping up to 4K slowly, also uphill or downgrade even, same thing, so i think that rules out float problems, unless it's still, as David S. says, the bowls just running out of fuel. the steady 3.5 psig minimum fule pressure at all revs i thought would rule that out.

this summer i'm going to enjoy what i have, and this fall take it all apart, send the bottom end to lindskog for balancing, do the mild cam, fasteners, mill the deck if need be, get the carb adapter sorted out or eliminated. the nice weather for driving doesn't last very long up here, so i'm going to enjoy it while i'm here, plently of nasty weather in november for being holed up in the garage.

cheers

 

[thinman56]

30 months isn't too long to solve an old problem, is it? you may recall that embedded in this long thread is the problem of the engine just giving it up around 4000 rpm. no matter the conditions, just spit, sputter and almost die.

so, i finally got around to the last thing i could think of, which was replacing the VALVE SPRINGS with stock 302 springs that i bought a year ago, as recommended by several people in other threads. interesting to look back at the beginning of this thread and see i suspected, then dismissed weak springs as the culprit based on fresh parts. fresh wrong parts, i guess. anyway, the problem is gone, took it out, warmed it up and stretched it out in second gear and it ran up near 5,000 rpm without flying apart (one of my fears immediately after any job involving dismantling). makes me feel kinda lazy for taking so long to get to it.

the bad news is, i notice it doesn't have much power after 4,000 rpm. hmm, must need a nice 274 cam.....

thanks again for all the previous responses.