j heads..more perf. questions

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RPM

RPM

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I didnt want to jump in and change 66dartmans thread on "j-head to eddie swap" but I think I have learned a bit about what I have from just reading that thread. Now, maybe someone can shed a bit-o-lite my direction on my J's that I have dumped toooooo much money in.

long story condensed.
'74 360 .60 over 9:1
Had originally had the j heads reworked and installed the 2.02 valve upgrade and had a performance job done on them....this was quite a few years ago.
ran this with the mopar stick .284/.484 and a sure grip set 3:91 and 727 with a 3000 stall.

My car was a real pig off the line, but once she got rollin hold on! she would take high RPM's like crazy and love d it up there.

Problems. They reared their ugly head shortly after the build.....I had taken the car back to the engine builder to see why no low end. (keep in mind this is about 5-6 years after the work was done) so no goin back on them. They said the car had no compression. What ? took the car back hoime with my tail between, and strated tearing the bastard apart. Removed the heads to find the pistons had a nice wobble side to side in them.....was at .40 over at the time. YUCK. Pulled engine and sent to a known good shop and they cleaned it up. They checked the heads and asked why it worked at all? Apparently they were pretty botched up. (have a list of what was wrong..not important here) they said they could fix them.....I beleive this shop. Got everything back together on the beast and fired it up. Seemed pretty good and ran better than before, but still a pig off the line. Can only get a bark from the rear tires WOT. So, through some research found that my cam como might have been a bit off. Purchased the xe268 Comp. cam and rechecked......gained....quite a bit....very noticeable difference on my take offs, but still only barking the tires.....pulls hard and fast though.
I am lost where to look now. I guess getting the tires to turn isnt a priority, especially cause it isnt going to be a racer, but it should and thats whats bugging me. So here is the current build. Does someone see a problem here?
360 at roughly 9:1 compression
j heads with perf job, large valves (maybe too much work for engine?)
eddy RPM intake
holley street avenger 780 ( I know what your all goin to say, but it likes this carb the best)
double roller/stock type rockers
MP ignition chrome box. accell distributor and super stock coil, 8mm wires
stock exhaust manifolds (this is a killer)
2 1/2 " tubes flowmaster 40s
trans = 727 loadflight / torqueflight (came from a truck) reworked with 3000 stall convertor.
8 3/4 rear with 3:91 sure grip grinders.
thats the main scoop. Shouldnt she burn the skins......can include tire size if any questions....
any one want to take this on? feel free to pm me too.....
sorry so long.

-RPM
 
Do you know actual CR? or deck height and CCs of the heads?
What initial advance and total mech advance and all in by what rpm? is the vacuum advance disconnected?
jets size in the carb?
from a dead start - what rpm will the convertor flash to?
 
Have you had your combo to the strip to see exactly what times it's runing in the 1/8 or 1/4 mile, or are you like most of us and using the time tested butt dyno? :)

All of what 388dart asked, plus I promise not to even mention the Holley Avenger.......
Did you degree your cam or install it straight up with the marks lined up?
Check that Accell dizzy VERY carefully. I ran Accell distributors for years until the problems finally out weighed the brand loyalty - that's also why I drive Mopars and not Chivvies now. :)
 
thanks guys,
I unfortunately dont have the cc's on the heads....probably can get them though, yes, the vacuum advance is hooked up. Didnt seem to make much difference disconnected either, I will have to run my advance checks here real soon, (burned through the wires on the old timing gun ..d'oh) need to get a new one. I know I have plenty of vacuum from the intake, have changed distributers and ignition out before and still ran identically. Havent messed with the carb, so dont know the jets, but will get them and pass that along. The new cam was installed normally, not degreed. With these questions.....none sound serious, but more like tuning issues, am I getting this could be a possiblilty? The car actually fires and runs like a top so its basic tune is good, possibly just tweak her around some more? I'll see about getting some more of that info. together.....in the mean time, any other suggestions, ideas or comments are greatly apprciated.
thanks!

oh.... and I never have rolled this one through a 1/4 mile track yet, but have done a self timed 1/4 mile give or take 13.7 @ around 102 mph that should be fairly close so anywhere between 13-14
-RPM
 
might have been 63dartman who started the thread cause I already blew the big bucks on the eddy heads and am so far happy with them. Anyhow, there are 2 things that are unknowns which could be hurting you. Compression and where the cam really is in relation to the crank. There is a good chance you are okay, but an equal chance that your cam is not where it should be. Also, do you know how far the piston is down in the hole? That could make your 9:1 ratio 8:1 real easy. Just a couple of things you probobly already know, but my 2c.
 
my apologies, it was 63dartman...
mrmopartech, the smaller valve heads seemed to be weighing in my mind as a possible answer. you stated that seemingly like you were sure of it.
That could be the possibility I was looking for too. Would going to the 318 heads with small valves be better than a set of cast 360 with stock vavle size? I just dont want to go to farther the other way either...you know.

thanks again all and I will try to get some of info. needed. The car will be going to the body shop here soon, so I cant do much to her right now....

-RPM
 
Without knowing the ability of the shops, it's all a guess. So dealing only with what the engine is telling you thru performnce...
My experience with Comp XE cams is they should work fantastic with that setup, 2.02s and manifolds included. a 360 can make very good use of 2.02s, and rarely have any loss in low end because of the 8% longer stroke. Was any porting done? It's much easier to harm low rpm performance by porting than build high rpm power. Also, one of the easiest ways to hurt low end is old valve and seat grinding equipment. So, I'd concentrate on timing curve and tune up. I'm assuming a stock factory balancer was re-used. That leads to the possibility of the outer ring moving. In any case, new or old, TDC should be verified on any balancer. It's easy. Using a piston stop available from Summit, or made from an old spark plug and bolt/nut, bring the engine around to about 45° after indicated TDC. Thread in the stop, so it sticks down into the chamber and lock it. Turn the engine backwards (CCW) gently, until the piston contacts the stop. Then, using a marker or paint, mark the balancer at the "0" mark. Then, turn the engine forward (CW) around until the piston contacts it again. Mark again. pull the stop, and measure between the marks. Exactly 1/2 way is true TDC. It should be the factory mark. If it's not, remark the balancer for 0, and reset your timing to what it should be. On the timing, I'd think initial of 12-14° would be fine, with a total (without vaccum..unhook and plug the hose) of 36-38° should be close. After timing is set, reset your idle and carb mix using a vaccum gage. Then take it for a ride. If it doesnt bog spit or sputter, it's time for carb tuning, which can be found in a bunch of write ups, from Hot Rod to HP Books on how to modify and rebuild your Holley carb. The manifolds are holding you back a little, but it should be enough with the stall and gearing to spin the tires.
 
RPM, not sure if your interested but your set up sounds alot like mine...I am running a 60 over 360 with completely stock bottom end, windage tray, true roller chain, tensioner, lunati cam, (450/475 i believe), 750 edie carb, rpm manifold, spitfire headers into duals with no crossover 8 3/4 posi 3.23 gears. This is in my 63 dart.
I'm not sure of the weight of your vehicle but, I just recently upgraded from a 318 to my 360, with the 318 my car ran good and could get a little tire spinning going on. Now that I have most of the bugs worked out of my 360 it will just about burn the tires off if I want it to. I know that tire spin isn't a good measure of performance but, it sure is fun......if you want I would be willing to discuss your setup with you and see if maybe there's something that your missing. I always feel that two heads are better than one when it comes to trying to figure stuff out. I am by no means an expert but, I have asked alot of questions here on the forum and learned quite a bit. If you want send me a pm with your number or just pm me to send mine to you. I know how frustrating this can be at times, I was expecting instant gratification from my swap to the 360. When it didn't happen I immediatly wanted to blame something in the engine build. After talking to several people here I started getting really good results with the things they told me to look at. I also learned not to overlook the little things......they all add up.
 
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