Cylinder head discussion 340 with stock above deck pistons

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nfhDODGEnfh said:
I find it interesting how far we have gotten from the original intent of this post. It's a question about heads. And it had turned into a bunch of guys saying that I'm slow..... like I said before a couple times. It's been down the 1/4 in one event. Of course it needs to be dialed in and I can hopefully find more speed in other areas too. Are you guys getting those numbers et/mph from internet calculators or having a similar setup with Timeslips showing these mid 12s or 11s as newbomb said without spray? That seems awfully fast for a car that might make 350 at the crank maybe less. If I can get my 60' down a couple 10ths I'll be in the 12s for sure. And it's something I'm gonna work on regardless. But I'm asking about aluminum heads. I plan on messing with the carb this season aswell but my WOT afr seems pretty good at around 12.6 and is similar while spraying. I run the light spring in my secondary. Could change the cam to a bit higher rpm but it's a street car mostly. By tune the carb you mean lean it out some more? Seems like it's in a decent range. I have an afr gauge in the dash. It idles a bit rich but WOT doesn't seem to bad
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iam not a fan of that carb go read when it fully open
i was asking if you had tuned the carb
 
Ok, 40 lbs off the nose is worth it alone. I have run the 65cc OOTB eddy RPM’s and run 12.3. My compression was about 9.75-10.0.with a solid flat tappet and stock 340 manifolds and a massaged stock 68-69 stock 340 intake with a 800 eddy AVS. I’m at 410 ci. The reasons to go aluminum, weight, starting with a better casting, and easier to get ported now a days and easier to weld, but don’t expect a huge gain.
 
nfhDODGEnfh said:
Not professionaly tuned but according to afr it seems ok? 12.6 at WOT? What's your recommendation
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with spray you dont want to be lean iam sure you know that
12.9 13.0 n/a
12.8 better to be safe then sorry
you can tune they spray be air/fuel and your plugs to see how far you can go with the tune
does not need to be a pro to tune it
carbs need tunning
That 3310 isnt fully open until 5600
 
First off is you need to be launching the car at a higher rpm, at least 5000 and ride the clutch out far enough so as to not let the rpm's drop more then a 1000 rpm's. If you have the close ratio 4 spd, then you have a 2.47 first gear coupled with a 3.55 rear gear give you a 8.76 starting ratio(not a good ratio to get off the line cleanly with) without slipping the hell out of the clutch. Get rid of the radials and put a short bias ply slicks on the car.
When you get to the point where you can keep the engine from bogging and keep the engine at peak torque or higher by slipping the clutch. The car shound 60 ft. good enough with the setup you have now to run in the 12's.
 
nfhDODGEnfh said:
I find it interesting how far we have gotten from the original intent of this post. It's a question about heads. And it had turned into a bunch of guys saying that I'm slow..... like I said before a couple times. It's been down the 1/4 in one event. Of course it needs to be dialed in and I can hopefully find more speed in other areas too. Are you guys getting those numbers et/mph from internet calculators or having a similar setup with Timeslips showing these mid 12s or 11s as newbomb said without spray? That seems awfully fast for a car that might make 350 at the crank maybe less. If I can get my 60' down a couple 10ths I'll be in the 12s for sure. And it's something I'm gonna work on regardless. But I'm asking about aluminum heads. I plan on messing with the carb this season aswell but my WOT afr seems pretty good at around 12.6 and is similar while spraying. I run the light spring in my secondary. Could change the cam to a bit higher rpm but it's a street car mostly. By tune the carb you mean lean it out some more? Seems like it's in a decent range. I have an afr gauge in the dash. It idles a bit rich but WOT doesn't seem to bad
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In that case, call Rod Bloomer and order a set of his heads.
 
nfhDODGEnfh said:
Not professionaly tuned but according to afr it seems ok? 12.6 at WOT? What's your recommendation
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Stuff coming off my dyno runs at 13.1 to 13.4 AFR. Not all O2 sensors read the same. Tune for MPH and read your plugs very close.

Once it's tuned that is the A/F ratio your engine wants and what your O2 sensor reads. Then you can always tune to that AFR.
 
The heads will definitely be an improvement.

BUT, for half the price of Eddy heads, you could put more gear out back and make some suspension upgrades and gain more than the heads will get you.

If you’re gonna go in the motor, put a better cam in it.


I’m not sure if anybody asked, but what’s the intentions/goals for this car?
 
a-bodyguy said:
with spray you dont want to be lean iam sure you know that
12.9 13.0 n/a
12.8 better to be safe then sorry
you can tune they spray be air/fuel and your plugs to see how far you can go with the tune
does not need to be a pro to tune it
carbs need tunning
That 3310 isnt fully open until 5600
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Yeah I've tuned the spray to make sure the fuel ring is in the right place and there is no black specks on the porcelain either. It seems to be at just the right spot for the spray at least. I'm gonna work on the carb this season with Inertia to try and dial it in a bit better but up till.now I've been trying to get the idle afr up as it's pretty low. Need to mess with the fuel transfer slots or hopefully just restrict the air bleeds a tiny bit.
 
vntned said:
The heads will definitely be an improvement.

BUT, for half the price of Eddy heads, you could put more gear out back and make some suspension upgrades and gain more than the heads will get you.

If you’re gonna go in the motor, put a better cam in it.


I’m not sure if anybody asked, but what’s the intentions/goals for this car?
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Goals for the car is just a fast street car that I take to the track. The nearest track is off the island I live on so I can't realistically get to a track more than a few times a year. Main goal is just improving speed and having a fun street car. Other things I've thought of putting on are caltracks but I still haven't reached the point of wheel spin off the line yet at the track. On the street with dry pavement and no burnout I can dump the clutch at 2500 and it just chirps the tire and then hooks up well. I have new leafs from mopar and poly bushings with a correctly set pinion sunbber. Still need to try higher rpm at the track off the launch next time I'm there but that won't be for months
 
nfhDODGEnfh said:
2.0 60' 13.1 at 108mph im running micky street slicks 235/60r15 if I can increase horsepower and get a better 60' that would be even better. I've always wanted to get better heads and increase some power. And lower the weight on front end too
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Your mph is enough to run low 12’s. I would work on your incrementals first. Especially the. 60 foot
 
As far as the original question with out going to far off track. Aluminum heads are definitely better. Lighter and usually flow better with probably a little more compression. As far as everything else I couldn’t say. One thing I do know is that the cam your running isn’t fully utilizing
 
duster 344 said:
As far as the original question with out going to far off track. Aluminum heads are definitely better. Lighter and usually flow better with probably a little more compression. As far as everything else I couldn’t say. One thing I do know is that the cam your running isn’t fully utilizing
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Maybe an xe284h would be a better cam, would have to cut the guides a beleive if it went in the stock j heads. But I would also probably need to go with 3.73 or 3.9 gears out back if I jump the cam up much
 
I see @Inertia has not answered yet. The stock amount for the early 340 positive deck height I believe is "around" .025" if I remember correctly. What I would do is allow the head gasket to set your quench distance. That's the easiest way to do it. Just let compression "fall where it may". It's gonna be pretty good, regardless.

Regarding the aluminum head changing compression theory. Look at it like this. Compression ratio is a physical comparison. It is a comparison of the cylinder volume at TDC to the cylinder volume at BDC. Let's say the volume of your cylinder is 1/12 the size at TDC than it is at BDC. Then you have a 12:1 compression ratio. Understand? That ratio, or comparison hasn't a thing to do with "whatever" material the cylinder head is made of. The head could be carved out of hickory and the compression ratio does not change, since it is a physical measurement and a physical comparison of volume. That volume doesn't care what material is around it. It's just volume.
 
I would avoid the snubber and the extra leaves. I would work on getting a quality double adjustable rear shock when you can. Most cars (including mine) are over sprung. The shocks will do a ton more for you than a snubber. Snubbers are not subtle. It will just bounce the tire. All they do is create body separation in an uncontrolled fashion. The A body from spring segment is so short you REALLY need to be hitting a BIG tire hard to get axle wrap.
 
Maybe the axle ratio would have to change. I’m working on a very similar build. If you pm me we can compare notes. I think my theory works on paper but hasn’t been proven yet
 
furrystump said:
I would avoid the snubber and the extra leaves. I would work on getting a quality double adjustable rear shock when you can. Most cars (including mine) are over sprung. The shocks will do a ton more for you than a snubber. Snubbers are not subtle. It will just bounce the tire. All they do is create body separation in an uncontrolled fashion. The A body from spring segment is so short you REALLY need to be hitting a BIG tire hard to get axle wrap.
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This post should be a sticky. Nice post!
 
furrystump said:
I would avoid the snubber and the extra leaves. I would work on getting a quality double adjustable rear shock when you can. Most cars (including mine) are over sprung. The shocks will do a ton more for you than a snubber. Snubbers are not subtle. It will just bounce the tire. All they do is create body separation in an uncontrolled fashion. The A body from spring segment is so short you REALLY need to be hitting a BIG tire hard to get axle wrap.
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I do have adjustable shocks front and rear in the car. The tire size is 235 60 15 so they aren't big tires and I've been considering adding clatracks. That being said I haven't had tire shake or jump yet off the line. It just plants and I go. This season I will be setting my 2 step up so I can dial my launch rpm in better.
 
RustyRatRod said:
The stock amount for the early 340 positive deck height I believe is "around" .025" if I remember correctly.
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My '71 motor which is standard bore and hasn't been decked as far as I can tell had the pistons at .023"-0.34" above deck, so I think you recall correctly. Some of that variation is in the factory machining of the pistons, rods, and block as well as the regound crank it has. I was planning on running a .065 gasket to get the right spacing, if I just plopped a set of small chamber ProMaxx aluminum heads on it.
 
gzig5 said:
My '71 motor which is standard bore and hasn't been decked as far as I can tell had the pistons at .023"-0.34" above deck, so I think you recall correctly. Some of that variation is in the factory machining of the pistons, rods, and block as well as the regound crank it has. I was planning on running a .065 gasket to get the right spacing, if I just plopped a set of small chamber ProMaxx aluminum heads on it.
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Thanks. I thought I was remembering it right. But I never know nowadays. lol
 
Like you said playing with launch rpm will help. Clutch Tamer would also make it much easier to repeat, but is almost cheating in the eyes of the stick guys. :):)
 
Thanks folks, These trips to the track with street tires and 3.55 are few and far between.
I don't have much experience with nitrous, so letting those that know give guidance.
Mikes a quick learner, and eager for knowledge.
The cars plant, launch really well, - till we put decent gearsets in, with decent tires, I don't expect "track" times.
One of my son's hi rpm launches, broke an axle, looked lazer cut, lol.
Their 3 trips to the track has whet their appetites, and they can certainly learn lots here.
Thank-you .
 
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