Any noticable torque ?

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cecil4speed

cecil4speed

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Hi guys. I'm going to do some mods to my engine this winter. She's a 69 340 with 10.5 pistons, and OEM thermoquad intake with TQ carb off a newer 340. I'm going to use a stock 69 camshaft or simular, 4 speed with 3.55 rear. She has cast x heads with 2.02 valves now. Would I gain any noticeable torque with going to maybe cast j heads with 1.88 valves? I heard some where that smaller valves may help low end torque over the 2.02s. Or is there another cast stock head that would give me a little more torque on the low end? Or will I not notice any measurable gain in doing this. I'm after as much bottom and mid-range as possible with stock engine without hurting top end too much. Going to 1.88 intake valve may hurt my top end, I'm not sure. I'd like to have off idle or 1000 to 5000 rpm response. She'll rev to 6500 now with now problem, but I usually only go to about 5200. I don't find any gain over that. I don't want to limit my top rpm much lower. I have the x heads, but I would have to purchase any thing else suggested. Money is tight, so this is a consideration as well. Thanks, Keith.
 
Since you are so limited on cash, I would go with a manifold swap to a Eddy Air Gap first. Your idea of going with a head with 1.88 valves has merit, but IMHO, only if the head has been gone through by a professional porter like BJR. Even the valve job is essential to good flow and is the first thing a porter does anyway.

The manifold swap should give you gains everywhere, but you'll also have to change to a square bore carb too.
 
IMHO You will get more noticeable improvement in low end power by changing out your rear gear to a 3.91/1 Sure Grip, coupled with a re-curved ignition, with all advance in by 3,000 RPM...
 
Please don't get me wrong. I know I have to spend some money. I'm pretty sure the heads have never had hardened valve seats installed for no lead fuel so they will have to be pulled to have these installed. I was going to do a home port and clean up job myself also. Not sure on what type of valve job yet, just clean up, 3 angle or what?
 
I was just tuning a '70 340 this weekend past. Complete with the factory intake and an Edelbrock Thunder carb and factory manifolds. This is an E body with a stick. I would recommend somethign similar.. the heads are factor yX heads... you will not gain anything going smaller. Nothing that you will feel anyway. Besides that, the only way to do that is replace the intake seats and it doesnt make much sense to me. You dont need any porting. Spend the coin on a good valve job, new guides, unleaded seats, and new performance valves. Have the intake valves backcut. Buying new valves meas the seat angles can be cut out near the edge of the chamber where they make the best power. Have the chambers measured and if needed milled to get the volume back down to aroun 70ccs. Run the XE268 cam. It makes great power, idles well and doesnt require much for head prep or special parts. And last, make sure teh ignition is curved and the car is tuned well. I think you have a great package there as it sits. gears don't give you power. They simply make use of what your engine makes. AS described above, that 340 will surprise you with the power they make. It's all in the tuning.
 
You say 10.5 pistons, are you sure thats the actual cr? before you buy an intake or carb, cam, valves ect.. take a compression test on all cyl with the engine warm and throttle wide open, if your around low 100 to 160psi it needs to be bumped up, 160 to 180 is ok, but for best torque 180 to 200 is what you need. i run about 205 psi, its a monster, blows the tires off at a half throttle blip. if your at the low end you need a smaller cam or mill the heads if your around 180 + then you can go for a better intake or try a square bore carb with ANNULAR boosters, but the t-quad is set up good is hard to beat. if you shoot for 200 psi you will need a freash air set up, loose converter, no heat in manifold, no machanical pump, and a cooling system that can hold temp in the 170/180 all the time.
 
BTW i am running a 360 with home ported j 2.02, 59cc, 11.25 cr single plane torker II with a 750 holley. Cly psi is what gives you good torque !!

ebay 008 (Small).jpg
 
EL5DEMON340 said:
You say 10.5 pistons, are you sure thats the actual cr? before you buy an intake or carb, cam, valves ect.. take a compression test on all cyl with the engine warm and throttle wide open, if your around low 100 to 160psi it needs to be bumped up, 160 to 180 is ok...

I don't know about the C/R for sure, but eng is supposed to have stock pistons and the 69s had 10.5. Sounds like your setup is what I want though. I want to be able to fry em at ease. My problem now is some one put a pretty rough cam in her and it pulls like a dog until about 35 to 4000, then pulls half decent. They had a Torquer II single plain on it too, but I replaced it with the OEM intake and TQ. Its better, but far from what I want. Its quite hard on gas yet. But I think with a closer to stock cam and some fine tuning it will be more gas friendly with a lot more torque.

PS: I will be doing a compression test before I lay the car up for the winter.
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i would say your low on cr. and overcammed. PM me if you like when you get a reading on the cyl psi. i wouldn't go out and spend any $$$ till you know whats going on in the engine. BTW i run my sb on 93.
 
Every engine is different, but my pump fuel max with open chamber iron is 185.psi. Getting the pressures is the fastest way to tell what your reality is, rather than what the catalogs said. The "10.5" pistons in an un-blueprinted deck block, with typical rebuilt heads, will end up around 9:1.
 
Compression definitly builds torque down low, but you will want to choose a cam that'll work well with the cranking pressure, but you also want a good quench to run on pump gas, i built a .060" 360 with KB 190s & stock J heads, they are a quench "step" dome, with 76cc heads & a .039" gasket, the compression was around 10.2/10.3, with a XE284H cam, the cranking pressure was 190 or 195 if memory serves me, at 3700ft. alt. it ran on 91 octane with ease, & i ran 4.56 gears & a 904, it was a neck snapper, even in a fully dressed 73 Swinger, that car was a blast to drive, even when are DA most of the time was around 5000ft, It would literally Fry the tires through 3rd. gear from a roll 8)
 
Ok guys. Thanks for the info. I think I will be sticking with the x heads. So the general perception is that cyinder pressure is what gives good low end torque? Also would I gain anything with going to 2.08 valves? Does flow give more torque or hp?
 
Skip the 2.08 valve and follow what Moper said. Use the thin Mopar head gasket since the Fel-Pro's and equal like gaskets are twice as thick and will drop the comp. ratio.

The stock intake is OK and fine. A upgrade, kind of would be the Weiand Action Plus. Aluminum and a Spreadbore, but without a choke well. Ports may need to be enlarged for a match to the heads, but that's not really a bad thing since your not really racing this engine and a smaller port would only help velocity and thereby torque.

You said it was hard on fuel. Bad mileage. Are you running rich?
 
dodge freak said:
What camshaft is in there now? I would leave the 2.02 intakes alone, the cam might be too big or worn out, same with the timing chain.
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Cam had been installed in the engine before I got it, but she's pretty lumpy, and they had a TorquerII on her. She pulls good aver 3 grand, but she's a dog on bottom end. I know she's over cammed. I took the single plane intake off and installed a TQ and OEM intake, it helped a little. If I drive 50 or below she's preety good on fuel, but anything over 50, she just drinks it. I'm replacing the cam this winter with a stock grind and duration or simular. I just want her to work like a good 340 should with lots of low to mid range torque, good off idle response and half decent on fuel.
 
rumblefish360 said:
Skip the 2.08 valve and follow what Moper said. Use the thin Mopar head gasket since the Fel-Pro's and equal like gaskets are twice as thick and will drop the comp. ratio.

The stock intake is OK and fine. A upgrade, kind of would be the Weiand Action Plus. Aluminum and a Spreadbore, but without a choke well. Ports may need to be enlarged for a match to the heads, but that's not really a bad thing since your not really racing this engine and a smaller port would only help velocity and thereby torque.

You said it was hard on fuel. Bad mileage. Are you running rich?
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She is running rich, and I have the carb leaned out pretty good. I think my problem is she is over cammed. I guess most are saying just use my x heads with the 2.02 valves, with a really good valve job, maybe go for new HP valves, do no porting on the runners as this will hurt bottom end, and bring my cyl pressure up as high as possible?
 
cecil4speed said:
She is running rich, and I have the carb leaned out pretty good. I think my problem is she is over cammed. I guess most are saying just use my x heads with the 2.02 valves, with a really good valve job, maybe go for new HP valves, do no porting on the runners as this will hurt bottom end, and bring my cyl pressure up as high as possible?
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Considering your future cam, I'd do nothing to the ports of the head, just leave'em stock and as so not to repeat what Moper said, Do what Moper said. That would be the best thing to do for your future set up.

As far as bringing cylinder pressure up, alot depends on where the pistons are at now. IF this engine has the positive deck height pistons (AKA popping out of the block.) No milling is required except enuff just to true the surface for excellent sealing. (Or, as little as possible.)

IF the pistons are below the deck, what you'll need to know is how far down the pistons are. Then with a known head gasket to be used, you can figure out how far you can mill the head for a given taget ratio.

IMO, I would not exceed 9.5-1.
 
The hardest thing about a T-Q is getting a verity or rods or jets to tune it up. To this end, I suggest (And it isn't to popular to be seen/read/heard of doing) is to bend AFB rods to fit the shorter height. Approx. 3/4 of an inch shorter. (Clip off the end not needed after the bend.)
If you can live with/do this, your tunabilty, abilty has gone through the roof with all the AFB rods as a choice to use.
You must be percise in where the bend is on every rod you bend.

Jets on the other hand are limited to what you have and what core T-Q's you get.
 
What you are seeing is not necessarilly the carb being "over rich". What you have is mismatched parts anda cam that is not doing what YOU need it to do in YOUR car. Too large a cam can allow or even encourage reversion, which is when the intake charge is partially pushed back up into the port and intake, and can let unburnt mixture go right out the tailpipes because the burn is terrible and the exh valve is open for too long. It's all about making the parts help each other. You placed a bandaid on the intake issue but the wound is still there. You're on the right track with wanting to replace the cam. But don't get carried away in applying racey technology to your street car or you'll end up right in the same spot with a different set of mismatched parts not doing what YOU want in YOUR car.
 
moper said:
What you are seeing is not necessarilly the carb being "over rich". What you have is mismatched parts anda cam that is not doing what YOU need it to do in YOUR car. Too large a cam can allow or even encourage reversion, which is when the intake charge is partially pushed back up into the port and intake, and can let unburnt mixture go right out the tailpipes because the burn is terrible and the exh valve is open for too long. It's all about making the parts help each other. You placed a bandaid on the intake issue but the wound is still there. You're on the right track with wanting to replace the cam. But don't get carried away in applying racey technology to your street car or you'll end up right in the same spot with a different set of mismatched parts not doing what YOU want in YOUR car.
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This is why I'm asking the questions now. I want the best running close to stock engine I can get, getting the most torque out of it possible. Here's what I'm thinking. Tell me where I'm wrong.
69 340 with 10.5 stock pistons (pull heads and verify pistons)
Get cyl pressure up as high as I can go, as long as I can run 93 pump gas
Use cast 2.02 valve x heads, have good performance valve job, maybe
new performance valves
Use close to 69 340 stock grind and duration camshaft, index cam
( Maybe get a set of Rhoads lifters - any advantage ?? )
Have distributor re curved for 34deg total at what 2800?
Use 850 TQ and OEM intake ( I have now ) or thinking of getting an RPM
air gap and new Edlebrock carb - what series and cfm ?
 
- yes try to get comp test first
-try to find out what cam is in it
-i wouldn't be to worried about new valves, have the heads checked out if they need a v/j have a nice 5 angle with backcut valves, your going for low end so you don't need hi rpm big valves ect.
- i wouldn't go over . 226 @ .050 for cam if you trully need TQ
- look into a modern grind spacific to mopars large lifter size
- if you find say 155psi, but the cam in the motor is the old 509 grind then all you would have to do is get a much smaller cam, and low end would/should pick up a bunch.
 
Forget the rhoads lifters, your intake would be good . but a RPM will pick up mid and hi rpm HP, keep the carb small 600 to 670 for low end, but if you still want HP over 5K i would go more toward 700/750
 
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