Engine wise it sounds like your in good shape. Compression is even Leak down test was good. No noises. It sounds like it might be some of the supporting hardware then such as maybe carb, cooling system, and torque converter. Keep us posted
You guys just cured me of ever putting a Q-Jet on my car, I can go out after 1 hr reach in and turn the key and that car will start right up and keep idling. if it is two hrs I guess it will need 1 slight pump of gas and it will fire right up. That SP3 does a good job. you have to set the choke so the car will run on the fast idle cam at about 1200 rpm When you push on the dashpot after the choke is closed it should open the choke about 1/8 inch, if it is too much or not enough you bend the link on the dashpot to have the choke more open (go past 1/8 inch) or close the choke more to 1/16 of inch, use a drill bit to set this. You play with this until the car keeps running at the 1200 or 1000 whichever you want to use for fast idle speed. I always like this challenge since in my day you had a 2bbl carb and points and that car had to start right up when it was 10 degrees out with a half spin of starter. When I first built the engine i bought a brand new radiator for a air conditioned 350 Buick and I have never went over the 180 on the temp. It has taken 25+ years to to go to 190 and will not go no higher I probably need to get the rad flushed now. you guys that get your 350's rebuilt should bump that comp to 10.1 obviously that 9.01 comp is giving issues with the cams and over heating. I am at 10.6 One more thing, I use a trans cooler that is in front of the rad and a cooler trans keeps the heat out of the rad, but I still use that part of rad to help warm up the trans too.
So what is the static compression ratio of this engine? Here is the Sumitt page on the Sealed Power 340P piston, https://www.summitracing.com/parts/slp-340p30#overview Compression height is 1.835". Stock 350 deck height is 10.187". 1/2 the stroke + rod length + compression height, subtracted from deck height = how much piston is in the hole. 3.85/2 + 6.387 + 1.835 = 10.147. 10.187 - 10.147 = .040" in the hole. What is the piston dish volume on the 340P? Without that, we can't know SCR. I'll post this article again on Dynamic compression, http://www.empirenet.com/pkelley2/DynamicCR.html The TA284-88H cam is 284/288 Adv duration with an LSA of 110* It takes 9.0:1 SCR to get to 7.0 DCR with the TA 284 cam installed at 106*.
I'm trying to follow along with the math as best as possible. I'm going to try to run some of these numbers on my own. But the dish volume should be right around 10.17 cc's. Knowing the pitons are .030 over, so the bore is 3.830 piston top volume of 10.17 Head gasket- Not sure- I used .040 stroke- 3.850 deck height of .04 ( however I dont know how much my heads may have been decked, but Im using stock length push rods, so I would assume the engine builder used the correct size head gasket to compensate for anything shaved off the heads?) Gasket thickness .04 And combustion chamber of 58cc Theoretically to me this calculates out to 9.72:1 SCR Does this sound right?
The Dynamic Compression Ratio article I linked for you has a really neat calculator at the end. You can download it and install it on your computer and play with the numbers. If the dish volume is correct at 10.17cc, the SCR is in fact 9.72. How sure are you of the dish cc's? Seems pretty shallow. And your DCR is 7.56, which is great.
Larry, I did try to download the calculator but had issues getting it open on my computer. Thanks for doing the calculations for me. And to be honest I'm not sure for my specific pistons. But doing some searching on the board and google found 3 different pages where people had either calculated, or measured the volume of the dish for the 340P pistons. I found between 10 and 10.17 were what the 3 different posts said, so that is what I went with. I believe they were advertised when I bought them as a 10:1 piston. Obviously I know that's only advertised and will vary with the amount of decking the head and block got. But 9.72 I would still be happy with.
Some 340P specs: Bore 3.8000 in (96.5000 mm) Compression Distance 1.835 Head Illustration 28 Head Type Recessed Head .085 Deep x 3.050 Diameter - 10.0:1 C.R. Minimum Clearance 0.0015 @ Bottom of Skirt Note 1 Oversize Inch .030 Oversize (in.) 0.03 Part Material Cast
Again using the calculation for volume Depth* pi*r^2 = .085*(3.14159*1.525^2) = .6210 in^3 .6210cubic inches = 10.17cc Even considering this as a theoretical measurement I wouldnt imagine it would vary significantly from this calculation. Knowing everything else I know about the engine, it sounds like hopefully, the compression ration is acceptable for this cam and should be ruled out as an issue if everything Larry says holds true.
Yup, looks good. I would concentrate on getting the right carburetor on there. Have one of the QJ guys here on the board build you a properly calibrated carburetor, or, get a wideband and see where the QFT carburetor is. Then, I would use a nice 2 row aluminum radiator with 1 1/4" tubes, and get one of Jim's 9.5" converters. You'll think you are driving a different car.
This guys car should run good and HARD. More often than not guys are dissatisfied with the 284 88h cam in a 350. TA should NOT be advertising this a slight improvement over the 212. Anyone who builds a motor and uses the 212 report back with nothing but positive experience. This guy has the stall, the gearing , and the compression which is what I lack but I have a better running car....I would not recommend the 284-88h to anyone at this point. I went through hell getting mine to run good. The OP has said that he has went through the motor twice now and everything checks out. This has to be fuel or ignition doesn't it? 284 88h needs the double pumper with 4 corner idle. Proform has a nice electric choke double pumper in stock at summit for less than $500. Rule out ignition then try the double pumper. My car runs at 190 degrees with a 90 dollar o'Reilly radiator.
Here are the other 2 calculations based on your numbers. Not sure why some guys have a problem getting that calculator to work on their computers. I keep it on my desk top for easy access.
His quickfuel slayer is most likely vacuum secondary and no secondary metering block. I'm starting to think all along it was never my single-plane intake causing my trouble. I think it's just the 284 camshaft. And I think that cam requires the 4 corner idle and double pumper and hours of tuning.
Larry I got it working now! Thanks! there was originally an issue with how the files unzipped. But Ive got all the same numbers you have now and everything looks to check out.
Reidk, Its true the QFT is a vacuum secondary and I dont believe it has 4 corner Idling. However, I should be able to get this to run with a properly tuned Q Jet no? Id prefer the Q jet, but at this point would try just about anything to get the motor to work. Honestly I agree with you on the 284... I originally called and ordered a 212 but somehow got talked into the 284 cam by whoever I was talking to on the phone.... boy do I regret that decision. So I'm trying to do as much as I can with this cam so I dont have to pull the motor and swap the cam.
If he had the SP3 intake, I would agree, but the Dual Plane TA 350 Stage1 intake should work with a good QJ. Holley type vacuum secondary carburetors are problematic for many. Yes the DP carburetors are way better. There is nothing like a good properly set up QJ IMHO. I use one on my current engine and it is seamless everywhere.
I agree with you but how long is it going to take to get that custom built carburetor? The ridiculous 284 88h camshaft might be the difference with what carburetor works the best.
Honestly I'm starting to think that our camshaft is not meant to be a nice streetable cam so I don't know what carburetor will work for you the best. There are stories on this website that go back several years. some guys just pulled their 284 out of frustration and put something different in.
