Hello all, I recently installed my rear end in my 75' Regal. I had 3.73 gears put in. The stock gears were 2.56. This seemed like a big jump numerically and I expected a big difference in off the line performance. But when I took the car out, it didn't seem like a really big difference from before. My mechanic friend says that I need to advance the distributor more until it starts to ping then back it off and test drive it till I get it right. I think he may be right because it does seem a little sluggish even though when he drove it it chirped the rear tire in second (non posi car) which it did not do with the 2.56 gears. I read LARRY70GS's excellent post on "Power Timing Your Buick V8" and I will recheck my initial timing & order an Hei recurve kit from Summit but in the kit what should I be looking for as they have different brands and combinations? Do I need the weights or will the Crane kit, which includes 6 springs, adjustable vacuum canister and a vacuum adv. limiter part# CRN-99600-1 be sufficient? Or should I only stick with the cheap spring kit? The car will primarily be a street car. Below are the engine & drive train specs. : 1975 350ci stock compression (8.1:1 to 8.5:1) rebuilt short block .040 overbore KB C-118 cam int.284/ex.304 lift 490/490 power range 2500-5500 (idles at 800rpm's in drive) T/A Stage 1 dual plane intake Fred Catlin 800cfm Quadrajet stock HEI distributor w/ Accel Super Coil KB 350 headers 2.25 dual exhaust KB 2200 stall converter TH350 w/ BM rebuild kit Any advice is greatly appreciated and thank you all in advance, Mario.
Mario, The GM HEI is a good low cost alternative to buying a new electronic ignition distributor like those offered by MSD, Mallory, etc. The downside to some HEI's is that they use a lot of mechanical advance. That limits the amount of initial advance you use, and that will make a big difference with the cam you are using. The 118 cam is a moderate cam for a 350, It will like a lot of initial advance. Depending on exactly which HEI you have (they are not all the same), this may or may not require modification. Unlike, the points distributors, you can easily replace the center plate for the weights, and the shape of that center plate and the matching weights can alter the amount of mechanical advance you have. Lighter springs will alter how fast the mechanical advance comes in, and that will also help a lot. Whenever you do that, you also need to limit the vacuum advance canister also. I have never used an HEI in any of my engines, so maybe someone can chime in on which kit they used, and how it worked. There is some feedback in the Power Timing thread, but you will have to find it. Being that you will need to modify the vacuum advance, a kit like this may be what you want. http://www.summitracing.com/parts/MRG-6011/ Again, I'm not sure which of the many kits have the best shape center plate and weight combination. Before you buy anything, let this thread play out for a few days. May be some one has some better feedback.
Thanks Larry. That's good advice. I'll wait for more responses and review the replies to your Power timing post. Mario.
Well, Mario you're getting good advice on power timing your distributor and that may be a major part of your slow acceleration off the line. But, I have another suspicion, your KB118 cam/converter combination! A few years ago, I built a very similar engine for my Son's '72 GS350. We used the same cam, intake, carb, and headers as you and ours had 3.42 gears. Initially, we tried it with a 2000 stall converter and it was very sluggish off the line until the engine hit about 3000 RPM, then it would go like a bat out of h---! In order to get it into the power band quicker, we changed the converter to a 2800 stall unit and that resolved the problem. We gained over a 1/2 second in the quarter and the car would fry the tires on the street! So, all that said, you have a cam that works best in the 2500-5500 RPM range operating thru a 2000 RPM converter. I would recommend at least a 2500 RPM 10 inch converter or even a 3000 RPM unit. You should then, have much better off the line performance with the distributor mods you will do. Good luck.
Thanks Ray. That makes a lot of sense. When the car gets up to its operating range, at about 3000 rpm's, like you said, it does fly. I think the problem may be solved with both your's and Larry's advice. When I bought that converter from Kenne-Bell years ago, it was the only one they had available for the 350 and the price was right at $99.00. I guess I should have done my homework better. Thanks again, Mario.
ditch that accel supercoil, a stock one is way better, and their plug wires too, if thats whats on the car...
Good advice so far. Let's take a look at the TA website: http://www.taperformance.com/proddetail.asp?prod=TA_C113-350 On the 455 version they actually recommend 10:1 minimum which is strange because you would think the opposite would better apply. With the low compression I'd actually go with the high range converter right to 3500 if it is a generic unit if you have good traction. The low compression 350 would drive about the same as a higher compression 455 would a 3000 stall when driving around town. What you could do after you get that timing right is install a 1" 4-hole spacer under the carb plus you could make sure the cam is advanced +4 minimum and maybe go for +8. That all will perk up the bottom end while waiting for the converter.
I agree with the others, get a quality converter from Jim W: http://www.v8buick.com/showthread.p...ers-Lifetime-warrantee!&p=2056212#post2056212 I would go with a 3000 stall with that cam. Also spend some time fine tuning the idle mixture screws to get the highest possible vacuum readings when the car is in gear with wheels blocked. having a stronger idle will help the throttle response. Another trick to help the low RPM power is using manifold vacuum source for the vacuum advance canister. I limit the canister to 10 degrees and then I can still run 34 degrees total plus the vacuum advance giving 44 when cruising. When I floor it the timing is at 34 as the vacuum advance goes away.
a stock sbb is more of a torque motor due to bore/stroke. it's not a fast rpm climber. when you add performance items to it, say for racing, it really doesn't come alive until the 3k range. it becomes more noticeable when you start adding the extreme stuff. feels like a shot of nos has just been added. properly built, the 350 will turn 7500 with ease. again, properly built. for your car 3.73's is the minimum gear with a 3k converter. if you wanted to keep the old converter, then 3.90's would be needed. one more item i would suggest is 2 1/2" exhaust. i found the more pipe(length) behind the headers, the slower it goes.
if you limit the mechanical advance to +/- 15 dgrees with no vacuum advance you can start at 19-20 degrees initial which with a slightly rich idle mixture will give you really good throttle response.
