Or possibly get the primary's closed to where they arent into the transfer slot and then you may get rid of the stumble as well :TU: As for converters,a good quality 10" unit ,shouldnt be too bad ,again if it is a quality piece
I've been off this board for about a year because some a-hole ticked me off. But I'm back and would like to add to this. I am pretty versed in the ways of 12 second 2500 pound sleds. I may have missed it, but this build in in your boattail, correct? With the TA cover comes an adjustable regulator. However TA doesn't turn up the adjustment on it when they install it and send it to you (at least they didn't on mine). My engine would knock TERRIBLY on start up even after sitting just 20 minutes when warm. Cranking in the adjustable regulator cured that by tightening the bypass and preventing drainback. Larry and Jim have already mentioned the cam. Unless you plan on building a serious HP engine, you don't need a massive cam to make power in a BBB. And you certainly don't need to rev a street BBB above 5500. The best thing any builder can do is match the cam to the converter. Yes, heads make the power. But all the head flow won't mean jack if the cam and converter aren't matched. When you swap the 200R4 back in, call a good converter company. I have a coan 3000 converter and coan trans. I hardly notice the converter slipping until I flash it. Then it just gets silly. With street tires it is literally impossible for me to get to the top of first gear in any way, shape or form. It just roasts the tires. I have a TA 413 cam, 1.6 roller rockers, pretty well ported iron Stage1 heads and SP1. Pretty basic build. Idles at 850. Dyno'd at 470. I shift at 5500 and run 12.9's on the east coast. (Ohio is always .4 to .5 slower.) You would do well to learn by our mistakes. Trying to "band aid" problems isn't the right way to go. Drilling holes in your butterflies to aid idling is something I've only seen necessary on 600+ HP engines. Your 430 should in no way need that. An off-idle stumble is always cured with pump nozzle and cam changes. if you can't get it cured there are other reasons. I think you would really enjoy your car better with a smaller cam. ---------- Post added at 02:50 PM ---------- Previous post was at 02:06 PM ---------- Oh, and $20 says your rear mail leaks. LOL
I cant think of anything cooler than a stock looking and sounding engine that just rips everything apart when leaving. My advise keep it as stock looking/sounding as long you dont have a direct race car. Just my two cents.
I hear what you are saying, i really do and trust me I'm already thinking about another camshaft. But, here are some things to offer: -I had a TA 284-88 cam in my old 455 and the power was less (although I do have fully ported heads this time) than this one in all areas but got about the same gas mileage as this one does...and it did that with fuel injection. Vacuum was just barely enough to work the brakes. -I know the TA cover is the cure all for oiling, but I wasn't about to tear the whole block down and mod the oil passages for a street driven car. I may drive it to 6k every now and then but again, my previous 455 had ALL the block mods done to it and i never even got close to 6k with it and still wiped out bearings. -The convertor was just a stop gap to allow me to drive the car. When i get my 200r4 back int he car, I FULLY intend on spending the money to have a proper convertor made for my combination. -As far as tuning the carb, it is taking some effort but honestly, I love it. I'm learning to do things I've never done before and so far every mod I've made has had a positive effect. When i jetted down the primaries from 80 to 76 the throttle response and fuel consumption has made a very positive change. But, as a sign of making progress and planning, what roller cam would every suggest? I REALLY enjoy the lope at idle and would like to keep it as close to possible. Power is really only secondary at this point. I will be moving to Cali in about 10 months so I'm looking for something that does well in stop and go traffic and the highway. ---------- Post added at 04:39 PM ---------- Previous post was at 04:36 PM ---------- Oh, what is a rear mail? Rear main? If you meant rear main, it does NOT leak a drop.
That's what I was thinking. My 212 ran around 14inHg at sea level and my current cam that has more duration and lift runs 12inHg. Hmm. Doesn't matter now, all new combination.
Maybe, I had it set to idle to low? It idled well at 850, with a total of 18* advanced timing and measured AFR was 14.7. Doesn't get better than that...
Could be the gauge too. I've seen a wide variation between some gauges. I have an Autometer I mounted in the engine compartment. I trust that.
I ran my 212 at 800rpm, and I run my current one at 950 just because (I've had it turned down to 650 at 7inHg, lol). Timing plays a ton in idle vacuum (18* seems reasonable IMO), and highest vacuum isn't necessarily achieved at stoichmetric AFR's.
So, I was looking at TA's hydraulic roller cams and $750+ for a cam and lifters is a bit much...especially, when i would need to notch the pistons and probably need roller rockers. If i change the cam, it looks like I'll stick with a standard hydraulic flat tappet. Hell, i could probably just swap my old 284-88 cam if i really wanted to stay cheap.
Did a little more tuning tonight, nothing major but I did find out some critical info. I originally had my timing set at 15* advanced so I turned it up some to see how that would affect the idle and settled at 24* initial and 36 total. I finally hooked up a vacuum gauge to the manifold and found I'm only making about 4 inHg! SOOOOOO, my power valves are open at idle. I've ordered some 2.5 power valves to see how that changes things. Tuning is fun, I actually really enjoy it.
Jason, 4'' of vacume @ idle (@ 800 - 1000 rpm) is off the chart ! How could you advance the int timing & decrease vacume from 12'' to 4'' ? I think you should look very strongly @ a known serviceable Holley, start without any last resort mods to the blades,idle bleeds & PVCR dia. then go from here. Start with 16*-18* int timing (30* - 32*) total 800 Holley DP 6.5 pv pri 80 mj / 6.5 pv sec 80 mj Vacume gauge hooked to known manifold vacume source & check for vacume leaks while @ idle closing the choke slightly or by just holding your hand over the carb body to see if you pick up idle speed & vacume . If vacume is still low (i.e. 4'' - 6'') remove spark plugs & preform compression test , if all cyl's read low (i.e. 70 -90 lbs.) I would then look @ camshaft timing (out of phase ) .... ck lifter preload & that the valves are closing . I have been told that this cam pulls 12''- 15'' @ idle in gear . I bet you will find the problem if you just take it one step @ a time. Good Luck Mark
I have no idea what those thumper cams are supposed to pull for vacuum, but it does sounds a bit low. For reference I run my idle timing at 23*.
Regarding the apparent over-camming issue: How about Rhoads lifters, especially the latest generation V-Max adjustable models? In theory, you'll reduce your carb tuning hassles and increase gas mileage and driveability at lower RPM (assuming that low vacuum is due only to the cam), yet still retain the power you gained at higher RPM. Unfortunately, you'll lose the sound of that choppy idle. I know Rhoads lifters are a compromise (band-aid?), but they may make your life easier for a relatively small investment. I also know how it feels when somebody blows your carefully laid out plans for an engine build combo out of the water (it's happened to more than once), but there aren't many people out there who know more about choosing the right parts for your Buick engine and trans than JW. Just out of curiosity, you did degree the cam and set the cam in accordance with the manufacturer's instructions, right?
I did not degree the camshaft. I installed it to match how the cam in my 455 was positioned (i was looking at it as I installed this cam). It seemd to me there was only one way to position the cam so the gear would bolt on and match the crank gear. Again, I matched it to how the cam looked in my 455. If a cam is "out of phase" why would it run so well? Other than tuning the idle, it runs like a dream. I'm sure I should've degree the cam and I have my flame suit on for what i know will follow but i really didn't see the point. But, i will take Marks advise and take things one step at a time and see what I come up with. As far as vacuum, from everything ive seen on the web, this and the bigger Thumpr cam have all been between 5-7 at idle. Oh, and the idle vacuum was never at 12...that was my old cam in my 455.
