Discussion in 'Race 400/430/455' started by GS Kubisch, Oct 21, 2007.
No, a sealed hood scoop is developing air pressure, the amount of which is relative to vehicle speed..
I have run open hood scoops, with tunnel rams with the carbs sticking up in the scoop, and the scoop sealed, as well as sealed scoops with single plane manifolds and single carbs.. never had any problems, and run everything from Dominators to Thermoquads to all types of Holleys and Q-jets..
As far as I am concerned air cleaners are for street cars.. unless your racing in a sandstorm..
Most cars pick up a little on the strip without an air cleaner, some may not, but it's always worth a try.
Ran 36*for a while but in good air it would detonate a little on the big end.After some experimenting I left it set at 34* w/o any retard and the car picked up solid w/o any detonation (to my knoledge) on 93 octane.I dont know how larry's getting away w 39* ,did you try another timing lite?Maybe it's that 118 cam(late intake valve closing,short overlap,wide Lsa.Every car-combo is and always will like somethig a little different.AS far as air cleaners go for my street car with stock hight hood iv'e tried alot of different combos of air cleaners over the years (it's the eisiest thing to change).Stock ram air,stock ram air w flipped lid,stock ram air w flpped lid and 4" k-n,morosso drop base w 3" k-n (4" wouldn't fit),morosso drop base w 3" k-n and k-n filter lid and open carb.car seems to run the worst w stock ram air and best w morosso drop base w k-n 3" filter not w the open carb. I was thinking of trying a k-n stub stack on the open carb to see if that helps w the turbulence,or rob c told me to try just the base of the air cleaner w the open carb.I guess i'll try those 2 next season but so far no luck w open carb just the thought of sucking a rock into the carb.O and dont waste your money on the k-n filter lid it didn't do a damn thing for me unless your looking for a used one in that case iv'e got one for sale
I could always hear my engine detonate, even at full throttle. My exhaust is not that loud. I haven't heard it detonate since going to the aluminum heads. It runs happily on 93. At Cecil, I added 2 gallons of 110 to about 6 gallons of pump 93. I eventually bumped the timing up to 38 or 39* It didn't detonate as far as I could tell. I realize that just because I didn't hear it doesn't mean there was no abnormal combustion at that timing. I don't intend to run that timing on my engine routinely. I just wanted to see what would happen at the track. The car definitely picked up. Knowing what I know now, I would have dialed in some retard at 5000 RPM plus. Maybe it is the engine combination that allows me to get away with that kind of timing. You guys with alot more compression 12-14:1, I'm not surprised that more than 32* makes no difference. I have 10.4:1 and a late closing intake valve.
Landshark1969, the KB118 cam is 228*/246* at .050, 118* LSA, .490/.490 lift. It was a cam made to crutch stock iron heads(18* more exhaust duration). It no longer fits the rest of my combination. I would like to try the 288-92H cam. That is the one JW recommended to me. That is 231*/234*, 110* LSA, .525/.525 lift. It would increase my DCR from 7.51 to 7.95
Found my last BBB blueprint and dyno sheet. AM&P did the work.
CI = 464 / Heads = worked over iron 1967 430s
Power band 4500-6500 RPM
Max Recommended RPM 6500
Compression Ratio 13.01 - 1.
Max HP 605 @ 6400
Mx Tq 567 @ 5000
Timing 36 degrees. Locked down.
int lift .600 adv dur / deg dur at.050 265 deg
exh lift .607 adv dur / deg dur at .050 274 deg
in lobe center 106 deg / ex lobe center 110 deg
installed - degreed in at 107 degrees.
Carb / Intake
1050 Dom - jetted 92sq. / SPX
This combo took my 3750lb (with me) ladder bar GS to a best of 10.52
I think I got 30 passes out of it before I blew up the motor.
From what I learned -- If I wanted to be "safe" I would have been better with an under 12:1 compression motor. With less than 34 degrees of timing. Shifting and through the traps at under 6000 RPM.
Not looking to re-hash any ill will. -- Just saying if I were to do it all over again in a very similiar manner I'd feel real confident taking the "safe" route. IMHO Would have still easily been in the high 10's on a "budget" no girdle, non aluminum headed motor. -- And probably still BBB powered today.
Motors get hurt for a lot of reasons.. now that we have the build, what exactly failed on it?..
While detonation can certainly be a factor, there are plenty of BBB with a similar description to yours in race cars, that live a long and healthy life, and while 36* is maybe higher than I would anticipate it would require, obviously Mike down at AMP dynoed it, and it apparently wanted that much timing, which is certainly possible.
What type of fuel were you running? What kind of fuel system?.. Detonation most often is caused by either inadaquate fuel for the combo, or a lean condition with the engine or some combination of both. I would be hesitant to say that if you had the timing set at 32* that it would still be around, certainly without seeing the engine and the failure points.
Was any post failure autopsy performed by the builder, to identify the exact cause of the problem? I know if I built it, and it failed in that time period, I would certainly want to see it again, to see if I could recitify the problem, and work with you to make you happy.. I am sure Mike is the same way.
That motor's power output is nearly identical to the alum head Level 2A motor I build here, and have had very good luck with several examples. No doubt due to the aluminum heads, that motor makes more torque, the same HP, and does it at 10.6 to 1 on pump gas with a much smaller cam. While it's a solid buildup, it's hardley exotic when it comes to Buick race engines.. no girdle, hydraulic cam, just good rods and pistons, our standard upgraded TA SE STG 1 heads ect ect..
When you get into the 800 HP range, with the big roller cams and such, then the Buick block issues rear their ugly head, and while I would recommend to anyone that is going to build a race motor with 600+ HP and is going to pound it consistantly at the track, that a girdle is a good insurance policy, I don't at all believe that power level is beyond the capability of our stock blocks, so I am curious as to the exact point and cause of the failure.
In most cases more timing will show more power on a dyno but it does not mean it will go faster on the track and it also does not mean the motor will live, I wasn't trying to make anyone mad by saying stupid, if you know me that is just how i talk. and i hate it when people blame the engine for blowing up.. it didnt blow itself up, 9 times out of 10 the reason the engine blows up is how its tuned
Rod, totally agree with you.
36 degrees on a dyno in a controlled environment is one thing. But at the track on a hot day with heat soak, high barometer, etc is another.
When Larry ran that much timing (39) it was after a rain, cool and breezy and the barometer had not started coming up much.
All this has to be taken into account.
I'd always want to have LESS timing than more....just not worth the risk.
Another point is that two motors can run the same ETs. One set up on the lean side and less timing or another rich with lots of timing.
EGT's is where you can see it and tune it.........my car runs best at 1410-1430 but is safer around 1350.
A motor will run the fastest at leanout....like when a motor runs out of gas.....speeds up right before it shuts off. But it's risky to run at lean max power.
We ou: have 3 different timing lights, Actron, snap on , and craftsman, all new, and they vary 2 degrees when checking the same engine.So we just use the craftsman on everything.
We took what was left and inspected with Mike. He was the first to open it up. There was much discussion in the past on this, and the bottom line determined nothing conclusive other than bearing seize/failure. Nothing bad on Mike or quality of workmanship implied here. He did offer to take care of me as you would as well. I decided to throw in the towel until something better comes along. Distance being the factor on AM&P, I've stayed with Opel Engineering in Streamwood Illinois. Otherwise, I'd would with no hesitation use Mike and AM&P again.
I understand your questions regarding fuel system etc. My entire combo and chassis was well overbuilt for the motor. That being said, when I went with the BBC I changed absolutely nothing with exception to a BOP tranny adapter plate and other basic swap mods. I've been very pleased having more time to race then wrench with two (reasonably) troublefree seasons.
Since then I've also improved my chassis to 8:50 certification and someday hope to put an aftermarket BBB combo back in.
What I'd like to see is something a little bit more conclusive on this thread. Like many others, it still seems circular with a ton of expert opinion. On the other hand -- maybe that's the best there is considering the circumstances and numerous flaws associated with pushing the limits on 32-38 year old blocks.
More good stuff here. I have experiment with the extended nose plugs even though a good engine builder told me to not run them, my car seems to like them and runs a little cleaner and faster with them. I agree with Rod and others, I just like to stay conservative on the timing. If I was running a class where I had to make every last hp like Tom Rix, then I might lean on it more. But an index class where the car can most of the time run .2 under, it makes no sense to get wild with timing and jetting. I like going rounds, not repairing engines all the time.
Jim witch Plugs are you Runing in your Stage2 heads.
Jeff, I have been using the Autolite AR3911, I don't know what others use , but they seem to work for me. I have run AR3934, but I didn't like the way it ran as well. I have a set AR3910 but have not tried them. What is everyone else runnning?
My Dad and myself run Stage 3 High Ports
We have run the Autolite 4055 and 4054's and the NGK BR8ES,BR9ES
Does anyone have cross reference for heat Ranges on NGKs to Autolites.
I would like to run the 5/8 Plug Socket size instead of the 13/16
The Autolites I run are the 5/8" socket. Are the 40 series hotter or extended tip , what's the difference with the 39 series?
in my 14.5 comp 535" I used 111 Accel
in my 10.6 comp 470" I use 114 Accel
starts right up EVERYTIME, idles like a purring kitten, good power, I tried every thing under the sun and these have ALWAYS been the fastest and most reliable
your choice may vary... :TU:
Jim I now on the A/C Plugs and Autolites the Lower the number the colder
the heat Range like the 39's would be colder and the 40s would be a
hotter heat range. On the NGK plugs they do things different they
go up in Numbers My friend that Runs Nitrous uses a NGK 10s when
running the Nitrous when he runs it on the motor he runs a NGK 8s.
If RACE engines should stay at 35 total timming or less after jetting and other factors are adjusted.....
How about the STREET/STRIP engine with these common specs?
9.0 to 10.5 compression
.075-.095 deck height
180-200 degrees engine temp
224-235 duration on intake
2800-3200 torque converter
3200-5700 RPM range
3.73-3.08 Gear ratio
93 Octane fuel
3800 LB. chassis
100 plus temp. of under hood intake air
I think most all RACE engines will have .040 deck height, polished chambers, cold air intake, etc, etc, and may have different timming needs..TRUE or FALSE??