i'm confused looking for suggestions, 454 new rebuild, wiseco piston 21.5 cc dome, 291 close chamber heads, bored .060, which gives about 11:1 cr, head gasket 1017, this engine runs very hot, i've changed the stat several times, the upper hose has alot of pressure, when the stat is removed the engine will not go above 120, i've removed the heads and had them magnaflux and they checked out ok. the other problem is that the engine runs very rich, the timing chain is on correct and holley 750 dbl pump power valve is good, no matter wear the mixtures screws are set it runs eye bleeding rich with white smoke at idle and somewhat clears after 2500 rpm, i beleive i have 2 problems but hope its just one, looking for some ideas

HERE WE GO AGAIN,this seems to be a very commom theme when new motors or motors with new perf cams are started when it comes to running hot & rich at the same time.

What is the base/initial & total timing set to at this time?

What are the cam spes?

This is often cause by runnng the initial timing too retartded with an aftermarket non stock perf cam. This causes the motor run hotter and to also have lower idle/low speed vacuum that can upset the idle/power circut causing the power enrichment/power valve to come in too early esp a low rpm speed cruise just off idle. This is due to the low idle or low speed cruise vacuum making the carb's power enrichment circut think the motor is under a load requiring more fuel when it really doesnt thus resulting in an overich mixture,the fumes when this happens will litterally burn your eyes. Thats because you have the timing so retartded your forced to adj the idle so high it also pushes the primary throtte plates past the idle circut into the main circut which is why the idle mixture screws done seem to have any affect.

A good place to start with dialing the ign timing with most aftermarket perf cams is 16-18 deg initial,not anywhere from 0-8 deg like a stock gm cam uses,thats way too retarded with even a mild perf cam that has considerably more duration then most stock gm cams had/have.

Make sure the idle is low like 600-650 rpms when setting initial to ensure the mech adv in the dist is not activated while setting the initial which will upset the initial timing setting usually making it retarded. dont forget to also unhook & plug the vac adv when setting the initial timing.

Then when you set the initial to 16-18 deg.

Now you rev the motor up untill it stops advancing and mark down that rpm along with the total deg's adv at that rpm. You may need to buy a timing tape for your h/ballancer if you dont have one to do this.

36-38 deg max all in by 2,800-3k max is where you want the total to be in most cases for a good starting point.

If the total is not at least 36 or its over 38 you must pull the dist to have a shop recurve the mech adv for 20 deg total all in by 2,800-3k rpms.

Then you will have 16-18 deg initial + 20 deg mech adv in dist = 36-38 total.

After your done setting the initial timing and checking the total reattach the vac adv hose & adjust the idle mixture & speed as required.

Also have them install a vac adv with approx 12-14 deg additional adv for 50-54 deg adv at part throttle cruise for better fuel economy/better throttle responce/and a little cooler running motor.

This is the correct way to setup the ign timing curve for most street perf sbc/bbc. I realize its a pia to the pull the dist to have the mech adv recurved if needed but you will be happy with the end result when its done if in fact this is your problem in the 1st place.

If you already have the initial timing set to 16-18 deg (with idle low & vac adv unhooked/plugged)then take a vacuum reading at idle (auto trans in gear) to see what it is.

Then if for example you have appox 10-12 " vac @ idle you should have a
6.0-6.5 p/v in the prim side so check this out too.

Also make sure the secondary throttle plates are not adj too far off the closed/ilde position too as this can add to the rich problem at time too.

You will need to clean or get new plugs too sicne your likely going to fuel foule the one currenlt in the motor so keep that in mind too it is start to misfie,pop/spit,or flat out loos a couple cylenders all together.

Check all this stuff out and let us know what you find & how the motor responds to any adj you make to the initial timing ,etc.

Scott

thanks for the reply, inially i had a internal vaccum leak and found that the intake was milled i then put on a new victor jr runs better but still rich approx 800 rpm have 11 in on the vaccum gage, have a mechanical advance dist MSD and 6a box and set the curve for no advance and timing at 34 the oil and plugs have been change do to gas wash, the water seems do flow strange to me, i have many sbc with up to 750hp and i never have seen a motor temp rise like this one when it has a stat in it.

I was going to post the same suggestion: retarded timing.

Am I understanding correctly that you have 34 degrees of advance at 800 RPM? Is this with vac advance connected?

no vac advance dist, its a MSD mech advance i have tried bringing down to 18 for idle sake but no difference,

another thing i found after the motor sat for a month and a half there was a considerable amount of milky oil on the under side of the valve cover not really mixed through engine, and when i removed the carb found water or condensation on the bottom of carb, thats what led me to pull heads and have checked

Setting the timing for total 34 is the wrong way to go about it not to mention thst a little retarded for total too not to mention very retartded for the initial.

Again whats is you initial timing 7 then total at this time,not just total?

Depending on how much mech adv your ign system has setup in it the initial timing usually ends up very retarded when just setting the timing for the total with out setting the initial 1st . Then doing it this way you can see what the total ends up being so you know how much mech adv you have in the dist when you subtract the initial from the total or whats set in your electronic ign system for a mech adv or total setting.

You need to set the BASE/INITIAL TIMNG TO 16-18 DEG 1ST,THATS A MUST FOR ANY AFTERMARKET PERF CAM,DONT SET THE TIMING NOT JUST FOR TOATL WHICH ENDS UP WITH THE INITIAL BEING RETARTDED IN 9 OF 10 CASES WHICH WILL CAUSE YOUR EXACT HEATING/RICH ISSUES EVERY TIME.

I have a good feeling this is why you have not been able to fix it yet because you have been litterally chasing your tail due to whats looking to me to be a retraded initial & total timing issue that you dont agree with me on which is fine,its your motor.

But if i were you i would do what ever you have to do with your MSd dist/ign system to end up with 16-18 initial/36-38 total and then install a vac adv on top of that if your msd dist will accept one. This is esp trure if this if this motor sees a fair amount of street duty which needs the additional timing esp at part throttle cruise for approx 50-54 deg with not much load at partial throttle,motor will run cooler,have better throttle responces,and use less fuel when running vac adv on street . If you just keep setting the timing for total you will never get the motor running right leaving the inital retartded. That's comming from 36+ yrs of my 1st hand experience tuning/dialing in sbc/bbc street & mild strip perf motors so trust when i say the timing curve i have suggested is a great place to start with your motor when trying to get the ign timing & fuel calibration all dialed in correctly.

After you do that then take another look at idle vacuum in gear with auto trans vs power valve in carb .

It doesnt seem like you have any serious issues other then your ign timing curve and fuel calibration curves all being totally out of wack/adj which can easily be cured if you apporach it correctly.

good luck

Scott

i guess i'm not getting my point in i have set it so it has a advance from idle to running, last time i set the timing i set it just like a drag car full advance so that means it does not use vacumm and it does not use mech advance its set this often gives you trouble when starting but i did this just to elimiate an advance curve problem, i've had it advance as much as 45 but know that is much to high and brought it back to 34, no matter where the advance is the motor still runs rich at idle or at run its rich smoke and gas out exhaust rich

Scott, I think what he is trying to say is his timing is locked at 34.

i respect what you are saying scott but the temp problem seems to be a bigger issue than the rich with a stat the motor can't run for more than 10 min

and has an extream amount of pressure in the top hose

try another carb

Not trying to talk over the top of Scott, but just so I am following correctly, you have 34 degrees of timing all the time, even at idle, locked out mechanical advance?

Yup,i got it guy's .

But if his timing is turely locked at 35 all the time (even at idle) like is being stated thats really not good either esp for hot start issues. 35 deg is way too much for safe hot starts that may possibly break the starter or worse yet break the block where the starter mounts,i have seen this happen mult times over the yrs with locked out timing like he is running,shouldnt be used for a street motor at all IMHO.

Since this is a street car/motor he needs to either modify his dist back to a more normal setup where he can run the proper initial and mechanical timing along with a vac adv or ger another stock dist and get that curved properly for street use. If he doesnt do this he will be chasing his tail with many dialing in tuinng driveability issues on his motor.

His motor would benefit so much from runing 18 initial/38 total at 3krpm(3 deg more then now ),and esp a vac adv adding an additional 12-14 deg ffor 50-54 deg at part throttle cruise.

His motor would feel more powerfull and the throttle resp would be so much better when at cruise rpms withe additonal timing from the vac adv,run cooler,use less fuel,etc.

I still believe this improper timing curve is part of his running hot & rich issues along with general dialing in of carb p/valve etc to better match his cams idle/low speed vacuum.

You can try to help but thats all you can do since he seems to want to keep running a strictly drag racing locked out ign timing curev/setup with a street motor which is the worng thing to do all the way around,i give up because there is nothing more i can suggest unless he 1st gets his ign timing curve corrected for a street motor setup.

Good luck

Scott

If you're getting white smoke (and not bluish white) water is getting into the combustion chamber. You said the heads were checked, which rules them out (as well as the intake and head gaskets as those would have been replaced in the process). That leaves the block. The rich idle could be a carb or ignition issue. Too much fuel going in or the right amount is going in but isn't getting burned in one or more cyls.

hot and rich? I had a girlfriend like that once. But I digress.....

see this thread http://www.chevelles.com/forums/showthread.php?t=181618

you mention rebuild, do you still have access to the head gaskets that were on it at the beginning? compare them to ones you have now. did it over heat before?

see this link: http://reviews.ebay.com/Big-Block-Chevy-quot-Generations-quot-A-primer_W0QQugidZ10000000001563647
read down far enough to see the section about the different cooling system patterns for BBCs.


then see this link for pics of the head gaskets involved.
http://www.hbassociates.us/gaskets.html

then go back to ebay and give the writer of the guide a thumbs-up, he deserves it.

all this talk about the timing absolutly can contribute too the rich probs but not to the hot trouble and the pressure in the upper rad hose, scott this motor is at least 11:1 probably more roughly 650hp so yes it gets setup like a drag car when i can find a reasonable solution to the heat i will put motor back together and setup ign exactly the way you describe. as for the block being possibly cracked, it had been running before it was torn apart to be built up, this has been a project for at least 3 years do to time and $, i'm leaning towards a flow problem and being .060 over at least 11:1 on pump gas; if i determine that the flow is ok i will reassemble and run race fuel thanks for the link i will read it over and over

but not to the hot trouble

Retarded timing will put more heat into the heads.

Has the bypass hose been removed?????
Mine ran real hot w/o the bypass
When I put the bypass back on-----viola----runs way cooler.

Hi Greg,i am not trying to be a wise guy or PIA at all so please dont take this wrong and i am really just trying to help you.

But i have to say your way off base when you stated " timing absolutly can contribute too the rich probs but not to the hot trouble " ,saying that ign timing doesnt affect motor temps is plain wrong.

I have run into this retarde timing issue thing with perf cams/motors 1st hand a hundred times over the past 36yrs i have been tuning perf sbc/bbc along with here in in t/chevelle too.

You really need to wake up and take note of what i am saying here and trying to get you to understand. Getting the timing curve more suited/setup correctly for the street use your motor is now seeing is very importatnt . It definatly affects the motor temps even though you dont think it does,trust me when i say it does especially with a 650hp output motor like your running.

If i were you i would pick up a used std gm dist and have i recurved like i suggested. You cluld also have an elec ign installed at the same time to eliminate the points or just buy one of the GM HEI perf dist they sell these days and have the ign curve setup like i suggested. This must be done before you go any further in trying toget your motor heating & tuning issues squared away. You cant just run a 35 deg locked out dist that primarily a darg race only setup on the street and expect good results. You dont have good results as your already experiencing many of which are due to this very issue,PERIOD.

I dont remember/know what you have for a cooling system or if you even mentioned what your complete cooling system setup is. But since your running what i feel is the wrong ign timing curve for the street that does in fact cause higher temps & you may also have other issues with your overall cooling system too making things collectively worse. 1st of all the radiator may not be up to the task of cooling 650hp,does the water pump have the ineffecient stamped steel impeller causing poor coolent flow or does it have the good cast iron impller,is the fan possibly not pulling enough enough air through rad at times or not spaced correctly in/out of shroud or to radiator ,if running elec fan/s are they blocking air flow at highway speeds,do you have a fan shroud for the fan/s,do you have an external trans cooler to remove that cooling load from the motors cooling system if your running an auto trans,you may very well be rich at idle /low speeds like you say but are the mains lean espcially when at higher highway crusing speeds causing the motor to run lean/hotter along with the retarded timing,now thats A RECIPE TO COOK A BBC FOR SURE any day of the week.

My point in mentioning the other possible cooling system issues is that between the timing issues which are real (running appox 15-20 retartded at cruise rpm/thats huge)and other possible fuel calibration/cooling system issues they are all ONE BY ONE COLLECTIVELY ADDING UP TO KILL YOUR COOLING SYSTEM EFFICIENCY putting you in the situation your in today with a very hot running BBC. I feel/know it will continue to be an issue if you stick with the 35 deg locked out dist on the street along with possibly other mult cooling system issues on top of that,enough said and i hope you can now see what i am getting at .

Scott

i understand that it can cause temps to rise but don't believe it can cause the top hose to be rock hard like it's filled with compression i have run the motor without a cap on the rad. and water shot out like a balloon at least a half gallon when the stat opened and you are 100% correct with the timing causing heat, what i'm trying to tell you is that with a stat in place no matter how the timing is set w/ w/o a curve the temp maxs before you can get 1/2 mile so i guess i'm trying to tell you that i have tried the curve with mech dist as well as tried locking the timing like i do with the race car, i trying to say i've never seen a motor hit max temp so fast without being able to see a major crack, leak, or blown gasket.

Has the bypass hose been removed?????
Mine ran real hot w/o the bypass
When I put the bypass back on-----viola----runs way cooler.

Waiting on the answer to this question. Its my understanding that if you don't run the bypass you have to drill holes in the t-stat. Could very well be your upper hose pressure problem.

ah thats sounds like a a place to look, i did drill one hole in the t-stat, maybe need more, do not have the bypass hose on, i will chech with edlebrok thats who the pump is made by, thanks Bryan!!! and Rob

which would make much sense seeing the motor runs to cool and won't get up to temp without a stat

Greg,A lot of people have deleted the bypass hose and drilled the stat on BBC and had no problems,it would be strange if that ended up being the problem of water shooting out of that rad after only a few mins of running.

But you never know stranger things have happened and that would be great if reimstalling the bypass fixed the high psi in the upper hose.

Having that fixed would allow you address the running rich ,timing,and also if the motor still ran somewhat hot even though the you had the high pressure in upper hose issue corrected.

Keep us posted along the way as you have already been doing in case someone else runs into a similer problem so they can see what your diagnostics were and what fixed it once you get the heating & running rich issues all squared away.

Good luck.

Scott

edelbrock told me that with this high volume pump the bbc especially need the by-pass hose or better yet by-pass kit they offer, talked w/ a local speed shop who runs all bbc in many forms of racing stated that any high volume pump requires a t-stat for high volume and if using a t-stat with holes you will have added pressure, he does not use a by-pass hose as most racers don't but reccomended the kit if going to drive on street, thanks to all with the input and hopefully will be running this weekend!!! all this and its not even my car, its my nieghbor i'm just trying to help and now i'm in deep! yikes!! keep you posted

To whom it may concern.. after putting motor back together, installed a high flow t-stat, and by-pass kit, i found the engine to run much cooler, as for running rich i started with the 4 adj. screws on the holley and turned the 2 secondary ones in all the way and the 2 primary screws one turn out, later bring them out a 1/4 more, timing set with a total of 36 advance, as well as putting in 103 octane fuel, all troubles were gone running excellent but of course could use fine tuning as time goes on. i did remove the by-pass kit to see if it made a difference and it did keep the motor 10-15 degrees cooler, right now the timing has an initial of about 18 and goes to 36 total, i'll probably keep it like this until we try and mix the fuel half super and half cam 2 hoping the motor will take it. End result is that the 11:1 with iron heads is just too high for pump gas and caused the motor to run hot as well as rich, the high flow water pumps really need the high flow t-stat and the by-pass hose is a must if driving on street, thanks for all your ideas on what to look for!!!!!

Greg,glad to see you got it all sorted out.

With the initial at 18 & total @ 36 the timing should be close to where it needs to be and you should not have to change it much from there,maybe just a tweak a deg or 2 up/down.

Its funny how different setups react different to the same mods on the same type motors,many guys get away without running the bypass but it really affected the temp a lot in your motor without it.

There have also been more then a few people that have recently had issues with rad hoses poping off even after they cleaned the paint off the rad connection points and resealed & clamped tight. I bet they also had issues with not running the hi flow stat with a high flow/output water pump.

Thanks a lot for taking the time to keep us posted on all the things you did and the results,its this kind of info that helps everone here in t/chevelle when sorting out issues.

Happy motoring.

Scott