Thread: Some problems with my 406

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I built a 406 some time ago and haven't been to happy with it. Its pretty simple. .030 flat tops w/5.7 rods, Comp 280 Magnum cam, Performer RPM manifold, 76cc heads w/ 1.94 I, 1.60 X valves. Performance balanced, Mel 55hv pump. First off, oil pressure sucks, at normal temp. 15 #'s at idle, 45-50 #'s at 2000 rpm's. Running straight 30wt oil. After a short trip, sometimes I pickup a slight sound of lifter noise.
2nd. is timing, running a stock distributor w/ Pertronix ignition kit. Sparknock is crazy, doesn't matter what I do under excelaration it pings. With or without vacum advance even tried a good Crane adj. vacum advance kit. Its a 9.5 comp. ratio and I run 93 octane. Someone told me it needed more cam but the Comp. cam is 230@ 050 and around .490 lift. Any ideas??

Just a couple thoughts! You may have a little too much clearance on the mains but its not all that bad. I dont see anything wrong with 45 to 50 lbs at 2000rpm . Almost seems a little high ar 2000. must be the HV pump. What is your total timing? How about trying it at 32 to 34 total . Your cam selection is good . I do not think the comp 280 is a problem. You never mentioned if you have good headers and exhaust, I hope so, Also what gear ratio are you running ? We're shooting in the dark here a little,so Im just throwing a few things for you to consider. I have built two 406s and loved the performance of both of them, 406 needs to breathe good--good heads ,valves, good exhaust, It doesn't need much gear.Iam just guessing here but I would be looking hard at heads and timing. I hope it turns out to be a simple fix for you. Good luck!

Me too...you have missed matched parts...As it sits you are very possible over 10:1 compression ( dished are closer to 9.2:1) as for oil pressure I think the compression coupled with the HV pump is the problem....Switch to a non HV pump....with a HV pump you are moving oil to fast thru the engine to disapate the heat thouroughly thus keeping the heat suspended in the oil....The hotter it is the thinner it gets.... add compression heat and your having a double whammy....the oil just can't take that kind of abuse..... simple solution....OIL cooler and/or head gasket shims....

There are many solutions here..... maybe a bigger cam to bleed off some low-end pressure....but you need to know the exact static compression.....

Neither a stock pump or a high volume will have any pressure at an idle with oil thinner than water nomatter what bearing clearances you have...... use a oil temp gauge and try to post the temps......

He asked a question....I gave an honest answer....all news sometimes is not good news....we can make his combo work and work right....bad thing is that it will cost him more coin....Sorry

Originally posted by dr_bowtie
Me too...you have missed matched parts...As it sits you are very possible over 10:1 compression ( dished are closer to 9.2:1) as for oil pressure I think the compression coupled with the HV pump is the problem....Switch to a non HV pump....with a HV pump you are moving oil to fast thru the engine to disapate the heat thouroughly thus keeping the heat suspended in the oil....The hotter it is the thinner it gets.... add compression heat and your having a double whammy....the oil just can't take that kind of abuse..... simple solution....OIL cooler and/or head gasket shims....

i dont think a hv pump moves more oil than a reg pump. 40 lbs of oil pressure is 40 lbs. of oil pressure no matter if its, reg. pump. hv pump or hp pump.

lt1s10.....

pressure and volume are two totally different aspects....

If you have a low volume pump and a high volume pump...of coarse the second one will move more oil....High volume....more volume...same thing....

lets say this...I have two waters hoses....1 has a 3/8 I.D. the other a 3in. I.D......both running 40 psi....

which one will get you more wet?.....

Originally posted by dr_bowtie
lt1s10.....

pressure and volume are two totally different aspects....

If you have a low volume pump and a high volume pump...of coarse the second one will move more oil....High volume....more volume...same thing....

you need to fill me in then. if you put a reg pump in a motor and have 40 lbs going down the road and you put a HV pump in the same motor with 40 lbs. going down the road then there is no dif. the bearing clearence determines what volumn pump you need. youre saying that a hv pump will increase pressure and i say with the same spring in both pumps it wont make no dif.

"High volume pumps are for increased demands on the oil system such as higher RPM usage, racing, remote filters and or coolers, etc." where extra oil is needed.

this is what i belive would be the only reason you would need a hv pump. if it moves the oil so fast at 50 mph@50 lbs. of pressure that it cant cool the oil i dont know. it is JMO that if you have a tight motor with the proper clearence then a hv pump wont make no dif.

Del ray, All of us are trying to help you and we all have different ideas about how to go about it. Your oil pressure may not be exactly like you would want it but its not all that bad. I personally would not think of pulling the engine back down at this point. I would go to chevrolet and buy some E.O.S.( engine oil supplement) I know someone who has the same situation with a boat with a 400.The E.O.S. helped his oil pressure and it has done well for over 400 hrs so far.Your clearances may not be perfect but You can live with it. Also that distributor bothers me. It wont cost much for you to have another distributor setup on a distributor machine and run no more than 34 total degrees of timing. Just to try it. I would leave the hv pump just as it is . A small block High volume pump just about amounts to a big block pump with a small block pickup. The H V pump has bigger gears and does exactly what it says. produces more volume. As For the cam, I think it's fine but Im not the cam expert. Tomorrow morning, Call Comp Cam Help Line 1-800-999-0853. Tell them everthing about your engine and your car . They can tell you whats what. For the most part I feel my thinking aligns with Denny's first and last post pertaining to oil pumps and oil pressure.I would be much more concerned about the spark knock than than the oil pressure at this point. Again after weighing out everyones input hopefully you can find some good solutions.

Denny and lt1s10.....

as far as the oil "pressure and volume" you both are right and wrong..... Denny.... your theory hold true under normal conditions.....as the oil gets hotter it also gets thinner thus needing to move a higher amount to keep the same pressure...

clearence is NOT the only thing affecting pressure....heat issues do to.... Yes you will gain 10-20% percent more pressure with a HV pump unless the oil is "overheated" which I think he is.... then when it is I don't care how much volume you move you ARE NOT going to have the sufficient pressure you should have.... re-read the post and try to understand were I am coming from...same theory as pulling a thermostat completely out.... if you do the engine WILL overheat....due to too much flow...same here applies.....

Techinspector.....What I was trying to explain here is that if he is too high on static compression he can use a head gasket shim to lower the compression to get into a safer level.....a .040 shim can drop it a bunch and is cheaper either milling the tops of the pistons or buying new ones and have them re-hung?....

I personally think his oil temps are way too high when he experiences the problem...( try an oil cooler) I get this from his compression and HV pump combined..... I made this mistake 20 years ago on my very first engine...

Hey thanks everyone for your ideas,The pistons are Seal Power flat tops Hyperutectic with the teflon skirts and the pin height set up for 5.7 rods. I believe the book said 9.5 compression ratio w/ 76 cc heads. Heads have 1.94 intakes and 1.60 exhaust. I'm running headers w/ Flowmasters and 2 1/2" out the back, breathing shouldn't be a problem. I think right now I'm going to run Straight 30 wt. oil and add a quart of Lucas oil additive.
As far as the Distributor I'm limited to a small size bodied one because of firewall clearance. (55 chevy) I'm really going to have to work on that timing. Probably going to dump on the vaccum advance and run just centrifical.
As far as deck height, the shop just kissed the block and heads anough to clean things up. I'm guessing .015 total and I'm just running the standard Blue permatorque fel-pro gaskets.
By the way whats the opinion on the Melling 10555 pump?
Also someone ask me about water temp. I'm running a new 4 row core radiator w/schroud and a good stainless fan. No problems, 180 degree's

Originally posted by techinspector1
By dr_bowtie: "head gasket shims...."

dr, where I was going with this is that the motor probably has no squish due to excessive deck height and too thick gasket. If the squish was tightened up to 0.035" - 0.040" by zero decking the block and running a 0.039" gasket, he should be able to run pump gas without detonation. Shimming the heads up further from the deck is only going to make the situation worse.

What is your suggestion on this? As far as changing head gaskets thats not a big deal. Just finding out what to use

I certainly will be glad to find out what the problem turns out to be. I'll stick my neck out. I will be SHOCKED if oil temp. has anything to do with it. ALSO , I doubt that compression has anything to do with it either, unless when they cleaned up the heads they took a lot more off than DelRay thinks they did.I may have to eat my hat here, Cant wait to see.

I got his water temp was 180? Even with water temp below 160 you can have oil temp over 400+.....water temp doesn't cool the oil....so to speak..

A 75 and newer HEI will fit in a 55-57 chevy I have one in mine....The plug boot does rub the firewall but it will fit....Vacuum advance has to point towards # 4....

i belive the problem is in the timing, and i really dont see how the oil temp. would show up that way. if the oil temp. was all that bad then he probably wouldnt have 15 lbs. at idle. could the cam be adv. enough to do that?