Thread: 454 2bolt hi-po question

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even before that----there are items in this thread that don't fit together-----------straighten out what he has and if its all from the same engine---------

I know guys, I would love to get new valves, but the shop said it would be 350 bucks...Yeah no...I am just having them replace the valve seals for now, I know my valves aren't bent so I'm not worried about that. In fact I don't exactly know why they would be leaking compression, Maybe its my so called bad valve guides, but correct me if I'm wrong, Valve guides shouldn't all go bad at once on a head and leak that much compression..Im sticking to my original thoughts that the seals are too blame for now. I know a budget build should be done over time, but when you have a wife on your ass every day about this kinda stuff, You kinda want it done soon. Rspears: that picture is about 5 months old now, I just love it and my daughter Jerry: I would love too but I had to stick into my budget of just getting the valve seals done up, I actually didn't think about getting the valves reseated though. Dave: I would love to wait, But they will go on for now. When I get the money again ill replace the heads with maybe a nice aluminum set, that will be awhile but hey it can be done.

Just to clarify, compression is going to have to leak by the valve seats, so having the valves & seats done, or maybe just lapping them in yourself with some compound and a cheap suction cup handle might help that issue, but if your valve guides are really bad then a valve or valves could be sloppy on the seat, too, but like you say it's likely not all of them at one time. The seals stop oil from leaking down the valve into the cylinder, generally seen as a big puff of blue/white smoke on startup due to oil leaking down and burning off on startup. You'll also suck oil at times when your vacuum is high, like idle and cruise, burning oil.

valve stems/guides need oil and gets it past the seals---the seals keep exhaust and inlet mixture out of the crank case---so seals must let SOME oil past or soon the guides/stems wear and then they don't do anything-------------------------------

Originally Posted by jerry clayton

valve stems/guides need oil and gets it past the seals---the seals keep exhaust and inlet mixture out of the crank case---so seals must let SOME oil past or soon the guides/stems wear and then they don't do anything-------------------------------

Sorry Jerry, should have said "...keeps excessive oil from running down the valves...."

I'm going to re-seat the valves myself with the method rspears said, Its a lot cheaper to just do it myself sadly. I didn't notice smoke on first start up, but since my heads are in the shop I might as well get the valve seals replaced anyways, its cheap insurance. My pistons did have a bit of carbon build up but that's probably due to bad fuel, and one carburetor that needs a tune. And quite possibly just a small amount of oil leaking into the cylinders at night. But hey, doing the valves myself will be cheaper by about 315 dollars, Sooo that's the route I will take.

Hell, While I'm at it, I might get some blue marking ink, and a couple gaskets and port my heads properly on the intake and chamber, and possibly the exhaust ports too. The thought of doing that makes me nervous but it should be easy as long as I don't take off too much material. That should make the 402 breath better.. Any thoughts on that?

It's not hard to do some bowl blending and port match the intake to the heads. But unless you really know what you are doing, I would advise against going any further than just cleaning up the surfaces on the exhaust ports.

It's not as easy as it appears. If you have no experience at it, you're taking quite a risk.

Yea...On that note, I'll hold off on that as I do lack the knowledge and experience on that kind of stuff.
I just cant wait to get my engine in perfect running order.

here some things to think about from a guy that builds and machines engines every day from what i see . most guys think a port match gasket must happen. false engine will not care. if you do it wrong make something that ok to alot on money and time to fix a bad job. any thing under 500 hp it not realy worth much if you do it right . but i will go down this road some. you need to know where the intake fits on the block just hanging a gasket off the head or intake will get you close . when heads are bolted down you may need to cut intake or go thicker gasket to get your ports line up you my find that there some shift side to side from intake ports to dowles on block . many more.. not going to list them. i do a fair amount of intake and head work yesterday day i spent most of the day cutting a intake out as it mosty a custom cast intake made for race only heads to fit 3 brands of heads were port can be oval to rect port .my rule is it always better to have the intake a bit small better for fuel and air somewhat helps if you get any reversion wave up the intake port . as for blending and bowl work is a wast of time by hand .if you have never done it you have angles on valve and valve seats the 45 is what your engine will be may time race stuff can be face seat angle of 45. 55.50 the valve job should be done first then blend off the last angle this has alot to do with what machine and cutters or stones .to do the valve job with . seat /guide machine or with stones .when cutting a new raw head i use cutter that will let me form all the seat . lest angle of one to 5 angles at one shot so that is why i said bowling them is wast of your time if the machine shop has the machine to do this work .by hand u can hit the main seating face angle and rune the valve job. when i know it stock job i use 3 angle cutter and is a 45 angle i use a 3 angle like 30.45.65. cutter if guy wants more then stock or wants to do bowl work. i us one of my race cutter after i am done a can go deeper with a cutter that cuts the better part of the bowl .if
my last angle of cut .then there not much hand work to do. i finish the clean up if needed by hand blend work die grinder .i have seen heads turn to junk or at the lest a new valve by a guy with a die grinder. many times i hand roll my angles up to the bottom of the 45 face angle this job is very tricky at best one wrong move then seat will have to be re ground if stone or reface with cutter. for this fine work i used a mounted point on a die grinder i use MX/ craytex grit they rubber/grit mount points were you can do fine work and not worry about a sanding roll come loose and hitting the face of the 45. a word about lapping valves you must make sure there is no lapping grit on valve face and valve seat has you used it to seat angle s the grit hanging around it can screw up valve work i use a very fine grit .i some times lapping the valve only to see the lay out or if the finish some seats with the metal make up of the seat finish could be a bit better i use a very fine clover like 600 grit when done i wash valves then go over the face with a scrub pad gray 3m fine .with titaniums valves i do not lap i lay out the read out to were valve is hitting the valve seat with a marker with felt chisel tip like 1/4 tip

Anymore these years I usually only use lapping compound to make mark on valve that I sometimes backcut at more angles for increased flow at the earlier openings-

I just want to fix most of my compression loss, No point in rebuilding a engine if I don't fix the heads ya know? A simple valve lapping should help out a bit. I want every bit of horse power and torque out of a fresh rebuild as I can get.

Also when my buddy and I took the heads off, we measured the valve faces and I do have over sized valves, SO I think chances are the valve seat wasnt adjusted to the bigger valves so they may not be sitting correctly in the first place.

SO I think chances are--------------??????????????????????


You thought you had a 454, but it was a 396/402-----------


Losing compression??????????did you do a leak down check before you took it apart?????????
burnt/leakie valve???if so you have to do a valve job----------if the valve was leaking bad enough to disassemble an engine lapping valves ain't gonna cut it!!!!!!!!!!!!!If your guides are bad, the valve stems probably are worn also and seals ain't gonna help--------------------


You need to positively identify what you have, what the problem was (and where--if only one cylinder ---if all cylinders----)and choose the repair depth accordingly.


what size valves are in it and what diameter stems???? you can fix worn guides by knurling, using guide liners or replacing guides----------


if the loss is via worn rings----you need to hone and rering or maybe even bore/hone and replace pistons---


Any way, I believe that you are over your head in what you think you have and how to go about repairing it---


Get us some numbers and sizes (maybe pics of parts ) and Pat and I can suggest a route to take for repair, replace or to find a boat that needs an anchor---------

Welcome to CHR Imbraced;

I’ve been reading this thread with a bit of a smile on my face and purposely held off posting because Jerry and Pat have forgotten more about big block Chevy’s than I’ll ever know. While I’m not a big block guy, I am a pretty fair motor guy and I thought I’d throw in a few general comments/suggestions based on my observation’s.
1. Buy a book on big block Chevy engines and read it cover-to-cover. Suggestion:
How to Rebuild Chevy 366, 396, 400, 402, 427, 454 Big-Block Engines
2. Repeat step 1 several times.

Take the time to write out what your long-term goal is for this engine. Determine what needs to be done and then take the time and spend the money to do it right. I can’t tell you the number of times I’ve heard about (and sometimes helped) folks who do the minimum required and end up really disappointed. In my industry, there is a well-known old adage, “The demands of the service and the importance of the job are never so great that we cannot take the time to do it correctly.” It sounds like your block is being prepped at the machine shop and that’s a good thing. At the very least, have the it decked and the mains bored to make sure the reciprocating mass will be square within the block. Also have them install your cam bearings as I’ll bet you haven’t done such before and it does take a skilled hand and special tools to accomplish correctly.

You’re all over the place with the heads. You haven’t explained how you determined that you were losing compression and as has been stated by others, valve seals are not the problem. The little I do know about big blocks tell me that the 781's and the 049 heads (last 3 digits casting numbers) are pretty decent oval port heads. They’re probably fine for making 500 plus horsepower - especially if you truly have 2.19/1.88 valves. I am a bit concerned with some of your statements, i.e., “Also when my buddy and I took the heads off, we measured the valve faces and I do have over sized valves, SO I think chances are the valve seat wasn’t adjusted to the bigger valves so they may not be sitting correctly in the first place.” If the heads were originally equipped with 2.06/1.72 and larger valves were installed without cutting the seats the engine would have been a scrap heap as soon as you tried to start it as in all likelihood there would be all kinds of collision going on inside the combustion chamber.

My two cents also says listen to Pat about matching ports. I’ve seen some real botch jobs when people take a grinder and try to do this by hand. At this level, you’ll never see any benefit from any porting work you may attempt. I’d really recommend you save some money and have your heads done correctly by a competent machinist. You’ll be sorry if you try and work around this by hand lapping the valves as this can cause more problems if not done correctly.

Stan Weiss has a web site with all the information you’ll ever need about heads and how they flow:
Stan Weiss' - Cylinder Head Flow Data at 28 Inches of Water -- DFW / FLW Flow Files for use with Engine Simulation Software

I would suggest that you perhaps, start fresh with us by taking pictures of what you have and providing numbers for the block and heads as well as telling us about what you have for intake, exhaust, cam, transmission, read end and oh yeah – what kind of vehicle is this engine pulling around? On one hand you say, “…I want every bit of horse power and torque out of a fresh rebuild as I can get.” But you also want to stay on the low-down where the money is concerned. These are mutually-exclusive targets. It costs money to build a good engine and believe me when I say if you can’t afford to do it correctly, just wait until you have to do it over.

We’re pretty knowledgeable here and the two guys I mentioned above have built literally hundreds of big blocks ranging from stump-pullers for trucks to national champion dragsters. Listen to them especially.

Regards,
Glenn