Removing heads with engine in car

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I am starting to think about the winter projects. I want to disassemble the top of my engine to check on condition after its first 10k miles. I will also like to remove the heads to possibly do some minor porting and shrouding. That said, i want to do it without removing the engine. I have done it with the engine removed so I understand the procedure but I was wondering if there are some other issues I need to be concerned with by removing the heads with the engine in the car. Do I get enough clearance past the shock towers? I have head studs so I would need a bit more clearance than if I had head bolts. On the driver's side I will have to fight the A/C hoses but I think I can get around them after loosening the compressor. I don't want to deal with emptying the A/C refrigertant.

 

c9zx

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" I have head studs so I would need a bit more clearance than if I had head bolts." The extra room you will need is the distance the studs protrude from the block. If you do manage to get them off, I'd go back with bolts. I got bitten by head studs in the late 70s. I've never used them on a street car since. I hope all goes well. Chuck

 

trillizo_y_uno

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Man Tony, pulling the heads off, just because?  I wish I had so much time in my life to burn!

BTW, isn't porting/unshrouding CC heads a bit of a catch 22?  You may be able to accomplish some unshrouding of the valves, but you will lose some compression.

 

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What don't you like about the engine's performance? Was it a disappointing dyno number or a 1/4 mile MPH number? What doesn't the car do that you want it do? Thirty years ago I spent a lot of time, effort, and money chasing a tenth of a second in the 1/4 mile and I never got there. It was a 13.09 second Boss 302 street car and I wanted a 12.99 second time slip. I'm sorry if I sound like crazy uncle Bob, just trying to help. Chuck

 

Bill73Ragtop

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former owner (25 yrs) of 1973 Convertible, 351c, A/C, RA
Don't brace your elbows on the top of the fenders when lifting out the heads....even with fender covers.  I did it once without thinking about it and the resulting dents were painful to see.

 
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Thank you for raising all very important points. Yes, in one way I ask myself, is it worth it to gain maybe 20 more HP? I also tell myself, if ain't broken don't mess with it. On the other end, I tell myself, you should have done this when you assembled the engine? And then I ask myself, if I can gain some performance with little monetary investment, why not? All these things are going though my head. If I can remove the heads in the car I don't think it is that much work specially over the long winter months where I have the luxury of many months of not using the car. It is also true that by shrouding you incrase the chamber size and so the CR goes down. However, I don't expect shrouding to be more than 1cc, probably less, which will reduce CR by 0.1. Also, I think the most gains are from shrouding the intake only so that way you can reduce the amount of material removed. An alternative is to search for thinner gaskets to compensate.

In any case, here is a recent chassis dyno sheet, which I think I have not yet published. Let's not focus too much on the numbers, but look at how the power is dying after 4,500-5,000 rpm. I understand that my cam lift is not that much but I was not expecting it to die off so early. This is one of the reasons why I think I should be able to gain some power by increasing flow by shrouding the intake valve. From my research most of the flow gains are below 0.600 lift, which is where my cam is. Yes, it is possible that I am being hopeful, but there is that hot rod mentality that pushes me to improve if within the possibilities. If not the heads, for sure I will be removing the valve covers to check that everything is good with the valvetrain. 

Dyno day at HRPT2021.jpg

Look at @73' mach 1 dyno run for comparison. He has a very similar setup except that he has a cam with slightly more lift and some minor heads porting.

Edit: notice also how the torque numbers are very similar between the two engines but my fall from the sky at about 4,500 rpm.

79518.jpeg.59ae3d7afbeb04bbbe5f33979d4682aa.jpeg

 
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trillizo_y_uno

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Hmmm, I'm no expert.  But as George Pence once said, "If you have an engine, equipped with 4V heads, that flattens out before 6000 rpm, it has a problem. Floating valves, collapsed tappets, valves sticking in their guides, carburetor secondaries that don't open, malfunctioning ignition, exhaust valves opening too late, somebody's pounded a potato up the tail pipe".  So looking at our dyno sheet, I don't think your issue has anything to do with valve shrouding.

 

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I assume you are using 351C 4V heads. An extra 10-15 CFM  of flow is not going to fix the problem. There is a fundamental problem somewhere else. Does the car lay down after 4500 RPM when you drive it (confirming dyno data)? I have no experience with aftermarket EFI but, I'd start by trying to determine if it is working properly and will support the power levels you should be seeing. I've seen dyno charts where the spring looses control of the intake valve and the numbers fall off a cliff. The basic cam specs you have published look pretty normal but they say nothing about the acceleration rates of the lobes. Controlling the large and heavy 2.19 valve at RPM can be a challenge. Do you have seat and over the nose spring pressures? If you want to talk to a pro I can recommend Brent Lykins, Lykins Motorsports or Mike Jones, Mike Jones Cams. I hope you get it figured out without too much drama. Chuck

 

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I'd be  curious to see A/F ratio along with the power. Can the FITech datalog? Can it log fuel pressure? I agree that there appears to be something that's holding your combo back above ~4500 RPM. Air filter/ cleaner assembly too restrictive, fuel delivery, injector capacity, something like that perhaps?

 

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Mebbe that will sound like a stupid question, but what kind of headers do you have? If you have hookers or similars, I'd take a closer look at the flanges of the one were your lambda is. I saw after having my sniper AFR going all over the place a few weeks back that my headers were the bad guys. (took me ages to find out what was going on) The thing is, even if on mine the gaps I've found were relatively bigger due to corrosion vs what you'd find on new ones, the way they are made, basically tubes being pressed/inserted from behind the flanges and then secured by a few welds doesn't cut it for the sensor. They are not air tight and the little tiny spaces do grow under pressure at higher rpm and when hot. No gasket can fix these either, you won't hear a leak and under load, they will let air enter at the port. They are fine for carbs but not for EFI's, causing the sensor to register foreign oxygen that should not be there. Which in return affects the mix. Welding them from the back of the flange did fix my fluctuating AFR issues.

As @mjlan said, do a datalog and check the afr values.

 
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Yes, that's the problem. Basically, it shouldn't be flattening so early and @trillizo_y_uno and @c9zx may be right that it is not an issue with shrouding. Actually, when I drive the car, it feels with power all the way to 6000+ rpm. It doesn't feel like laying down. However, I don't have anything else to compare to except the Ferrari I tested the other day. :whistling:

EFI/fuel: @mjlan I don't believe it is an EFI issue. The AFR stay in the low 12 range all the way up to 6,000. Unfortunately with all what was going on at the dyno I forgot to turn on the data log, but I have logged acceleration passes many times before and after the dyno. The AFR stays within the 12 range. I admit it is a bit on the rich side, but that shouldn't be causing it to drop so much. After getting hammered in Facebook with comments, I have since upped the AFR target to 12.8 from 12-12.2.

Headers: @Fabrice see above. AFR steady on the rich side but not totally out of whack. They are Hookers, headers to be specific :biggrin: .

Valves/Springs/Lifters: @trillizo_y_uno@c9zxthis winter, the first step will be to remove the valve covers and intake manifold to check the valve train. My springs are allegedly those recommended for the cam, but I will double check with Comp. They are Comp 924-16 with a rate of 347 lbs. My lifters are Gaterman, which are one of the bests out there. My whole combo was sourced/adviced by Tim Mayer, who is an expert in the subject. The valves/guides/springs were installed by him as well. They also took care of the installed height, but I will double check that over the winter. That said, is there a way to check or confirm that valve float/sticking is physically occurring or has occurred? However, do you think that with a relatively low lift of 0.558" I will be having valve float so early? 

Air filter: @mjlan I don't believe this is an issue since we tested with the hood open on the second run. Having RAM air, the air filter is completely open at the top. The air filter has less than 10k miles on it.

I welcome all your input. Thank you. :help:

 
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mjlan

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In my experience if the valve spring open pressure is too low you would know it- not only would it show up on the dyno plot as a more drastic drop in power as Chuck mentioned, but you would probably also feel it in the seat-of-the-pants dyno. The car will fall on its face like its on the rev limiter...

Dumb question: are you getting full throttle? I know this sounds silly but I suspect with your torque numbers you have traction issues, and its tough (for me anyway) to get to 5k+ RPM on the street at full throttle in a gear that won't blow the tires away...

 

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I would try to eliminate the simpler stuff first.  Could very well be an ignition issue.  What is your ignition setup?  Is spark jumping at high RPMs?  Is your spark plug gap right?  Is spark getting blown out at higher RPMs?  Do you have a carb you could quickly toss on for a dyno run to compare to the EFI?

 

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Gatorman lifters require tall lifter bores to keep the oil band from coming up out of the lifter bores. Do you have lifter bushings that extend up enough? Otherwise the lifters will loose pressure every time they are pushed up, resulting in collapsing at higher speeds. A reduced base circle camshaft also helps.

 

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"Actually, when I drive the car, it feels with power all the way to 6000+ rpm. It doesn't feel like laying down."  You would feel that drastic of a drop off in power. I'd find another chassis dyno and make sure there is no tire slippage. I'd want another pass to confirm or refute the first dyno chart before starting to disassemble the engine. Trust but verify. Chuck

 

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Tony-muscle,

Looking at your GREEN hp numbers in the 5 to 6 K range, where the hp is falling off. i see a small dip then it comes up a little then a bigger dip then it comes back again, that should never happen.

I dont have a lot of v-8 dyno experience, but over 60 runs with my shovelhead stroker, and have spent a lot a lot of time analyzing dyno charts.

As c9zx states, get a backup run from someone else before you wrench, may save hair and money.

 
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In my experience if the valve spring open pressure is too low you would know it- not only would it show up on the dyno plot as a more drastic drop in power as Chuck mentioned, but you would probably also feel it in the seat-of-the-pants dyno. The car will fall on its face like its on the rev limiter...

Dumb question: are you getting full throttle? I know this sounds silly but I suspect with your torque numbers you have traction issues, and its tough (for me anyway) to get to 5k+ RPM on the street at full throttle in a gear that won't blow the tires away...
Actually, good question. I checked that over the weekend and is good. Plus, the EFI data log is showing 99-100% TPS.

I would try to eliminate the simpler stuff first.  Could very well be an ignition issue.  What is your ignition setup?  Is spark jumping at high RPMs?  Is your spark plug gap right?  Is spark getting blown out at higher RPMs?  Do you have a carb you could quickly toss on for a dyno run to compare to the EFI?
I have a Spectra Duraspark distributor with a MSD Street Fire CDI. Spark plugs are gapped correctly. The car runs very well at WOT with no hesitation or misfire.

Gatorman lifters require tall lifter bores to keep the oil band from coming up out of the lifter bores. Do you have lifter bushings that extend up enough? Otherwise the lifters will loose pressure every time they are pushed up, resulting in collapsing at higher speeds. A reduced base circle camshaft also helps.
Don, I never heard of that for mine. It was Tim Mayer's recommendation so I trust they work. I reviewed the pictures and the oil passages don't look above the lifter bore. I have the Gaterman 1014 with a Comp roller lifter retainer "spider".

Tony-muscle,

Looking at your GREEN hp numbers in the 5 to 6 K range, where the hp is falling off. i see a small dip then it comes up a little then a bigger dip then it comes back again, that should never happen.

I dont have a lot of v-8 dyno experience, but over 60 runs with my shovelhead stroker, and have spent a lot a lot of time analyzing dyno charts.

As c9zx states, get a backup run from someone else before you wrench, may save hair and money.
Interesting observation. The two runs look similar. Another dyno run is big bucks around here. I was lucky to do this one in the HRPT which was very affordable since they were doing a lot of cars during the week.

I will at least remove the valve covers over the winter to check how things look. I have been wanting to do this for a while anyways. I will also do a compression check in all cylinders just in case. No money spent, just time.

 
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Hmmm, I'm no expert.  But as George Pence once said, "If you have an engine, equipped with 4V heads, that flattens out before 6000 rpm, it has a problem. 
I was thinking about this, so I am wondering if Pence's opinion still holds true for a 408 that in theory is breathing about 16% more air than a 351, or about 1,000 rpms?

 
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trillizo_y_uno

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I was thinking about this, so I am wondering if Pence's opinion still holds true for a 408 that in theory is breathing about 16% more air than a 351, or about 1,000 rpms?
I would think so.  Remember, 4V ports are huge and should be more than capable of flowing whatever your 408 can throw at it.  My main point, there is something else going on here.  You aren't falling off a cliff at 5K RPMs because of valve shrouding.

 
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