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What to do to 351c 4v heads?
#41
(11-04-2018, 09:15 AM)scgamecock Wrote: No have not ran a compression check.  What should the cylinder pressure be?  

You just put a guage with a spark plug adapter on it and disable the ignition and spin the motor over right???

The important factor in determining if valves or rings might be bad in a few cylinders is the difference in pressure between cylinders. There will typically be some difference due to various factors however, this difference shouldn't be more than around 15 psi between the highest and lowest reading, and hopefully less.

If you have a difference of 20 or more, then there is likely some type of issue although it is nit a huge one. If it has broken rings or a severely burnt valve, that cylinder may be around 40 psi or more, less than the highest one.

A cheap gauge can read inaccurately by up to 20 psi or more.



Below is one method for doing the test.


1. Remove the coil wire completely from the car.

2. Prop the throttle open. You can just open it by hand then put the tip of a screwdriver down into the venturis to hold it open.

3. Crank the engine over one revolution by jumping the front battery post to the nearest small post on the solenoid or use a jump start button. Some auto shops may loan them. One revolution will be the first pule (increase in pressure) you see on the gauge. Write that number down then crank the engine over 3 more revolutions and write that number down. Do this twice with each cylinder.
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#42
Ok motor is coming out this week or next. Heads going in for service next week. Here is the updated list of what I plan on having done.

To do:
-Machine for screw in studs and guide plates
-hot tank and check
-New springs and retainers to match roller cam
-Match spring height and seat pressure to cam spec
-New Ferrea intake and exhaust valves

What else????
-Have machinist lap the valves in?

I am taking the heads in bare and ordering all the parts myself to save a little on cost. I would like to assemble them too but not sure that is feasible with everything on the to do list???

Thanks!
Wade
1972 Mach 1 351 cj 4speed
"We confide in our strength, without boasting of it; we respect that of others, without fearing it."--Thomas Jefferson

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#43
Seats?
Guides?
Valve seals?
Are you having a 3 angle valve job done?

I would let the shop assemble them but that is just me.

73 Grandé H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

- Jason


[Image: 082-hot-rod-power-tour-2017-1970-1970s.jpg]
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#44
I just picked up some closed chamber heads and I’m having the machine shop set it all up. I don’t want to drop a valve or have any problems so I will have them set them up right.
I’m having my engine all rebuilt, and I want it done correct. It’s a big investment and I want it done right. No need for penny-pinching here!

run_horse Run Horse Run!
John 72 Q Code
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#45
(11-19-2018, 09:11 AM)jpaz Wrote: I just picked up some closed chamber heads and I’m having the machine shop set it all up. I don’t want to drop a valve or have any problems so I will have them set them up right.
I’m having my engine all rebuilt, and I want it done correct. It’s a big investment and I want it done right. No need for penny-pinching here!

don't forget to get pistons that will match the volume of the combustion chambers to give you the compression you want.
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#46
(11-19-2018, 08:59 PM)barnett468 Wrote:
(11-19-2018, 09:11 AM)jpaz Wrote: I just picked up some closed chamber heads and I’m having the machine shop set it all up. I don’t want to drop a valve or have any problems so I will have them set them up right.
I’m having my engine all rebuilt, and I want it done correct. It’s a big investment and I want it done right. No need for penny-pinching here!

don't forget to get pistons that will match the volume of the combustion chambers to give you the compression you want.
Will definitely get new ones, thanks.

run_horse Run Horse Run!
John 72 Q Code
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