I have a 68 442 with a 400 engine with C heads. The engine is running sluggish and sputtering slightly. A mechanic friend of mine is of the opinion that I have weak/broken valve springs, possibly bent/burnt valve.

I've done a compression test and #1&3 cylinders were on the low side at 115psi, while the rest ran between 193-206. Wet test compression pointed to the valves. There's no oil in the radiator and no antifreeze in the oil, so I don't believe it to be a head gasket. Vacuum is normal.

My next step is to replace all the springs on that head and see if that takes care of the issue before going as far as pulling the head.

My question is what size spring do I Look for as a replacement? I'm just looking for an OE replacement but I want to know what size is correct? I saw somewhere on the www that max pressure is 84 and min pressure is 76 with an installed height of 1.67"? The max pressure seems kinda soft to me?

Anyone with experience on this issue your input would definitely be welcomed! Thanks in advance!

 

1.437 OD. Edelbrock 5812 is cheap enough. I use engine pro springs. they're 110 on the seat and 280 open, a little stronger.

 

Will using these springs require me to make changes elsewhere? Admittedly I have no experience with the valve train so I don't know what the hell Im doing. I'd like to change the springs on the affected head alone to see if weak/broke springs are indeed my problem, before going further.

How will putting stiffer springs on one head and not the other affect the rest of the engine? I'm confident I can replace the springs with no problem but don't wanna go into it half cocked. Thanks again for any input.

 

Well I stand corrected on it not being blown head gasket! My buddy stopped by today and we pressurized one of the two cylinders and got air outta the other plug hole. So looks like I'll be adding head removal to my résumé!

 

When you remove the heads take them to a machinist. The machinist will tell you if you need new valves or springs.

 

Yes sir, that's the plan!

 

Nice Ride!

 

thank you!