TedH

Compressed #1 exhaust valve starting to replace the valve springs, retainers, seals and locks. The valve is loose when the spring pressure is released.

Time to pull the heads for guide replacement?

Tried the intake valve on same cylinder. Also loose in the bore.

Starting to wonder now if the valvetrain noise I was getting in the car was loose valves and not the cam/lifters. I pulled the (hydraulic flat-tappet) lifters from the bores yesterday. Normal light wear, no gouges or marks to indicate the cam and lifters were failing and getting noisy.

I have cylinder head gaskets so I am going to go ahead and pull the driver's side cylinder head today.

I have a variable speed drill press... is this a job left to the pro's? I will see what it costs to have the guides replaced and the valves lapped. May have the heads cleaned and resurfaced while at it... starting to wonder if I should buy a pair of bare heads and put the valves and my new hardware in them... Perhaps a replacement pair from DART.

For now, will strip the heads down and get a machining estimate. Will decide on replacements after that. Hope the valves can be reused.

OMF

This is the sort of thing best left for the pros to do. You may be able to drill out the guide and geta new one in there, but there is no way it will be concentric with the valve seat. The accuracy of a drill press isn't even close to what you need. Then you need to cut or regrind the seat using the new valve guide as a centre......just let the pros do it.
Now if your reworking an older set of stock heads, your better off to lay down a few more bucks and get a modern set of heads. Aluminum or cast iron....your choice on how much to spend. If you go with new heads, I'm sure you'll be pleased with the results.

George Ries

what you will spend redoing your old heads the right way new ones wont be much more

TedH

These are DART Iron Eagle 180cc heads. Guides need replacing after my removal and tear-down of the driver's cylinder head. #3 and #7 exhaust guides are visibly worn on the top but the #1 and #5 exhaust guides are also much looser. Intake guides are worn on all four but not nearly as bad as the exhaust. No wonder the umbrella seals on #3 and #7 are destroyed, the valves were moving side-to-side in the guides.

I'll see what local machine shops charge for guide replacement. With cleaning of the heads, I may be ahead to get a pair of bare heads. I can get 'bare' replacement DARTs for $800 plus shipping. I'll comparison shop other brands also.

I want to clean up my valves regardless.

Suggestions for lapping/cleaning valve stems?

donnie1956

Recently got a quote for old SBC iron heads and the machine shop wanted $250 per head to rebuild with parts.

TedH

I'll see what the price is for the guides only. I'll be taking the bare heads in for guide replacement.

OMF

How many miles are on these heads? If there aren't many, then maybe your pushrod length is wrong and that is causing your rockers to push sideways on the valve stem at max valve lift, which will wear out guides in a hurry.....something to look at when your reassembling

TedH

It was about 30K miles over a 12-year period. Most of those miles occurred in the first 4 years; it sat a lot the last 8 years because of the increasing valvetrain noise. It had stock length push rods since DART specs call for them.

George Ries

just redo your heads and check everything at the most 650.00

7t9l82

see if they hone the guides after they ream them. shops that do the extra step are worth it.

TedH

I'll see if the machine shop can confirm the valve train geometry once they install the new guides.

TedH

I'll pull the passenger head this evening...

George Ries

good what rocker ratio are you using 1.5 or 1.6 and what brand or rockers are you using full roller or just roller tips?

TedH

I had long-slot Summit stamped steel 1.5 ratio (non-roller tip). I'm guessing I was getting 1.45 ratio out of them at best given they are stamped steel of questionable origin (I see Summit gets some of its parts from China). I had stock length hardened pushrods. The DART heads have manley #42151 raised guide plates and 3/8" screw-in rocker studs.

Once I have the guides replaced, I will be installing a Comp Retro Roller K-Kit with matched pushrods, spring kit, timing set/button, cam and lifters and I have the 1.52 ratio ultra pro magnum roller rockers.

George Ries

Check out scorpion endurance or race true rollers rockers they are made in the USA and have a lifetime warranty

George Ries

Or use what you got

TedH

Already bought the set of 1.52R Comp Ultra Pro Magnum. Will be driving this car on the street. Not endurance or race. Just need reliable, durable street performance.

TedH

Turns out that #3 and #7 exhaust valve guides were the very worst. Exhaust valve guides on 2/4/6/8 were worn but not visibly at the top. Intake guides were fairly 'good' like on 1/3/5/7. Umbrella seals on 2/4/6/8 were intact. Shows the exhaust guides were not as badly worn on passenger side.

Got a quote: $300 plus tax. Includes:

• All new guides
• Valve job (I will take the castings with the valves, all other moving parts removed)
• resurface the heads (faces of valves and combustion chambers

got a question: What is the BEST valve guide for a 'driver'? I had two styles of aftermarket guides on the DART heads. Magnesium Bronze (intake?) and Phosphorus Bronze (exhaust?). DART offered them for RACE applications. I'm guessing they were not intended for STREET use?!? Too exotic? Hey, if cast iron guides on all 16 valves means 100k miles of durability, I'd go with it. Will see what guides the machine shop intends to install. Definitely NOT going to have them knurl the existing guides.

George Ries

Is that 300 a head?

cv67

Dont use iron guides on the heads