Porting the LT1 heads checking the valve guides for wear

[@Ronnie631000]

Hello. I have a early 94` Z28 conv. single cat. Do you still do these heads? I would like to have mine done. Or buy the Edelbrock heads. Thank you.

[@HeadFlowInc]

The Edelbrock heads look like a stock replacement style head with small valves and only a 170cc intake port. Im not sure what a set cost? What condition are your castings? Because of age/mileage the older LT1 heads I’ve done needed new valve guides. I’d upgrade to at least a 2.00” intake valve with a larger 180+ cc intake port. Email me jeffdubray@gmail

[@Ronnie631000]

@@HeadFlowInc Hello. My engine just turned 100,000. I read that the head gaskets go out around a 100,000 mi. I would like to replace them before they blow. While it is apart I can inspect the cam for wear. If the cam is OK , I will leave it alone. I will then replace the head gaskets. Install Edelbrock intake. Have the stock heads cleaned-up! Port and polish or just polish? If the cam is too worn I will not bother and order a Golin LT1 383 500hp Long-block to replace the stock engine this fall. I am ordering this engine anyway, but would like to get some more miles out of the stock motor. It runs awesome, just down on power by today's standards. I just installed a built transmission for 650 hp. I got a Moser GM 12-bolt in the crate to install. Is a 100,000 miles too much wear to bother with a top-end kit? Heads,Cam, intake. I talked with golin and they have an openning for Sept build. If the cam is OK and I decide to just have the stock heads done, will you do the job for me? The long block will cost me $9000. Thank you

[@canadianmarauder1923]

I have same issue with my 4.6 DOHC heads. Bought some new powdered metal guides and I gonna try change them myself. Must be a different style guide on ur head?

[@HeadFlowInc]

Sean Desrosiers I’m not sure if our guide material are the same but I’d guess they are. Remember you’ll need a final size reamer to fit the guides to the valve stems, the guides don’t come ready to run. Also, make sure the check the valve seal between the valves and seats, many shops require a fresh valve job after guide work. I’m not 100% convinced you’ll need a valve job, I mean you’re technically recentering the valve, so 🤷‍♂️. Good luck, verify if you’re going to need any type of sealant on the new guides or if they drive in dry. JD

[@canadianmarauder1923]

I been stressing about these heads for over a year. I figured I’d have to ream guides to size as well but the old valves fit the new guides perfect. Guess I should mic the inside of the guide. The new guides have a circular groove cut into the inside that extends about 75% of the way down. Never seen a new guide before. Was going to lap valves and hope for the best. Trying to avoid machine shop if possible. Read so many horror stories about machine shops. Be a long time till I get to the engine. Been painting frame and underside lately then the 8.8 then 4r70 then engine. I’m just researching, buying tools and learning from your videos. You are a big help. Wish I lived next to you.

[@lexteakmialoki5544]

Can you tell us how high the valve is out of the stem. That distance would affect the measurement.

[@HeadFlowInc]

This was a long time ago I do not have those measurements. The machine shop verified the guides were bad as well, so we did the guides and fresh valve job. Whether you unseat the valve .250 or .750”+ shouldn’t change the measurement since the valve stem is still fully through/engaging the valve guide length. JD

[@skylinefever]

Would it be less expensive to buy a valve with an oversize thickness and ream out the guides?

[@HeadFlowInc]

Skyline Fever I’m not aware of any 11/32” guides that would accept the bore for a 3/8” valve. Two concerns I can think of: 1. A 3/8” stem valve would be heavier than the 11/32” 2. The guides wear differently top to bottom and tend to egg shape slightly do to side loading wear. I’m not sure if you could true up the bore of a warn guide to a larger side. 🤔 Performance wise, we should have committed to changing to 8mm valve stems since all the guides needed replacement. Going down to the 8mm stems gains port flow plus would allow the use of LS valves like the 2.00/1.57” also improving flow with the proper bowl work. JD

[@skylinefever]

@@HeadFlowInc What I was thinking was that some companies sell valves that are about .003 wider, so they would fit an 11/32 guide that was honed out.

[@TPVPRO]

Mine are that loose I said F-it if I drop a valve I drop a valve. "I know the risk" I don't plan on running my LT1 for much more than 2 seasons.

[@HeadFlowInc]

TPV Productions I’ve seen and run heads with loose guides, mostly you’ll see a puff of smoke on start up, oil on the spark plug threads and have oily buildup in the exhaust ports.. Good positive seals would help! I just didn’t want any oil consumption issues so we decided to bite the bullet and have them repaired. I can’t wait to see how it runs! 👍

[@TPVPRO]

@@HeadFlowInc Oh for sure, if I was doing a customers head like you are doing, I would only finish it if they agreed to have guides done. I'm going to run a good hit if N2o on mine so the plugs won't be in long enough to accumulate oil. Great video BTW and keep them coming.💪