Technical Q&A

Q: When resurfacing an aluminum head with intake seats that protrude into the deck, we use a CBN cutter (instead of our PCD) and have difficulty getting a good surface finish across from the seat. We WD40 and no material appears to be sticking to the cutter. Any tips for improving a “bi-metallic” cut?

A: Any time you cut two different materials with CBN, you’re going to create a wave pattern showing up right after the tool tip leaves the hard material going into a softer material. If your machine uses 3/8″ diameter tips, I would suggest you use a carbide tip (Goodson #RCI-38A) for this application, combined with our Cutting & Tapping Fluid (CTF-14). This will give you the best chance to maintain the cosmetics when cutting through the two materials. If you have a combo grinding/cutting machine, I suggest you always grind those headsusing the Salt & Pepper looking stones (GS-PBS-2) with lots of coolant. Remember, WD-40 stands for “water displacement #40” and does not do that great of a job for any type of surfacing operation, but it works great to open sticky door locks.

 

Q: I have a new set of heads with 3/8 inch guides. The ID is .373 in. I would like to use 11/32 in. valves. Could I use the Classic thinwall bronze liners to reduce the guides?

A: Yes … IF … your valve guide ID does not exceed .3735in. you can simply drive an 11/32 valve guide liner into that bore. First make sure the ID is round and straight. This is possible, due to the fact that normally we would bore a standard 11/32 in. valve guide .030in. over which is: .343 + .030 = .373 in.

Then you would size the ID of the liner accordingly to set the valve stem clearance you want to achieve.

 

Q: I’ve got an Ironhead Sportster that I want to R&R the valve guides. Kibblewhite racing recommends sizing the guides by honing. Can I do this with a flexhone or do I have to ream it and then finish it off with a hone?

A: The valve guides being used in this instance are of a material that does not size with a conventional reamer. The material or hardness of the guide dictates the use of a fixed hone. A flex-hone is like a lazy river or man – it takes the path of least resistance. It removes material at the ends of guides, bell mouthing and very little in the center. Flex-hones are recommended for final finish only. For universal material removal, use the P-190 hone unit. With the use of a quality measuring gauge, guides can be sized correctly and a desirable finish created using this fixed hone.

 

Q: I have been considerng the purchase of a spray welding kit in order to perform repairs to cast iron heads. The process seems to make sense, but I´m concerned about the temperature required for consistent results. I believe you need to keep actual weld time to short increments then put the head back in the oven to bring the temperature back up before welding again. I keep reading and hearing conflicting recommendations about temperatures. Some say 500 to 600 degrees, other say 700 and some suggest 900 plus. Which is it? Also, will your benchtop oven DHR-34 or something with a temperature range up to 550-600 adequately handle the heating requirements? If these types of ovens can’t handle the heating, what are other people using?

A: The correct welding temperature is between 650 and 900 degrees. It´s very important that you maintain no less than 400 degrees after you reach your welding temp. Keep in mind that would be the mass temperature. In other words, the farthest point away from the welded area must not drop below 400 degrees. Keep in mind that the higher the maintained temperature, the better the overall weld will be.

Also note, on cast iron with press-in studs, the studs will expand and contract at a different rate than the rest of the workpiece. You may experience loose rocker studs. Always check the rocker studs before AND after welding.

Our DHR-34 oven will not reach the correct temperature for welding. The DHR-34 was designed for head straightening or powder coating. There are ovens available that perform other functions. They are used for thermo cleaning and welding. They are designed to achieve the higher temps required for both welding and cleaning.

 

Q: What’s the best way to drill the outer bolt holes on a block when installing the caps?

A: When installing aftermarket main caps you want to make sure that they fit the block registers tightly. Once they are installed, there is a drill bushing available that will keep your drill bit aligned to the proper angle for drecise drilling. After drilling is complete, remove the bushing and tap the drilled holes. Then clean, lube and install all fastners and torque main caps into place. Finish by align honing the block. Measure everything twice.

Take your time, If you don’t have the complete tooling and align hone to perform this operation, take it to a shop that can.

 

Q: I´m building 4-cycle go-kart racing engines and I´m having problems getting the rings to seal. I think the problem is in the block prep. The engine is a steel sleeve motor. I clean the cylinder after honing using a flex-hone with brake/parts cleaner and paper towels. Do you have any suggestions for doing honing/block prep that will help?

A: Hot soapy water, followed by a clean clear rinse. It´s the only way to finish clean. Get out your magnifying glass and take a look at the piston ring-to-cylinder contact area. You´re looking for scratch marks across the face of the ring. If there are none, you´ve done your job correctly. There should be no evidence of dirt or partially severed cylinder material abrading your rings.

 

Q: Is there an easy way to calculate CI when modifications have been made?

A: Formula is: bore x bore x stroke x .7853982 x number of cylinders.

 

Q: I´m using your multi-purpose coolant (CGC-5288) in my crank grinder. Good stuff, doesn´t smell. But I find it sticking up on me. The product is sticky – syrup like – and makes my dial equipment sticky. The ways on the grinder bed have a sticky feel to them. I have to spray it up with Brake Clean to cure the problem temporarily. Has this happened to other customers? Is there something I´m doing wrong? Is there something I can do to alleviate the problem?

A: Your mixture is way too concentrated! Double check the mixture ratio you’re using. A word of caution … brake clean or any other tramp oils that are added to the coolant will kill the biocide package in the fluid. In other words, it will become rancid before its time.

 

Q: What is the purpose of overstroking and is there a down side to loosening a main cap that is cleaning up faster than the others?

A: The purpose of overstroking is to ensure that you are using the full length of the stones and not just wearing the middle. If you have one cap that is cleaning up faster than the other, you either have a misalignment issue with the block or you removed more material from one cap when you ground them prior to align honing.

NEVER loosen a cap when honing. The idea here is to have all the bores in alignment with each other and all to the same size. Loosening a cap will leave one bore undersized and/or out of alignment and not concentric.

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