As some of you know, #1 and #2 cylinders of my back-up race engine are pretty low on compression (110 and 115 psi) compared to #3 and #4 (145 and 150 psi). I squirted a bit of oil in the cylinders and the compression only gained a few psi.

So, I have a little break in the racing and I decided to pull the heads and do whatever valve work is required. Here are some pics.

Looks like the intake valves hit the pistons a little bit, maybe on a over-rev during a downshift.

Cyl #1 and #2

Cyl #3 and #4

Cyl head #1 and #2

Cyl head #3 and #4

Any thoughts or insights gleened from the condition of the heads and combustion chambers?

Toss the head gaskets. While your in there snatch the cylinders off and run a dingleberry hone through the cylinders and slap some new rings in there? A little extra cylinderwall clearence in your case will free up a little HP. You may also look at having the cylinder tops and bottoms trued up on the lathe. Set your deck height up to .040 and no more. This will get your compression up. I'll toss some springs in the box with the fan. They have a little more pressure to protect you from float. They are new so you can put them on the heads and not worry about them.

While your in there unshroud the exhaust valves little and polish the chambers too.

looks like your mixture is off on one cylinder....
Darker brown intake valve..

Also to much blow by.

Get some rings, hone them out and re seat the new rings...do it like jake does....he goes for at least a full hour at 2500 to break in everything.

Rich

Thanks for the help...

So, you're thinking I need rings at least, maybe I'll do the pistons and cylinders. Boy, this gets expensive quickly.

There has been some porting on this head. I just don't know if it's any good or not.

Rings are cheap. Get a set of Hastings rings they will probably run you 40$ the hone will cost a little more, but you might be able to find a motorcycle shop or snowmobile shop around that can hone the cylinders if you don't want to. Probably cost you 10$ per hole. I'll send you some gaskets to cut that cost.

Kevin,

Good pics.

Starting with the pistons, I agree with Brett, reassemble using no head gasket and set the deck height at .038-.040. Your number 1-2 cylinder are closer on the deck clearance than the 3-4. you can see this from the clean (no carbon) ring around the top of the piston and the 1-2 head is also cleaner.

If you don't have a dingle ball hone, buy one their cheap. just make sure you don't hone the thing very long and don't hone it flat, meaning stroke the hone in and out ( no sexual connotations here) so you achieve a 45 degree crosshatch pattern and do throw some new rings in it. I would recommend a total seal top ring. Even though I know some people don't like them I have had good luck with 914's. Are these 93 mm pistons or 94mm pistons?

Without good accurate deck height the squish will compromised and the power will be reduced. As for the porting job, nothing you can do here, except a valve job.
Have the machinist do a small 30 degree back cut on the valve when he does you valve job and that should pick up the flow a touch. also the guides in your heads are TOO long. You need valve support but I think yours are a little too long. Don't think the machinist will be able to do anything about them. Check the guide for wear, and if you weigh the valve, keeper retainer valve spring, and tell me the seat pressure you are running, and what the valve spring pressure is at full lift. I can look at your valve springs. Brett may have some good springs it sounds like. Also remember,sometimes the case center is not in the center of the motor, causing the deck to be more on one side than the other. It happens. Otherwise, looks like a decent B motor.


Erik Madsen

Wow this should win the best thread of the week award. Actually some really good real life stuff about fixing a motor. and the "hey I'll even throw in some parts to help with cost stuff" I love it. This is why I hang out here.
well and the occasional boob shot.

The intake port is kinda funny looking. DIY with a touch of "never done it before" What does the exhaust look like? same thing?
ALWAYS use caution when porting heads. It's easy to take too much. Smaller passage promotes more velocity. at least that what I believe.

I just dropped the heads off with a local shop for a refresh. I'll take the cylinders in to him tomorrow to make sure we get a good fit and I'll run it without the top gaskets. The shop also suggested taking a little more out of the sealing groove to bump the compression a bit more, but we need to confirm that will work with these cylinders.

With these improvements, I'll have a bonified back-up engine for the monster Jake's building for me.

Joe-the exhaust does look the same, but harder to see because of the carbon deposits. I don't have the history of who, what or when or how on this engine. I'm just happy that it has held together this long.

I'll also order some rings once I confirm that I have 94mm cylinders. Thanks for the advice!

Hastings list the number as 2C5599. You can run a 2M5599 which is a standard moly faced cast iron ring or you could run the standard 5599. Don't know why they list the Chrome ring as the standard. Your local machine shop should be able to order those rings in a couple of days.