During last race, the engine started to idle rough and even stopped idling a couple of times. My BATT/Dynamo light was on so, I thought ok Dynamo is fried. And after checking it was. Had the Dynamo refurbished and it worked ok again. But the engine was still idling strange. Felt like a sparkplug. Changed the sparkplugs..still nothing. Checked the entire carb, cleaned it, checked the for vacuumleaks..nothing. Checked the distributor..nothing wrong there either. Mmm, did a compression test on al 8 cylinders, and Cylinders nr 1 was at 9.5 compression and the rest were al 10 or higher between 10-11. Did a leakdowntest on Nr1 cylinder, turn the motor by hand so the intake and exhaust valves were closed on Nr1.. and the meter was at 70%, when you open up the carbs butterflies, you could hear the air coming in to the intake. Did a comparision on Nr2 Cylinder and the meter was at 100%, and the noise at the car/intake was a far away sizzling noise. So it looks like on nr1 the intakevalve isn't sealing like it should anymore. What are the possibilities? Bent valve, bad/loose valve retainer? The lifter work ok, the valve clearances are also ok. So I do not know why this has happened. No overrevving the engine, cause we have a rev limiter on the car. Last race was a slippery track so we lost traction a couple of times, perhaps the engine revved to fast when the car lost traction and it caused this? So need to pull the head and see what is going on there. Any insights if I need to look for something special, cause these are aluheads and my experience are more with the old Iron heads. We won a 3th place cup that race, and that was hard work to do! I hope the engine will be feeling fine soon again.
And here a couple of shots of the car at the track last year I have to put up the new footage still: <iframe width="560" height="315" src="http://www.youtube.com/embed/aFVKxcttL2w" frameborder="0" allowfullscreen></iframe> <iframe width="560" height="315" src="http://www.youtube.com/embed/B6ubsIhGRTI" frameborder="0" allowfullscreen></iframe>
Robert Loved the videos,not much traction on the roundy-round track. Do your leak down with the engine warm,gives more accurate results.Maybe you did. Could be bent valve or seat needs to be redone.Is it a hydraulic cam? If so maybe the preload needs to be redone,you may have too much. gary
Hello Gary, No not much traction on the circuit track, last summer on the strip here it was much worse, its was the first time that I had driven in both lanes, in one single run. And had a hardtime improving my times with my dragslicks last summer over the times I had put in the race before on my streettires!ou: Oh well hope they get the traction back next year. We did the leakdowntest with a cooled down engine. The 475 has a 308S cam in it. @sailbird You mean the valve lash, we checked the valve lash and that was ok valve could move up and down normally and the lash was still like we set them a few months back when we checked all the valves lash.
Gary, what could have caused a bent valve or damage to the valveseat? These heads are like new, and I haven't made a lot of runs with it yet. So wondering why this happened, so I can and try to avoid such a thing next time out.
I Phoned JW, and talked with him about it. Got some info to check somethings first before removing the head. Will do that tomorrow and will report back if that helped correct it. :TU:
Update nothing seem to work to get the valve to close completly, so we are removing the head to see whats up with that intake valve. hope I will have the parts list in a couple of days so we can order the parts we need to fix her up and put her back together again.
pulled the head of, and very little damage to the intake valve, valve is still useable and will clean up nicely. The biggest problem was that when we pulled the intake, is that on the other bank, where all the sparkplugs were black and wet, is that the intake gasket on thatside was folded up between the intake ports (all four) and was leaking air and sucking between the mainfold and the head, also it picked up that way some oil, hence the black and wet sparkplugs. The other bank were the intake gasket was installed correctly all the 4 plugs were grey in color and dry. Since the engine is opened up now, we are going to pull the other head also clean it up and install/upgrade to a better headgasket. Then the standard street felpro gasket that is on it now.
You talked of not having much traction. Do you have a rev limiter on the engine? If not, I was thinking you may have over reved the engine and hurt/brokened a valve spring. Check your valve spring pressures.
Yes a MSD rev limiter, but Devon tnx anyway will check the valvespring just to be sure. :TU: Just need to wait untill the headgaskets and intakegasket gets here to put it back together again. This engine has many headbolts in comparison with my old all iron 464 stage 1 engine. But since all is new and aluminium, removing everything was a breeze in comparison to the all iron 464 that 9 years in use, and where some headbolt were rusted tight in the water passages. I have a Question, in the Headgasket there is a very tiny hole on every spot were a waterchannel/hole is. The block and head waterhole is much bigger then the little waterhole in the headgasket. I'm planing to make those holes two times bigger then it is now for more volume water. Since I have a 55GPH Electric Mezier waterpump , I do not need to worry about having not enough flow. Any thoughts/comments on that guys? Greetz Robert
Robert, those small holes are there in the gaskets only to prevent air pockets from forming in those areas. The holes in the block are larger simply due to the need to get the sand out of the water jackets after the block casting process. Here's what TA says about this in their catalog: Devon
I will give TA a call to see what they say about it when your using an electric waterpump, in combo with a 3/4 filled block. tnx Devon. :TU:
The Felpro headgaskets are finally here, and the TA SP2A intake gaskets are on there way. I pulled the other head also to clean it up, and brought the all the valves to the machinist to have them checked if the were bent or not, and have them all checked and cut again. Now we need to polish them untill they seat correctly. We did this cause when doing a leak test on all of them with the heads off the car, all of them after after a few hours were leaking the fluid between the valves. two valves had light scratches on the flat outside of the valve, but the piston was clean of scracthes and had nothing. So with the right bank had a bad intake gasket leak and the cylinder Nr1 a intake valve leak, I think when its all back together the engine will have all of his power back again. And installing the 2 inch cloverleaf spacer after this, to get me 35HP more. Gonna cut up the fiber GS hood so there will be room for the carb to stick out and the K&N aircleaner to be placed on.
