Hi,I hope its OK to ask this here since it not really Buick related but is there a epoxy that is tough enough to hold up inside a intake port? I am talking cast iron. I am asking because I built a modified Kohler flat head engine for garden tractor pulling and when we dynoed it I am about 4 or 5 hp short of the better engines in my class. I think the problem is in the intake port shape but to make it better I need to fill in the area where the valve guide enters the port, for some reason they have it sunk way down in a hole so I can't make a nice round curve from the carb mount side of the port to the intake valve. On a flat head just picture the ports on a over head valve engine but turned upside down, the short turn is on top and the long turn on the bottom. I found out that guys are reshaping the port with epoxy but no one is willing to tell me much about what kind of epoxy they are using and how to apply it so it stays there. I figured I could get a honest answer on here if anyone has ever messed with epoxy to fix a cast iron head before. Tom
I had a set of 430 heads that had epoxy inside the intake runners and the epoxy started to break loose and close up my spark plug gap. So i pulled the heads and removed that stuff. Billy.
I did some searching and found something about a A\B epoxy that Moroso and others sell. They claim it works well in intake manifold and intake ports with proper use. Oil, gas and alcohol won't effect it they claim. I would hate to wreck a engine because a piece of epoxy came loose. There is also some nasty vibration in a single cylinder engine at 7500+ rpm that probably won't help things either.
Any type of epoxy filling whether it is plugging holes or shaping runners needs to be anchored. Depending on location, drilling holes or multiple recessions will usually hold it in place. The real drawback is the need to check occasionally to make sure it is secure.
I'd contact AM&P. They used a type of epoxy to extensively reshape the ports on the Engine Masters Challenge 434 (see pics). http://automachperf.com/434emcspecs.html Devon
One local engine builder around here uses the same stuff that they glue the reflectors on roadways with. Seems to work fine. Says he's never had any flake off.
Hey Tom.Not sure how tight the area is that your working on, but you can also braze it.Epoxy would be easier though.Ive also used the titanium epoxy like Greg said , and it worked great also.
I guy I go racing with had a nasty sbc with an old weiland single plane intake. it had an epoxy poured floor. car ran 10.30s all day long. no idea what it was though.
I have thought of brazing, but I am afraid that it will crack or at least warp the block. I ended up doing some more port work on it without adding anything to the port for now. I also installed a better flowing intake valve. I had a steel back cut 305 Chevy 1.84" intake valve in it. I got a new Manley stainless high flow valve for a 350 Chevy and cut it down to 1.84". The block is getting pretty thin in the intake port and seat area and I didn't want to try and open up the seat to take a 1.94" intake valve, I am afraid of breaking through. I have seen the intake port break off engines like this from vibration and the weight of the carb and intake pipe hanging on a paper thin port. I have a aluminum intake support plate on my engine to help hold things together. I also got a better cylinder head that should allow the ports to flow better and the spark plug is in a better place for methanol fuel. I will find out this weekend if my changes helped or not.
devcon is some of the best epoxy made.racers regularly use epoxy in the intake tract,ruff up the surface before hand
Well my new cylinder head ran like crap so I went back to the old one. These little flat head engines are so touchy its hard to change things without having it on a dyno. It runs great going down the track, but right at the end of the pull it just don't hang in there long enough. I am going to advance the cam some more for this weekend to see if that helps it lug better. The gear bolts to the cam and has slotted holes so all I have to do is remove the cam cover, loosen 4 bolts and move the cam and tighten it back up. The ignition points run off the cam so all I have to do is put a light on the points to tell me when the points just open and then I can look at the timing marks on the flywheel to see how many degrees I moved the cam. When the cam is where I want it all I have to do is reset the points to get the ignition timing back to where it needs to be. I also built a different exhaust pipe that I think will help give it more low end torque. I have another gear in the trans that is one tooth slower than the gear I have been running which would help at the end of the pull, but I don't know how much ground speed I would loose coming down the track. I might try it this weekend if the track is taking allot of power, maybe the motor will turn enough rpm to keep the ground speed up. If I do go down a gear the motor will probably see close to 8000 rpm coming down the track. Tom
Retarding the cam will help the top end, but likely at the expense of lower end performance. Make sure it's getting all the fuel it needs. Devon
Advancing will improve bottom end at the expense of higher rpm...I thought you were trying to get more out of the upper rpms. Devon
Hi, it makes allot of rpm in the middle of the run now, my problem is it don't hang in there long enough at the end of the run. The class is so close that sometimes there is only 4 or 5 ft difference from 1st place to 6th or 7th place. If I could get it to average 3 ft farther than it has been would help me allot. I checked the cam timing today and it was advanced almost as far is it would go, I got maybe 1 more degree out of it. The cam is now 5 degrees advanced from straight up. I can take about .050 off the head and still clear the valves to get some more compression. Some guys are running 2 spark plugs in these things and make allot of power, but no one will talk much about what they have in there motors or what they are running for timing with the twin plugs. I probably shouldn't be talking about this stuff on a Buick forum, sorry. Tom
Hey Tom.How long is your exhaust?Years ago, my dad put on a really long exhaust on me and my brothers quarter midget, (1981) , and it made a huge diff in low end, and it didnt seem to fall off at high rpm.That was on a daco engine.Not sure if it would help or hurt ya on your engine , but just an idea.It sounds like what you are doing is a blast.Where do you guys pull at??
Hi, The pipe I have been running is about 24" long. I just built another one that is longer and the end of it steps up to the next size bigger pipe. I have noticed that some of the real good running engines from a local guy are running pipes with 3 or 4 steps in them now. Most of our pulls are in central Wisconsin. I did some work inside the head to hopefully help the valves flow better, I also "relieved" the block by the intake valve toward the cylinder which should also help. Maybe these mods and the longer stepped pipe will help it some. We have a pull tonight {Friday} so I will find out real soon if it helps or not. Tom
