The Stovebolt Site Forums The Shop Area Engine Shop Head troubles again

It is but for some reason my 216 carb had elongated bolt holes and fits both manifolds
I am using the 235 manifold and have a Carter YF carb.

The new carb was remaned by Holly and is a rochester B for the 54 235.

For some reason my Carter YF from the 216 has elongated bolt holes so it fits the 235 manifold I am using as well as the 216 manifold on the old motor.

The new carb is a rochester B remaned by Holly. Specifically for the 1954 235.

I think it was previously explained that it has a 216 carb with modified mounting holes. I think the proper carb will make a difference.

Truckernix

Yes definitely. I put the rochester on and after some fine tuning the truck increased about another 10% in power and pick up (so I am up about 30% in total. I still have some more tweaking to do.

It is stumbling at high rpms again (but just slightly) so I checked the timing as well. If you remember I had to advance the timing about 10 degrees to get it to run to take it back for service.

The mechanic who serviced it told me the timing was way off (duh) and that he set the timing, valves and carb settings (old carb) after changing the head gasket. Funny all I changed was the carb and the timing is still 10 degrees advanced just like I left it. I am sure changing the carb did not affect the timing.

I am sure with all that was done to this engine the timing marks are not as important as the timing itself. I always adjusted the timing a little advanced based on vacuum and ping. Get max vacuum and back of until it does not ping at high rpm. I think I read that on this site somewhere.

Rich

ok...I have placed a new mark on the flywheel where TDC is according to the piston and valve position. It is about 10 degrees after the ball bearing. about 1/2 inch past the "C" marking. I now have a reference for TDC when timing.

I did a compression test and I got 110 from each cylinder except for #4. That one only has 90. (results were the same wet or dry for each cylinder...#4 still only had 90)

The spec for this motor is 130 minumum which may be the result of the newness of it. It could increase over the next 1000 miles as it breaks in.

I am concerned about the #4 cylinder as I remember the exhuast valve on that cylinder was tougher than the rest to remove. I thought it might be bent and did point that out to the shop when I brought it in for the rebuild. I will do a leak down test later this week.

Does anyone think I am being too fussy. Should I run the motor and check compression in a few hundred miles? Could this resolve over time as it breaks in? I hate the thought of a valve job on a new motor but I do have a warantee.

I would guess I am as sick of these problems as the machine shop is of me at this point. however I did pay them a lot of money to quote them..."do everything to make the engine run right".

I would give it a few miles, check it again before the warrenty ends and see where you stand. The compression could be a worn cam or lifter, valve adjustment, valve seat or valve face, bent valve, worn rings or cylinder, or even a cracked piston. You cold eliminate a bunch of these since its rebuilt, but one or more is letting the compression out or not letting enough air in to #4 cylinder.

Get some highway miles on it to really seat the rings and valves. Get everything adjusted the best you can and then retest. The worst that could happens is #4 needs a new guide and valve.

Joe

Thanks Joe
I will drive this as much as possible in the next few months.
I don't suppose it would hurt to let the shop know I am having some issues

I feel pretty confident based on the list of replacement parts and testing that this is valve related. I had the original shop do the valve adjustment so it was down by a qualified mechanic.

I do have another professional mechanic who actually has a corvette with this same engine in it. I might pay him to check the valve adjustment after a few weeks of running

Rich

Just keep your ears open for anything out of the ordinary. If the valve is bent or hanging a little, you will start to hear a miss in the exhaust and the rocker arm will start to clatter more. If the intake hangs open, you hear it out the carburetor.

Joe

Joe,
This engine sounds as smooth as glass (and quiet) when it runs. It does miss out the exhaust but now where near as bad as my old 216.

I will keep an eye/ear on it
Thanks

Truck ran much better tonight I put a 1/2 a tank of hi test gas in with the regular gas and changed the oil to 10-30 from straight 30 figuring this was better for the hydraulics and less drag on the internal engine parts.

Maybe my imagination but I think I gained another 10% of power. It loses much less speed on the long highway inclines (dropping for 60 to 55 instead of 60 to 48 on the same hills as last week. I did not notice any misses out the exhaust tonight.

It is running much smoother...not prefect but much better. This could also be a product of the break in as well. I am driving the truck as much as I can.

I will continue to drive it and maybe bring it to my mechanic friend to do a final check/adjust on the valves.

A much happier RB53

Could the timing be advanced to far.

Dan
I have been tinkering with the timing recently
Due to the rebuild and the new cam and hydraulic lifters the timing marks are not accurate
I was timing by vacuum but I have now marked the flywheel at tdc to make it easier.

I believe there is a sticking valve as the vacuum a gauge drops slightly at irregular intervals but is other wise pretty smooth.

I appreciate the advice though as I try to dial this in

Rich

I don't think TDC changes by installing a new cam. TDC should be marked with "UDC" and a triangle. The valves may open differently but TDC stays the same.

Isn't TDC defined as #1 piston at the top of the cylinder with both valves closed?

This was a total rebuild with a different flywheel, cam, lifters, crankshaft grind etc.

I can tell you if i set the timing on the ball...the engine barely runs. It is set advanced past the "c" (could be what's left of my UDC) on the fly wheel.

It could be because it is a different flywheel. but with the #1 piston at the top of the cylinder the pointer is no where near the ball or other markings on the flywheel.

I will dial the timing back in tiny increments and see if I get any improvement. If it ever stops raining here,

Rich

If you have a different flywheel then that can change the indication. TDC is when the #1 piston is at the top, regardless of the valves.

It doesn't really matter where the marks are, if it runs right where you set it, then thats the right spot.

If you used a solid stopper in the spark plug hole, and slowly rotated the engine both directions, marking the balancer at each solid stop, then split the difference of the two marks, you then would have true TDC. Thats the only way to do it with the head on the engine. But in the end, its where it runs the best that counts.

Joe

Guys excuse my ingnorance but aren't there 2 opportunities per cycle for the piston to be at the top of the cylinder(compression and exhaust) Hence you can set the dizzy 180 out of sequence.

I thought TDC on compression was when the piston was at the top and the valves were closed (hence compression stroke)

(gee I used hence twice in the same message)

Am I mistaken is the exhuast stroke also considered TDC?

The term TDC refers to Top Dead Center and that is where the piston is at that point. You are right that it passes through there twice during the four cycles. The old flywheels had a UDC marking for Upper Dead Center.

Ok thanks

You can put the distributor in any way you want and just move the wires so it fires correctly. The factory had them in the same position always. It is interesting to see the odd truck on display with the wires displaced from the factory position.

Yes, my dizzy is in backwards because I rotated the engine and placed it with the valve cover on figuring I had a 50/50 chance of getting it right. Of course Murphy's law prevailed so I just rearranged the wires.

I don't think you can put the flywheel on out of sync though due to the pins. They are not equal distances. i think the flywheel only goes on one way. If you had a flywheel form a different motoer (like in my case) the marks might be irrelevant.

Any time there is a 50-50 chance of getting something right there is a 90 percent probability that you will get it wrong.