PR8urVtec

iTrader: (1)

Hello all,

I have lurked this forum for a while and have searched and read through some previous post about snapping timing belts but I need some help here.

I built an LS/VTEC engine.

Specs

Stock B16 head (milled for a flat surface)
B18B block (decked for a flat surface)
B18B rods shot peened and resized with ARP rod bolts
JDM ITR pistons 81mm bore
ACL bearings
ITR water pump
ITR oil pump
P72 timing belt
OEM headgasket from Golden Eagle
Golden Eagle LS/Vtec conversion kit
ARP head studs
Honda S300v2 (P28 ECU)

I'm using an ITR base map that is in the hondata library. Started the motor up with 30w non detergent motor oil and drove it for 15 miles while doing some fuel tuning on the low speed cam. Got my fuel 1% (+/-) from my target. Started getting on the high speed cam a bit and adjusted fuel. Brought the car home and changed the oil and filter with non synthetic motor oil (mobile 5000). Took the car out again to keep tuning the fuel map on the high speed cam. Got the car revved up and my timing belt snapped. The motor shut off so I pulled over. Not know the belt snapped I tried to crank it over and if just spun. Popped the hood and saw the belt had broken. I pushed the car back to my house and ordered a new timing belt. From what I have read I needed to do a compression test. Got the new belt on and did the test. I got 180psi on 3 cylinders and 190psi on 1 cylinder. This is on a cold motor and the rings are still breaking in b/c it's a new engine. I looked at the valve train with the valve cover off and all looked well. I did not check the lash. I cranked the engine up and it started up with no problem but I do have a ticking noise coming from (what sounds like to me) the head of the motor. I placed a long screw driver on it and started listening and I can't really hear the noise in the engine. After a while of idling pretty stable it seems like the engine is missing or something. I pulled the plugs one at a time to see if I Was missing but all cylinders are firing off. I can hear the miss a lot from my exhaust tip so I know it's not running right. The idle isn't fluctuating bad or anything. Could this just be a valve lash problem or a slightly bent valve(s)? I'm not really sure what to check now. I really don't want to pull the head off already but if I have to I will. Is there another way to checking for bent valves without taking the head off? Wouldn't my compression be lopsided if I have a bent valve? Could this just be the LMA? The ticking is consistent and speeds with the revs. Any help would be appreciated or if you have links to threads maybe I missed please paste them so I can read through. This would be a bummer if I already have to pull the motor out but if I have to redo the valves I'm going to build the head while it's off.

Thanks for any help
Ryan

Rjonesdc01

it sounds like you bent a valve. if you dont want to remove the head to determine the problem. you could try a leak down test. you put the piston to tdc compression stroke on the cylinder you want to diagnose, introduce compressed air, listen through the exhaust or air intake. if you hear air coming out the exhaust its a exhaust valve, or intake its an intake valve if you hear it through the dipstick or oil cap or pcv. then it would be blowby, but you just had a fresh rebuild. normally a bent valve nets zero or a low value on a compression test for that cylinder.

PR8urVtec

iTrader: (1)

About how much compressed air do I need to pump into the cylinder? I can get a smaller air compressor at my house but I don't have a large compressor yet. I can get the tester tool. Might just go a head and take the head off to check things out or bring it to the machine shop for them to measure everything.

Rjonesdc01

if the leak is small then your compressor will be sufficient. once you determine which valves are bad then pull the head inspect the pistons for damage. if they were contacted then it would be worth removing that rod cap to look at the bearings associated with that cylinder. generally they absorb the shock from contact.

PR8urVtec

iTrader: (1)

I'll give it a try when the tester come in. Might as well buy it so I have it any time. Thanks for the replies.

Tyler Dirden

iTrader: (3)

I have never seen one of these that hadn't bent a valve with a broken belt. It still may be possible to start the motor but the ticking is likly to be the valve to seat noise. You can find the bent valve by removing the VC and lightly tapping on the adjuster with a hammer, the bent valve will make a different sound when it hits the seat. you must be sure the valve is closed to hear the difference.
The bigger problem is, what caused the belt to break in the first place? Are you running covers? Any small rock whatever can ruin a belt. Once a small whatever gets down there it runs under the belt and pulley possibly dozens of times before it will break the belt. It can't really chuck it out.

PR8urVtec

iTrader: (1)

I'm going to pull the head and see if I find bent valves. I've excepted that they are probably bent. Should I just get new valves and bring the head to the machine shop for install? Or should I be able to install the valves myself? If they need to machine the head I'm going to get it ported and polished while it's apart. What valves, springs, retainers should I go with? I here good things about brian crower cams. What other head work should be do besides port and polish. Looking to spend like 1200-1500 for everything. Going to replace the LMAs and valve seals as well. Should I get new guides while it's all apart?

I think the culprit was the belt tensioner. It didn't spin free when I pulled it off the motor. Might have put a lot of drag on the belt and at 7500 rpm it snapped. I didn't see any damage to the sprocket on the crank or to the pulley. I'll post some pics up when I get the head off.

kyden

if it bent valves, it probably needs guides.

PR8urVtec

iTrader: (1)

I haven't updated the thread in a while, but I finally got some time to pull the motor and remove the head to look at the internals.

This is what pistons 1 and 4 look like on the exhaust valve relief. Cylinder 2 and 3 look fine and all the intake side looks good. I'm going to put rubbing alcohol in the port to test the seals while it's out.

Top of block


Piston top


Piston exhaust valve relief


combustion chamber


Should I just bring it to the machine shop to get looked over?

darnizzle8805

iTrader: (1)

If you have the ability to remove the valves, do so and roll each one on a flat surface to determine which ones are bent. Replace all bent valves and lap them.

PR8urVtec

iTrader: (1)

Yeah, I can take them out tomorrow and roll them on the counter top.

slowsleeper

Pretty sure your valves are bent, you can even see the exhaust valves printed in the reliefs on the pistons.

PR8urVtec

iTrader: (1)

That's what I think too. I'm going to bring it in to the machine shop and let them clean it up. Seems like a good time to get new valves.

Can the head gasket be reused? It was new and the engine has maybe 50 miles on it before the belt snapped.

darnizzle8805

iTrader: (1)

Not a good idea to reuse an MLS head gasket

Runnerdown

Yep there's obviously valve contact. I would reuse the gasket I have done so many times if the viton coating is still in good shape.

PR8urVtec

iTrader: (1)

The gasket looks perfect. I have read people putting copper coat on the gasket to help and never had a problem with reusing it. If it leaks I will replace it. Doesn't take to long for me to pull the head.

Fliptard

I've re-used a D series gasket and H series at least 3 times with no issues.

PR8urVtec

iTrader: (1)

Would replacing the valves with ITR valves be worth it? From what I have read, they're ligther than stock B16 valves. I'm staying all motor with this build and looking to make close to 200hp. Not sure what cams I want to use yet.

I just noticed that my head has dual valve springs on both intake and exhaust side of the valvetrain. From what I remember, I thought first gen B16a had no inner springs and second gen and on had dual springs on the intake side only. I'm going to take a closer look to see if I can spot a part number or name brand or something.

Edit: I did some research and found that my exhaust valve springs have a blue paint mark indicating that they are ITR exhaust valve springs or B16a2/3 intake valve springs. I'm going to check the intake side and see if they have a yellow paint mark. That would actually work out nice b/c my brother has a set of ITR cams I wanted to buy from him. Might save me on valve spring cost.

My concern is that I have stock B16a cams in right now. Is it bad to have B16 cams on ITR valvtrain?

Farmer89511

I had my timing belt tensioner back out on me once and all my exhaust valves were bent and I had a ls-vtec with a 1st gen B16 Head with a ferrea valve train running Buddy Club spec 3s. B16 cams will do fine on an ITR valve train it just has little bet more stiffer springs. and all B series vtec heads have an inner and outter springs.

PR8urVtec

iTrader: (1)

All manual B series VTEC engines came with dual springs on intake and exhaust sides? Just want to make sure of what springs I have. I'm just reading so many different things from searching so I don't know.

Thanks for input!

PR8urVtec

iTrader: (1)

This is the link that I found with info.

https://honda-tech.com/forums/all-motor-naturally-aspirated-44/b16-gsr-itr-valve-springs-all-same-1792532/

PR8urVtec

iTrader: (1)

So after I found that I have ITR valvesprings in the head, my brother suggested to look the cams over and compare them to FF Squads pics that show the variations between cams (to identify) and I found that I have ITR cams as well. Talk about a win. I traded someone local an extra LS cable transmission (got it free with a b20 motor I pulled) I had laying around and put $100 on top. I thought it was a good deal with just having some AEM cam gears on but now I find out it was all Type R but the valves and cast. Saved me some money lol.