349 CI on the cheap

-
Status
Not open for further replies.
What are your thoughts on degreeing the cam?
I have a Purple Shaft Cam
Adv. Duration: .268°/272°
Dur. @ .050'': 228°/231°
Lift: .450''/.455''
Centerline: 110°
Basic RPM: 1500-5800 RPM
I will redo a set of heads in the future, 302 castings if I can find them.
How much carb can I use for street/ strip...this is in a 2700 lb car
I am learning so any and all info gets written down. If I remember when I bought my short block it was .30 over with 4 valve relief pistons. How much is too much when milling 318 heads, are there any castings that are as good as the 302's if I can't find them. When I pull my motor for freshening I will go through it and have the block gone over, prepped for the 360 crank. Looking forward to looking stock and clean clock......Thanks for all the info..
 
64,
To get the most out of any camshaft you really need to degree it in. Most cams aren't ground perfectly as the specs. would have us think. Any cam thats custom ground should be right on spec. this is why you pay so much for them. Also degreeing the cam will help eliminate any mistakes that the cam grinder would have made in centerlines. Most el cheapo cams have something wrong with them or they wouldn't be so cheap, most times it's the centerlines that off. I degree every cam that I use, and any engine builder worth there salt should also. This is part of the reason that most engines don't run like they should. IMO
 
Well the engine is in and running but not without a few small problems, like the oil line decided to start leaking or had a small crack in it right at the fitting. Then the valve covers didn't seal as they were a friends that I borrowed, but I can't complain he offered but I guess it just wasn't in the cards. But a new set of Moroso covers will be here next week so that will cure that problem, and a new ferrel fixed the oil line. Now I have to do the break in and change the oil and jet the carb up as it built heat very, very quickly and it shouldn't have. But thats a simple fix also, something to do tomorrow. I also have to set the timing. But hey it's up and running so I figured that I would have some bugs to fix, at least it's nothing major.
 
Well didn't get a chance to run the engine as of yet. While looking at everything yesterday I noticed what looked like oil splashed on the inside of the front tire. But to find out that one of the Drag Front's was actually very, very dry rotted and cracked. Now keep in mind that these tires were purchased just 8 months ago new. The other tire was just like new, so it was a good thing that I didn't go yesterday as this may have been a accident waiting to happen. And with the expense that I have both in time and $$$$ in the car I don't need to see if the rollbars will work like they should.

Just another set back that has to be addressed. I'm going this morning to see what the company will do about the tire and if they have had this problem before. Heck the matting rib from where they put the tire together is still very visable in the center of the tire and they don't have more than 50 runs on them. Hopefully they'll do something about it, and maybe send the tire back for inspection and cause.
 
Well, Finally recieved a new tire yesterday from Mickey Thompson at no charge, so hopefully this friday night I will get to see what the new engine does. I'm mainly going for T-N-T for the first night, and if everything go's right in time trials then maybe I would go in to race. But you just don't know whats going to happen. I should have some numbers on Saturday. The engine sounds very very strong, so if this is any indication this thing is going to fly. But we'll wait and see.
 
Dang I like this thread...........I probably would not have done my 410 stroker if I came across this earlier...........dang it would have saved me about 7k
 
As for the chambers they have been in the .095 to .105 in chamber depth stock,
Click to expand...

So now we have a positive deck of .041 with the gasket in place, or
Click to expand...
.

For this cam the pistons will have to be notched, so we notched them .200 as the pistons are forged and are .400 thick.
Click to expand...

Now we have a actual net lift of .540.
Click to expand...

So with the valve reliefs we should have .100-.130 valve to piston clearence depending on the gasket thickness.
Click to expand...

Hi Bobby

Ive quoted the important bits, but I cant figure how you have enough P-V clearance.

You have a net lift of .540, but by my reckoning, you only have:

Chamber depth of .095 less + deck of .041 = .054

+ piston notches of 200th = .254th clearance.

Call me dumb but how will the valves not hit the slugs if the lift is over twice the clearance??
 
Mal,
As you quoted above, I'll explain what happends. If the piston is .041 above the deck with the gasket in place, and the chamber is .095 deep, you have to take .095 - .041 = .054 at TDC + .200 for the valve relief in the piston, and you end up with .254 at TDC. Now the valves are closed at this point and as the valve starts to open, the piston starts to move down. Sometimes the valve opens sooner than the piston starts to move and this is why the pockets have to be so deep in the pistons. To take up the additional movement of the valve and to keep from hitting the pistons.

The valve doesn't get to full lift until BDC or just before. At this point the piston is 3" away from the valves. As the valves open the piston moves away and the valve vritually chases the pistons down the bore. The oppisite happends with the exh. valve. It opens just before BDC and the piston chases the valve closed so the pressure that the piston makes comming up the cylinder bore pushes the spent gasses out the exh. port and into the hedders. But usually the exh. valve doesn't need to be as deep as the intake valve pocket as the valve is further up in the chamber and further from the deck surface. But this is all dependant in the centerlines and duration at .050, which would open or close the valves eariler or later depending on how the cam is ground.

This is where the machinist really needs to know his stuff to make a high compression engine work with tight clearences. Hopefully you understand it now.
 
Jack,
I guess he was thinking that the valve is a full lift at TDC and at this point the valve would hit the piston.
 
In the 344 engine which is a std. bore 318 instead of .030. I used a stock cheater cam and a set of 318 heads. The heads have .120 in stock uncut form from the deck to the chamber roof at the quench area. I used the 1.78 intake valves and the 1.60 exh. valves. This way I have high compression and a good quench as the piston comes out of the block .075 and I used a .020 MP head gasket so the piston sticks up out of the hole .055. Then I machined the top of the piston as shown eariler, so that the top of the piston would go into the open part of the chamber and make my quench .038 after machining the heads to match. This way I can use the open style heads from eariler years. This gives me close to 15:1 but a cyl. pressure of only 150 @ cranking, because of the bleed off of the cams overlap. According to my program it should make 638 HP @ 6,500 rpms and 542 ft. lbs @ 4,500 rpms. And it sounds like it too.

The heads flow 215 @ .400 lift and the cam opens to .473 int. and .494 on the exh. CL is 106 straight up. The 318 heads also flow 198 @ .300 with the small valves. The exh. peak flow is 207 @ .600 lift but this is just for reference as the cam doesn't open this far. I'm looking for solid 6 sec. passes in the 1/8 Friday night. But once again will see as anything can happen.

Oh the cam has 275/272 @ .050 duration.
 
BJR Racing said:
Jack,
I guess he was thinking that the valve is a full lift at TDC and at this point the valve would hit the piston.
Click to expand...

Sort of - I assumed the valves and pistons would play "tag" with each other.

I have two more questions.........

At TDC both valves are closed...so this clearance issue only occurrs on the "overlap" or second cycle of the crank, correct?

Also - In your experience what duration and lift would you say that this all starts getting too "tight" for a zero deck fly cut slug with an open chamber head?
 
What are the valve sizes, and the cam used?
As for which cycle it occurs at will depend on the cam and how it's been ground. The cam it self creates this problem with a 0 deck piston. Most aftermarket pistons have the valve reliefs already in them and deep enough for a large cam.

As for the piston and cam comming together I would say 0 deck and 240 or greater duration @ .050 and less than 108 centerlines.
 
As for the piston and cam comming together I would say 0 deck and 240 or greater duration @ .050 and less than 108 centerlines.
Click to expand...

Thats what I was after , thanx Bobby - just wanted an appx for when things get "close" using factory flat tops with shallow reliefs.
 
Well, It's like this, on Thursday afternoon when we finished making changes and fired the engine again, everything sounded real good, oil pressure was up to 75 psi. Everything sounding strong and just double checking everything. Then the engine just quits like you turned the ignition off. Go to restart the engine and it won't turn. Water level is fine so out with the plugs and all are dry and looking like they should until the last one. The plug came out real hard, keep in mind I just put these plugs in so I know that there wasn't any issues with them. Upon taking the plug out of #5 cylinder the tip was gone. The engine never made a noise, but just quit. Then after some thought I took the head and intake off and found that a valve on the #5 exh. had broken the head of the valve off and lodged between the head and the piston. Needless to say the piston is trashed and will be replaced. I'll need to put a seat in the head also. When the valve broke the valve head flipped over using the valve stem as a punching tool and punched 4 nice little holes in the top of the piston, before jamming the engine. So I never made it to the track, man what a dissapointment. But hey life go's on.

So today I pulled the pan and removed the rod and piston and found no metal in the pan except the 4 punched out pieces of piston. Everything in the bottom end was as clean as when built. So I have another piston but will need to get another intake and exh valve. Just go's to show that even the best parts fail. It looked like the valve wasn't fully heat treated properly, and how are we to know what the valve is when you take it out of the box. You can only trust the manufacture with there product. But hey S**T happends, it's a part of racing and engine building, as most go right some don't, this just happens to be one of the times that it didn't.

Being that I have a piston here I'll only be out about $100.00 for oil and rings and a rod bearing. I have more head gaskets and intake gaskets so if anything went right I guess that you could say it did. As it could have been much worse, good thing it was idleing, but 1,300 rpm's still did a good bit of damage.

Now there calling for rain for the next 10 days here, so this gives me time to get the parts fixed and reassembled. I'll be ready for the next time. So sorry for no news on the engine. But we took 2 other cars and made it down to 3 cars again with one of them. So all in all the weekend turned out OK as the money that we made will fix the engine. But hey we'll get it, it's just a small set back. I guess the time wasn't right for it yet, but I'll let you know as soon as I get the chance to get it there.
 
BJR Racing said:
Well, It's like this, on Thursday afternoon when we finished making changes and fired the engine again, everything sounded real good, oil pressure was up to 75 psi. Everything sounding strong and just double checking everything. Then the engine just quits like you turned the ignition off. Go to restart the engine and it won't turn. Water level is fine so out with the plugs and all are dry and looking like they should until the last one. The plug came out real hard, keep in mind I just put these plugs in so I know that there wasn't any issues with them. Upon taking the plug out of #5 cylinder the tip was gone. The engine never made a noise, but just quit. Then after some thought I took the head and intake off and found that a valve on the #5 exh. had broken the head of the valve off and lodged between the head and the piston. Needless to say the piston is trashed and will be replaced. I'll need to put a seat in the head also. When the valve broke the valve head flipped over using the valve stem as a punching tool and punched 4 nice little holes in the top of the piston, before jamming the engine. So I never made it to the track, man what a dissapointment. But hey life go's on.

So today I pulled the pan and removed the rod and piston and found no metal in the pan except the 4 punched out pieces of piston. Everything in the bottom end was as clean as when built. So I have another piston but will need to get another intake and exh valve. Just go's to show that even the best parts fail. It looked like the valve wasn't fully heat treated properly, and how are we to know what the valve is when you take it out of the box. You can only trust the manufacture with there product. But hey S**T happends, it's a part of racing and engine building, as most go right some don't, this just happens to be one of the times that it didn't.

Being that I have a piston here I'll only be out about $100.00 for oil and rings and a rod bearing. I have more head gaskets and intake gaskets so if anything went right I guess that you could say it did. As it could have been much worse, good thing it was idleing, but 1,300 rpm's still did a good bit of damage.

Now there calling for rain for the next 10 days here, so this gives me time to get the parts fixed and reassembled. I'll be ready for the next time. So sorry for no news on the engine. But we took 2 other cars and made it down to 3 cars again with one of them. So all in all the weekend turned out OK as the money that we made will fix the engine. But hey we'll get it, it's just a small set back. I guess the time wasn't right for it yet, but I'll let you know as soon as I get the chance to get it there.
Click to expand...

That SUCKS! Can even happen with stock stuff...
 
BJR RACING,

Stuff does happen. We all appreciate your Honesty and Integrity to take the time and tell it like it is. I very much appreciate the time and energy you have put into this post...........for sure I WILL be building this combination in the near future but it will be only in HOT street trim with lower compression and forged parts...............

Would you ever think about throwing some nitrous at this same combination?? Would it be able to take it??

Thanks a bunch!!
 
Mad Dart,
You could put NOS to it without any problems, but the amount that you could use would be less, as the compression ratio is fairly high. I suppose that it would handle a 250 or 300 shot pretty well. And maybe more with stronger rods and pistons. Because the piston comes out of the deck so far that you would have to cut about .060 off the top of the pistons and this would put you near 10.5:1, with the pistons still being out about .015-.020. Then camming it properly for NOS it should make a very good street engine, and depending on how much NOS you intend to use, this engine could make between 500 and 750 HP and still be streetable.
 
That just sucks Bobby. At least it didn't happen at the 1/8 mile mark where it probably would have ventilated the block. Congrats on getting down to 3, that is some consolation anyway.

Jack
 
Thanks Jack,
I must say that we've been pretty fortunate that we have extra cars to race with. And out of the last 11 times to the track we've been either in the winner circle or in the money 7 of those times. And always to 3 or 4 cars if we didn't win it.
 
BJR Racing said:
Mad Dart,
You could put NOS to it without any problems, but the amount that you could use would be less, as the compression ratio is fairly high. I suppose that it would handle a 250 or 300 shot pretty well. And maybe more with stronger rods and pistons. Because the piston comes out of the deck so far that you would have to cut about .060 off the top of the pistons and this would put you near 10.5:1, with the pistons still being out about .015-.020. Then camming it properly for NOS it should make a very good street engine, and depending on how much NOS you intend to use, this engine could make between 500 and 750 HP and still be streetable.
Click to expand...

I would only hit it with a 150 shot maxxx. 10.5:1 would work work well for my application on the street.....250 to 300 is WAY out of my league. Dang that is alot.......WOW!! I think I would Crap my pants from the anxiety just before I hit a 250-300 shot. I would almost think that without a R3 block it would squeeze out the gaskets with that much juice.
 
Nope we've had 500 shot on a stock block but we had to O ring the heads and block. Along with copper gaskets.
 
Status
Not open for further replies.
-

Back
Top