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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
I am putting together a 383, as kind of a temporary thing while I am saving money for the 496 build. I am going with cnc-motorsports rotating assembly kit, where they advertise 10.5 to 1. I picked up a 4 bolt 880 block, that I am going to have machined, instead of my factory 2 bolt l98.
With my XFI 280 cam I calculated my DCR to be around 8.12 or so. Will this be alright on pump gas with my iron vortecs? I searched all over and haven't found much more than aim for 8.0 to 8.5 dcr.
I've gone 8.4 DCR with Vortecs and it wasn't pump gas friendly. Had to pull a lot of timing out of it to keep it out of detonation. 94 octane fuel.
I wouldn't hesitate to run the 8.12 you've arrived at though.
May I ask whose calculator you use? Any engine specs you care to share? The engine builder may advertise 10.5:1 but that doesn't mean much if you're adding your own heads, head gasket, etc.
I'm running 8.1 DCR (using the Pat Kelley calculator) with stock Vortec heads on the car you see in my sig. Everything was measured except chamber cc, which I assumed at 64cc. It runs fine on 87 octane. 180 deg tstat. Carburated.
Edit: I also run a fairly tight quench (.025 deck clearance + .015 gasket = .038") which helps matters significantly.
Thats getting up there on iron heads. -5cc flat top is closer to 11:1 if the heads are 64cc. Come claim they are alittle more than that so if 68 cc its 10.5:1.
I think it could work, run it cool and run a cold plug and sneak up on timing. 30 deg may be perfect, vortecs dont need alot
Thanks for the replies guys! I didn't get any notifications in my emails and was kind of bummed. Then I checked the forum and saw I did get some replies.
SkinnyZ for the SCR I used CNC Motorsports advertisement then used the Wallaceracing DCR calculator.
When I used Pat's calculator (some unknowns) it calculated 11.1 SCR, and 8.49 DCR. Funny Orr, you are probably right about the SCR, that's what kind of scares me. So do you think it would be safer to run their "9.9 to 1" kit with the -12 cc dish?
I am running the 411 computer, and the tune is going to be pretty spot on. The motor will have quite a bit of nitrous run through it though. If .5 on the compression ratio will only give me about 2% more power output I may just stay on the conservative side. I am just worried about leaving a lot on the table with the cam.
Depends on the deck height as well.
Example:
65 cc head
5 cc piston
.014 deck
.026 gasket
10.39:1 SCR.
Keep in mind that's it's not just your total timing you should be concerned about. Part throttle and RPMs below 3000 will need to be addressed too. I found cruise RPMs of 2000-2500 were affected more than total timing at WOT. The 8.4 version rattled badly while cruising. I will admit that I deliberately targeted lean A/F ratios but why would i want to fatten up the mixture AND pull timing when it wasn't necessary had I paid attention to the resulting DCR. Mileage suffered as did performance.
Keep in mind that ignition timing has a greater impact on engine performance than does the compression ratio.
As for the different kits available, you need more information. Stay with the flat top if you can and target a .040" quench/piston to head clearance. The 280 cam should work well with 10-10.5:1 SCR but you need ALL of the specs before moving forward. At 10.4:1 and a 224 @ .050" cam (276 advertised) the Vortecs weren't the best choice. I eventually settled on slightly less than 10:1. Worked well.
EDIT: Those SCR calculations are based on a 355.
If spraying and wish to be more conservative, 9.9:1 wouldnt kill much. Deck the heads abit to get low 10's :1
I have been in mid 9's:1 comp alum headed motors with similar cams and they were no slouches
Do you have any future plans of aluminum head upgrades? If so stay flat top and just tune richer for now and take out alot of timing
Nitrous is gonna want alot more timing pulled and two steps colder plugs. I'd run a ngk 7 on spray
I have been considering the AFR 190 vortec swap down the road, that's why I was leaning towards the 10.5 to 1. But, I think that is probably not going to happen, because deals on these don't come around often, and I might as well throw that money towards the Gen VI BBC build. I ran these vortecs on my stock short block, and I wouldn't call it a slouch and it was a lot less than 9.9 to 1.
I sent an email to CNC regarding the differences between the 10.5 and 11 to 1 5 cc flat top packages. We will see what the difference is.
Depends on the deck height as well.
Example:
65 cc head
5 cc piston
.014 deck
.026 gasket
10.39:1 SCR.
Keep in mind that's it's not just your total timing you should be concerned about. Part throttle and RPMs below 3000 will need to be addressed too. I found cruise RPMs of 2000-2500 were affected more than total timing at WOT. The 8.4 version rattled badly while cruising. I will admit that I deliberately targeted lean A/F ratios but why would i want to fatten up the mixture AND pull timing when it wasn't necessary had I paid attention to the resulting DCR. Mileage suffered as did performance.
Keep in mind that ignition timing has a greater impact on engine performance than does the compression ratio.
As for the different kits available, you need more information. Stay with the flat top if you can and target a .040" quench/piston to head clearance. The 280 cam should work well with 10-10.5:1 SCR but you need ALL of the specs before moving forward. At 10.4:1 and a 224 @ .050" cam (276 advertised) the Vortecs weren't the best choice. I eventually settled on slightly less than 10:1. Worked well.
411 should handle the part throttle spark and fueling. I saw best performance around 32 degrees total with my current setup for WOT. I really need to take the block in and see what I am working with (need to have the block decked etc).
iroc, You are correct, the Pat Kelley calculator shows 11.2X SCR and 8.6X DCR with a quench of .035" (which you SHOULD be targeting as your maximum for any build where you have control over it).
That's really pushing it for iron heads.
If we assume actual head volume as 66cc, the numbers are 11.0 SCR and 8.5 DCR, still at the top edge of the comfort zone.
I'd go with -12cc dish and mill the heads to about a 62cc chamber to end up with 10.6SCR/8.2DCR.
Oh, and I wouldn't waste my time nor money building anything but a low rpm truck motor with either of those cast cranks. Please reconsider! They are both junk.
iroc, You are correct, the Pat Kelley calculator shows 11.2X SCR and 8.6X DCR with a quench of .035" (which you SHOULD be targeting as your maximum for any build where you have control over it).
That's really pushing it for iron heads.
If we assume actual head volume as 66cc, the numbers are 11.0 SCR and 8.5 DCR, still at the top edge of the comfort zone.
I'd go with -12cc dish and mill the heads to about a 62cc chamber to end up with 10.6SCR/8.2DCR.
Oh, and I wouldn't waste my time nor money building anything but a low rpm truck motor with either of those cast cranks. Please reconsider! They are both junk.
Yea, I am leaning more and more towards the "9.9" kit. The crank is going to be a custom deal since I am internally balanced front externally balanced rear. Scat 9000 I believe is what I will be getting.
Scat makes a decent crank. But forgings are best especially with nitrous
Almost everything I read rates the Scat 9000 to 600 hp and 7000 rpms. Scat rates them to 7200. I wont be near that in power even with a 150 shot. Plus the block will probably give out before then. Not worth the extra 500 thats not really in the budget anyway.
I have put quite a bit of nitrous and rpms through the factory crank with no issues, so surely the Scat will be up to the task.
Almost everything I read rates the Scat 9000 to 600 hp and 7000 rpms. Scat rates them to 7200. I wont be near that in power even with a 150 shot. Plus the block will probably give out before then. Not worth the extra 500 thats not really in the budget anyway.
I have put quite a bit of nitrous and rpms through the factory crank with no issues, so surely the Scat will be up to the task.
WHOA! stop! Major fallacy here. Yes, the factory crank will do 600 hp and 7000 rpm without breaking a sweat. ANY...I REPEAT...ANY aftermarket cast crank will be in pieces sooner rather than later at those levels. And no, the block will not give out before then
If a forged crank is not in your budget, you'd be better off building a 355 and re-using/reconditioning a factory crank. Seriously.
If you check around enough you will see alot of guys having good experience with scat 9000 at those rpms. And as with any part, you'll find some bad lol
I would look at scats forged cranks or howards for more budget stuff
Unless I were building a 400 hp street engine with the occasional dragstrip blast, I wouldn't consider a cast crank regardless of where it comes from. You KNOW it'll have a limited life if you pursue sustained RPMs in excess of 6000-6500.
You guys have been there and done that. So have I.
There could be some tolerance and deflection in the system. This is why you degree wheel the cam on install and have adjustable timing gearset to allow movement of cam position. Are you sure its in straight up dot to dot? Accurately gauge tdc? 77 seems a good bit off of spec. Cam should be advanced abit to get it back
There could be some tolerance and deflection in the system. This is why you degree wheel the cam on install and have adjustable timing gearset to allow movement of cam position. Are you sure its in straight up dot to dot? Accurately gauge tdc? 77 seems a good bit off of spec. Cam should be advanced abit to get it back
Yes ,dot to dot.TDC checked with Mitutoyo 0-20mm dial indicator+degree wheel.Timing set is cloyes 9-3145(-4,0,+4degrees),installed straight up.
Here is what readings I got: https://www.thirdgen.org/forums/tech...am-events.html
It is funny that intake centerline is 109.5degrees (cam card 109degrees)and 0.05" values are ~+3dergees,but 0.006" values are off.
I had difficulty getting repeatable results by measuring from the edge of the lifter body. It seems the curve of the dial tip was enough to cause errors as the tip would pivot slightly of the thin edge of the lifter. Greater accuracy was found by placing the dial tip in the pushrod cup. It will register slightly in the oiling hole and does not pivot. I also measure from the tip of the push rod using the oiling hole there. Using the pushrod allows you to align the dial plunger centre line parallel to the pushrod. There's a good visual reference. Even slight deviations in the direction the plunger travels makes a difference.
These are my experiences. Perhaps they compare yours.
I talked to CNC motorsports about the different compression ratios for the same -5cc piston. Apparently that's the difference between how Eagle and Scat rate their rotating assembles (Scat lies), and that my calculations were right it would be about 11 to 1 SCR for both. I ended up ordering another rotating assembly all together one that would put me at about 9.5 to 1 with -19.6cc pistons (Icons). It was 250 dollars cheaper than the kit with the Mahles that would put me at 9.9 to 1. I figured less than 1/2 a point compression is worth about what 5 hp, not worth the extra 250.
CNC called me 4 days later to apologize for not shipping the rotating assembly out, and that the Icon pistons were on back-order. The good news is they upgraded me to coated Weisco pistons that are supposed to put me at around 9.9 to 1 for free . Worked out well.
With the 9.9 to 1 SCR it puts my DCR at about 7.67, I am debating on having the vortecs milled a tad bit, at least to clean them off.
Block is done, and the machine shop wants the rotating assembly to do the final hone. It will all be here Friday.
Another note, I took down my old l98. One rod had a worn bearing, the rest were tight. The rest of the bearings didn't really look that bad. The cam looked brand new, along with the original lifters. Cam will be reused, but with ls7 lifters. There was a ton of rust in the block which was probably why I had a hard time keeping it cool. Heads didn't have any cracks in them, so they will be reused.
Is that with the XFI 280 cam?
Are you Weisco dished (and if so what 's the dish shape) or flat top?
And yes, milling the heads to bring up the CR isn't a bad idea. You'll find that 7.67 DCR will be a little weak at lower engine speeds.
Is that with the XFI 280 cam?
Are you Weisco dished (and if so what 's the dish shape) or flat top?
And yes, milling the heads to bring up the CR isn't a bad idea. You'll find that 7.67 DCR will be a little weak at lower engine speeds.
Not really sure which Weiscos are coming, I'll find out tomorrow. The only thing I could find was "reverse dome 20 cc". They rate them at 9.9 to 1 with 6 inch rod and .030 bore.
I am going to find out if my machine shop can do an angle mill. I heard it was a bad idea to do a regular mill is a no no for vortec heads because the castings are so thin to begin with.
My old setup was around 9 to 1, it wasn't really to bad of a slouch down low (unless you compare it to my original LTR setup).
Is that setup with the same cam? I can't imagine a 9:1 engine and 280 cam being very snappy. The again there are a lot of other parts in play as well.
I can't comment on the Vortec head milling. I've only gone about .006" as a clean up on my old set. I had never heard about the castings being thin though and I thought I had read everything about those heads at one time or another.
You could install the cam in an advanced position too.
Is that setup with the same cam? I can't imagine a 9:1 engine and 280 cam being very snappy. The again there are a lot of other parts in play as well.
I can't comment on the Vortec head milling. I've only gone about .006" as a clean up on my old set. I had never heard about the castings being thin though and I thought I had read everything about those heads at one time or another.
You could install the cam in an advanced position too.
Yes sir, same cam. Maybe the vortec heads smaller port/velocity? I agree in theory it should have been a sloth. However, it was real peppy on the bottom end and I got great mpg's.
Ha, I know that's true, probably because they have been run so many budget builds. I do have another set that came off of this block. Both of them were cracked right down the middle. I'll probably just have them clean them up like you did.
Yea good point on advancing the cam. I might run some simulations on desktop dyno and see what it says. I can always advance it down the road if I want more.
Well just got back from the machine shop, spend an hour in there talking with my machine shop guy John Deere (I know heck of a name).
They are going to "deck" the heads which will get them down a couple of cc's he said for 80 bucks.
The main issue I ran into is when assembling the pistons the rods I noticed the rods were hitting the bottom of the piston. Mr. Deere said this is not normal (obviously), and that the rods and pistons probably aren't meant to work together. He showed me a bunch of different rods that had a different contours on the wristpin area of the rod. Ho hum, back two steps, I will be on the phone with cnc-Motorsports on Monday to discuss options. Anybody ever seen anything like this?
Oh btw the pistons are Wiseco pts534a3, They have a 20 cc dish, but a 1.125 compression height. They rate them at 9.9 to 1 with 64 cc heads. I guess compression height is the variable I haven't been considering. It's weird the online compression calculators don't have this variable.
The calculators rely on the piston to deck value so the compression height is taken into account already.
As for your rod to piston interference, is there a balancing pad on the small end? It may be possible to reduce the size of the pad and eliminate the interference. Sounds like with your mix and match rotating assembly that a rebalance is in order anyway.
The calculators rely on the piston to deck value so the compression height is taken into account already.
As for your rod to piston interference, is there a balancing pad on the small end? It may be possible to reduce the size of the pad and eliminate the interference. Sounds like with your mix and match rotating assembly that a rebalance is in order anyway.
First off thanks Skinny for keepin up/following up on my build. I value ur input.
I wonder if Wiseco's calculation assumes the deck has been zero'ed instead of the light decking from stock my block has. Ill prol call them on Monday too.
There is an area on the small end of the rod, and actually thats why I took it into the machine shop to see if it just needed to be ground off. He said it would throw the weights of the rods off, and even though it was going to be rebalanced anyway he was worried about there not being enough clearance when they pistons warm up and expand.
I did a little googe search, and haven't found anything on this exact issue.
Ill see what cnc says on Monday, heck maybe they'll give me another free upgrade.
You would have to rebalance the rods if you were to go at the balance pad but that would be the case anyway if you were starting from scratch and trying to keep the rods as light as possible. That was the way in the "old days" when aftermarket rods were few and far between. It's possible to build your own rod balance fixture if you wanted to work on the small end for clearance, match the big end and then make all of the rods the same. Then balance the reciprocating assembly which you may have to do anyway.
As far as any manufacturer stating what a given compression ratio might be... it's only an estimate unless said manufacturer is supplying an entire long block. They would work on an average deck height, which would vary from manufacturer to manufacturer and then guess at the rest. I've seen it stated as "10:1 with 64 cc heads" but that still leaves a lot of variables unaccounted for. A phone call may clear that up.
You would have to rebalance the rods if you were to go at the balance pad but that would be the case anyway if you were starting from scratch and trying to keep the rods as light as possible. That was the way in the "old days" when aftermarket rods were few and far between. It's possible to build your own rod balance fixture if you wanted to work on the small end for clearance, match the big end and then make all of the rods the same. Then balance the reciprocating assembly which you may have to do anyway.
As far as any manufacturer stating what a given compression ratio might be... it's only an estimate unless said manufacturer is supplying an entire long block. They would work on an average deck height, which would vary from manufacturer to manufacturer and then guess at the rest. I've seen it stated as "10:1 with 64 cc heads" but that still leaves a lot of variables unaccounted for. A phone call may clear that up.
Just a little update. I talked to CNC motorsports, Weisco, and Scat. CNC wanted me to machine the top of the rods, my machine shop was not comfortable with that. I called Scat, they said Wiesco's "tolerances" were bad and to not clearance the top of the rod and instead clearance the bottom of the piston. Weisco stated the bottom of the piston could be clearance but would require a bridge something or other, and it wasn't so simple. They recommended different set of rods, and tried to sell me some 500 dollar K2's.
Scat had another option of using their 7/16 procomp rod, which CNCmotorsports upgraded for me, they clear fine.
Weisco stated they calculate their compression ratio assuming a .020 in the hole because machine shops usually take .005 off when they deck a block. Just so happens to be exactly what my machine shop took off.
I bought some ARP main bolts, and the machine shop align honed the block for me. I should be picking everything up tomorrow.
I decided to do a little cleanup on my heads. I did some bowl work, and cut the lip under the valves, along with a smoothing of the valve guides. I polished the exhaust, but left a rough cut on the intake valves. I also did a fair bit of cleanup of the ports. I am going to have them flow-benched, and milled at another race machine shop later this week.
I'll be interested in your flow numbers. If you can, get the test bore diameter of the fixture used and whether they use a pipe on the exhaust.
Sounds you're coming together. Did you end up with 6" rods? You had mentioned that in the Wiseco spec but I don't recall what you've settled on. If you're getting the pistons listed (PTS534A3), then you'll be using a 6" rod anyway. It'll make a difference in your DCR calculations.
EDIT: I tried to find a picture of the PTS534A3 and I don't think the picture I was looking at was the piston you've mentioned. Do you have any?
I'll be interested in your flow numbers. If you can, get the test bore diameter of the fixture used and whether they use a pipe on the exhaust.
Sounds you're coming together. Did you end up with 6" rods? You had mentioned that in the Wiseco spec but I don't recall what you've settled on. If you're getting the pistons listed (PTS534A3), then you'll be using a 6" rod anyway. It'll make a difference in your DCR calculations.
EDIT: I tried to find a picture of the PTS534A3 and I don't think the picture I was looking at was the piston you've mentioned. Do you have any?
Just the pictures above (which don't really show much). I would take some pics but they are still at the machine shop (saying next Tuesday now in line for the line hone).
Got the heads back, here are the flow numbers: Superflow 600 @ 28 inches. 4.125 test bore diameter, and no pipe on the exhaust. He said people have told him that his flow bench tests low.
I was pretty disappointed right off the bat. He told me that was about what factory vortecs flow on their flow bench. He mentioned my short side work was pretty good, and that there was no turbulence on the chambers. He said the lower lift numbers did show some improvement, but the valve job is what was really holding me back from bigger high lift numbers. They want $180 to do a 3 angle valve job, so now I am considering going that route, and maybe a bigger intake valve.
I don't know how much is to be gained really and might just throw them on there.
They took off 10 thousands which they said was about 2 cc's. I am going to measure them this weekend, along with the port sizes.
My understanding of the Vortec head is that it IS the valve job that gives them their exceptional low lift (.050" - .200") flow. I'm sure many a Vortec head has yielded diminished results after a shop, with the best of intentions, cut a valve job that wasn't as the factory spec. Now this is what I understand to be true although I've never done a before and after flow bench test despite having my heads at the shop more than once. Further to that, the addition of a larger intake valve, can do more harm than good if additional work on the valve seat form and beyond isn't performed. I would think that any reputable machine shop that specializes in racing engines rather than daily drivers would understand this.
That said, if the existing valve job is still good and the guides are ok (and the factory cast iron guides seem to last forever) then I'd skip the valve job. This is an engine that is just filling in the gap before the big block isn't it?
As for your flow numbers, they look to be on par with what's out there in terms of data. Check out the Stan Weiss Cylinder head Flow website. There are about a dozen Vortec bench tests there. Some modified, some stock.
If you take an aftermarket Vortec casting such as RHS or EQ (both with 170 cc intake ports), the as supplied larger valves (2.02/1.60), some bowl blending and a little additional port work ( not a full out assault ) will yield numbers like these.
This is the result of some professional port work at AMS Racing Engines. (Edmonton, Alberta)
I hope these heads and the XR288HR will take my 355 up a notch.
Post up your cc tests. I've seen where the Vortecs actually measure in at 63 cc. If yours are down to 61, that'll have implications on your target SCR/DCR.
My understanding of the Vortec head is that it IS the valve job that gives them their exceptional low lift (.050" - .200") flow. I'm sure many a Vortec head has yielded diminished results after a shop, with the best of intentions, cut a valve job that wasn't as the factory spec. Now this is what I understand to be true although I've never done a before and after flow bench test despite having my heads at the shop more than once. Further to that, the addition of a larger intake valve, can do more harm than good if additional work on the valve seat form and beyond isn't performed. I would think that any reputable machine shop that specializes in racing engines rather than daily drivers would understand this.
That said, if the existing valve job is still good and the guides are ok (and the factory cast iron guides seem to last forever) then I'd skip the valve job. This is an engine that is just filling in the gap before the big block isn't it?
As for your flow numbers, they look to be on par with what's out there in terms of data. Check out the Stan Weiss Cylinder head Flow website. There are about a dozen Vortec bench tests there. Some modified, some stock.
If you take an aftermarket Vortec casting such as RHS or EQ (both with 170 cc intake ports), the as supplied larger valves (2.02/1.60), some bowl blending and a little additional port work ( not a full out assault ) will yield numbers like these.
This is the result of some professional port work at AMS Racing Engines. (Edmonton, Alberta)
I hope these heads and the XR288HR will take my 355 up a notch.
Post up your cc tests. I've seen where the Vortecs actually measure in at 63 cc. If yours are down to 61, that'll have implications on your target SCR/DCR.
After reading it looks like they may be breathing a little better on exhaust than stock. Intake, about factory, who knows maybe different flow bench/different numbers. He also mentioned the middle cylinders always flow more than the outer ones, they tested the outer ones.
The valve job is in good shape, so I think I will just throw them on there. They look like new heads with the mill work, and polished chambers. I called back and asked about the valve job. He recommended I not waste the money.
Ill be ccing them tomorrow to see where im at, Ill post the results (doing it at home)
Your right I need to keep this all in perspective. The plan is to get some dyno and quarter mile runs in and start building the 496 this spring. Hopefully sell this motor off to pay for a nice set of heads.
Just a little update, I CC'ed the heads, I did a couple of different chambers, and they averaged about 63 cc (looks like they were about 65 from the factory). I only did the intake port and came up with 158 cc, after doing it three times.
The piston is about .020 under the deck, so I bought a .015 felpro steel gasket.
Crank bearing clearance was around .002, and thrust was at .007.
I ran into a struggle on the rod bearings. I was between .001 and .0015 for clearance on all of them (too tight). I ran and got some "undersized" bearings from O'reilly only to find out undersized actually means a thicker bearing. I took them back and ordered some ACL performance bearings that are .001 extra clearance (should be in on Wednesday).
Piston rings were file fit for high performance, within .02 of an inch.
One more point of anxiety is the clearance between the small end of the rod and the bottom of the piston. Even with the new rods, it looks like I am at right at .050 of clearance. Wiseco recommends .060, so I am a little tight there. They are supposed to be talking to the engineers to see if that will be enough.
Motor is in and I started driving it today, couple of things. If anybody has an opinion it would be much appreciated.
It smokes white smoke on start up every once and a while. Oils leaking from something on the top of the block, I am hoping that is whats causing it.
The starter is having a hard time turning over, I am wondering if the compression is too much for the stock style. I have a mini starter but it needs a rebuild. If I hook a charger up to it it will start after a while. I am going to take it back to Orielly's to trade it out for a new one.
The factory 1 core radiator is not keeping the motor cool. It is getting up over 200 driving around in 80 degree weather.
I am using the stock truck dipstick, but it seems to be holding a lot of oil before it gets on the dipstick (5.5 quarts already). I am using a fbody oil pan.
I can't see where an external oil leak is going to give you any issues at start-up.
It may take a while and a few tests and observations to determine where the white smoke is coming from.
As for the hard time turning the engine over, I've run as high as 205 (+) PSI on a compression test and the factory starter was always up to the task. Both the conventional old school massive Delco starter as well as the smaller versions available.
What did you work out your final static and dynamic compression ratios to be?
Do you have solid network of power cabling for the starting system? Heavy wire (min #4 gauge, prefer #1 or better) directly to the block from the battery. Same size from the battery to the starter lug. Starter is securely fastened to the block and the interface between the block and the starter are clean?
The stock rad may be on the small side. I'm running a 2" thick aftermarket aluminium rad with a 180 t-stat. Fan is set to come on 195-200. Off again at 185.
Check your timing. Idle timing should be minimum 16 degrees. Add another 16 degrees for your full manifold vacuum advance. The advanced timing really helps with reducing idle temps. That will spill over into the overall performance of the cooling system.
Regarding the oil level. If it takes 5.5 quarts and only then appears on the dipstick, I would say that there's a mismatch somewhere.
Maybe you'll have an opportunity to do a compression test...
....As for the hard time turning the engine over, I've run as high as 205 (+) PSI on a compression test and the factory starter was always up to the task. Both the conventional old school massive Delco starter as well as the smaller versions available....
Agreed. It doesn't require more than a stock starter. I've used both old "massive" and ministarter on 230psi cranking pressure with no issues. As skinny says, your cabling and connections are key.
I'll add to that by stating that even at 205 PSI, I was running 16 degrees of spark lead and still had no issues.
(230 PSI ! That must have been interesting.)
I'll add to that by stating that even at 205 PSI, I was running 16 degrees of spark lead and still had no issues.
(230 PSI ! That must have been interesting.)
Drama free. That was my 12:1 stock bottom LT1. Drove and drag raced it for 6 years on 93 octane. Ran race gas only at the roadcourse when getting it super hot, or when spraying at the strip. Reverse cooled motors are wonderful!
Idle (950 rpm) timing was 18 deg. Cranking advance was somewhat lower than that.
Total timing for WOT best power was 33 deg.
True that. Something I neglect to consider when discussing the LT small block variant.
I'm struggling to get my cranking pressure up with the new cam and limited SCR available given my heads and short block. Sadly, a DCR of less than 8:1 and 165 PSI of cranking pressure are what I have to work with now. It doesn't help to be doing this at 2200' elevation. It's not a mile high but it does make a difference.
I can't see where an external oil leak is going to give you any issues at start-up.
It may take a while and a few tests and observations to determine where the white smoke is coming from.
As for the hard time turning the engine over, I've run as high as 205 (+) PSI on a compression test and the factory starter was always up to the task. Both the conventional old school massive Delco starter as well as the smaller versions available.
What did you work out your final static and dynamic compression ratios to be?
Do you have solid network of power cabling for the starting system? Heavy wire (min #4 gauge, prefer #1 or better) directly to the block from the battery. Same size from the battery to the starter lug. Starter is securely fastened to the block and the interface between the block and the starter are clean?
The stock rad may be on the small side. I'm running a 2" thick aftermarket aluminium rad with a 180 t-stat. Fan is set to come on 195-200. Off again at 185.
Check your timing. Idle timing should be minimum 16 degrees. Add another 16 degrees for your full manifold vacuum advance. The advanced timing really helps with reducing idle temps. That will spill over into the overall performance of the cooling system.
Regarding the oil level. If it takes 5.5 quarts and only then appears on the dipstick, I would say that there's a mismatch somewhere.
Maybe you'll have an opportunity to do a compression test...
Thanks again for helping me out.
The static compression ratio should be about 10.2, about 7.89 DCR.
I am with you on the starter. Now that I am thinking about it, on the last leg of the power tour when the motor was dying it was getting harder to start (I attributed it to the motor losing oil pressure). I am going to swap the starter out for a fresh one. I have all the factory starter wiring, covered in the DEI heat wrap, all connectors were just cleaned.
I can't remember where the idle timing was programmed at (411 pcm), I am thinking it liked it better around 21 or so, when I brought it down it got a little choppy. I'll check it out once I get the oil leak fixed.
The oil leak is coming from the back of the manifold, it looks like the little plug that fills the hole where the old school oil pressure sensors went. I am looking for one of the square sockets to pull it out and put a new one in, with thread sealer.
I am going to be looking into a bigger radiator, and possibly going to an aftermarket push fan setup. The factory dual electric originals have been pretty reliable, but they just aren't cutting it anymore. I am not running a thermostat right now so that's why I was worried about the temp going up.
Dipstick tube is more of a concern, I haven't been able to find anything online to give me a direction. My train of thought was this was the original dipstick for this block. The oil pan did change, but I was thinking full would be at the same level no matter what oil pan was on there.
The smoking, has all the symptoms of a valve seal issue. These valve seals only have about 10,000 miles on them, but drove 250+ miles on low oil pressure, so they may be shot.
Reasonable numbers so I would expect cranking compression to be in-line. Doubtful that it would present a problem for the starting system. I would be interested to know what your cranking compression is though. Just for my data collection files.
Certainly, 21 degrees is not over doing it on timing. As I said, I'm running 32 and the engine will happily absorb more. But at 21 degrees, yours is advanced enough not to be dumping overly hot exhaust gases into the headers and driving up idle temps.
Bigger radiators are never a bad thing. I have a universal fit Griffin rad (PN 1-25272-X) and the OEM single fan. Works very well. The rad needed the mounting provisions revisited but it wasn't a big deal.
You would think that the dipstick would be OK but then again, perhaps the F-body pan has more capacity than the truck pan. Can't comment for sure on that one. Your thinking that the full should be the same regardless is reasonable. I have a Canton road racing oil pan. At the full mark, I've got 6 litres in there. Just under 6 1/2 (U.S.) quarts. At the full mark, do you see any evidence of oil foaming? How about oil pressure? Is is steady? If the rotating assembly is beating on the oil level, it would certainly help to aerate the oil. More so than just the normal windage present in the crankcase.
Reasonable numbers so I would expect cranking compression to be in-line. Doubtful that it would present a problem for the starting system. I would be interested to know what your cranking compression is though. Just for my data collection files.
Certainly, 21 degrees is not over doing it on timing. As I said, I'm running 32 and the engine will happily absorb more. But at 21 degrees, yours is advanced enough not to be dumping overly hot exhaust gases into the headers and driving up idle temps.
Bigger radiators are never a bad thing. I have a universal fit Griffin rad (PN 1-25272-X) and the OEM single fan. Works very well. The rad needed the mounting provisions revisited but it wasn't a big deal.
You would think that the dipstick would be OK but then again, perhaps the F-body pan has more capacity than the truck pan. Can't comment for sure on that one. Your thinking that the full should be the same regardless is reasonable. I have a Canton road racing oil pan. At the full mark, I've got 6 litres in there. Just under 6 1/2 (U.S.) quarts. At the full mark, do you see any evidence of oil foaming? How about oil pressure? Is is steady? If the rotating assembly is beating on the oil level, it would certainly help to aerate the oil. More so than just the normal windage present in the crankcase.
The pan is an aftermarket chrome one, but who knows it may be a little bigger. Looked exactly the same size side by side with my original one.
No oil froth yet. I have about 5 miles on the engine, and need to change out the break in oil. I am going to keep adding oil and see how much it takes to get it on the dipstick, then drain it and see how much.
I will rent a compression checker from Autozone, and try to get to it this weekend.
For that Griffin, good price on the radiator, what did it take to get it mounted? Can I use the factory plastic fan shroud/mount on top?
I was looking at a 2 or 3 core cheapy on ebay, there was one a lot of people have had luck with. This radiator is a new one from Orielly's, only about 500 miles on it, I'll see if they will trade it out for store credit.
Regarding the rad: I had to notch the lower rad support to accept the rubber isolators for the bottom of the rad. Up top, I built an extension to the upper rad support out of 1/4" aluminium flat stock (1/4" x 2"). The flat stock bolts to the rad support and the fan shroud bolts to the flat stock. (I'll post up some pictures later). This rad has one size larger inlet and outlet fittings than the stock rad. It makes the inlet on the rad the same size as the t-stat housing and the outlet on the rad the same size as the water pump outlet (whereas it's usually 1/4" in the difference with the rad being a smaller I.D.) I found an over the counter replacement for the upper hose. The lower hose is spliced from two different hoses. The bottom of the fan shroud (a single OEM 3rd gen electric fan in my case) bolts to the stock location.
The oil leak was a mixture of the distributer not sealing up against the intake, I added another round gasket in, and it drastically slowed it down (still leaking a bit). Also the china wall was leaking so I took the intake off and put a ton more RTV on this time.
I added oil until it was on the right place on the dipstick and drained it. I got out about 5 quarts, so it looks like I was just losing a ton of oil out the back of the engine, hopefully didn't starve the new parts on oil.
The battery was the main starting problem, I think the starter should have been shimmed out a little more, combined with the weak battery made it hard to start. I got a new starter and shimmed it out more. With the new battery it starts quick.
Smoking, for the most part is cleared up. I think the big leak on the back of the manifold was spraying oil on my ypipe, and burning it off.
Under heavy load there is a little bit of a smoke smell but nothing visible. I did gap the rings for nitrous so who knows. Maybe it will clear up as the motor is broke in.
The tune was way more lean than I was expecting, I have been adding as much as 10 on the ve chart to bring it into Stoich while cruising.
It runs very strong, and pulls a lot harder at lower RPMs, and up top its a little scary. I really haven't given it much hell until I put a few more miles on it.
Hopefully after Thanksgiving I will get to doing a compression check, and once broke in I will get some dyno/track times.
07-28-2016, 06:44 PM
. Worked out well.
