small block chevy timing.
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=33052
Printed Date: October-08-2024 at 3:20pm
Topic: small block chevy timing.
Posted By: forvicjr
Subject: small block chevy timing.
Date Posted: March-17-2014 at 6:54pm
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I know the specs for timing at idle but what are you guys with chevys running on the other end. I never checked my old prestolite to see when all the timing was in rpm wize and at how many degrees. Now with the marine HEI im all in at 2000 rpm and at 36* with my distributor that leaves me with 16* at idle. The Hei has 20* mechanical advance I never tested the prestolite to see what was built in on it.I was wondering if I need to put more mechanical advance in my hei so I can get it back down to the 12* mark at idle, or back off my total timing or a little of both. Ideas?? ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Replies:
Posted By: baitkiller
Date Posted: March-17-2014 at 7:36pm
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You are gonna smoke a piston at 36 total. I'll bet it lunges at starting? Mine is pretty tight and the best I can get with 90 octane gas is about 12* base with about 28 at 4000 running a Thunderbolt V system. It runs really well there/ Any higher and it will start to ping. I would like to squeeze that last degree out and I may yet, just haven't done it yet. ------------- Jesus was a bare-footer............. |
Posted By: baitkiller
Date Posted: March-17-2014 at 7:38pm
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And BTW. What the heck are you doing with a SBC in that boat? I thought I was the only hack on here?????? ------------- Jesus was a bare-footer............. |
Posted By: TRBenj
Date Posted: March-17-2014 at 7:59pm
Chevy was a factory option... OMC offered the 307 then 305 and 350. PCM offered the 350 later as well. Of course, they all spun the proper way. 
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Posted By: forvicjr
Date Posted: March-17-2014 at 8:01pm
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No hack here. Mine is factory GM R Rotation. ;-) I am testing a shortblock I built over the winter. Its a 408 with vortec heads and a factory camshaft for right now. No hard starting At 16* mine seems to like the timing but cant tell if I have ping. If I do its unnoticeable. Compression is a tad over nine to one with my current setup. I just wanted to know what everyone was running as a total advance with small block chevy for power. ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: forvicjr
Date Posted: March-17-2014 at 8:04pm
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And a side note, I believe I will be buying another prop. I went out the other day and twisted her to 5500 RPM and it would have gone much further. This was going off the factory tach so that could be off by some. I dono?? ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: baitkiller
Date Posted: March-17-2014 at 8:31pm
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A stroker with Vortech heads? So sweet. What did you do for a cam? I have been quietly shopping heads while the wife is asleep. Just the heads and intake will take me to 310. Being a lefty I can find a cam for short money to go further. However I run in salt water so intake plenums are extremely limited. I am interested and a bit jealous of your project. But if it aint lunging at 16* base I got nothing for you. Out of my league. ------------- Jesus was a bare-footer............. |
Posted By: oldcuda
Date Posted: March-17-2014 at 8:33pm
| Hey some of us love our Chevy boat motors |
Posted By: TRBenj
Date Posted: March-17-2014 at 8:37pm
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Havent played with a SBC but our big block doesnt lug at 16... seems happy so we left it. Extra cubes means you pushed the torque curve up, not just extended it to the right. Increasing pitch goes hand and hand with increasing cubes. You ended up with an OJ, right? 12x13? Going all the way to 400ci, I'd guess you want a 12x15 at least, maybe 12x16. Acme 1214 (12x13) would be the equivalent, it spins similar to the OJ 12x15. |
Posted By: baitkiller
Date Posted: March-17-2014 at 8:55pm
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Not that it applies but I turn the OJ 13 square 4850 at 48 mph with 280 estimated hp. 1979 SN ------------- Jesus was a bare-footer............. |
Posted By: forvicjr
Date Posted: March-17-2014 at 8:55pm
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Tim I took your advise on the last prop. It has an acme 1210 on it now. This motor seems to over power it quite a bit. At times it feels like a slipping auto trans. I think its 12&1/2x10 pitch. I got 54.5 @ 5550 rpm according to garmin and factory tach. ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: forvicjr
Date Posted: March-17-2014 at 8:57pm
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Correction 12.5x12 ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: TRBenj
Date Posted: March-17-2014 at 9:02pm
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Oh, I thought you didnt like the 1210, something about harmonics in your hollow hull? Maybe my memory is fading. The 1210 is 12.5x12 and it turns comparable revs to an OJ 12x13, so just a few revs more than the 12x14 Federal, which was the common factory prop. Some boats (like yours and mine, if I remember correctly) came with 12x15 Federals, but mine could never quite pull it well (4200). My 302 loves the 1210 at 4500. Going from 305 to 408 cubes will overwhelm a prop meant for the smaller engine for sure. Going to the 12.5x13 Acme (1214) would calm it right down- that wheel works well on a 375hp 347 stroker in Reid's Mustang. The 13" diameter version (430) works well on higher hp/tq versions of the larger boats. Getting the revs down will help performance if youve got a baby cam in there- peak power is probably 5k ish? You must have had more throttle left at 54.5? I bet its got more with that many cubes in such a small boat. Probably a bit hairy at speed? Ive been in a few 16 footers capable of 55-57mph and its a wild ride. |
Posted By: forvicjr
Date Posted: March-17-2014 at 9:07pm
Bait killer, im still running a stock cam. Im just testing this for now. If it gives me problems im going to snatch it out and run the 350 during the peak of the summer. Still might pull it anyway untill i get the cam i want. I dont have the prop selection tim has and the cam could possibly change that too.As for as the motor its not stroked. Its a fourty over 400 with 5.7 rods and steel splayed mains with a steel crank, stock out of the box vortec heads and performer rpm intake. It does have the stock gearset pcm used and mixed 1.5 int and 1.6 exh roller tipped rockers. ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
baitkiller wrote:Posted By: forvicjr
Date Posted: March-17-2014 at 9:19pm
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The acme wasnt the noise. It was a bent shaft that had been checked. Not well enough obviously. The 54.5 was on rough water and if you want to call leaving the water for extended amount of time porpoising so be it. Ill let it be known I didnt hold it there very long! On smooth water and the right prop im hoping to flirt with sixty mph. I might cam it some so the 1214 would still be ok? And your correct my boat did come with the 12x15. :-) ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: forvicjr
Date Posted: March-17-2014 at 9:23pm
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Tim what is your timing on the big block all in? I know the BBs dont like as much timing as small blocks just trying to get a safe number. As I said before if its pinging at 36* I cant tell. Is it noticable above the exhaust note? (No mufflers) ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: dwouncmd
Date Posted: March-17-2014 at 10:15pm
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My Tique is repowered with a chevy 350 (thanks to Waterdog/Andy); his description "350 cu in chevy with 9.2 comp. 4 bolt main caps, windage tray, Performer intake, ARP rod bolts, gear drive timing set, DUI ignition, 4160 holley". Runs just over 50 mph. By the way, that jabsco impeller is a pain without a puller... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=6535&sort=&pagenum=2" rel="nofollow - 89 SN <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=6567&sort=&pagenum=1" rel="nofollow">7 |
Posted By: baitkiller
Date Posted: March-17-2014 at 10:32pm
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I think you are backerds.. Big blocks run more timing.. Now i gotta Google it, should have done that first. ------------- Jesus was a bare-footer............. |
Posted By: forvicjr
Date Posted: March-17-2014 at 10:40pm
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Dwouncmd i dont know what it is but this boat hasnt matched up with the average correct craft. This thing ran a constant 47 mph with a bone stock 305 12x15 federal. I changed the bottom end to a 350 ci performer rpm and marine hei and reused the 305 heads cam etc and it picked up to 49.5/50 mph gps. It was running one to one with the acme 1210 (2500 rpm 25 mph)(4000rpm 40mph)which tim said that was unusual. Now with the 408 its doing 54.5 on crap water with an obvious undersized prop and stock cam. Maybe its the fact that its now foamless (weight?) Or just better hull bottom for some reason?? Maybe the hook changed after stringer work? All three motors were ran on new stringers. Ohh and I dont have the jabsco pump its a sherwood.lol ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: baitkiller
Date Posted: March-17-2014 at 10:43pm
Ill show you mine.... ------------- Jesus was a bare-footer............. |
Posted By: forvicjr
Date Posted: March-17-2014 at 10:44pm
In my experience with old chevy hot rods the big blocks dont like as much timing a a small block. But it could be different in the boat world. ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: forvicjr
Date Posted: March-17-2014 at 11:10pm
http://s1324.photobucket.com/user/forvicjr1/media/Mobile%20Uploads/2014-01/IMG_20130403_155737_332_zps1867538f.jpg.html" rel="nofollow"> This is the 350. 400 looks no different. I havent took any of it yet.lol ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: baitkiller
Date Posted: March-17-2014 at 11:26pm
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Very nice. The decks, stern area and side walls bring back some recent memories. In fact it looks just like my boat did last year. Right down to grind marks running up the old carpet glue and the blower hoses shoved up over the fuel tank. You should try to organize a serpentine belt set up while you are messing around. It is a luxury I have grown quite fond of. No dust, never loses tension, never slips and lasts seemingly forever. Parts are pretty easy at the scraper. ------------- Jesus was a bare-footer............. |
Posted By: TRBenj
Date Posted: March-17-2014 at 11:36pm
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Vic, your Tique sounds very average to me. I've seen stock 302's and 305's run anywhere from 45 to 51mph in the 16'5" hull. 47-48 is the norm. My skier is about the slowest example I can think of- it has touched 47 but is a 45.x boat on any given day. It tracks 1:1 speed vs rpm with the 1210. I would think that even a bone stock 260hp 350 should push one of these hulls over 50 easily. You never updated us on the bent shaft... You seemed convinced the Acme shook the boat. One of us should dig that thread up and update it for anyone reading it in the future. I want to say we run around 35 total timing on our 454. It doesn't ping now, it was obvious when it did, you could hear and feel it loud and clear. Our engines are miles apart of course, big block vs small, were a tad over 10:1, etc. I know less about SBC's than just about anything. Slight to moderate chop will result in a faster top speed, as it helps introduce air under the hull. Bouncing speeds you up as well. With 400ci, you gotta be all of 350-400hp, so I'd be surprised if you weren't close to 60. |
Posted By: baitkiller
Date Posted: March-17-2014 at 11:48pm
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I think your right Tim. Just the heads takes him into the 310 ball park. Add another 50 cubes and nothing else should see the 360 ish neighborhood. Cam, intake and ignition, maybe a little valve train love and four and a quarter is pretty real. WOW! Put some copper pipes on it so everybody can hear it. ------------- Jesus was a bare-footer............. |
Posted By: forvicjr
Date Posted: March-17-2014 at 11:59pm
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Tim the bent shaft went with my buddy to his work. He is a cnc supervisor. He put it on a machinist table and said that he couldnt get a three thosandths shim under it anywhere. I installed in the boat and found later that was bent just aft of the log. And yes I need to update.sorry...lol. what fooled me was that the federal didnt amplify the issue like the acme did.. I guess ill keep it at 36* and keep my ears open. Bait killer, pretty cool serp set up. Been contemplating it but the sherwood pump is going to screw me unfortunately. Also shes loud and proud with the copper tone already buddy. First mod was copper pipes...:-D ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: lewy2001
Date Posted: March-18-2014 at 3:57am
Had a warm 350 Chev SB in one of my old ski boats. It was a auto engine with a local Aussie marine kit. With a Accel mechanical dissy and points used to run it at around 16-18 degrees static to get it to 38 total. The SBC can take 40 degrees but ran it a little conservative. It had no pinging or hard hot start issues although it never seen much more than 4K rpms for any length of time. ------------- If you're going through hell, keep going http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
Posted By: uk1979
Date Posted: March-18-2014 at 9:49am
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Vic cool project...if the heads haven’t already been pre prepped for bigger lift cam you will need to work on the vortec valve seal height/spring pads or longer valve stems and beehive springs over around 470 lift... machining is easy to do with the right cutters and hand drill, rocker posts are best changed from push in to tapped screw in type. Keep us posted on your build. Roger. ------------- Lets have a go 56 Starflite 77 SN 78 SN 80 BFN |
Posted By: backfoot100
Date Posted: March-18-2014 at 10:33am
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You should be able to easily run 38 total advance. I was running 12 static and 38 total with my stock motor without any issues at all. Running the same with my stroker now. I ran it up to 42 total and never had any issues but I didn't gain anything either so I backed it down to where it was the lowest advance without losing anything. ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: GottaSki
Date Posted: March-18-2014 at 11:11am
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Remember, Higher the compression, both static and dynamic, will require less final timing. Stroke/rode ratio are also serious factors. It has to do with the speed the flame front travels (faster with higher compression) and when peak cyllinder pressure occurs. Spark plug placement and combustion chamber shape are also factors. So, to sum up, lots of numbers supplied here, but when one makes a stroker, changes heads, pistons and cam, thre is no 'chevy's run this' simple answer. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: forvicjr
Date Posted: March-18-2014 at 11:48am
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Gottaski, I realize the every engine is different thing. Most of my engine knowledge comes from drag racing. And a general rule for small blocks is between 34*/38. Some like 36 some like more. I was just looking for that safe range that most run. My motor was intentionally kept around nine to one. As my opinion building a boat motor is a lot like building a truck engine for pulling heavy loads. Ping is very easy to run into with high compression combined with high running temps and high timing crappy fuel etc. I just didnt want to base my knowledge of timing this thing from the auto side. I thought there mightbe a chance with the constant loads a marine engine has that in the boat world the timing might be a little less aggressive. I think if tim is running 34* on that big block with ten to one im probably ok with the thirty six at nine to one. After all im only 46 cubes away from tim with less compression. ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: MrMcD
Date Posted: March-18-2014 at 7:05pm
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forvicjr, your engine is unique, the Vortec heads were never factory on a SBC 400. They are a very good head up to 5,500 RPM. In many tests they hold their own against AFR, Dart, Edelbrock and many other quality aftermarket heads. The Vortec uses a small chamber with a very good design. You will find a Vortec design maxes power at about 28 degree's total timing. If you were running other design heads the GM small blocks perform best with 36 degree's approximately. Some use 1 or 2 more or less depending on the combination. Hypereutectic pistons are very popular today and they reflect more heat into the chamber, the extra heat reflection will have you backing the timing off 1 or 2 degree's compared to a forged or factory cast piston. The Vortec head is the best factory flowing small block GM head ever built even though it runs 1.94 intake valves and 1.5 exhaust but with your 400 inches you will max the head around 5,500 RPM. Because of the small chamber used in the Vortec heads you will have very high compression unless your pistons use a deep dish design I would bet you are actually at 10.5:1 or more. The 5.7 Rod combo really helps your 400 internally, it takes a lot of side load out of the piston and free's up power and efficiency. Hope you get to enjoy it. .040 over, so you are running a 408. Big engine, nice, I bet it pulls like a freight train. |
Posted By: forvicjr
Date Posted: March-18-2014 at 7:30pm
Mrmcd you are correct with what you said about vortec heads. I have ran them on several motors in the past. They perform very well for the money. I will correct you on my comp ratio as im sure of what I have. I personally CCed the Mahl pistons and chambers of the vortecs. Im sure you know you can very easily aquire compression with these heads especially with the bore and stroke im running. Im running dish pistons that I had my machinest deepen the valve reliefs and running extra thick (0.051) head gaskets to cut the compression back. I didnt want anything higher as I once built a sb for pulling and went a little stupid with the CR and it did not like it. I had to run the vac advance to manifold vac to pull timing out of the thing as load increased just to stop the pinging. Lol. Ill never do that again. Edit. Also the pistons pin hieght is custom to my application. The block I used was a zero deck block from a previous build. I ordered the pistons with a higher pin height to compensate also. ;-) ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: 8122pbrainard
Date Posted: March-18-2014 at 8:32pm
Vic, It sounds like your supervisor friend needs some training!  The best way is not on a "machine table" as you call it. Hopefully it was a granite surface plate. Properly, you set up the shaft in V blocks, put a dial indicator on it and rotate the shaft. Aft of the strut on the taper is very common due to prop hits especially if there is too much shaft between the prop and strut. WHY didn't your friend check the shaft at the taper??? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: MrMcD
Date Posted: March-18-2014 at 9:00pm
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Sounds like you are all over the proper compression ratio, glad to hear it. I have seen guys destroy pistons putting Vortec heads on without other changes. The timing difference is real if running Vortec you will probably be happy at 28 degree's total. It has to do with the chamber design. Mahle makes good pistons and they are forged so you have extra insurance against failure. |
Posted By: forvicjr
Date Posted: March-18-2014 at 10:09pm
Pete. Glad to hear from the grumpy ole man.lol I told him to check it and that how he did it. He is very anal and I think it was ok. I think something happened to it during the stringer replacement after he checked it. It was sitting around in the shop and could have gotten damaged in that time. I found it by holding a sharpie against the hull at the log and rotated the shaft. The marker showed a high spot half way around the shaft.After seeing that I seen no need for a dial indicator. This I think he would have spotted on the " granite surface table" lol ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: 8122pbrainard
Date Posted: March-19-2014 at 9:02pm
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Vic, Sorry but I don't believe anything during the stringer replacement project could have bent it. Try and bend a 1" shaft by hand cold sometime! Unless your friend had set up a dial indicator on the granite, I question how he was measuring the taper section with feeler gauges. You found it with a Sharpie!!!! ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: forvicjr
Date Posted: March-22-2014 at 11:08am
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I dono pete. Where the bend is would be right smack in the middle of the shaft. Roll the thing across the table and it would be hopping around like a rabbit. Seriously I never measured it but im sure you would be stacking many feeler gauges to measure it. Any way its fixed now. Still a mystery though. Im not convinced he missed it. And the boat didnt vibrate before the stringer replacement. Hell who knows lol. ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |
Posted By: hotboat
Date Posted: March-22-2014 at 11:22am
 ------------- Brian |
Posted By: forvicjr
Date Posted: March-22-2014 at 12:28pm
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Whatever gets the job done...lol...:-D ------------- “Tact is the ability to step on a man's toes without messing up the shine on his shoes.” ― Harry S. Truman |