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Need ya'lls opinions on SBC heads

12K views 37 replies 8 participants last post by  cobalt327 
#1 · (Edited)
Hello fellow hot rodders, I built a .030 over 350 flat top motor instead of the 327 for my '68 Impala. The motor hasn't been decked or anything just the overbore. I put my "186" camel hump heads on it that have been cut 0.010, previous owner ported to the max, on the runners anyway, 2.02/1.60 valves, screw in studs and guide plates. I'm running an Isky 284 Mega cam, 236/236 @ 050/ 0.510/0.510 lift on a 106 LSA with matching springs. I went with Doug Herbert anti pump-up lifters. Pete Jackson geardrive, TH400 with a Hughes 3500 stall and running a 3.73 gear, will be changing to a 4.10 over the winter months. After breaking the cam in I found one lifter that is bad, bleeding down very fast, so I pulled the intake, Tunnel Ram with two 1850-2 600 Holleys, and am going to replace all the lifters. Well, right after I built the 350 and put it in the car I ran across a 400SBC thats standard bore and it came with a pair of brand new, new style, Patriot Freedom heads for a super good price so I bought it. Now, i've got the intake off my 355 to put the new lifters in so my question is, do I leave the "186" heads on it or would I be able to tell a large difference by putting the aluminum Patriots on? If so, now is the time to do it lol. I haven't driven the car much at all due to the bad lifter but when I did drive it down the road, that's when the ticking started, the motor has very good power. This is my weekend toy for next year and it will be on the drag strip very little for tuning purposes and to have fun with my buddy's. My next build is gonna be the 400 for my S10 with just an RV cam and a good set of heads as it's going to be a semi daily driver. I value ya'lls knowledge alot and have done a whole lot of reading on here. Thanks
 
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#4 ·
Yep lol I know. I'm gonna take the bad lifter apart and see whats going on before I put the new set in, should have said that in my post, sorry. If I do have to put the new lifters in I'm going to do the cam break-in again and keep my fingers crossed. When I first heard the ticking that's what I thought had happened, a lobe going bad. When I let the motor cool down I pulled the cover off to see if one of my locks had come loose on a rocker but it hadn't. I pulled the plugs and got that cylinder, #4, on TDC and readjusted the rocker. I looked at the plugs to see how my carb tune was, put the plugs back in and gettin ready to put the cover back on and just felt of the rocker arm, well all of them on that side, and it was very loose again. I took the rocker completely off to inspect, everything looked good, put it back on and readjusted. Went inside to eat supper, came back out to put the cover back on, felt of the rocker again and it was loose again, by loose I mean sloppy loose. So that's how I determined it was a lifter bleeding down.
 
#6 · (Edited)
If they are the Patriot Freedom heads 2168 with the 185cc runners they should work real well with your 355 motor. The 64cc chambers with the flat top pistons will have about 10:1 compression which is good for aluminum. I would be worried about detonation with the iron heads especially after being milled. Be sure to have the matching valve springs for your camshaft installed on the new heads. If you install new lifters get some 30w Royal Purple break-in oil. Do the cam break-in procedure for about 20-30 minutes at 2500 RPMs. When changing oil after break-in use 10w30 or 10w40 oil with the ZDDP additive and a good filter. When time come to build the 400 motor you will need a set of heads with about 210-215 intake runners.
 
#8 · (Edited)
If they are the Patriot Freedom heads 2168 with the 185cc runners they should work real well with your 355 motor. The 64cc chambers with the flat top pistons will have about 10:1 compression which is good for aluminum. I would be worried about detonation with the iron heads especially after being milled. Be sure to have the matching valve springs for your camshaft installed on the new heads.
I knew I would get some great opinions but never thought they would come this fast. Thank ya'll so much. I was kinda worried about detonation when I first put the heads on but I took a chance and am running my timing a little lower than I normally do and also raised my octane level to 102. I think I'm gonna pull the heads and go with the Patriots, which are the 64cc. 185cc., and run a set of "462" on my 400. If I found a pair of good Vortec heads, would I have to drill the steam holes in them to run em on my 400?
 
#15 ·
These heads are all similar. Prolly not a 5 hp difference between them as long as the are prepared the same. The 041 is supposed to have a little more meat under the spring seat and is "stealthy" in that it doesn't have the double hump identifier.

Pay attention to the compression ratio- a 64cc chamber on a 400 SBC w/flat tops and a tight quench can exceed 11.5:1- higher than pump gas will allow w/o detonation. A 22cc dished piston will put you at about 9.75:1, the absolute limit I would recommend using iron heads- and even then the cam has to be chosen carefully so the dynamic compression ratio isn't too high.

Calculators
Static compression ratio
*Interactive JavaScript to Calculate Engine's Compression Ratio (CR)

Dynamic compression ratio
*Dynamic CR
*United Engine & Machine Co. Incorporated

You should CC the heads to be sure that each pair are the same, and that none were milled excessively. Even if they are as cast and never been milled, the chamber volumes can vary from published figures.
 
#13 ·
Thanks for your advice feller. I failed to mention that I'm going back with a dual plane and a Holley 4779-2. I've got to do a couple of motor swaps and my Impala is going to have to stay outside for a few weeks and I don't really want to have to cover the motor up, due to rain and maybe snow, and I can put the hood back on if I leave the tunnel ram off. But, it will be going back on before spring if the good Lord is willing.
 
#19 ·
Here's a link to an online cam degree calculator that you can use to determine the intake closing angle. Using this in conjunction with the United Engine & Machine online DCR calculator will give a more accurate dcr than just using the generic "add 15 degrees to the duration at 050" in the dcr calculations. This gives almost identical results as the Pat Kelley calculator. Wallace Racing - Cam Degree Calculator
 
#22 ·
When your dealing with 4 bad lifters,you want to treat the cause and not the effect,the four bad lifters.Deductive logic says there is a reason behind why four lifters when bad.Question if you have a blocked oil gallery.But to find the root cause is going to prevent it happening again with the new set of lifters.Those lifters once preloaded have to turn in their bores while the engine is being turned over and you can check that with the intake off.Also the lobes and just the way they look really doesn't mean much.What they measure as will tell apart of the story.
 
#23 ·
Thank you for your input. I marked a small line from the block to lifter on all the lifters with a white welders pencil and made sure all of them were turning before I checked with my dial indicator. Everything is oiling great as far as I can tell but I only took 3 of the lifters apart. The motor ran great it just developed a lifter tick from the #4 exh. I adjusted it twice and one time for my buddy, to show him what was going on, and it would adjust but after letting it sit for about 10min. you could go back and check it by hand and the rocker would be sloppy loose again. I mean just sittin there, not starting the motor. I ordered a new cam of the exact specs just a little bit ago and it should be here Tuesday so I will let you know what happens in about a week as I'm disabled and have to do everything very slow, lol. I built this motor myself and after checking everything I opted to not have any machine work done. I honed the cylinders, washed and blew out all the passages, cleaned the ring grooves etc..., lapped the valves and installed positive lock seals, correct springs etc... broke the cam in by the instructions from Isky etc etc etc... I used Clevite bearings and Hastings rings, Melling HV55 pump, Pete Jackson gear drive, had to machine the back pin on the drive gear where it touches the block but you know what I'm saying. In my opinion I built the motor just like I was taught years ago and to the best of my ability. When I changed the oil after breaking in the cam after cool down I ran a magnet through the oil and by the magnet and by eye the oil looked great, felt great etc... Nothing abnormal I should say, lol. Once again, Thank you for your input.
 
#24 ·
I applaud you for everything you have done.I'm not being critical.What caught my eye is gear drives can be hard on cams,cam bearings,etc.They where at one time a favorite at one time and what was found they really didn't work well for street use and had limited race applications where changing cam timing often was needed.Since the gear drives came out other systems have evolved.
 
#29 ·
It looks to be like it's all still stock, never opened up and if it has been it's been awhile. I won't sell it as I try to save as much old chevy stuff as I can. I plan on leaving each one of my nephews, I have 3, a "60's model GM car or truck and they can split all the goodies I have collected. I have built my oldest nephews truck, he is 5yrs. old, 1969 SWB .040 over flat top 454, the engine in it is my avatar. My 1968 Impala I'm building is for the middle one, 3 yrs. old. I have been looking for a '68-'69 Nova to build for the youngest, almost 2 yrs. old.
 
#31 ·
Well, it's been a few days but I got the Impala back together, new cam broke in etc... I didn't go back with the Tunnel Ram, due to the Impala having to be outside while I pull the motor in the S10, I went with an old intake and carb I had put back, a Stealth and 670 Street Avenger. I figured the motor would really have some bottem end but I swear, I think it ran better with the Tunnel Ram and two 1850's. I do think the motor is running on the lean side with the 670. I have the timing turned down just a tad and the 670 adjusted rich as I can untill I get a 4779 built for it. I have the kit but I want to get this motor out first, lol. Also, I bought a pair of Magnaflow's #10416 as I read they flow alot better than Flowmaster, which is what's on the Impala now, but haven't had time to have exhaust put on yet. I do have the S10 in the garage and plan on starting on it today.
On a side note, I saw a post where Tech Inspector was talking about going an 1/8th of a turn after zero lash on valve adjustment but the OP was talking about his hyd. roller lifters. I wonder if Tech was meaning an 1/8th turn on all hyd. lifters or just rollers. I may post back on that posting and ask, unless he see's this, lol. Anyway, I will post pictures of the motor when I get it out and cleaned up.
 
#32 ·
For someone who was injured a while back, you sure get a lot done. Makes me kind of embarrassed! lol

Not speaking for TI but you can use 1/8 turn on flat tappet hydraulic lifters.

A page he wrote is here. Not sure how it happened but there's another one here. Chances are the second article was added w/o knowledge there was one already started.:confused:

Adjusting the valves w/the engine running is also a very good, foolproof way to do it, but they have to be adjusted at least close enough that the engine will run w/o popping through the carb or backfiring, etc.

Adjusting valves w/the engine running leaves no doubt when there is clearance and when zero lash is reached- the sounds are unmistakeable. Only thing about doing it w/the engine running is it can be messy. To help w/the oil spraying/splashing around, an old valve cover can be modified by cutting the top out of it (see below, photo from member Double_v23). This keeps most of the oil where it belongs. There are also small clips sold to clip onto stamped steel (stock type) rockers that deflect the oil, but those alone can still let oil splash around some. Using both should stop 90% of it, though.

 
#34 ·
Using 1/8 turn gives less clearance for the lifters to pump up. In most cases where the engine is equipped w/the right springs and the engine isn't over revved, there's no advantage over using 1/2 turn- which is what I (and your Dad) recommend you use.

The possible problem w/using a small preload or zero lashing the lifters is that it gives the chance for the lifter inner plunger to contact the retainer. Most lifters use round wire retainer clips (center and right, below); these can be driven out of their grooves allowing the lifter to come apart under severe conditions, like when the lifter pumps up. Lifters designed to be zero lashed and solid lifters will use an internal C-clip type retainer (below left).

From here:
 
#35 ·
camaronut if you run the 400 block be sure to lay a 400 gasket on the head you decide to run an drill the steam hole 3/16 in replacement head 2 per side this will keep it from overheating i ran these blocks for years on dirt track late model modified with good results i would buy 2 bolt blocks drill for 4 bolt sprayed caps 2 bolt blocks worked good for us factorf 4 bolt 400 castihg 509 and 511 seemed to crack in main webs if tou can find a 4wd blazer block without center freeze plugs that is the best block we have foubd hopes this helps
 
#37 ·
Got the motor and trans out tonight and I've got to make an appointment with the eye doctor ASAP. The casting number is "3956618" and the number stamped on the front pad is "V0331HN" which is showing up as a 1969 350 300HP passenger car. Also, it doesn't have a steel crank like I originally thought when looking at the end of the crank while under the S10. Even though it's not a 302, it's found it's home till I leave this world. The heads are "186". I also thought it looked like it had never been opened up but after gettin it out so I could really look at it I think with 98% certainty that it has been opened up. I didn't pull the pan, just one valve cover as my body was really going down on me fast. I'm taking tomorrow to myself and spend the day riding in my Impala so hopefully Monday I can get back at it. I wish everyone a very happy Thanksgiving.
 
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