hahaha thanks man
Top end build l48
Le Mans Master
Joined: May 2007
Posts: 5,028
Likes: 1,120
From: North tonawanda NY
I have a carbed 84 Z51. I bought the Summit/Dart large valve cast iron heads part #152123. They come fully assembled with 72cc modern chambers, screw in studs. .525 lift springs and are $630 shipped to your door. Nice heads for sure. Forget the thumper cam, way too much cam. I ran a crane 274h06 218-218 .450 lift cam on a 106LSA. It is an old circle track cam that will give you the rump rump sound but comes up on the cam really quickly and still builds good cylinder pressure for a low c.r. 350. The cam had lots of low and midrange power but with the overlap of the cam it was a little bit much with my automatic trans in gear at 650 rpm. I later swapped the 274 cam for an Isky Z-20 solid lifter cam with 228-228-.450 lift 108 LSA. Isky sells it ground on a 112 LSA also. My idle is much improved with around 17" of vac at 900 and 14" at 700 rpm. Lots of low and mid range. I had a 76 L82 with a T400 and 3.36 rear gear and I replaced the stock L82 with an Isky 264 Mega cam with 214-214 .450 lift on a 108 LSA and it had much better low and mid range than the L82 cam. I have used Isky cams for many years with no problems. Most of their street cams are very easy on your valve train too. Even the old school Comp 268HE cam or Crane energizer 272 cam would give you a big boost in power. I am using a ZZ4 intake and a 600 cfm 1405 Edel. carb but I am probably going to go back to an aluminum Q-jet intake and Q-jet carb. If you already have the Qjet intake and carb I would keep it and try the 152123 Summit/Dart heads. Good luck on your build.
Thread Starter
Racer
Joined: Apr 2013
Posts: 366
Likes: 0
Here is something to think about:
http://www.speedwaymotors.com/Flo-Te...lug,25118.html
You can read up on what Car Craft thought about these heads here:
http://www.carcraft.com/techarticles...t/viewall.html
I've never used them, so I can't speak from experience, but Speedway Motors has a pretty good reputation, and in the Car Craft test, they made power comparable to the Vortec heads, they're aluminum, 64cc combustion chambers, and you don't need a special intake manifold, valve covers, and rocker arms. Which means you can scare up an old Performer intake on the internet for about 50 bucks. I'm going to be giving them a try when I do the top end on my engine. Like I said, just something to think about........
Here's a link to the head gasket iokepakai is talking about, it's the cheapest I have been able to find it:
http://www.northernautoparts.com/Pro...tModelId=22765
Scott
http://www.speedwaymotors.com/Flo-Te...lug,25118.html
You can read up on what Car Craft thought about these heads here:
http://www.carcraft.com/techarticles...t/viewall.html
I've never used them, so I can't speak from experience, but Speedway Motors has a pretty good reputation, and in the Car Craft test, they made power comparable to the Vortec heads, they're aluminum, 64cc combustion chambers, and you don't need a special intake manifold, valve covers, and rocker arms. Which means you can scare up an old Performer intake on the internet for about 50 bucks. I'm going to be giving them a try when I do the top end on my engine. Like I said, just something to think about........
Here's a link to the head gasket iokepakai is talking about, it's the cheapest I have been able to find it:
http://www.northernautoparts.com/Pro...tModelId=22765
Scott
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Should be able to, if they're in good shape, (they might interfere with the springs) but you can get new ones for pretty short money:
http://www.summitracing.com/parts/su...make/chevrolet
Starting to add up..........timing chain set, 40 bucks for head gaskets, etc.......it's all the nickel and dime stuff that gets ya!
Ya know, as long as you have the whole front of the engine off, you might as well drop the oil pan, and install one of those rubber one piece gaskets..........and, as long as the oil pan's off, you might as well throw a new oil pump in there...........and a new rear main seal.........
Scott
http://www.summitracing.com/parts/su...make/chevrolet
Starting to add up..........timing chain set, 40 bucks for head gaskets, etc.......it's all the nickel and dime stuff that gets ya!
Ya know, as long as you have the whole front of the engine off, you might as well drop the oil pan, and install one of those rubber one piece gaskets..........and, as long as the oil pan's off, you might as well throw a new oil pump in there...........and a new rear main seal.........
Scott
Last edited by scottyp99; Jun 4, 2013 at 05:49 PM.
Thread Starter
Racer
Joined: Apr 2013
Posts: 366
Likes: 0
Should be able to, if they're in good shape, (they might interfere with the springs) but you can get new ones for pretty short money:
http://www.summitracing.com/parts/su...make/chevrolet
Starting to add up..........timing chain set, 40 bucks for head gaskets, etc.......it's all the nickel and dime stuff that gets ya!
Ya know, as long as you have the whole front of the engine off, you might as well drop the oil pan, and install one of those rubber one piece gaskets..........and, as long as the oil pan's off, you might as well throw a new oil pump in there...........and a new rear main seal.........
Scott
http://www.summitracing.com/parts/su...make/chevrolet
Starting to add up..........timing chain set, 40 bucks for head gaskets, etc.......it's all the nickel and dime stuff that gets ya!
Ya know, as long as you have the whole front of the engine off, you might as well drop the oil pan, and install one of those rubber one piece gaskets..........and, as long as the oil pan's off, you might as well throw a new oil pump in there...........and a new rear main seal.........
Scott
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Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
I would go with something like the xe268h or the voodoo equivalent..... You want something that performs well and has good torque in the street driving rpm range unless you got the money for new rear end gears and a high stall converter if you have and auto....
Torque is what throws you back in your seat and what you feel not HP.
The Thumpr cam is tuned to sound good idling and pulling in to the local car show or mcdonalds... its basically a poser cam meant to mimic the sound of a much bigger cam... You will constantly be defending yourself around anyone that's car savvy. t is not designed for performance or to be efficient...performance is secondary to "sounding cool" it reminds me of the fart cans on the ricers. With it, you give up about 3mpg compared to other cams that give you more power .the tight lsa causes much of the gas to go out the tailpipe unburnt. Also the vacuum is poor with it so your power brakes and such won't work well without additional hardware.... just Google it and read about it.... there's a few exceptions like super Buick guy here that seem happy with it but almost all of the reviews are poor and that that arent are bias and don't compare them fairly to a properly set up similar cam intentionally. And you won't find one single review where someone actually swapped a similar sized aftermarket cam for it and liked it.... but you find a few that are the opposite.
Torque is what throws you back in your seat and what you feel not HP.
The Thumpr cam is tuned to sound good idling and pulling in to the local car show or mcdonalds... its basically a poser cam meant to mimic the sound of a much bigger cam... You will constantly be defending yourself around anyone that's car savvy. t is not designed for performance or to be efficient...performance is secondary to "sounding cool" it reminds me of the fart cans on the ricers. With it, you give up about 3mpg compared to other cams that give you more power .the tight lsa causes much of the gas to go out the tailpipe unburnt. Also the vacuum is poor with it so your power brakes and such won't work well without additional hardware.... just Google it and read about it.... there's a few exceptions like super Buick guy here that seem happy with it but almost all of the reviews are poor and that that arent are bias and don't compare them fairly to a properly set up similar cam intentionally. And you won't find one single review where someone actually swapped a similar sized aftermarket cam for it and liked it.... but you find a few that are the opposite.
Melting Slicks
Joined: Aug 2012
Posts: 2,548
Likes: 379
From: Woodinville WA
there's what they look like - slotted is on the left
Melting Slicks
Joined: Aug 2012
Posts: 2,548
Likes: 379
From: Woodinville WA
I love being misquoted - but it's okay, I suspect I'm the only one on this entire thread that's used both of those cams (and tons of other cames) - so the trolls really will troll.
The thumpr cam sounds excellent, but it's not the reason for using it. The Vortec heads (which you'll notice I recommended with the cam) holds the exhaust valve open longer than other cams - in this case, it bandaids a problem with the vortec heads - namely they do a great job of getting the fuel/air mixture into the motor, but with its small exhaust valve and tight turns - does a terrible job of getting it out. The Thumpr cam was designed for just this problem, but giving it more time (at the expense of intake open timing), it runs better. WITH THIS PARTICULAR SETUP
So to recap.... an L48 motor is a low-compression motor. The Vortec head raises the compression and is one of the best bang-for-buck efficient heads. The thumpr cam is in conjunction with those heads to get max hp out of that set up.
if the haters paid any attention at all, they'd see that the high-hp recommendation I always make is a 5.3L LS motor with at least one turbo... unless, of course, you're building a 50 Buick Sedanet, then I'd recommend a twin turbo 455, sleeved to 430 motor with large by huge turbos....
of course, then they couldn't rant and troll - so carry on
The thumpr cam sounds excellent, but it's not the reason for using it. The Vortec heads (which you'll notice I recommended with the cam) holds the exhaust valve open longer than other cams - in this case, it bandaids a problem with the vortec heads - namely they do a great job of getting the fuel/air mixture into the motor, but with its small exhaust valve and tight turns - does a terrible job of getting it out. The Thumpr cam was designed for just this problem, but giving it more time (at the expense of intake open timing), it runs better. WITH THIS PARTICULAR SETUP
So to recap.... an L48 motor is a low-compression motor. The Vortec head raises the compression and is one of the best bang-for-buck efficient heads. The thumpr cam is in conjunction with those heads to get max hp out of that set up.
if the haters paid any attention at all, they'd see that the high-hp recommendation I always make is a 5.3L LS motor with at least one turbo... unless, of course, you're building a 50 Buick Sedanet, then I'd recommend a twin turbo 455, sleeved to 430 motor with large by huge turbos....
of course, then they couldn't rant and troll - so carry on
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
That article also contains data for the Speedway head, and if you study it, you'll see that the speedway head has a much better intake to exhaust ratio. (I think this has more to do with a weak intake port than a strong exhaust port, but still, the ratio exists as it does.) Therefore, a straight-grind cam may be better for use with the Speedway heads. That's what I figure, anyway, and so, my plan is to use this cam with the Speedway heads:
http://www.summitracing.com/parts/cr...make/chevrolet
(actually, it's a Summit house brand cam with identical specs, that they don't offer anymore, for some reason. I don't think Crane is making cams for them anymore.)
Anyway, there are a lot of choices to make, aren't there? Sometimes, having too many choices is worse than not enough! Good luck,
Scott
Safety Car
Joined: Jan 2009
Posts: 3,736
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From: anchorage ak
your right, I didn't run one. When I did the top end of the l48, I ran the 262xe. A friend of mine started with the thumper, it sounded great but was doggy. Wwhich is why I stayed away from that series. We all know that it's all in the combination, having never ran vortecs I couldn't say that it wouldnth work great there and apparently you can, my friend went to the 268xe and it was night and day difference, his heads werent vortec neither.
Thread Starter
Racer
Joined: Apr 2013
Posts: 366
Likes: 0
i think ill go with this voodoo cam and speedway heads and buy new oem rockers.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
That looks like a good cam for your application. LSA a little wider than I prefer but should provide good bottom end torque and rpm operating range.
Get smallest combustion chamber on the heads you can get with the use of the stock pistons. The pistons for a L-48 have 17c's of volume. Use this number to compute your CR. Try to get at least 9.0:1 CR.
I use this calculator to figure this stuff out.
http://www.jeepstrokers.com/calculator/
If you have a stock deck at .025" and stock bore at 4.0" with stock stroke of 3.48" and con rods of 5.7" Then a 64cc head would get you 9.0:1 Cr if you use a felpro .015" head gasket.
With that cam your DCR is 7.53, well below the limit for iron heads and 91 octane fuel.
Your quench would be .040" which is ideal for a good burn as well.
Get smallest combustion chamber on the heads you can get with the use of the stock pistons. The pistons for a L-48 have 17c's of volume. Use this number to compute your CR. Try to get at least 9.0:1 CR.
I use this calculator to figure this stuff out.
http://www.jeepstrokers.com/calculator/
If you have a stock deck at .025" and stock bore at 4.0" with stock stroke of 3.48" and con rods of 5.7" Then a 64cc head would get you 9.0:1 Cr if you use a felpro .015" head gasket.
With that cam your DCR is 7.53, well below the limit for iron heads and 91 octane fuel.
Your quench would be .040" which is ideal for a good burn as well.
Last edited by REELAV8R; Jun 5, 2013 at 03:00 PM.
Thread Starter
Racer
Joined: Apr 2013
Posts: 366
Likes: 0
Great! I will use that cam with 64cc heads and am using the felpro gasket. Everything lines up now. Now I just got to find someone that can pull my engine for me lol. My mechanic man has vanished last couple weeks.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Were all assuming you have a 3.08 rear end on this with a th400 or th350 is this the case?
If you use the speed way heads #7222000 like the ones in the car craft article scotty linked they did their test at 9.6:1 CR. So yours would not be exactly the same. They also used a longer duration cam so peak HP might be higher on their tests as well. If you use aluminum heads... well any different heads then the pushrods may have to be changed because the head may require a different length pushrod.
A top end can be done with the engine in the car just not as easy as with it out.
Another consideration, how many miles on that bottom end? May want to give it a new set of rod and main bearings. Not expensive just one more thing to do.
If you use the speed way heads #7222000 like the ones in the car craft article scotty linked they did their test at 9.6:1 CR. So yours would not be exactly the same. They also used a longer duration cam so peak HP might be higher on their tests as well. If you use aluminum heads... well any different heads then the pushrods may have to be changed because the head may require a different length pushrod.
A top end can be done with the engine in the car just not as easy as with it out.
Another consideration, how many miles on that bottom end? May want to give it a new set of rod and main bearings. Not expensive just one more thing to do.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Were all assuming you have a 3.08 rear end on this with a th400 or th350 is this the case?
If you use the speed way heads #7222000 like the ones in the car craft article scotty linked they did their test at 9.6:1 CR. So yours would not be exactly the same. They also used a longer duration cam so peak HP might be higher on their tests as well. If you use aluminum heads... well any different heads then the pushrods may have to be changed because the head may require a different length pushrod.
A top end can be done with the engine in the car just not as easy as with it out.
Another consideration, how many miles on that bottom end? May want to give it a new set of rod and main bearings. Not expensive just one more thing to do.
If you use the speed way heads #7222000 like the ones in the car craft article scotty linked they did their test at 9.6:1 CR. So yours would not be exactly the same. They also used a longer duration cam so peak HP might be higher on their tests as well. If you use aluminum heads... well any different heads then the pushrods may have to be changed because the head may require a different length pushrod.
A top end can be done with the engine in the car just not as easy as with it out.
Another consideration, how many miles on that bottom end? May want to give it a new set of rod and main bearings. Not expensive just one more thing to do.
So, have a compression test done, and post the results. We'll advise you from there. It would be nice to know what diff ratio you are running, too. It will have a bearing on cam selection. also, what intake manifold are you running now? The stock cast iron manifold? If so, dump that boat anchor, you can find 2101 Performer manifolds on the internet for 50 bucks, and still use your Q-jet with it.
Also, keep this in mind: Those Speedway heads are not very popular, yet, so you are going to be the guinea pig here, so to speak. We're going to be counting on you to give us a report on them. If you could find some way to actually measure the combustion chambers before you install them, that would be totally awesome! Most any automotive performance machine shop can do it for you, and I can't imagine it would cost very much at all to do, it's actually pretty easy if you have a few pretty basic pieces of equipment. Reelav8r has done it with a piece of plexiglass and a syringe. This won't just be for our benefit, either, knowing the actual combustion chamber volume will enable you to much more accurately compute your compression ratio, which will be another factor in camshaft choice. Once you know the actual combustion chamber volume, (aftermarket combustion chambers can be way off from what is advertised, by as much as 3-4ccs) you can make the choice if you want to have them milled in order to increase compression ratio, or leave them as is, and go with a smaller cam, or whatever.
Don't go off half-cocked, and start ordering stuff just yet. If you want the thing to be a runner, you need to carefully research a few things, in order to spend your money wisely. For example, diff gear will dictate cam choice, as I said earlier. Now, get cracking, and get us that info!
Scott
Last edited by scottyp99; Jun 5, 2013 at 07:12 PM.