Phlebmaster Posted February 15, 2010 Share Posted February 15, 2010 (edited) Grumpy, Here I am at a crossroads with my 350 engine build I am working on for my truck...see my project thread (link in my sig). Here is the deal.... I am running a nice set of 081 305 heads on my 350 with 58cc chambers, 1.84 intakes and 1.50 exhaust valves. I have lots of compression aprox 9.7:1, and can run premium fuel with no detonation. But my RPMs are limited. I also just acquired a nice rebuilt set of 462624 smog 350 heads with 76cc chambers, 1.94 intakes and 1.50 exhaust valves. These heads will drop my compression back down to 8.5:1 YUK!... The block I am building up has dished pistons with 4 valve reliefs...just stock smog era pistons. I will be putting in a 470 lift cam..just in case that matters. HELP ME PLEASE decide which to use! Thank you. Here are some flow numbers for the 305 heads I am running now. I can't find the numbers for the 624 heads. 081 heads flow referenceQuote:081 iron head (305 cylinder #14014416 airflow #'s): 195 intake; 110 exh (ME Leigh) Flow chart for stock #14101081 305 head 87 91 Intake lift (in) Flow (cfm) Exhaust lift (in) Flow (cfm) Ratio E/I flow (%) 0.050 31 0.050 15 49 0.100 63 0.100 37 58 0.150 92 0.150 61 67 0.200 116 0.200 78 68 0.250 134 0.250 92 69 0.300 157 0.300 101 64 0.350 170 0.350 105 62 0.400 182 0.400 107 59 0.450 189 0.450 109 58 0.500 195 0.500 110 56 I did find some info on the 624 heads.... http://www.antechlabs.com/K0GFM/GMCylinderHeadInfo.pdf "624" – 462624, 426624, or 458624. The 458624 was a truck head, with 1.72/1.50 valves – non performance. The other castings were used mid 70's and up on 350 engines, they came with 1.94/1.50" or 2.02/1.60" valves, had 76CC combustion chambers, DO have accessory holes, intake port volume is 161CC's, exhaust port volume is 62CC's. These heads are made of thinner castings and are prone to cracking. Thanks! Edited February 15, 2010 by Phlebmaster Quote Link to comment Share on other sites More sharing options...
Tanman280z Posted February 15, 2010 Share Posted February 15, 2010 I have a 77' 280z with a SBC vette engine with a holley four barrel carb. When I step on the gas after I am sitting at a stop light, it acts like it is going to die until I let off the gas and wait a sec. Everyone tells me to have it tuned, but it has done this ever sence I got it back from the shop. They said everytime they drive it, its fine. They are full of Sh**. I dont know if you might have a better insight on whats wrong, or a better way to diagnose the situation. Thanks. I am building a custom air intake system becasue I think it might be the lack of cool air and too much fuel. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 15, 2010 Author Share Posted February 15, 2010 (edited) Grumpy, Here I am at a crossroads with my 350 engine build I am working on for my truck...see my project thread (link in my sig). Here is the deal.... I am running a nice set of 081 305 heads on my 350 with 58cc chambers, 1.84 intakes and 1.50 exhaust valves. I have lots of compression aprox 9.7:1, and can run premium fuel with no detonation. But my RPMs are limited. I also just acquired a nice rebuilt set of 462624 smog 350 heads with 76cc chambers, 1.94 intakes and 1.50 exhaust valves. These heads will drop my compression back down to 8.5:1 YUK!... The block I am building up has dished pistons with 4 valve reliefs...just stock smog era pistons. I will be putting in a 470 lift cam..just in case that matters. HELP ME PLEASE decide which to use! Thank you. Here are some flow numbers for the 305 heads I am running now. I can't find the numbers for the 624 heads. I did find some info on the 624 heads.... Thanks! http://www.antechlabs.com/K0GFM/GMCylinderHeadInfo.pdf both those heads are basically VERY RESTRICTIVE and ID use them only for engines designed to operate like a taxi, (low rpms 99% of the time) the 624 heads flow about 194cfm, they came on the cross fire corvettes and are one of the least effective heads available, and a light weight casting that's slightly more prone to cracks http://books.google.com/books?id=78TGjioWJOIC&pg=PA60&lpg=PA60&dq=chevy+%23624+heads&source=bl&ots=N7fqUhwDpf&sig=4w8BXJojywNqfRbQAQawGvt7DZM&hl=en&ei=oVN5S5w8qKa2B8KPrMYK&sa=X&oi=book_result&ct=result&resnum=6&ved=0CCkQ6AEwBQ#v=onepage&q=&f=false yes JUST LIKE YOU .PROBABLY ARE< Im buck$ down and can,t afford to buy a lot better heads, but theres no sense in lying,or telling you to port them, those heads have extremely limited power potential, and youll be far better off looking thru salvage yard for at least vortec truck heads yes you can improve either set of heads some with careful port work but its still beating a long dead horse http://forum.grumpysperformance.com/viewtopic.php?f=52&t=1563 http://forum.grumpysperformance.com/viewtopic.php?f=52&t=240 Edited February 15, 2010 by grumpyvette Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 15, 2010 Author Share Posted February 15, 2010 I have a 77' 280z with a SBC vette engine with a holley four barrel carb. When I step on the gas after I am sitting at a stop light, it acts like it is going to die until I let off the gas and wait a sec. Everyone tells me to have it tuned, but it has done this ever sence I got it back from the shop. They said everytime they drive it, its fine. They are full of Sh**. I dont know if you might have a better insight on whats wrong, or a better way to diagnose the situation. Thanks. I am building a custom air intake system becasue I think it might be the lack of cool air and too much fuel. it sounds like the accellerator pumps not adjusted or the floats are not set correctly. possiably the power valves bad, start by verifying your fuel pressure is a constant 5 psi and the floats are correctly adjusted and that theres no vacuum leaks http://forum.grumpysperformance.com/viewtopic.php?f=55&t=109 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1966 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1790 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1115 Quote Link to comment Share on other sites More sharing options...
sweetride2go Posted February 16, 2010 Share Posted February 16, 2010 Aaron, if you end up looking for the vortec heads, they are not that hard to find, but the problem that we have found around here with used vortec heads is cracks on the exhaust valve seats. So if you do look for those, try and find them yourself, or get them from someone that will swap out bad ones until you get a usable set. Just some FYI. Cheers Ryan~ Quote Link to comment Share on other sites More sharing options...
bearcat Posted February 16, 2010 Share Posted February 16, 2010 Good to see you here, GrumpyVette. I remember you from the Chevy Talk forum. I'm a big block Vette owner, but I'm trying to get myself a little Z. Don't think I'll V8 it though, I've got lots of those. Might turbocharge it though. Cheers. Quote Link to comment Share on other sites More sharing options...
bearcat Posted February 16, 2010 Share Posted February 16, 2010 it sounds like the accellerator pumps not adjusted or the floats are not set correctly. possiably the power valves bad, start by verifying your fuel pressure is a constant 5 psi and the floats are correctly adjusted and that theres no vacuum leaks http://forum.grumpysperformance.com/viewtopic.php?f=55&t=109 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1966 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1790 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1115 First thing I would look at here is your squirter size. Seems to me you're just not getting enough of a shot of fuel when you romp on the throttle. That's usually the simplest cause. You could also change your accelerator pump cam, that little colored plastic piece on the throttle plate's lever arm, held in by one screw. They have different sizes, and you have to experiment between cam profile and squirter size. Your motor wants more fuel and is not getting enough out of the squirters. If you go up in squirter size, jump a couple of numbers. For example, if you have #30, try #33. This is a trial and error adjustment, and it is part of the tuning. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 21, 2010 Author Share Posted February 21, 2010 Ok... I realise this is the Gen I & II CHEV board and I've settled on a Ford Cleveland as the engine I'll be building up. but my Q is a bit more general than just model specific. Of a choice between a stroked 393 N/A motor and a twin turbo (one per bank) EFI 302 motor with a moderate PSI boost setting, which is more likely to produce a comfortable forgiving ride? larger displacements almost always have more consistant and lower rpm range torque, which tends to make driving them easier once your driving style matches the cars power curve Quote Link to comment Share on other sites More sharing options...
Geking Posted February 28, 2010 Share Posted February 28, 2010 Grumpy, first of all, your awesome to answer all our questions, thanks. I have a LT1 iron head motor that I installed in my 280Z using Megasquirt, a 80s camaro t5 and a 3.54 rear (I think). I am not sure what year my motor is, it had 96 written on it, but it does not have a CAS and it was wired for batch injection. The motor runs fine, but I know soon I am going to want more power. My question is, what can I do for at most $1500 to up the power. I don't mind doing the work myself (I don't know how to port and polish) and I already have 36 lb/hr injectors. Let me know if you need any other information, and thanks again. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 28, 2010 Author Share Posted February 28, 2010 (edited) it will help to know more about the rear gear ratio and compression etc. but its been my experience that the iron LT1 heads flow slightly better than the aluminum heads and that a cam swap does wonders for those engines, your manual transmission helps a great deal heres crowers number 619-661-6477 something like(but not necessarily) this cam below with its reasonable lift and increased duration will produce more hp at the cost of a lopey idle and loss of some lower rpm drive-ability , but a decent low restriction exhaust and headers will also be required to maximize the combo http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=00418LM&x=23&y=4 Edited February 28, 2010 by grumpyvette Quote Link to comment Share on other sites More sharing options...
spacecase70 Posted March 19, 2010 Share Posted March 19, 2010 Grumpy would have a copy of JTR manual on one of your hard drives that you could e-mail to me? maybe even the dimentions of the set back brackets and the thickness of the spacers? i really want to do the swap, I am usin an 89 camaro rs for the donor. is has no mods that i can identify, and has a th700r4, like the fact of the overdrive! I will be using an r200 with 3.54 gears, and 280z components from a 76 on a 74. any help you could provide me would be greatly appreciated! just dont have the resources to get the book, but have the machine tools to make the parts! anywho I really could use your valuable information on this build! Quote Link to comment Share on other sites More sharing options...
Kevin.pk Posted March 19, 2010 Share Posted March 19, 2010 (edited) Grumpy would have a copy of JTR manual on one of your hard drives that you could e-mail to me? maybe even the dimentions of the set back brackets and the thickness of the spacers? i really want to do the swap, I am usin an 89 camaro rs for the donor. is has no mods that i can identify, and has a th700r4, like the fact of the overdrive! I will be using an r200 with 3.54 gears, and 280z components from a 76 on a 74. any help you could provide me would be greatly appreciated! just dont have the resources to get the book, but have the machine tools to make the parts! anywho I really could use your valuable information on this build! It's copyrighted. Just buy the JTR book. If you don't have the resources to get the book, you may rethink doing a swap as it can get pricey quickly. Our cars have so few vendors, so support the ones that are available to us. Edited March 19, 2010 by 280zcar Quote Link to comment Share on other sites More sharing options...
sweetride2go Posted May 10, 2010 Share Posted May 10, 2010 Hey grumpy, you have been a great source of knowledge here for me before. But now I have a problem trying to fine tune my 4150 holley(Proform) on my SBC Z car. I went to your other site and searched around and fallowed links, and that gave me a few things to try but so far no luck. The engine is a 383 with a lumpy hyd. roller, unfortunately I don't remember the specs on the cam. The car has two hesitations when I accelerate, one with the inital movement of the throttle and another a couple seconds later. It doesn't stall, just kinda hesitates, accelerates, and then accelerates more without any more throttle input. Sometimes it will pop back through the carb. The car was initially dyno tuned and we had things pretty close, but in our last adjustments(on the floor) we made things worse, which is where I am now. Also the 4 corner screws are uneven, set up by the shop that way. The primary screws are roughly 1.5 turns and the secondary's are at .5 turns. My best guess is accelerator pump nozzles(31) and/or cam(black cam), and maybe the air bleed jets(? don't know if that's what they are called) near the choke flap? Thanks Ryan Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted May 11, 2010 Author Share Posted May 11, 2010 (edited) Hey grumpy, you have been a great source of knowledge here for me before. But now I have a problem trying to fine tune my 4150 holley(Proform) on my SBC Z car. I went to your other site and searched around and fallowed links, and that gave me a few things to try but so far no luck. The engine is a 383 with a lumpy hyd. roller, unfortunately I don't remember the specs on the cam. The car has two hesitations when I accelerate, one with the inital movement of the throttle and another a couple seconds later. It doesn't stall, just kinda hesitates, accelerates, and then accelerates more without any more throttle input. Sometimes it will pop back through the carb. The car was initially dyno tuned and we had things pretty close, but in our last adjustments(on the floor) we made things worse, which is where I am now. Also the 4 corner screws are uneven, set up by the shop that way. The primary screws are roughly 1.5 turns and the secondary's are at .5 turns. My best guess is accelerator pump nozzles(31) and/or cam(black cam), and maybe the air bleed jets(? don't know if that's what they are called) near the choke flap? Thanks Ryan step one swap to the BLUE CAM and verify your float levels are set correctly and that you have a constant 4.5-5 psi of fuel pressure , this usually requires a return style fuel pressure regulator and a fuel pressure gauge. post clear pictures of your spark plugs with the cylinders numbered and set your ignition timing after verifying tdc at about 12 btdc at idle and verify its reaches full advance at about 36 degrees btdc at 3100rpm http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1790 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=109 heres a cheap professional version but you can make a really nice one for a couple dollars that will last your lifetime its amazing what you can learn about engine combustion chamber conditions, air/fuel distribution and temps, from reading spark plugs Edited May 11, 2010 by grumpyvette Quote Link to comment Share on other sites More sharing options...
spacecase70 Posted May 14, 2010 Share Posted May 14, 2010 Ok Grumpy, I took your advice and bought the JTR book! so next question, I am planning on using a 5.0 and th700R4 from a 1989 Camaro and using the stock everything, just one problem.. I dont hae the wire harness or computer from the doner vehicle because it burned up in a garage fire, engine compartmint was untouched and i was thinking of using the bosche unit for a z in the TBI is it possible to use this or should i look in a JY to fine the proper pars? Quote Link to comment Share on other sites More sharing options...
sweetride2go Posted May 15, 2010 Share Posted May 15, 2010 You could get a harness and computer from Street and Performance. Of course it will be $$$ but the harness will be trimmed down and the ecu modified for you needs a bit. page 62 http://www.hotrodlane.cc/09%20catalog/sp2010/index.html Cheers Ryan Quote Link to comment Share on other sites More sharing options...
cockerstar Posted May 16, 2010 Share Posted May 16, 2010 (edited) Grumpy, what's your opinion on this exhaust? http://www.jegs.com/i/Hooker-Headers/520/2131-1K4/10002/-1?parentProductId=759933#moreDetails I already have a set of long tubes and was planning on replicating it with a set of flowmaster super 44's. Will be going on a '69 camaro that's running 2" drop spindles, so ground clearance is a concern. Engine is a 355 with a set of 202/160 iron heads with a mild port and polish. Cam is an elgin .463/.485 lift 290/300 advertised duration on a 107/117 lsa. Intake is an edelbrock 1407 (750cfm, vacuum secondaries) on a performer intake (looking to pick up an air gap in the future). I've pieced everything together at $385 through all of the individual pieces on jegs, so I'm looking in the sub-$400 range. Any tips on what I should be looking for with a well designed system? Thanks, Ryan Edited May 16, 2010 by cockerstar Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted May 16, 2010 Author Share Posted May 16, 2010 (edited) your choice looks good!and the price seems reasonable, if they made something similar in STAINLESS it would be about ideal. a basic exhaust laided out similar to these pictures above with headers feeding 3" exhaust and an (X) pipe tends to provide excellent results, if matched to low restriction mufflers, adding an (H) pipe just in front of the muffler entrance point can slightly further reduce noise and mellow the tone, just remember the main goal is improved cylinder scavenging and low restriction to flow while reducing the noise level, in roughly that order but obviously theres compromises that are made due to clearances and noise ordinances http://forum.grumpysperformance.com/viewtopic.php?f=56&t=1303 http://forum.grumpysperformance.com/viewtopic.php?f=56&t=495 http://www.boyleworks.com/ta400/psp/exhaust3.html http://www.boyleworks.com/ta400/psp/exhaust.html Edited May 16, 2010 by grumpyvette Quote Link to comment Share on other sites More sharing options...
cockerstar Posted May 18, 2010 Share Posted May 18, 2010 Thanks for the feedback and links Grumpy! They'll really come in handy when I'm trying to explain why backpressure is not your friend. Everyone around me seems to think that "you need to have a little backpressure on the valves to flow well" and are pretty set in their ways of thinking I have another one for you. I like this stainless system on summit except for the unknown mufflers in it. http://www.summitracing.com/parts/PYE-SGF63R/?rtype=10 I would love to be able to add the rear pipes that come out of the mufflers and over the rear axle to the system I have pieced together above, but don't know where I can buy just those two pre-bent pieces. Do you know of a source? Thanks again! -Ryan Quote Link to comment Share on other sites More sharing options...
rheng Posted May 18, 2010 Share Posted May 18, 2010 Grumpy, Where do i start? I just acquired a 240z swapped with a 1996 z28 lt1 from my dad, but i really have no idea where to start. All it needs right now is the tach and speedo to be hooked up and i can go get it registered. What are some good resources for learning more about my options for the car, how to go about doing said options, etc. (aside from here)? Engine swaps, z's , and american engines are all new to me. I come from the world of bolt on subaru's lol. thanks! Quote Link to comment Share on other sites More sharing options...
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