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!
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In the Near future I would like to go from small block 305 tbi lo3, to a Big block(not sure which one yet). What modification will I need to expect? New springs??? thing like that. Also would it be Worth a Big block or going to a 383?? thanks
When you say would it be "worth" it do you mean $$$ or power. It would be worth tons of torque but it would also be worth a lot of $$$. Do you want/need to be able to light the tires up at 30-40 MPH just by easing on the pedal? If so, go for the big block if you have the money.
please list some more specific Qs. I can walk you through most of this swap (and hopefully save you some of the trial and error I went through). There is NO substitute for cubic inches.
How about your exhaust? I've got a 454 in my 84 Camaro but I haven't decided on my exhaust system yet.
Up to this point, my HEI distributor clears fine. I have heard of some that did not. There is very little clearance on the A/C box on the passenger side. I used stock small block mounts and now have Moroso solid mounts. Both fit equally well. Stock hood clearance should be possible with a low intake and air cleaner.
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92 Convertible Trans Am: Mostly stock, L98 long block, ported heads, SLP Headers, Hypertech, K&N.
9.0l firebird, I was talking more of any problems with the swap and also what kind of
suspention mod. would I need. 88 427, will check your page out. thanks all
Problems: Cooling- I went with a Griffin 31x19 two row aluminum radiator (a new 350 rad w/ special cooling turned out to be worthless) 2 flex a lite 12" fans are ok up until about 90* outside. Motor mounts- used the moroso pads and mounts, but redrilled the motor mounts to sit the engine 1" lower in the chassis and moved the motor back about 3/4". Exhaust- tried Hooker super comps with less than impressive results (1 7/8 with a 3" collector is too small) and fit like crap. Ed quay race cars and Davis headers make great fitting headers for this car in any size you want (mine are 2 1/8 x 2 1/4 steps with 3.5" or 4" collectors) I picked up 2 tenths and 4 mph with the davis headers over the hookers. suspension- worn 6 cyl springs up front (very high tech) with Koni adjustable struts by tru choice allowed the best weight transfer (lakewood 90/10s DO NOT work in these cars). Changed the PS to manual with the help of an '84 S10 pu steering box. With a mild street 454 (oval port heads, 10:1, no nitrous), the car went 10.94 @ 124 and got 8-10 mpg to the dragstrip (35 miles) or cruising keeping your foot out of it. I was able to use the flat hood with a tall single plane manifold (no air cleaner). Hope this helps you get started.
Guess I should have elaborated. 9.0L Firebird, what did you run for a cam. I'm curious when you state a mild 454 and turn sub 11 sec times. Miles, what casting number are your heads? I was looking over your website again and I didn't see where it was stated anywhere.
92TAConv, I have not yet installed my motor so I do not yet know of the fitment issue, from what I have heard from everyone is that they fit like A S S !! I think I will run the Davis headers also if I can find some info on them.
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BigBlockJason
85 Z28 T-Tops
468 Big Block Chevy
From what I hear alot of the trouble people run in to is when they don't run the stock small block engine mounts. Hooker didn't do a good job with the headers though. They made them too big and too long. They should have stuck with a 1 3/4" big block version of the small block shorty headers. They would fit better and deal with things like different engine mounts better. I have to agree that the Hooker chromed big block headers are a mess and you are better off making your own.
I agree with the mild comment. I consider my motor mild and for me to run 10's I will need a lot more gear and converter and to drop 500-600lbs. But everyones definition of mild is different.
I don't have the head casting numbers right now. If you really want to know, I can dig them up but here is what they are:
Stock cast iron open chamber oval port heads from a 335hp 1969 427bbc that was originally in a station wagon. The combustion chambers measure out to 100cc now, have 2.19/1.88 valves and have been pretty heavily worked over, especially on the exhaust side. I don't have the flow numbers with me, but here is a copy of one of the dyno pulls. Note the VE of over 100% from 4300 to 5300rpms. http://geocities.com/mek88427/dyno.jpg
If its not too much trouble throw the flow numbers up some time. I'll catalog them for future use. What you told me gives me a pretty good idea of what you have. Basically they are large port oval heads that have been fitted with L-88 valves. I was curious if you were running the small port or large port oval heads. Anyways, thanks for the information.
A few responses: 1. 454 cam specs crane street roller 246*/254* @ .050 .636/.615 lift 110* lobe separation. I had a larger Comp cams street roller in it previously (260/260 .650/.650) that killed all the low end torque but sounded like a pro stock. If I had it to do over i would go with the same crane cam with 114* separation. 2. heads are #781 castings (early 70's low performance) heavily massaged with 2.19/1.88s). Davis headers can be reached at
Davis Step Headers
135 S Oaks Ave
Ontario, CA 91762
(909) 391-2332
They do not have website. Jack is an old timer. He was the head of R&D at Hooker Headers before starting his own business. These are more race headers than street setups (i.e. slip on collectors and tight oil filter clearance); but they fit like a glove.
Has anyone seen the Sanderson headers at www.sandersonheaders.com ? I am considering running them with a custom 3" y-pipe and 4" mufflex cat back system without the cat. I am building my motor in the 450-500 HP range and feel that should be adaquate.
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92 Convertible Trans Am: Mostly stock, L98 long block, ported heads, SLP Headers, Hypertech, K&N.
Davis headers were $675 4 years ago. The quays were $575 in their last price list. Quay headers must be used with their modified K member ($350 with core). Stahl also makes headers for this combo, but I have not seen them installed.
Yeeowch. They are just pipe you know. Go down to Home Depot and blow $400 on a mig welder. Then after you are done making your own headers you can move on to making a new rear axle. I don't know guys, am I just cheap or am I resourceful? Gives me the jitters every time I hear of someone paying $2500 for a rear axle or $600-$800 for a set of headers.
LOL Doc, I hear ya and so does my wallet, but im afraid i really dont have the skills or the patience for making headers. Hell, I even pay people to change my oil !!
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BigBlockJason
85 Z28 T-Tops
468 Big Block Chevy
Sorry, no pics. you cannot see very much from the topside anyway. I am pricing new headers for the big motor and am getting quotes in the $1,200 range (uncoated)!?! At the same time you generally get what you pay for. I can bolt in the motor and trans (with starter) and assemble the headers after the motor and trans are bolted in. spark plug clearance is great as well as ground clearance. good hooker headers are $350+ these were about twice that but worth the difference. I wish i had started with these to begin with. Also bear in mind i am using these headers with a non-standard combination. these were made for GM heads, I am using them with Dart heads that have the exhaust ports raised 3/4". And yes, sticker shock is beginning to set in on this project. th400 upgrade to powerglide trans & converter -> $5,000 !?!
I just got my 85Z back. It has been at Custom Craft in Midland, AR having a set of big block headers made. They are 2" primaries with slip on collectors. They can be installed or removed with the engine in with ease. Have plenty of oil filter clearance, and can change the starter without any problem, but removing one tube from the passenger side makes it really easy. Custom Craft also coated them, so they look killer too.ALsogota3disc setup which they make and sell to Summit and Jegs, haven't got it running yet but was told that the discs makeitasquiet as mufflers. I need a fuel system. Could someone give me the web address to Ed Quay, I heard they make a neat fuel cell/battery tray setup. Hope to have it going soon. Taking suggestions on the fuel system?
i like the big blocks, but not in these cars. i'd chose the 383 myself. take alot of work to get the big block as a nice set up worth being a daily driver. remember, if you can't drive it everyday it's pretty well pointless to own.
