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Thread: 400FWHP TBI build attempt thread

  1. #31
    Fuel Injected!
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    Mar 2015
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    59
    Rather old first attempt at building and smoothing a VE table, based on... gut I guess. No idea if I'm even close but this is what I started with, dreaming back in Dec. 2016. screen shots of both graphs as well. For spark tables I considered working with Vortec head stock tables as a fairly conservative ballpark, maybe even stock aluminum head LTI F body tables and dialing it back pretty broadly since classic Gen I SBC isn't reverse cooled. No chance of making 46* anywhere like an LT1, especially at 10.2:1 lol. This is where I really have no idea to build a spark table. I still think the Vortec tables are decent place to start, maybe something like an aluminum headed L98 as a base? The ProMaxx 2169 heads' flow numbers are well published, they post them on their site, Skip White measured them a year ago, I think HotRod magazine online had a budget head shootout with flow numbers when they were still Patriot heads, though I'm pretty sure that was a previous design.
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  2. #32
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    Mar 2015
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    Havenít touched it for 12 days until tonight, very brief time spent. Cleaned up the spider I acquired from a boneyard LT1 D body. Also soaked the new lifters in virgin mineral spirits for an hour to clean them. Blew them dry with air and put them in the oil bath until tomorrow evening.

    What I have been able to do is study the hell out of VE and spark tables from a variety of engines similar to what Iím putting together. Iím most familiar with F body LT1s. With a 218/224 - .528/.535 cam in 185cc aluminum heads Iím not too far away from an LT4ís flow characteristics. Iím a tiny bit bigger on cam, tiny bit smaller on heads (heard LT4s were 190cc heads, maybe not accurate). My goal is to put together a better 2nd attempt on the VE tables and take a stab at the spark tables in the bin and upload that in a couple of days. Scrutiny of more experienced guys would be welcomed.
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  3. #33
    Fuel Injected!
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    Feb 2013
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    Euless, TX
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    Quote Originally Posted by Gojira94 View Post
    Havenít touched it for 12 days until tonight, very brief time spent. Cleaned up the spider I acquired from a boneyard LT1 D body. Also soaked the new lifters in virgin mineral spirits for an hour to clean them. Blew them dry with air and put them in the oil bath until tomorrow evening.

    What I have been able to do is study the hell out of VE and spark tables from a variety of engines similar to what Iím putting together. Iím most familiar with F body LT1s. With a 218/224 - .528/.535 cam in 185cc aluminum heads Iím not too far away from an LT4ís flow characteristics. Iím a tiny bit bigger on cam, tiny bit smaller on heads (heard LT4s were 190cc heads, maybe not accurate). My goal is to put together a better 2nd attempt on the VE tables and take a stab at the spark tables in the bin and upload that in a couple of days. Scrutiny of more experienced guys would be welcomed.
    LT4 heads are195cc with 2.00/1.55 valves. Their smallish chambers have them at 10.8:1 with the flat top piston. The cam is 203/210 @ .050 and they run 1.6 roller rockers from GM.

    I have 205cc copies of Dart Pro1 Platinums on the L31 in my Express van. With a 215/224 cam and 1.7 roller rockers. With the MAF disabled I had to add a good bit of VE above 2,500 rpm. With SD disabled the MAF only required slight tweaking in the lower rpm, lighter load areas to get the fueling back to optimal. Once they were both fixed it was noticeably smoother and stronger across the whole RPM range. Converter stalls 2,500 rpm and I have 4.56 gears with the 30.5" tall tires. I turn 2,600 rpm @ 70 mph in OD. With the travel trailer in tow I have found any real grade has me in 3rd @ 3,500 rpm and if the climb is long enough or steep enough I have plenty of RPM left in 2nd gear if needed as well. 2nd puts me at 5,200 rpm @ 70. My shift points in Tow/Haul let it grunt a bit though and I do not downshift to 2nd unless I am under 65 mph in Tow/Haul.

  4. #34
    Fuel Injected!
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    Mar 2015
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    Quote Originally Posted by Fast355 View Post
    LT4 heads are195cc with 2.00/1.55 valves. Their smallish chambers have them at 10.8:1 with the flat top piston. The cam is 203/210 @ .050 and they run 1.6 roller rockers from GM.

    I have 205cc copies of Dart Pro1 Platinums on the L31 in my Express van. With a 215/224 cam and 1.7 roller rockers. With the MAF disabled I had to add a good bit of VE above 2,500 rpm. With SD disabled the MAF only required slight tweaking in the lower rpm, lighter load areas to get the fueling back to optimal. Once they were both fixed it was noticeably smoother and stronger across the whole RPM range. Converter stalls 2,500 rpm and I have 4.56 gears with the 30.5" tall tires. I turn 2,600 rpm @ 70 mph in OD. With the travel trailer in tow I have found any real grade has me in 3rd @ 3,500 rpm and if the climb is long enough or steep enough I have plenty of RPM left in 2nd gear if needed as well. 2nd puts me at 5,200 rpm @ 70. My shift points in Tow/Haul let it grunt a bit though and I do not downshift to 2nd unless I am under 65 mph in Tow/Haul.
    That's right, I conveniently forgot LT1/LT4 heads have 58-53cc chambers, noticeably smaller than my 64cc. I'm running a 2.02 intake and 1.6 exhaust valve. 2200-2500 stall converter in front of a built 700R4 and 3.73s. I'm thinking (stop me if I'm wrong) that my engine's overall VE is higher than either the LT1 or LT4 but similar enough that I can base at least some of what I need from them, scaled up to start with. Timing I'm thinking Vortec tables provided in EBL and multiply by about 4-5% and mostly focus on crank and idle timing (like as much as 12-14* cranking and 8-10* idle, maybe a hair more). If it starts on what I throw at it I'll be happy, if it runs well enough to drive a short distance and seat the rings I'll be ecstatic. Though I don't see if going over the center field wall on the first swing. I'm all MAP/SD with no IAT (yet).

  5. #35
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    Mar 2015
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    Lifters and retainers installed, did paint the water pump Old Ford Blue. Hope to get the intake on after I check the pushrod clearance in the heads. I have 3 that are looking a bit close. I think the min. clearance is supposed to be .060" with rockers centered across the valve stems. We'll see soon enough if I need 2 piece guide plates to help with that.
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  6. #36
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    Mar 2015
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    I started mocking up the valve train using a spare set of 7.2” pushrods from a 64,000 mile LT1. ARP 3/8” studs and Summit stainless 1.6rr. Guide plates are Dart 1 piece. The valves and studs are very slightly offset so there is a small angle split for the rockers to be centered across the tip of the valves. I tweaked the plates under the studs back and forth and checked the clearance for the pushrods at the optimal locations and the clearance from the head castings is adequate for 5/16” pushrods so that’s one worry eliminated.3/8” would require additional clearancing for sure. Looking at the resting position of the rockers on the closed valves it looks like 7.2” will be very close to correct length but I will definitely measure once I get the studs and plates locked down.

    The Summit rockers are ok though one is in need of cleanup in the stud hole. Bad news is the poly locks are garbage, out of concentric and have thread issues (10 of 16 are junk). ARP makes replacements for those too, lol. The locators for the poly locks are also too narrow for the poly locks included with my Comp stud girdles, which I was going to use anyway. So... I think for now I may run without girdles and pick up a set of better quality rockers in the not too distant future. I think I’m pretty far past return on these rockers but I’ll check with Summit on Monday. They were like $199 and if I can pay the difference on something better that works with the girdles I may go ahead and pull the trigger on Monday. Always issues with any build, this is the penalty for trying to find a stainless 3/8” 1.6 rocker set under $200. Duh.
    Last edited by Gojira94; 06-23-2018 at 07:21 AM. Reason: clarification/ price correction

  7. #37
    Fuel Injected!
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    Mar 2015
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    Replacement rocker arms should be here today and I can get the pushrod measurement finalized. I mocked up the intake and made sure the brackets for the MAP and the throttle will clear the valve covers and work as intended. The ESC module I'm going to mount on the rear pass. side corner of the intake pad with a small handmade bracket of some sort. Got the oil cooler block mounted with new o-ring, internal gasket and quick connect fittings, hoses are in good shape and cleaned up. Got the damper and crank belt pulley on as well. Engine mount brackets are on. Just about ready to go back in with it. Plenty to do after that to get it ready to start as well.

    Sorry this thread is almost all mechanical so far, tuning will come soon. Every tuner I've ever talked to says to make sure you have no mechanical issues before tuning or you're asking to go around in circles. So I'm taking the time to do this as correctly as I'm able in the pockets of time I have to get things done.
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  8. #38
    Fuel Injected!
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    Mar 2015
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    Long overdue update. I swapped the Summit rocker arms for some Scorpions. Stud girdle is in, pushrods measured out at exactly 7.2", intake is installed, distributor is within 2* of zero with #1 at TDC. Found a crack in the oil cooler housing when I primed the oiling system. Found one in the local boneyard for $6. It's pretty much ready to drop back in and start buttoning everything back up. A little over a week ago I went back to the tune and tried to make some decent progress. Some is based on educated guesswork. Bin file and change log attached, as well as a worksheet I started putting together to compare spark and VE parameters between stock TBI, Vortec, LT1, LT4 and an LT1 Cadillac with a towing package option. Here's what I haven't addressed yet in the tune, notes about what I need to cover:

    AE - Acceleration Enrichment parameters
    HotRST - Hot restart parameters
    Find and set idle parameters
    Find SA Latency on the Ramjet distributor's ignition module for "SA - Latency" table
    Tune out EGR*
    Engine and Vehicle Speed Limiting
    IAC parameters


    1104060 distributor, used on the fuel injected Ram Jet 350 and Ram Jet 502. Includes ignition module P/N 10482830, cap P/N 19166099 and rotor P/N 10477219.
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