spitfireguy

Bringing this to a close... I have solved this issue now. Alec, 2.5piman, V8Nick and especially Nick, I really appreciate all your advice and suggestions. I can't find a forum anywhere else that has straight-forward advice like here. I put in a new 45D4 distributor (41449) with points. This was what was needed all along, not really the HS4's, even though symptoms suggested so, it was the ignition all along. With the new distributor, my idle was smooth and even, acceleration was stronger, higher RPM's were attained with no stutter or hesitation. Next I added the Pertronix unit which made it even better, bagged the points and put them in the boot, replaced the coil. I'm on the right track now. BP6ES plugs are in the mail and will be installed this week. New plug wires were installed as well as an FYI. Summary, the TrueSpark electronic distributor I purchased from a US British Parts specialist was all wrong. 2.5piman sent me down the right road questioning the advance curve on this distributor. I spent many hours studying and learning about advance curves, etc. and knew I was chasing my tail working on the carbs rather than ignition. So to help anyone else that may be in the same boat, I do not recommend the TrueSpark distributor for a 1500 Spitfire. It's all wrong. Can't say THANK YOU enough to the forum regulars that have in the past, and have again with this issue helped me immensely. Thanks. Mike Omaha, NE

Nick and Alec: Thanks for the link and explaining the 1-2-3 ignition. I'm hesitant to throw more money at my problem, although truthfully, I have and am doing so now. Based on the reaction you both had with the TruSpark distributor, I switched my focus to studying up more about timing, distributors, etc. I have a 45DE4 in my parts boxes that presumably was on the engine at one time, but I can't remember. I believe the vacuum component is a 'retard' rather than an advance? None the less, I do want to know more about the distributor. I was able to get a bit better running at higher RPM's with my current TruSpark if I started with about 16 Degrees static. So, throwing more money at the problem, but with the idea of isolating the problem, I bought a 45D4 brand new from SpitBits yesterday. Standard points, etc. I'll be following Nick's lead by installing the distributor, NEW plug wires, NGK's and swapping in a coil of the previous mentioned changes prove no difference. This has been a long process, but I've learned a lot from you both, Alec and Nick, and appreciate you taking the time to stay with me here working this out. Mike

V8 Nick: Sorry to be so stupid, but what is programmable 1-2-3? Is that the wideband sensor suggested earlier? Pulled my old distributor out and it is the US spec 45DE4.. with the black box electronic ignition.. neither of which I am using obviously. At the Autocross this past Sunday, I was talking with one of the old-timers in the club and once I added 'ignition and distributor' into the conversation, after talking tuning the carbs for a while, his eyes lit up and said yes and agreed you fellas have been guiding me down the right track. I've sent an inquiry to this guy: http://www.advanceddistributors.com/ Jeff is his name and once I mention him, several people say he knows his stuff. The go to guy here in the states for distributors. I believe I will work with him rebuilding my 45DE4 or whatever else he suggests after I hear back from him. on a side note.. Pertronix, Crane, or ? is best in your mind? Mike

Alec, V8Nick and Nick: I know I've been concentrating on the Carbs, so much that I've kept the ignition discussion on the back burner. It finally dawned on me that as you all have suggested at one time or another that my distributor (and other parts of the ingnition) may be the culprit. I'm very much in agreement now. I have an older distributor, not sure if it's a 45D4 or not, but I'm going to rummage through my parts boxes until I find it and do some experimenting. I probably won't have anything to report back for a week or two, but again, I can't thank you enough for your ongoing suggestions and thoughts. I'm going to get this right, and I owe that to you guys. Thanks... OH.. the O2 sensor.. I'll look into that a bit too. Will do distributor first, then may fall back on O2 later. Thanks.. Mike

Nick... I always appreciate how you hang in there with me on my stupid questions... really I do! I had red springs in the carbs, but bought brand new red springs to make sure the 4 1/2oz or whatever was more accurate, I also have brand new Yellow springs as well. I can't think of ANY place near me that would be able to do a dyno thing... We do have a repair shop called "Mr. Sports Car" and he is in my British Car Club, but his shop isn't much more than a lift and some tools. I DO plan on pulling a few club members aside this Sunday at the Autocross event, maybe their collective wisdom will help as well. The air filters I have are K&N cone style. I have the MGB round, venturi type things mounted on the carbs, and the air filters attach to that via large hose clamp. Last night I went for a long cruise... If I accelerate full throttle down, it's really gassy smelling. Accelerate half throttle and short shift, not so bad. Cruising down the highway, steady throttle at 4000 RPM, it stutters on and off. Based on the Minty Lamb charts would the AAR or AAF be better than my current AAM? It's really the 6-9 needle position that I need to worry about, right? Since I've messed around with these needles so many times, perhaps I'm going about it wrong. If you think a different needle should be tried.. I know this is a lot to ask, but after I insert the new needles, tell me the steps you would take.. maybe I'm missing something? Mike

Nick and 2.5Piman.. I'm getting more and more convinced it's not the needles or carbs as much as it is most likely ignition as Nick keeps suggesting. I have a graph identical with what you posted above Nick, and looking at stations 6-9 I can't make a change of needle that makes any difference, discernible that is. I replaced the two fuel bowl shutoff things last night, only because I had just ordered them last week. Opening the tops of the fuel bowls showed the top level of gas was even between the two carbs, about 3/4 inch to 1 inch below tops of bowls. I should have measured, but neglected to do so. this is the distributor I installed: here and the coil is the recommended match. My plugs are new, gapped at .030 and are NGK BP5ES Anyway, last night I played with the timing a bit. First however, when I rebuilt the engine, I did use a dial caliper and my #1 cylinder TDC was pretty close to the zero on the timing cover marks when compared. Last night I advanced it up to about 16 degrees BTDC at idle with the vacuum advance pinched off. The idle increased as I did so, (which I used the idle adjustments on the carbs and knocked it back down, also checking for balanced air flow using unisyn) and it 'did' seem to drive better picking up power swifter and the higher revs were better, so I believe I can get this working better with Ignition changes now. I have the 'green' ignition wires, brand uncertain, that I think were listed as 'standard' when I bought them from the same source I linked to above. OH, and to address the quoted suggestions, I did recheck valve clearance a week ago and set them at .012 (even tho book says .010?) I just don't know what the next step is... How do I fiddle with timing maybe? new plug wires? I still get a heavy gas smell when pushing the throttle down to floor and climbing up through the gears. My son was with a friend driving behind me a while back, and they both smelled gas. This thread has gone WAY to long, and I apologize to all for that.. but frustration still exists and I'm ready to just 'live with it' and smell like gas after every drive. Unfortunately, that keeps me from driving it to work as I don't want to smell bad sitting next to teammates. Thanks again all. Mike

Alec; Thanks for that explanation on pinking, which indeed helps me understand it better. I have messed with the timing advance at idle, but can't seem to figure whether I'm better or worse off after moving it around. I need to study up more on the whole deal. I've used ATF fluid in the dashpots, and I've used SAE 30 weight as well. I can't tell any significant difference there either. I understand the purpose, but these carbs are frustrating me beyond anything else this car has ever presented me with and seeing differences now with any of my changes is eluding me. I'll head home after work today and fiddle around more. I have a performance event (Autocross, solo event) on Sunday and would like to be respectable against a couple of the bugeye and midget guys. (on a side note, we have a very active British Car Club here in Omaha/Lincoln and a monthly autocross with all British Cars.. fun times) I don't like sputtering about on course and having the others think poorly of my car. I never imagined setting up twin HS4's would be such a headache. Thanks again.. Mike

Nick and Alec: thanks for the input. Alec, the engine is newly rebuilt, balanced and should be in good order. I checked the valves a week or so back, and all was good. I've not done a compression test on each cylinder, but I"m assuming all is well. All ignition parts are new, coil, distributor, plug wires, etc. I don't have a good understanding of 'timing' or 'pinking' but I have played with the timing a bit and started with the standard 10 BTDC. and have pushed that out to 14. I'm doing this at idle and with vacuum advance pinched off. Would like some tips on timing as this is the part I least understand. oh, and I do have the pistons rising and lowering the same via visual inspection during rev up. I have a range of needles for these carbs.. I can swap them out and get idle adjusted fine. this is where I agree with you Nick.. I can get the same stuttering at 4K and higher with different needles, so I'm just puzzled, and have consumed too many 'frustration beverages' than I should. Mike

Still can't get these carbs tuned. One more question: I have the 'non adjustable' floats in the fuel bowls. I have ordered new (official name escapes me at the moment) but the brass pointed things that the float pushes up to shutoff fuel from entering the fuel bowl. Float Needle and seat? I also ordered some of those thin 'washers' to put in the screw in part (the seat?) which supposedly 'adjusts' the float needle? How could that thin of a thing actually help? I also have a filter king filter and regulator on the skuttle about 12 inches upstream from the rear carb. I ordered a fuel pressure gauge that I will plumb in and double check the pressure is at 2-3 lbs... is that correct? With these non adjustable floats, how do I make sure the gas level in the bowls is lower than at the jets? Mike

Hello all... took another crack at this yesterday afternoon. (Nice to have a boss that understands my Spitfire counts as a 'sick kid' and I can take time off) I'm still fiddling with these twin carbs. A couple things I learned, which means listing them here will reveal my stupidity in varying degrees, but I hope it will help someone else on the forum down the line. As I previously mentioned, I had to adjust the jets on the carbs different, as in the read was measured with a caliper further down from the bridge than the front carb. As suggested, I was paying more attention to the pistons drop speed, and some other things, and when I reassembled the carbs, warmed it up, I could see the rear carb piston rise earlier and higher than the front carb when revving the engine. Sometimes, I guess, when you are solely concentrated on JETS, you fail to notice the rest of the moving parts. My rear carb, where the linkage that connects both carbs together, throttle linkage, well, the 'rod' part that enters the hollow nut and pivots within, was stuck on the rear carb, but moving freely on the front carb. that was causing the difference in the two carbs.. I have that corrected by bending up the two ears that secure the nut, then backing up the nut a bit, and now the linkage bar rotates freely in both carbs. Of course that meant taking the carb off the intake manifold and it took me forever in 90 degree heat in my garage to get it all back together, choke linkage and throttle linkage inserted in both carbs, then bolted back up. I called it quits after that. I will try tonight to get them in sync better, balance and fiddle with the jets. I do have one question: When raising the piston 1/16th inch to see if the revs go up, down, or stay same, (rich, lean, good) I have one source that says: raise the piston on front carb, depending on result, adjust the rear carb, and vice versa. so, if you raise front carb, exhaust sound goes up, it means REAR carb is too rich? Does this make sense? Clues welcome. Mike

Thanks for the great ideas and suggestions. My answers are as follows: Nick: the rear carb is the first in line from the pump. It is the carb that has the jet lower/richer than the front carb. I have Vizard's book, so I'll investigate what you and Alec both say, drop speed of the pistons... Alec: I"ll have to test out the piston falling drop speed.. I'll have to research that a bit more to get a better understanding. I also didn't mention in prior posts that I'm using RED springs and they are brand new. I also have a set of Yellow for experimenting, but have chosen to stay with the reds. Zetecspeed: I have used carb cleaner before to isolate the butterfly spindle bushes as my original air leak, but I've not thought of checking again, even after suspecting I have a lead still.. will do that soon just to eliminate, I hope, that issue. Thanks all.. Mike

To close this out, I'm much closer now than I was last week, however I've changed very little. I checked fuel bowls as suggested, same and good. I rechecked timing and set in the 12 to 14 degree area. Valve clearance was checked/reset and now valve clearance is 12 thou. All was good with the valves prior to adjusting, so I was happy with that as doing valve clearances is not my favorite activity. I should note at this time that I tried the pull the plug, stop on the road deal and found cylinders 3-4 were ash colored, but 1-2 were black and obviously rich. After reading all my reference materials over and over, I started again by setting the jets down .04 (inch?). Needles are AAM. Used a paint pen to mark the 'flat' that was facing outwards for reference. warmed the car up, choke was disconnected, and got a pretty steady idle at 1000 and balanced the air flow. (I believe I should replace both springs under the idle adjusting screw as one feels weak.) Air flow balanced, I did the screw driver under the piston test. Front carb revs went up and stayed up, rear carb revs went down and bogged the engine. To make the carbs behave the same, I had to go richer on the rear carb, and leaner on the front carb. Jets are not equal now. The only thing that comes to mind is an air-leak. I had the spindles rebushed, so I'm guessing either a leak at the heat shield between carb and intake manifold, or between manifold and head. Would love some comments/suggestions on that please? The end result, however, is I now can rev through the power band and not get hardly any hesitation at all, so I'm pleased to a point that I'm close. Probably will just leave it as is. Always appreciate the collective wisdom of this group. I go nowhere else when I'm stumped. Thanks.. Mike

Hello, I'm pretty close tuning my dual HS4 carbs on my '78 1500 Spitfire. I've purchased and read several books, scoured the web, but just can't hit the sweet spot on my carbs. I'm setting them up for aggressive driving fpr solo Autocross events. I can't seem to solve for a stumble under full throttle at the upper RPM range 4000 RPM and above. Can anyone suggest a course of action to assist me? I know the tune of the car matters to setting, so here is what I have. Newly rebuilt engine, 270 cam, flat top pistons, valves adjusted and readjusted to .012 thousands, NGK sparkplugs with .030 gap. Header is 4-2-1 with standard diameter tailpipe into a standard muffler As I said, I purchased dual HS4 carbs and manifold, rebuilt the carbs and had Joe Curto put new bushings in, all should be well. no air leaks that I can determine. Butterfly is not the pop off type but solid. running 92 octane premium gas Timing has been played with, from 10 BTDC to 14 BTDC... would like suggestions here. Distributor is a "Flame Thrower" electronic ignition with matching Flame Thrower Coil. Standard Green colored wires. I have several HS4 Needles to use: ABF - AAR - AAF - AAM - AAB I am using the AAM at this point. (this selection of needles is an indication of how long I've been putzing with these carbs trying to get the car to run. ATF in dashpots, is that ok? So with that, assume valves are set, timing is at 14BTDC at this point, I warm up the car. Disconnect the Choke. Pull the carb tops and set the jets. I've started with the '12 flats down' setting which if I remember comes out to about .08 on the caliper? (not sure if I have the decimal or the proper unit of measure, just that I use it to match both sides, analog dial) I've started at .05 as well. I balance the carbs using my Uni-Syn.. tweaking the idle to about 1000 to keep it running without stutter and air flow is balanced. As far as the needles go, I've learned they all are about the same at idle, 1st and 2nd stage on the needle. I've used the Minty-Lamb comparo-rama charts to compare needles. From this point, my next steps to attempt a tune vary depending on the source book, website, manuals I have. this is where I need some help. When I go full throttle in 4th gear, as the car is pulling or gaining speed, as the RPM's rise, I start to get a stutter and power falloff at about 4000 RPM. (this is the same if I'm at an autocross and at 4000 in 2nd gear, full throttle) I'm no genius, but I'm assuming Rich as I do smell gas, or exhaust slightly at this point.) and of note: I've never driven the car on the road, cut the engine at 4000, coasted to a stop and pulled the plugs. Once I"m at this point, How do you move forward and what do you do? I know that's a lot to take in, but I'm pretty close.. 'cept for the stutter at the higher rpm which I'd like to solve for. Thanks in advance and hope to get a reply with some ideas.... Mike Omaha, NE USA

If this isn't one of the most stupid questions posed here, I'd be surprised. I was NOT surprised that searching prior to posting I couldn't find anything close. As I was adding shocks/springs to the front of my 78 Spitfire, depending on the location of where I placed the adjustable spring 'perch' I would have some fender rub. After a lot of adjusting, I noticed that not only the rear of my car leans to the right (passenger side) but so does the front? I sandblasted this GT6 frame and painted it, etc, but never bothered to measure it up for square, stupid me #1. I moved the tub over from a bad frame to this new shiny frame and added the shims and pads per the manual, I believe. I thought the lean to the right on the rear was the rear spring, but after replacing that, it still leaned. (I had yet to discover the front leans as well.) Presently, I have three fingers gap between front and rear tire to fender lip on the left, but barely one finger front and rear on the right? The gaps are equal front to rear on each side. What the heck should I do? Is it ok to just add a few more shims at the body to frame mounting points on the right side in an attempt to level it out? What could I have done wrong and what's the best advice to get myself level here? Mike

Hello... I wanted to bring this thread to a close. Thanks to Nick for the assistance and advice. I reassembled everything, with hesitation because I didn't really see anything wrong when I tore it apart. The few things that changed: New Laygear, new reverse gear, new 1st/2nd synchro assembly (the three springs inside were noticeably longer than the old gearset, maybe one option for the problem) new release bearing, and pin on clutch fork, new main bearings and all the other little bits and parts. Long story short, I'm driving, shifting, and all is well. After so many years of rebuilding this car, I'm now past the restore phase and into the sorting out phase. Since I always have good help from everyone here on this forum, I'll include a tip I discovered that helped me re-install the entire transmission all by myself, no helping hands. I cut the heads off two 3/8th bolts, ground the cut portion down to round points, inserted them finger tight and they allowed me to guide the bell housing onto the back plate so very easily. Once I had the Dowell bolt and a few others, I removed them and replaced with the proper studs. They held the weight of the transmission as I guided it forward into place. If this isn't new to you fellows, I'm sorry, but I hope is helps someone else down the line. Mike