95 BLKDOUT Drop Top Posted February 18, 2007 Report Share Posted February 18, 2007 I wes reading up on the differences on the 3100 and the 3400 to see where the biggest differences are because i wanted to do a 3400 top end swap. I found that the bore is different. the 3100's bore is 91mm and the 3400 is 92mm, so wouldnt that make the heads not fit on the 3100 block? i didnt get as far as the intake manifold differences but are the port sizes dif? I jus was wondering before i go oout and actually spend the money on a 3400 top end and i wont be able to use it. Quote Link to comment Share on other sites More sharing options...
GutlessSupreme Posted February 18, 2007 Report Share Posted February 18, 2007 After '00 the heads are identical. before '00 the only difference was the port size. I don't think the combustion chamber was different at all between the two. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted February 22, 2007 Report Share Posted February 22, 2007 I wes reading up on the differences on the 3100 and the 3400 to see where the biggest differences are because i wanted to do a 3400 top end swap. I found that the bore is different. the 3100's bore is 91mm and the 3400 is 92mm, so wouldnt that make the heads not fit on the 3100 block? i didnt get as far as the intake manifold differences but are the port sizes dif? I jus was wondering before i go oout and actually spend the money on a 3400 top end and i wont be able to use it. sounds like the engine block bore... the heads are cloase enough they could be interswapped... I actually took the intakes off a 3400 venture van... which had one 3400 and one 3100 head! I think the valves have changed size slightly??? but even then... if your engine is fine and you are just doing the topend swap the benefit of swapping the heads is not worth doing IMO, unless your existing heads will not accept roller rockers. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted February 22, 2007 Report Share Posted February 22, 2007 FYI: the 3100 bore is 89mm and the 3400 is 92mm. The only difference between the two was the port sizes. The valves where the same, 1.50intake and 1.70exhaust ( although dont quote me on that exact sizes ) Quote Link to comment Share on other sites More sharing options...
95 BLKDOUT Drop Top Posted February 22, 2007 Author Report Share Posted February 22, 2007 so could i just do the upper and lower intake and throttle body swap? or would i have to do the heads too? i dont want to waste any money and if the 3400 heads wont be worth the swap them i dont want to do it unless i really have too. Ive heard of ppl doing just the throttle body swap, and just the upper and lower intake, and gettin a small power gain so i figure if i grab the upper, lower, and TB off of a 3400 and throw it on my 3100 i should gain some power. Nad Im also lookin for the UDP but thats another thread Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted February 22, 2007 Report Share Posted February 22, 2007 Well if you put the 3400 heads on as well, youll see more of a gain in performance than that of just the UIM,LIM,TB. Quote Link to comment Share on other sites More sharing options...
95 BLKDOUT Drop Top Posted February 22, 2007 Author Report Share Posted February 22, 2007 well i figured that much but im tryin to figure out the Power VS Price ratio. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted February 22, 2007 Report Share Posted February 22, 2007 Then just drop in a complete 3400... Quote Link to comment Share on other sites More sharing options...
95 BLKDOUT Drop Top Posted February 22, 2007 Author Report Share Posted February 22, 2007 well that would be th eideal thing but im tryin to save as much money as possible Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted February 22, 2007 Report Share Posted February 22, 2007 You can get a complete 3400 for like $500! Quote Link to comment Share on other sites More sharing options...
Crazy K Posted February 22, 2007 Report Share Posted February 22, 2007 I did my first 3400 topend swap for $35 plus the cost of gaskets ie $80 for high quality perma-dry. and even if you bought a $500 3400 you would want to do the gaskets before install, plus the cost of installation or time and equipment if you do it yourself. if your engine is fine.... do not bother changing the heads... as long as your heads can accept roller rockers. I will be investigating whether the non-roller rockers can be used with the 3400 topend for my 94 CS. It cannot take roller rockers. theoretically you have to grind off material from the lower intake... but how much and will the required amount for clearance leave a hole through the intake???? My ass-dyno tells me..... enough of an increase in high end power to make a difference... I have had two hard throttle instances where I totally free-wheeled from too much power... something the 3100 could never do no matter how hard I tried! Quote Link to comment Share on other sites More sharing options...
95 BLKDOUT Drop Top Posted February 23, 2007 Author Report Share Posted February 23, 2007 I mean im sure a 3400 swap would be beautiful, ive researched that for years now but i just dont have the time, money and patience to completly swap in a 3400, Its more to it than jus 3100 out 3400 in... not much more but it aint that simple. and the money... well im a college student, enough said. so the UIM, LIM, and TB are all i can do at this time if it will work, that was the whole purpose of this thread. so in order for a 3400 intake to work on my 3100, its gotta be able to accept roller rockers? OK so if my 31 didnt come with RR's (wich im not to sure about, ive heard different things about this and since ive never opened up my 3100, im not to sure) the heads would have to be swapped out? im goning to make a new thread about the 3100 to 3400 intake and TB swap and what will and wont work Quote Link to comment Share on other sites More sharing options...
BIGBULS Posted February 23, 2007 Report Share Posted February 23, 2007 LA1 and LG8 heads have 1.76in intake valves............L82's are only 1.72in. Then there are the port size differences as well..........not to mention the completely redesigned rear exhaust manifold that actually has a semi-decent collector on it. Finally............there is the roller rocker issue (as in......you not having any on your 95 L82). With those three things in mind, I WOULD do the head swap in addition to the big port IM's and larger 56mm LA1 TB (LG8's and L82's are only 52mm). I bet there is an easy 10hp if you do ALL of the above...........and probably a bit MORE past the power peak (~5K)..............such a pity the stock shift logic will limit your ability to take advantage of the top-end gains............. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted February 23, 2007 Report Share Posted February 23, 2007 1.76 vs 1.72 seems like a minimal change. so I'll call it as I see it, it seems minimal port size differences may slightly restrict flow but seem to not have harmed my swap if you utillze the 3400 exhaust manifold you will have to change the downpipe. ask Brian P. 95 3100's may have notched heads beneath each rocker. if it has the notched pedestal, it should accept the roller rocker. I'm running with 95 3100 heads with added roller rockers. If you can run with roller rockers I would do that Quote Link to comment Share on other sites More sharing options...
95 BLKDOUT Drop Top Posted February 23, 2007 Author Report Share Posted February 23, 2007 well i guess i gotta open her up and check, i was on 60degreeV6.com and it says that 3100's didnt get roller rockers till 96 so with this in mind should i even bother? Quote Link to comment Share on other sites More sharing options...
GP1138 Posted February 23, 2007 Report Share Posted February 23, 2007 well i guess i gotta open her up and check, i was on 60degreeV6.com and it says that 3100's didnt get roller rockers till 96 so with this in mind should i even bother? If your car is a late model '95, it's entirely possible the heads are notched on the pedestals for the roller rockers, even though they have the stamped rockers. You'd have to open the engine up to see, but check the manufacturing date on the door, if it was actually manufactured in 1995, I'd wager dollars to exhaust donuts that you have the notches for roller rockers. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted February 23, 2007 Report Share Posted February 23, 2007 well i guess i gotta open her up and check, i was on 60degreeV6.com and it says that 3100's didnt get roller rockers till 96 so with this in mind should i even bother? If your car is a late model '95, it's entirely possible the heads are notched on the pedestals for the roller rockers, even though they have the stamped rockers. You'd have to open the engine up to see, but check the manufacturing date on the door, if it was actually manufactured in 1995, I'd wager dollars to exhaust donuts that you have the notches for roller rockers. Is this the point of contention??? the 95's didn't have roller rockers but as john says too, many 95 built 3100s have the updated heads and can utilize the 96+ rockers simply by you bolting them on. Quote Link to comment Share on other sites More sharing options...
95 BLKDOUT Drop Top Posted February 23, 2007 Author Report Share Posted February 23, 2007 well mine is a 95 model but im not sure what part of 94 or 95 mine was built, i kno they changed the interior in 95 but im not sure if it was available in 94 as a 95 model, and i do kno they stopped making the convertibles in aug 95 so would they bother to put the 96+ heads on a car that they knew the were going to stop making in 95 Quote Link to comment Share on other sites More sharing options...
Crazy K Posted February 23, 2007 Report Share Posted February 23, 2007 look in the drivers doorjamb. find the big sticker. it should say the date as MM/YY in fact. give me the last 6 digits of your vin and I can rough estimate it's date of creation! I am collecting vert VIN info anyhow. if you'd like to share I'd be happy to collect your vin for my records. (Please PM only) The engine in your car didn't choose your car... GM did. Your 3100 will have the newer heads if is was made after the changeover point. the difference is simply a difference in the casting. Gm was pre-planning roller rockers for 96, and modified the casting molds ahead of time. The difference was so minor it didn't substantiate waiting till 96 to do, even though it was not used on 95s. Quote Link to comment Share on other sites More sharing options...
Brian P Posted February 23, 2007 Report Share Posted February 23, 2007 regarding clearance, many 3400 LIM's are ALREADY clearanced (shaved down slightly) by GM. The writeup on 60degree was done using a LIM that was not clearanced, so if you look underneath yours, and you see "flat" spots towards the upper half of the manifold, you SHOULD be ok (though double checking is worth $1000) Quote Link to comment Share on other sites More sharing options...
Crazy K Posted February 23, 2007 Report Share Posted February 23, 2007 regarding clearance, many 3400 LIM's are ALREADY clearanced (shaved down slightly) by GM. The writeup on 60degree was done using a LIM that was not clearanced, so if you look underneath yours, and you see "flat" spots towards the upper half of the manifold, you SHOULD be ok (though double checking is worth $1000) link? that will be good to know. I want to stick the 3400 intakes on a 94 3100 that has roller-rocker-incompatable heads. so I'll stick with the original heads and rockers then. Quote Link to comment Share on other sites More sharing options...
95 BLKDOUT Drop Top Posted February 24, 2007 Author Report Share Posted February 24, 2007 the 3400 top end wont work because the car's build date is 09/94 Quote Link to comment Share on other sites More sharing options...
BIGBULS Posted February 24, 2007 Report Share Posted February 24, 2007 It'll still work fine if you do it from the heads UP...... Which means you DO get all of the benefits. As for the downpipe issue...........yes you DO need a new one...........but that's just an excuse to design a GOOD exhaust that actually flows. Sure it's yet more $$, but if you actually want a decently fast car........... Quote Link to comment Share on other sites More sharing options...
Crazy K Posted February 24, 2007 Report Share Posted February 24, 2007 the 3400 top end wont work because the car's build date is 09/94 the change-over date is uncertain... while I think your car will not have roller-rocker compatible heads if the motor is original... you would have to look to be certain. but if i understand what was said above, Brian P is saying that you can still do the upper intake swap even with the original rocker arms, as long as the intake is clearanced. while the 3400 exhaust and downpipe would rock... you don't have to do it to see reasonable gains. so dollars to donuts.. do it only if you need to. after all, the 3100 exhaust manifolds will still work on the 3400 heads/long block. here's some info: http://www.3400swap.com/guide_ver_2_5_5.pdf Quote Link to comment Share on other sites More sharing options...
95 BLKDOUT Drop Top Posted February 24, 2007 Author Report Share Posted February 24, 2007 so i can at least do the upper intake and TB? Im so confused right now on what will work and what wont work. Quote Link to comment Share on other sites More sharing options...
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